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=0) 

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Radio News for November, 1928 

-s01 

EARNED $500 

SPARE TIME 

WITH RADIO 

Coplay, Pa., June 4 -(RA)- During the 

few months that Frank J. Deutsch has 

been a member of the Radio Association 

of America, he has made over $500 out of 

Radio in his spare time. 

"Four super -heterodyne sets of my own 

construction brought me a profit of $60.00 

each, and the other profit was from sales 

of supplies purchased through the Wholesale 

Department. of the Association," he 

said. "The Association certainly has a 

great plan for ambitious men." 

In a neighboring state, Werner Eichler, 

Rochester, N. Y., another member of the 

Association, has been making $50 a week 

during his spare time. 

They are only two of the hundreds of 

Radio Association members who are making 

money out of Radio in their spare time. 

BECOMES RADIO 

ENGINEER IN 

ONE YEAR 

Toronto, Canada, May 20 -(RA) -One 

of the newly admitted associate members 

of the Institute of Radio Engineers is 

(laude DeGrave, a member of the engineering 

staff of the DeForest Company of 

t his city. "I knew nothing about Radio 

and started from the ground up," Mr. 

DeGrave stated, "when I enrolled a year 

ago in the Radio Association. Its easy 

lessons and superb training made it possible 

for me to become a Radio Expert in less 

than a year's time. My income is now 

about ;225'¿ more than at the time I joined 

the Association." 

The Institute of Radio Engineers is a very 

exclusive organization, and its membership 

requirements are very rigid, so that Mr. 

DeGrave has reason to be proud of his 

election. 

Clerk Doubles Income In 

Six Months Through Radio 

Chicago, Ill., May 9-Even though his 

membership in the Radio Association has 

resulted in W. E. Thon securing the managership 

of a Radio Department in a large 

Chicago store, his ambition was not satisfied. 

Six months later, he started his own store. 

"The Radio Association has an excellent 

plan for the man who wants to get out of 

the rut and succeed," says this man who 

quickly rose from clerkdom to the proprietorship 

of a profitable radio store. "I 

attribute my success entirely to the Radio 

Association of America. Six months after 

I had enrolled, I had doubled my income 

through its help." 

Please 

MODERNIZE OLD SETS 

WITH ONE DIAL CONTPAL 

say you saw it in 


E\CII of these plans, developed by tic lladio 

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Set owners everywhere want to get rid of static, to 

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the tone improved, and the volume increased, and 

transformed into single -dial controls. Phonograph 

owners want their machines electrified and radiofied. 

If you learn to render these services, you can easily 

make $3.00 an hour for your spare time, to say nothing 

of the money you can make installing, servicing, 

repairing, and building radio sets, and selling supplies. 

Over $600,000,000 is being spent yearly for sets, 

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bigger pay for you. 

a cent! 

A membership need not coat iion 

'l'he Association will give you a comprehensive, 

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To it limited number of ambitious men, we will give 

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COUPON 

RADIO ASSOCIATION OF .AMERICA 

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Gentlemen: 

Please send nie by return mail full details of your 

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look, "Your Opportunity in the Radio Industry:' 

Name 

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RADIO NEINS 

State


402 Radio News for November, 1928 

i/ 

NOVEMBER, 1928 Number 5 

HUGO GERNSBACK, Editor -in -Chief 

ROBERT HERTZBERG, M:.naging Editor 

C. P. MASON, Associate Editor BERYL B. BRYANT, Laboratory Director 

C. WALTER PALMER, Director Information Service 

Future Progress in Television 

By Hugo Gernsback 

Successful Television Programs Broadcast 

by RADIO NEWS Station WRNY 

By Robert Hertzberg 

"Radio Movies" from KDKA 

How "Stereoscopic" Television is Shown 

By R. F. Tiltman 

Televentures, Telewitticisms and the 

Televoca hula ry 

The Jenkins "Radio- Movie" Reception 

Methods 

Successful DX Work Marks "Radio - 

Movie" Transmissions 

Synchronized Broadcast Joins 

and Music 

Contents of This Issue 

Images 

The Neon Tuhe - Television's "Loud 

Speaker" By D. E. Replogle 

How to Adjust the Television Receiver 

for Operation 

Television Teems with Trials for Telex - 

perimenters 

List of Broadcast Station Calls 

411 

412 

41G 

ta "Rays of Justice" By C. Sterling Gleason 

What's New in Radio 

Putting the Aerial in Shape for Winter 

By L. B. ltuuuins 

Electrodynamic Speakers Become Popular 

By Fred H. Canfield 438 

The Radio Beginner -Sonie Facts About 

418 Transformers By C. Walter Palmer 

Broadcastatics 

419 

420 

421 

426 

427 

428 

429 

How to Construct the "Pre- Selector" 

By S. Gordon Taylor 446 

Magneto -Striction By M. J. Cuttler 450 

Ways of Sensitizing the R.F. Amplifier 

with Stability 

Radio Wrinkles 

On the Short Waves 

The Radio Constructor's Own Pages 

RADIO NEWS Laboratories 

I Want to Know 

Radiotics 

Radio as an Advertising Force 

430 zia Radio "Bugs" 

By C. W. Palmer 

432 

434 

437 

442 

445 

453 

45.4 

456 

458 

460 

462 

470 

472 

474 

RADIO NEWS 1s published on the 10th of each preceding month. There are 12 

numbers per year. Subscription price is 22.50 a year in U. S. and possessions. 

Canada and foreign countries, $3.00 per year. U. S. Coin as well as U. S. Stamps 

accepted (no foreign coins or stamps). Single copies, 25 cents each. Checks and 

money orders should be drawn to order of E_XPERDIENTER PUBLISHING 

CO., INC. 

All communications and contributions to this journal should be addressed to 

Editor. RADIO NEWS, 230 Fifth Ave., New York, N. T. Unaccepted contributions 

cannot be returned unless full postage has been included. All accepted contributions 

are paid for on publication. A special rate Is paid for novel experiments; 

good photographs accompanying them are highly desirable. Publishers are 

not responsible for loss of manuscripts, although every precaution is taken with 

such manuscripts. upon receipt thereof. 

RADIO NEWS. Monthly. Entered as second -class matter, July 12, 1924, at the 

Post Omre at New York, N. Y., under the Act of March 3. 1879. Additional entry 

at Dunellen. N. J. and San Francisco, Calif. Tille registered U. S. Patent Office, 

Copyright, 1928. by The Experimenter Publishing Co.. Inc., 230 Fifth Ave., 

reproduced Translated 1i the United States without giving gntng full credit to the publication. 

Translation into foreign languages must not be merle unless permission is 

The contents of RADIO NEWS are indexed in the Industrial 

obtained from the publishers. Copyrighted in Germany. Reproduction of articles 

in Germany is reserved for Radio. Berlin 42. 

RADIO NEWS is for sale at all newsstands in the United States and Canada, 

and at Brentanó s, Ave. de L'Opera, Paris, France. European agents: S. J. Wise 

Et Cie, 40 Place Verte, Antwerp, Belgium. 

HOW TO SUBSCRIBE FOR RADIO NEWS. Send your name, address and remittance 

to Experimenter Publishing Co., 230 Fifth Ave.. New York. Mention the 

name of the magazine you are ordering. We also publish SCIENCE AND INVEN- 

TION, RADIO LISTENERS' GUIDE and AMAZING STORIES. Write clearly. 

RATES AND TERMS. The subscription rate for RADIO NEWS is 22.50 per 

year. (12 numbers). When remitting do so by check. money order, or registered 

letter if rash is enclosed. Avoid sending cash through the mall if possible. Subscriptions 

for less than one year are nut accepted. Subscription may be made in 

combination with SCIENCE 8- IilT'ENTION, RADIO LISTENERS' GUIDE. 

and AMAZING STORIES. 

POSTAGE. We prepay postage in all parts of the United States, Mexico and 

island possessions. For foreign or Canadian subscriptions we require 50 cents in 

addition to the subscription price for additional postage charge. 

CHANGE OF ADDRESS. Notify us as far in advance as possible. It requires 

several weeks to make an address change on our records. Always write clearly. 

Arta Index, coptes of which can be found in every library. 

Published by Experimenter Publishing Company, Inc. 

H. GERNSBACK, President S. GERNSBACK, Vice -President and Treasurer ALFRED A. COHEN, Secretary 

Member: Audit Bureau of Circulations 

Radio Magazine Publishers Association 

Advertising Representatives: RHODES & LEISENRING 

New York Offices: 624 Graybar Building 

Chicago Offices: 307 North Michigan Ave. 

Editorial and General Offices 

230 Fifth Avenue, New York City

Radie News for November, 1928 403 

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RADIO NEWS 

State

40 -i Radio News for November, 1928 

INDEX TO ADVERTISERS 

A 

Page 

.1cro Products, Inc 480 

Aerovox Wireless Corp 482 

Allied Radio Corp. 

482- 489 -490 -492- 503 -507 -509 -510 -512 

Aluminum Company of America 467 

American Radio & Mere. Co 496 

American Sales Co 497 

American Transformer Co 482 

Arcturus Radio Co 506 

B 

Barawik Co., The 

476 -480- 483- 485 -486 -491 -492- 495 -496- 

498 -501- 503 -505 -506 -507 -509 -510 

Belden Mfg. Co 

Benjamin Electric Mfg. Co 

Browning -Drake Corp. 

C 

501 

505 

496 

Carter Radio Co 507 

CeCo Mfg. Co 474 

Central Radio Labs 494 

Chemical Inst. of N. Y., Inc 473 

Chicago Radio Apparatus Co 50.5 

Chicago Stock Gear Works 495 

Clark & Tilson, Inc 495 

Consrad Co., Inc., The 494498 

Consumers Radio Co. 503 

Coyne Electrical School 506 

Craftsman Radio Products 476 

Cunningham, Inc., E. T 466 

D 

Daven Radio Corp 491 -498 

1)eForest Radio Co., The 506 

Deutschmann Co., Tobe 476 

Diamond Radio Co 507 

Directory Section of Radio News 477 

])resner Radio Mfg. Corp 494 

Dubilier Condenser Corp 470 

E 

Electrad, Inc. 485 -493 

Electric Specialty Co 497 

I!lectro- Chemical Company of America 486 

Elkon, Inc. 409 

Excello Products Corp 505 

N 

Page 

Fanspeaker Radio Co 482 

Flechtheini & Co., Inc., A. M 485 

Freshman Co., Inc., Chas 483 

G 

General Radio Co 508 

Gernsback, S. 502 

Gray & Danielson Mfg. Co 486 

Gustin- Bacon Mfg. Co 508 

H 

Hammarhmd Mfg. Co 487 

Hanimarlund- Roberts, Inc. 408 

Hotel Lafayette 501 

Hotel McAlpin 490 

I 

Illinois Transformer Co 503 

Independent Electric Works 480 

J 

J -M -P Mfg. Co 505 

K 

Maras Electric Co. 489- 493 -507 -509 

Knapp Electric Co 481 

Lacault, Inc., R. E 

Lacey and Lacey 

Leutz, Inc., C. R 

L 

Lynch, Inc., Arthur H 

Mc 

McSweeney Electrical Schools 

M 

479 

507 

410 

501 

595 

31assachusetts Radio & 'l'el. School _ 483 

Metro Electric Co 465 

Midwest Radio Corp. 

N 

Back Cover 

National Co Inc 491 

National Electrical School 486 

National Radio Institute 405 -475 

New England Mills Co 494 

Norden- Hauck, Inc. 483 -495 

O 

Oak Park Mfg. Co 494 

Packard Radio Co 

.Please .car von saw it in 


P 

Page 

Pathfinder 483 

Per -Con Mfg. Co 491 

Potter Mfg. Co 490 

Press Guild, Inc 499 

R 

Radiali Co. 503 

Radio Association of America 401 

Radio Doctórs, Inc 487 

Radio Equipment Co 503 

Radió Institute of America 499 

Radio Producer Co 490 

Radio Specialty Co 471 

Raytheon Mfg. Co 472 

Scott Transformer Co 

S 

Inside Back Cover 

See Jay Battery Co 483 

Setbuilders Supply Co 407 -480 

Shanklin Mfg. Co 482 

Silver JIarshall, Inc. _ 406 

Smith, B. Hawley 507 

Southern Toy Co 496 

T 

'l'arbell System, Inc 498 

Teleplex Co. 509 

Televocal Corp. 509 

Thodarson Elec. Mfg. Co. 

Inside Front Cover 

Townsend Labs. 489 

Transformer Corp. of America 

'' 

486 

yrman Elec. Corp 511 

U 

Underground Aerial Systems 

Van Ashe Radio Co 

V 

W 

469 

4811 

Walker Co., The Geo. W 468 

Webster Co., The 509 

Western Radio Mfg. Co 497 

Wirt Co. 49.2 

X -L Radio Labs. 

403 Yaxley Mfg. Co 

RADIO NEWS 

X 

Y 

506 

503



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Down to 

"BRASS TACKS 

ON AUDIOS 

(whether it hurls or not) 

"Silver- Marshall unconditionally guarantees the new 

S -M Clough system audio transformers to give greater 

amplification, finer tone, and less distortion than any 

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CONTRAST this straight- from -the -shoulder guarantee with the advertising 

phrases used by other manufacturers -not one dares offer the guarantee that 

S -M has given for two consecutive years -ever since the first 220 transformers 

were produced. 

Not all radio fans have been able to attend the public comparative tests that 

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cities. These are the very surest proof that the new transformers are far superior to 

any and all other types. If you find it hard to believe that any transformers can be 

so far ahead of the audio equipment which you have been using, we can only say 

o you: "Buy a 225 and a 226, or a 255 and a 256; hook them up properly and test - 

them. Then, if you're not satisfied that they are better than anything you've ever 

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Research engineers- eminent designers -men who know, not guess -all acknowledge 

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examination by all listeners -and remember the above -quoted positive guarantee! 

I 

i 

I 

If you don't wish to build, yet want your 

radio to be custom made, with all the ad 

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on the other hand, you build sets professionally, 

and are interested in learning 

whether there are valuable Service Station 

franchises yet open in your territory; 

please write us. 

Silver- 

Marshall, Inc. 

848 W. Jackson Blvd., Chicago, U. S. A. 

.Please send me, free, the complete S-M 

Catalog; also sample copy of The Radiobuilder 

For enclosed 

in stamps, send nue the 

following: 

.... (50e) Next 12 issues of The Radiobuilder 

($1.00) Next 25 issues of The Radiobuilder 

S-M DATA SHEETS as follows, at 2c each: 

....No. 1. 670B, 670ABC Reservoir Power Units 

....No. 2. 685 Public Address Unipac 

....No. 3. 730. 731, 732 "Round-the-World" Short 

Wave Sets 

....No. 4. 223, 225. 226, 255, 256. 251 Audio Transformers 

....No. 5. 720 Screen Grid Six Receiver 

....No. 6. 740 "Coast-to-Coast" Screen Grid Four 

....No. 7. 675ABC 

- 

High --Voltage Power Supply and 

676 Dynamic 

-- 

Speaker Amplifier 

....No. 8 Sargent- Rayment Seven 

Name 

Address 

IN the chart at the right, E 

is the two -stage curve for 

the large -size transformers 

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2nd stage, $9.00 each); D is 

that of the smaller ones 

(S -M 255 and 256, $6.00 

each). Note the marked advantage 

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all standard eight and ten 

dollar transformers under 

equal conditions. 

..:}-- 

Are you getting "The Radiobuilder ?" It's a little monthly magazine devoted to the 

interests of all who build sets. The coupon at the left 

will bring you a sample copy. 

SILVER- MARSHALL, Inc. 

848 West Jackson Blvd., Chicago, U. S. A4 

Please say you Soso if in RADIO NEWS 

w 

W


Radio News for November, 1928 407 

710 Sargent -Rayment Seven 

A precision laboratory instrument for the veteran fan -with 

single -dial tuning feature and separate stage verniers. There 

are four screen grid t.r.f. stages -five circuits in all are tuned 

by the single illuminated drum. One knob controls volume. 

Each circuit is individually shielded, by- passed, and isolated 

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aluminum cabinet. Incorporates new Clough system 

audios with output filter. The kit is $130.00 complete; or 

factory wired and tested, $175.00. 

730 Short -Wave 

Kit 

All the thrills of code and 

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after night with the new S -M 

730 "Round-the-World" Four. 

It has one screen -grid r.f. 

stage, regenerative detector 

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the S -M Clough- system audio stages. Four plug-hi coils fit a 

5 -prong socket, accessible on top of the aluminum cabinet. The 

complete 730 kit, including cabinet, is $51.00; the 731 Adapter, 

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any set to long -distance short-wave reception. The 732 Essential 

Kit is only $16.50. 

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Please say pon sow it in RADIO NEWS

Editorial and General Offices, 230 Fifth Avenue. New York 

Vol. 10 NOVEMBER, 1928 

No. 5 

Future Progress in Television 

WHEN broadcasting first started in 1921, a great deal 

of speculation was rife as to what form the new art 

was to take and what could he expected from it. For 

u long time, broadcasting was rather crude; and no one 

had a definite idea what it was really all about. Only a good 

deal later did paid advertising creep into the programs, and we 

are still traveling along this road; either in the way of direct 

advertising, which seems to be on the decline, or the indirect form 

of advertising, better known under the term of "sponsored" programs. 

But, even today, exactly what ultimate form commercial 

broadcasting will take is not known, because changes are occurring 

continually while the art is progressing. 

In television we are faced with a similar situation; for, ,just 

at present, no one knows exactly what it is all about, or what 

television will really mean to the world at large. 

It is probably a foregone conclusion that, sooner or later, all 

broadcast stations will be sending out television impulses in one 

way or another. A number of stations -as, for instance, WGY and 

WY lt NY-are now broadcasting true television programs; while 

others -such as 8XAV at Pittsburgh and 3XK at Washington, 

D.C.-are broadcasting only "radio movies." The latter is not 

true television, according to my definition, because it is not "instantaneous 

sight at a distance," but rather "canned" sight. 

When WRNY went on a regular schedule, August 12 last, with 

television, a tremendous amount of interest was created immediately 

in business quarters. One leading department store sent 

its representative to the station, to find out if it were possible 

to televise a fashion review which the store was sponsoring. The 

management was told that, unfortunately, this is not as yet possible, 

because the art has not progressed sufficiently; and, even 

if it had, there are not yet enough television receivers to make 

it worth while to put on such a review. 

Another advertiser wanted to know Whether the station would 

accept a contract to televise the images of articles of merchandise, 

interspersed with music and sales talk. _\ large publishing firm 

wanted merely to televise the cover of its latest book. .\ certain 

advertising agency wished to build a program around a well -known 

brand of cigarettes, televising the actual cigarette package from 

time to time. 

Of course, most of these things are feasible today, in a way, 

and there is little doubt that, in the not- too -distant future, such 

commercial considerations will provide additional revenue for 

broadcast stations; hut, at this time, simply because there are 

not enough television receivers in use. it would not be a paying 

proposition for advertisers, and they will be told so by any honest 

station management. Perhaps within six months, perhaps within 

a year, such commercial, "sponsored" television broadcasts will 

become an every -day occurrence and no one will think otherwise 

of them. 

Of course, the serions difficulty with television today is that, at 

least on a single broadcast channel, we cannot have sound and 

vision at the same time. No simultaneous broadcast is yet possible. 

'l'he few stations that are now broadcasting television have 

trouble even switch rapidly from "aural" programs -those which 

can be heard -to "visual" programs. WRNY was perhaps the first 

that managed to alternate the "aural" program quickly with the 

images that are hieing televised. Less than a fraction of a second 

now intervenes during the switching from television to regular 

broadcasting, but this is, of course. not the final solution. We 

simply must have simultaneous television and "aural" broadcasting; 

but it is doubtful that we can have this on single broadcast channels 

for some time to come, unless an entirely new invention is 

made, and this, as yet, does not seem to be in sight. 

It is, of course, quite possible to do it on two or more broadcast 

channels; but then, again, at the receiving end, we would need 

apparatus tuned in to diJrerent wavelengths, and that is evidently 

rather difficult to incorporate into a single set, although not impossible. 

While simultaneous television and "aural" broadcasting will 

By HUGO GERNSBACK 

be comparatively simple on the low -wave channels, the trouble here 

is that for some years. this must be a strictly experimental enterprise; 

because, even though the larger manufacturers were to put 

forth a combined television and broadcast set to operate on the 

low waves, most of the listeners in the country would not be able 

to get such programs with their present sets. It would take years 

before such a change, from higher waves to lower waves, could be 

completely effected. 

At one time, it was thought that broadcasting on the low waves 

would be the one cure -all for every radio ill. Unfortunately, this 

is not the case, mainly because there is such a thing as "skip distance." 

In large cities, it would be most difficult to receive the 

short waves and, on such wavelengths, few stations could be operated 

successfully as locals. A short -wave broadcast station located 

in New York or Chicago might be very powerful; yet no one in 

the same city could get the broadcasts at all, due to the "skip- 

distance" effect. 'l'he programs probably would come in much 

better two hundred miles away than twenty miles from the 

transmitter. 

Of course, all of this discussion presupposes the dispelling of the 

synchronization bugaboo which, at the present time, is the nightmare 

of all television experimenters. It is like a similar situation 

which prevailed in the early history of radio, away hack in the 

coherer days, when it was almost impossible at times to decipher the 

simple signals of the coherer, on account of static and other 

troubles. Very often the signals became totally unrecognizable, 

just as today, because of imperfect synchronization, the signals on 

the television disc are often badly blurred and unrecognizable. So, 

just as in the old coherer and crystal days the amateur had to use 

his imagination in order to decipher the code messages, so the 

present -day television experimenter must use his imagination to 

recognize the visual images. But these, of course, are the usual 

infantile diseases of a new art and will be speedily overcome as 

others have been overcome in allied arts. 

That we will require an entirely new technique of televising 

various subjects, is, of course, a foregone conclusion. Just as there 

is a "radio personality "-because certain voices and certain sounds 

broadcast well and others do not -so it will he in television. Not 

everything is fit for televising; this holds true of faces as well as 

of objects. 'l'he matter of the subject, is, of course, all important. 

It was quickly found at WRNY, that certain faces, for instance, 

did not televise well at all. For instance, subjects with eye -glasses 

are entirely hopeless, because of their reflection. Oil' skins broadcast 

better than dry skins. A woman with a large hat became a 

total loss during transmission, while as woman with a small closefitting 

hat or none at all was far superior as as subject. 

Also, if the subject is to" snuill -such as for instance, a small 

toy monkey -it becomes unrecognizable. But on the other hand, 

if the subject is too large, the whole of it cannot he seen in the 

receiver, because of the small size of the image. Those received 

at the present time are usually only about one and one -half by 

one and one -quarter inches, hieing limited by the extent of the plate 

of the neon lamp, and size of the rotating disc. 

On the other hand, engineers are now beginning to remedy the 

condition last mentioned, through enlarging the image by means 

of special lenses. Most of the trouble seems to lie in the fact that, 

at the present time, the neon tube does not give a sufficient amount 

of light to permit of enlarging the image; but this is also being 

overcome gradually. We probably will he soon using a multiplicity 

of tubes, concentrating their light on one pant of the disc, and then 

enlarging the received homage by means of lenses; or else improved 

tubes, giving greater light, will be developed. 

It is quite possible that, before r year has passed, the 24 -inch 

disc will have shrunk to a 5 -inch diameter and the much smaller 

and sharper resulting image will be enlarged and thrown on raj 

screen. Such television scenes will he much better in detail and 

more easily visible than the admittedly -crude images received at 

present. 

Hr. Hugo Gernsback speaks every Tuesday at 9.30 P. M. from Stations WRNY (326 meters) and 28AL (30.91 meters) on various radio and scientific subjects. 

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to be shown. Credit 

for the achievement 

of the feat is due to 

John Geloso, chief 

engineer of the Pilot 

Electric Manufacturing 

Company, who worked 

day and night for more 

than three months designing, 

constructing and 

perfecting the televisor 

which is now in daily use 

at WRNY and W2 \AL. 

Some of Mr. Gelosti s 

preliminary experiments 

in the Pilot laboratories, 

in Brooklyn (New York 

City) were described in 

the September number of 

ItAnio NEWS, to which the 

reader is referred. (Pages 

221 -25G.) 

Mr. Geloso received 

considerable assistance 

from the technical staff 

of ltAnio NEWS, the members 

of which furnished 

many special television 

parts and offered numerous 

suggestions as to the 

const ruction and a rrangenient 

of the parts in 

irr 

. 

YORK TIMES. MONDAY. AUGUST 13. 

l'18 

WRNY to Start Daily Television Broadcasts; 

Radio Audience Will See Studio Artists 

The first regular broadcasting of 

images by televisioa over the radio 

from New York will begin tomorrow. 

it was learned last night from Station 

WRNY in the Hotel Roosevelt. 

WRNY, which is owned by 'The 

Radio News Magazine, has recently 

completed the Installatiod of equipment 

for broadcasting images, and 

yesterday it conducted its first experimental 

broadcast - 

The broadcasting was done from 

the station's transmitting .plant at 

Villa Richard. Coyfesville. N. J. The 

images sent consisted of the faces of 

John Geloso, engineer of the Pilot 

Electrical Company, and John Maresca. 

chief engineer of WRNY. The 

first broa .cast began at 6:43 P. M. 

and continued until 6:30. The second 

began at 11 P. M. 

There is no telling how many persons 

saw the Images, according to 

Hugo Gernsback. President of 

WRNY. He estimated that there 

are about 2,000 sets in the metropolitan 

area equipped for television reception. 

Owners of sets unequipped 

for television heard the television 

transmission as an intermittent high - 

pitched whirr, varying with the action 

before the transmitter. 

Officers of. WRNY saw the images 

-at a set installed in a private home 

a few hundred. yards from the transmitting 

station. 

The television broadcasting scheduled 

to begin today will be made a 

part of WRNY's usual programs, 

Mr. Gernsback said. After a singer 

or other entertainer has finished, his 

or her face will be sent out over. the 

air by television. Thus the schedule 

for the television will be the same as 

for the regular broadcasting of this 

station. 

Considerable experimenting already 

has been made with television broad - 

pasting by other stations. For sortie 

weeks C. Francis Jenkins has been 

transmitting silhouettes by radio, 

and other stations which have been 

developing the television field are 

WGY, at Schenectady; WLEX. near 

Boston, and WCFL, the labor station 

at Chicago. 

Mr. Gernsback said that WRNY 

has received thousands of letter 

asking for television broadcasting 

413 

the successful televisor. 

As a matter of 

fact, the whole project 

w a s sponsored by 

RAmo NEWS, with Mr. 

Geloso doing the actual 

experimental work. After 

performing successfully 

in the laboratory, the 

televisor described in the 

aforementioned a rtiel e 

was moved on August 1.2 

from Brooklyn to the 

WRNY transmitter house 

at Coytesville, N. .1., 

,just across the Hudson 

River from New York. 

An experimental receiver 

was set up a quarter of a 

mile from the transmit- 

Left, facsimile of clipping 

from the New fork Times of 

August 13. 1928, recording 

the news of the first successful 

television broadcasting 

through WRNY. The statement 

in the headline, "Radio 

audience will see the studio 

artists," was incorrect, however, 

as explained in the accornpaaying 

article. 

A general view of the Pilot televisor used at WRNY. The powerful 

arc light is in the square black can at the extreme right. The 

edge of the scanning disc is risible above the top of the small 

table, which holds the audio amplifiers for the photoelectric cells, 

which are the large round objects faced by the subject being tele- 

vised; they are shielded by copper mesh. Above, the author 

of the accompanying article is shown adjusting one of the 

amplifier control rheostats, while he is being "televised.". A. 

shielded cable runs from the photoelectric cells to the amplifier] 

on the table.



ter, which is on the very edge of the Palisades 

cliffs, overlooking the entire island 

of Manhattan. Mrs. Geloso, wife of the 

inventor, was the first subject televised. 

Her husband, operating the receiver, tuned 

in the WRNY signals, adjusted the speed 

of his scanning disc, and emitted a loud 

whoop of joy when he recognized the clear 

image of his wife. These first images, about 

one and a half inches square, were slightly 

streaked and had a tendency to move "out 

of frame;" but they were comparable to 

average newspaper halftones in clarity. The 

broadcastü'g, it should be noted carefully, 

was done on the regular 326 -meter wave of 

WRNY, and required no changes in the 

regular Western Electric transmitter. 

On August 14, Mr. Geloso moved the 

receiver to the home of Hugo Gernsback, 

editor of RADIO NEWS, at 180 Riverside 

Drive, New York; this location is about 

five miles in an air line from the WRNY 

transmitter. With no opportunity for preliminary 

trial or adjustment, Mr. Geloso 

turned on the set at tén o'clock in the evening 

and again succeeded in reproducing 

the image of his wife, who was seated before 

the televisor at Coytesville. This feat 

was especially noteworthy because the transmitter 

and the receiver were operating on 

entirely -separated power lines, and absolutely 

no means of synchronizing the scanning 

discs was used. Because of the lack 

of perfect synchronization, the images 

wandered out of frame frequently; but for 

six or seven seconds at a time they were 

as clear as photographs. 

DEMONSTRATION INTERESTS PUBLIC 

After this private exhibition, it was decided 

to stage a public demonstration for 

members of the radio trade and of the 

press. The place chosen was Philosophy 

Hall, at New York University, 181st Street 

and University Avenue in the Borough of 

the Bronx (New York City) and the date, 

August 21, 1928. This demonstration was 

a marked success, having been attended by 

more than 600 people, all agog with interest, 

and many were unable to find room in 

John Geloso, seated before 

a complete broadcast - 

and television receiver, 

viewing the television images 

through the square 

opening near the top of 

the cabinet; the scanning 

disc is about si.r inches 

behind fhc front panel of 

the set. An experimenter 

who is just starting 

in television should not 

build his apparatus into a 

large cabinet like this 

one until he has first succeeded 

in obtaining good 

results with a rough table 

layout. This receiver is 

the one used in the public 

demonstration at New 

York University. 

the hall. 

Although no 

automatic system of 

synchronizing the 

transmitting and receiving 

discs had yet 

been installed, Mr. 

Geloso managed to 

o b t a i n satisfactory 

images of the subjects 

televised. The 

images were not perfect, 

but as Mr. Gemsback 

remarked in his 

introductory address, 

which was broadcast 

by remote control 

from the hall over 

WRNY previous to 

the television transmission, 

television is 

now in the "spark- 

coil -and -coherer stage," and too much cannot 

be expected of it for the present. 

The first printed radio program listing 

television transmissions as a regular feature 

appeared on the morning of that day; a 

typical program, taken from the New York 

Times of August 21, is reproduced on the 

first page of this article. All the WRNY 

programs which have appeared since that 

date have carried the exact time of each 

television broadcast. 

At present, it is not possible to broadcast 

the images of the artists who are performing 

in the WRNY studio in the Hotel 

Roosevelt, New York. Because of land -line 

problems the televisor must be close to the 

actual broadcast transmitter; so only the 

images of the WRNY operators and other 

persons at the transmitting room will be 

broadcast, for some time to come. At the 

start of each transmission, a white card 

bearing the letters WRNY in heavy, black 

letters is held before the televisor; so that 

the experimenter can make the required 

preliminary adjustment on his scanning disc 

to receive the transmitted image of a human 

television subject. 

SCHEDULE NOW FOLLOWED 

The lover half of the "works" of the receiver shown above. In the lower left corner is a 

three -stage resistance -coupled amplifier, with each stage individually shielded. In the right corner 

is a power -pack supplying "R" potential to the amplifier tubes. The broadcast tuner, of straight 

T.R.F. design, is in a can behind the disc 

Television images are broadcast simultaneously 

by WRNY on 326 meters and by 

W2XAL on 30.91, the first five minutes 

of every hour that the stations are on the 

air. The complete schedule of television 

transmissions is as follows (cut this out and 

and save it, for it will be very useful when 

you make your own television receiver, as 

described elsewhere in this number), and all 

times are Eastern Standard.; add five hours 

for Greenwich time: 

Mondays: 7.00 to 7.05 a. m.; 8.00 to 8.05 

a. ni.; 11.00 to 11.05 a. ni.; 12.00 (noon) to 

12.05 p. m.; 2.00 to 2.05 p. m.; 3.00 to 3.03 

p. m.; 4.00 to 4.05 p. m.; 5.00 to 5.0.5 p. m.; 

6.00 to 6.05 p. ni.; 6.40 p. ni. to 7.00 p. m. 

(20- minute period). 

Tuesdays: 7.00 to 7.05 a. m.; 8.00 to 8.05 

a. m.; 11.00 to 11.05 a. ni.; 12.00 (noon) to 

12.05 p. m.; 7.00 to 7.05 p. m.; 8.00 to 8.0.5 

p. m.; 9.00 to 9.05 p. m.; 10.00 to 10.05 

p. m.; 11.00 to 11.05 p. m.; midnight to 

12.20 a. m. (20- minute period). 

'Wednesdays: 7.00 to 7.05 a. m.; 8.00 to 

8.05 a. m.; 11.00 to 11.05 a. m.; 12.00 (noon)



to 12.05 p. m.; 2.00 to 2.05 p. im ; 3.00 to 

3.05 p. in.; 4.00 to 4.05 p. tn.; 5.00 to 5.05 

p. ni.; 6.00 to 6.05 p. m.; 7.00 to 7.05 p. ni.; 

8.00 to 8.05 p. m. 

Thursdays: 7.00 to 7.05 a. m.; 8.00 to 8.05 

a. nn.; 11.00 to 11.05 a. In.; 12.00 (noon) to 

12.05 p. in. 

Friday.: 7.00 to 7.05 a. m.; 8.00 to 8.05 

p. m.; 11.00 to 11.05 a. tn.; 12.00 (noon) to 

12.0.5 p. ni.; 2.00 to 2.05 p. in.; 3.00 to 3.05 

p. ni.; 4.00 to -4.05 p. nt.; 5.00 to 5.05 p. m.: 

6.00 to 6.05 p. nn.; 7.00 to 7.05 p. w.; 8.00 to 

8.05 p. In.; 9.00 to 9.05 p. m.; 10.00 to 

10.05 p. nt. 

Safurdaya: 7.00 to 7.05 a. w.; 8.00 to S.05 

a. m.; 11.00 to 11.05 a. nt.; 12.00 (noon) to 

12.05 p. tu.; :3.40 to 4.00 p. m. (20- minute 

period); 7.00 to 7.05 p. nt.; 8.00 to 8.05 

p. nt.; 9.00 to 9.05 p. m. 

Sundays: 7.00 to 7.05 a. in.; 8.00 to 8.05 

a. m.; 11.00 to 11.0.5 a. nn.; 12.00 (noon) to 

12.05 p. tn.; 2.00 to 2.05 p. m. ; 3.00 to 3.05 

IL HI.; 4.00 to 4.05 p. m.; 5.00 to 5.05 p. m. 

Most of the periods specified are of only 

live: minutes duration, but it will be noted 

that there are also three twenty -minute periods, 

one each on Monday, Tuesday and 

Saturday. These longer transmissions enable 

the experimenter to adjust his receiving 

apparatus more carefully and to receive 

a greater percentage of perfect images than 

the shorter live- ndoute broadcasts allow. 

An announcer breaks in several tintes, 

(luring each twenty-minute period, to tell 

what is being broadcast. WCRNY now televises 

the following: faces of living people, 

the Wit NY placard previously mentioned. 

a moving toy monkey, and a moving "rolypoly 

man." 

Those living in the vicinity of New York 

may tune in WRNY's regular 32G -meter 

wave on their regular broadcast receivers; 

experimenters outside of the New York 

local area can do best by using a simply 

fl'hat the back of the 

television machine shown 

on the opposite page looks 

like. The scanning disc, 

driving motor and neon 

glow -tube occupy the top 

half of the cabinet; while 

the audio amplifier and 

power pack fill the bottom. 

The three cans at 

the feet of Mr. Geloso 

(left) and his assistant, 

Frank T. Sullivan, are 

the shields for the audioamplifier 

stages. The 

glow -lamp is in front of 

the scanning disc, directly 

under Mr. Stufi 

can's right fist. Tite 

broadcast tuner itself is 

behind the scanning disc. 

short -wave set. RADIO 

NEWS has available a 

number of. free blueprints 

of inexpensive 

short -wave receivers; 

if you already do not 

own a short -wave set, 

drop us a postcard or 

a letter and we will 

send you a set of blueprints 

free of cost. 

(Ask for blueprint 

No. 58, if in doubt.) 

SIMPLICITY OF THE 

TRANSMITTER 

The Pilot televisor 

now in use at WItNY 

is comparatively simple in construction, as 

television apparatus goes. As can be seen 

from the picture at the bottom of page 413 

it consists of four fundamental units: a 

source of light (an arc lamp), a scanning 

disc, a nest of three large photoelectric 

cells, and an amplifier for the output of 

the latter. 

The person to be televised sits in a cloth - 

covered booth facing the photoelectric cells, 

which are arranged in a triangle' in a 

wooden frame, through the center of which 

is an opening about six inches square. These 

cells (which are the subject of a separate 

article on page 221 of the September number 

of RADIO NEws, previously mentioned) 

are completely shielded on all sides; the exposed 

portions of their bulbs are covered 

with copper mesh, while the wooden containing 

box is lined with sheet copper. The 

mesh acts as an electrical screen, but does 

not keep out light. 

On the other side of the frame holding 

the photoelectric cells is a flat aluminum 

scanning disc, 24 inches in diameter, pierced 

by a spiral of 48 holes. This rotates, at the 

rate of 450 revolutions a minute, in front of 

a powerful electric arc, the light of which 

passes through the holes and falls on the 

face of the subject. The side of the disc 

facing the arc is "masked" in such a manner 

that only one hole at a time passes light on 

to the subject. As soon as one hole is swept 

past the arc it runs behind the mask, just as 

the next hole of the spiral comes into view. 

As the holes are arranged in a spiral (each 

being slightly nearer the center of the disc 

than the preceding one), a series of -48 

separate rays of light, one directly under 

and following the other, flash across the 

subject's face (see page 222 of the September 

issue for a fuller explanation). These 

rays of light are reflected into the photoelectric 

cells, which produce electrical cur- 

rents corresponding in intensity to the 

amount of reflection from the light and dark 

portions of the skin and hair; this action 

may be compared to that of a microphone in 

translating the tones of the voice into elec- 

trical vibrations. The impulses generated 

by the cells are amplified by a bank of 

specially -shielded resistance- coupled amplifiers, 

which in turn feed the modulator tubes 

of the broadcast transmitters. The latter 

send out signals which are plainly audible 

in any ordinary broadcast set tuned to 326 

meters, or in any short -wave set adjusted 

to 30.91 meters- within reception range of 

the station -as a peculiar noise with a fundamentally 

low -pitched note, mingled with 

shriller ones, depending on the character of 

the image. (Continued on page 4.90) 

A close -up of the scanning machinery; the synchronous A.C. motor, revolving at 1800 r.p.m., turns 

the disc through a 1:4 reduction worm gear. The neon glose -lamp is supported on an adjustable 

stand immediately behind (here seen in front of) the scanting disc. Tite disc is 24 inches in 

diameter, has a spiral of 48 holes, and turns "counterclockwise" at 450 r.p.m.



-_ . 

****-44... 

PP 

Nviovirs 

REGULAR PROGVAMS 

ON THE S I1 O RT 

WAVES GROIIISEG 

:(bore: 1)r. Frank Conrail, research engineer of the Westinghouse Company, s(ondiag 

behind his "re.,lio- morie" transmitter. 

ON August 8 the Westinghouse Electric 

and :Manufacturing Company 

demonstrated a system of "radio 

movies" to members of the press 

and a group of distinguished radio men at 

station KDKA, East Pittsburgh, Pa. The 

demonstration was very successful and convincing, 

but the daily newspapers which 

mistakenly heralded it as the "first trans - 

:.lssion of motion pictures through the air 

i.1 the history of the world," either over - 

l:oked or were in entire ignorance of the 

work which C. Francis Jenkins had been 

doing in Washington for months before the 

Pittsburgh showing; as they gave him no 

credit at all for his own previous successful 

broadcasting of "movies." RADIO NEWS 

wishes to straighten out this matter merely 

as a matter of historical interest, and not 

to disparage in any way the very admirable 

achievements of the Westinghouse research 

engineers. 

The Jenkins "radio- movie" apparatus was 

the subject of the front -cover illustration 

of Rimo NEWS for August, 1928, and was 

c:escribed in great detail in a three -page 

article in that number. A member of the 

editorial staff who made a trip from 

New York to Washington, for the special 

purpose of examining the equipment, 

reported his observations in that . article. 

The reader who is interested in the general 

subject of animated radio telephotography 

(the correct designation of "radio movies ") 

is referred to this for the details of the 

. Tenkins system, which works very well and 

which is now on the air, on short waves, 

three times a week. 

'l'he statement issued by the Westinghouse 

company at the time of the demonstration 

promised that regular "radio- 

movie" transmissions through KDKA would 

commence "within a few weeks," although 

no data concerning wavelength or details 

of the transmitting system were given. The 

New York office of the company yielded the 

more definite information that one of 

KDKA's short -wave channels will he used. 

This will be good news to thousands of radio 

experimenters all over the world, as KDKA 

is the most consistent and reliable shortwave 

broadcaster on the air today. 

In the demonstration of August 8, the 

"radio- movie" signals traversed a distance 

of abòut four miles: two miles over wires 

from the television laboratory to the broadcast 

station proper, two miles away, and 

two miles back to the same laboratory by 

radio. They could just as well have been 

sent a greater distance; but the object was 

to show the operation of the whole system, 

both transmitter and receiver, to the assembled 

guests. 

METHODS AND APPARATUS 

As explained by the Westinghouse engineers, 

the operation of the "radio- movie" 

system is as follows: 

Photography in its simplest form consists 

,of the reproduction of spots of light and 

shadow in the same arrangement which they 

occupy in the subject photographed. In 

screening a motion picture, a roll of film is 

operated at a speed which sends sixteen 

pictures a second before a projecting bean 

of light. Because of the structure of the 

human eye, if pictures follow each other in 

a regular series at the rate of eight or more 

per second, the eye sees a single moving 

picture. To broadcast the "radio movies" 

requires all this, with the addition that the 

spots of light must be transformed into 

electrical vibrations, which are in turn 

caused to modulate a radio "wave." In 

the reception of the pictures, the process is 

reversed. The electrical energy representing 

the radio "wave" is picked up, amplified, 

demodulated, and the electrical vibrations 

are returned to the forni of lights and 

shadows, which, when viewed by the human 

eye, constitute the "radio movie." 

In the first step of the transmitting 

process, a sharp beam of light traverses each 

picture or "frame" on the roll of film, in 

parallel paths, 60 times. A sixteenth of a 

second, the length of time each "frame" is 

kept in view, is required for this scanning. 

A sixty -line picture is as clear as the usual 

good newspaper halftone. 

The sharp beam of light is produced by 

the interposition of a scanning disc which 

has a series of minute square holes arranged 

in a circle near its rim. This type of scanning 

disc should be distinguished from the 

usual television disc in which the holes arr



Dr. Conrad at his "radio-movie" apparatus. The square can next to his right hand 

contains a powerful lamp which produces the light used for "scanning" the 

movie film. Pictures of the receiver are not get available. 

arranged in a spiral. A circle of holes is 

used in the Westinghouse system, and not a 

spiral; because the movie filet itself is steadily 

moving past the beams of light, and thus 

the whole surface of the filar is scanned. 

In a television system such as WIRNY uses, 

the subject (corresponding to the pictures 

on the film) is stafionaay; so the scanning 

holes must be arranged spirally in order to 

cover the suh,ject completely. 

'l'he Westinghouse disc is so arranged 

that all_ light is excluded from the filmy except 

that which conies through the square 

holes. 'l'he disc turns very fast and, as it 

turns, flings the beaus of light across each 

frame from top to bottom (side to side of 

the picture), so that the whole is "scanned." 

'l'he beaus of light passing through the 

film falls into an "electric eye," or light - 

sensitive cell, which is not unlike an oversized 

incandescent lamp in external appearance. 

Within the cell is a thin coating of 

caesium, a rare "alkaline" metal. The 

amount of light falling on this cell determines 

the amount of current passing 

through it the result is that each individual 

beaus of light produces an electrical impulse 

which varies in intensity directly in proportion 

to the amount of light (or shade) 

at the point of the film through which it 

is passing. The impulses are amplified and 

then conducted to the broadcast tsaaismitter. 

According to Dr. Frank Conrad, who designed 

the Westinghouse "radio- movie" apparatus, 

the frequency of the picture impulses 

thus obtained ranges from 500 to 

about 60,000 cycles. The width of this band 

makes the application of the present system 

to the regular broadcast band out of the 

question; on the short waves, of course, 

transmission can be handled more easily. 

dim as fast as the current changes, and its 

light at any instant is in proportion to the 

light that the electric eye "sees" in the same 

instant at the transmitter. To return the 

dots of light to their original pattern, a revolving 

scanning disc is used. This disc 

must, of necessity, contain its holes in a 

spiral arrangement, in order to build up 

the necessary 60 lines corresponding to the 

scanning lines at the transmitter; and the 

lamp is mounted, presumably, at the top, 

in order to obtain proper scanning of the 

reproduced image. 

According to the statement released by 

the Westinghouse company, the use of a 

"mercury arc" lamp permits the received 

images to be projected upon a ground -glass 

screen. As the company is decidedly reticent 

about divulging the details of the receiver, 

we cannot give the exact dimensions 

of the received images in this article; but, 

as soon as the information is forthcoming, 

RADIO News will publish it. 

The accompanying illustrations give a 

good idea of the construction of the transmitting 

apparatus; the picture bearing title 

shows Dr. Conrad standing behind the machine, 

while the lettered picture on this 

page shows a close -up of the parts. L1 is a 

powerful lens which concentrates the light 

from an incandescent lamp (contained in 

the square -shaped can in front of Dr. Con - 

rad's arm in the title cut). The light beam 

passes through the square holes of the scanning 

disc D and, after coming out on the 

other side of the disc, is further concentrated 

by a second lens, 1.2. The tiny "pinhead" 

beam from this lens sweeps across 

and through the film F, which is moved boizontally 

from one reel to the other by a 

suitable ratchet mechanism which engages 

the slots in its sides. The photoelectric cell 

P is contained in a shield can, located between 

the film reels. 

'l'he construction of the scanning disc may 

furnish home television experimenters with 

an idea. The minute scanning holes are 

drilled, not directly through the disc itself, 

but through little individual metal tabs 

which are adjustable and attached to the 

disc. Of course, a circle of larger holes is 

first drilled into the disc, and these allow 

the light from the tiny square holes to pass 

through. 

The Westinghouse company is definitely 

contemplating the manufacture of commercial 

"radio-movie" receivers, according to its 

announcement; when these are ready they 

will be sold through the Radio Corporation 

of America. A Westinghouse official, when 

questioned by RADIO NEWS, stated that no 

one in the company has any idea when the 

instruments will be ready, as the experimental 

work on them has not yet been completed 

and much remains to be done. 

At present station 8XAV, using one of 

the several short -wave transmitters at East 

Pittsburgh, is transmitting these "radio 

movies," though as yet not on any regular 

schedule. Owners of short -wave receivers 

can probably pick up the signals if they 

will tune to 62.5 meters. 

TILE RECEIVER 

'l'he receiving end of the system appears 

to be practically identical with other existing 

disc systems. The received impulses are 

detected and amplified and then led to a 

mercury -vapor lamp, which corresponds to 

the neon -gas glow -lamp of less expensive 

receivers. The mercury lamp goes bright or 

A close -up of the "radio-movie" transmitter: LI, lens concentrating a powerful 

beam of light on the scanning disc D; L2, second lens producing sharp "pinpoint" 

of light on the floe F. P is the photoelectric cell.



SCANNING 

DISC 

SCANNING 

1 

MOTOR 

- 

MOTOR 

FIG. t A 

SPOTLIGHTS 

LENSES 

E ( 

HEAD OF PERSON 

BEING TRANSMITTED 

NEON TUBE 

VIEWING 

DEVICE 

I 

- 

PHOTOELECTRIC CELLS 

t 

OBSERVER'S 

HEAD 

FIG. t 

TRANSMITTER 

RECEIVER 

The "Stereoscopic" transmitter is shown in diagram form at the left, and the receiver at the right. The disc (Fig. 1A) scans two 

distinct images, one for each eye. 

How "Stereoscopic" Television Is Shown 

J 

John L. Baird Produces Moving Images Which Are 

Given the Appearance of Solidity 

By R. F. Tiltman 

THE last few months have witnessed 

spectacular advances in television. 

In June, John L. Baird demonstrated 

before Professor Fleming and other 

distinguished scientists and press representatives 

the transmissions of persons illuminated 

only by ordinary daylight, thus removing 

television from the laboratory to the 

out -of- doors. This was followed almost immediately 

by transmission of objects in 

natural colors, as described in RADIO NEWS 

for October; and now, immediately on top 

of all this, comes the demonstration of 

stereoscopic television. 

Television images in, apparently, three 

dimelisions were demonstrated for the first 

In this picture of the Baird transmitter, the photoelectric cells are in the box at the 

right: S, light- source; D, scanning disc; L, lens; C, cloth covering cells; 

P, subject undergoing -television. 

time on August 10 in the Baird laboratories 

in Long Acre, before an audience of scientists 

and representatives of the press. 

THE PRINCIPLE OF THE STEREOSCOPE 

Stereoscopic television gives the image 

the appearance of solidity or depth, so that 

it does not look like a flat picture, but like 

an actual living object. The stereoscope 

does the same thing for photography and, 

in explaining stereoscopic television, we 

must first of all examine the principles of 

stereoscopy. The appearance of solidity or 

depth which we have arises from the fact 

that we view the exterior world through two 

eyes, each of which sees the scene from a 

slightly different viewpoint. The mind combines 

these two different images into one, 

and it is the blending of the left -eye and 

right -eye images that gives the impression 

of depth. 

In the stereoscope, with which we are all 

familiar, two photographs, taken by cameras 

separated a distance equal to or greater 

than the distance between the two eyes, are 

placed side by side in a viewing device consisting 

of two prisms, so arranged that on 

looking through the prisms the images are 

converged and made to overlap. The extraordinary 

result is then obtained that, instead 

of our seeing two overlapping images, 

the mind combines these two dissimilar pictures 

into one composite view; and this


Radio. News for November, 1928 

composite view does not appear as a flat 

photograph, but gives the observer the impression 

that he is looking into the actual 

scene itself. The illusion is very striking. 

A DOUBLE TELEVISION IMAGE 

By applying the stereoscopic principle to 

television, it has now become possible to 

transmit television images with all the appearance 

of depth and solidity; and, by a 

further combination of colored television 

with stereoscopic television, the complete 

illusion of images in natural colors, and 

with depth and solidity becomes possible. 

All this has recently been demonstrated in 

the Baird laboratories. 

The transmitting apparatus consists of a 

disc, perforated as shown in Fig. lA with 

two spirals; the first spiral being arranged 

round one -half of the circumference of the 

disc. The other spiral occupies the other 

semi -circumference, about four inches further 

in; the separation corresponds to the 

distance between the eyes of a human being. 

Behind the disc, when it is mounted in the 

transmitter, as shown at the left of Fig. 1, 

is arranged an intense source of light. In 

front of the disc, and in line with the light - 

source, a lens is placed in such relation to 

the disc that a spot of transmitted light is 

caused to traverse the object. This arrangement 

is duplicated, so that each spiral has 

its lens and light- source; thus, two light 

spots traverse the object alternately, and 

two images are transmitted, one for the 

left eye and one correspondingly for the 

right eye. 

At the receiving station a similar device 

is used, as indicated at the right of Fig 1. 

A disc with the same arrangement of holes 

runs exactly in step with the transmitting 

disc; but behind the receiving disc is a neon 

tube, arranged as in ordinary television. 

The neon tube, however, covers both spirals 

and illuminates them alternately; so that 

on the receiving screen appear two images 

side by side, and separated by approximately 

half an inch. One of these corresponds 

to the object as seen by the right 

3fr. Baird (right) is here shown demonstrating his "stereovision 

receiver. The familiar eyepiece with its twin 

prisms is at the right of the apparatus; the Baird receivers 

"frame" the image at the side of the scanning disc instead 

of the top. The microphone in front of this receiver is 

for communication with the transmitting room. 

eye, the other to the object as seen by the 

left eye. These images are then viewed 

through a stereoscopic viewing device, consisting 

of two prisms, which cause the 

images to converge and blend into one, just 

as in the ordinary stereoscope for photograph 

viewing. 

It may be of interest to note that this 

stereoscopic viewing device is really unnecessary, 

and those who have the knack 

can make the images blend without the use 

of prisms; merely by looking fixedly at the 

images, and concentrating, by an act of will, 

the left eye upon the image at the left and 

the right eye upon the other. This is, in 

fact, the method used by most experts in 

stereoscopy. They seldom use the stereo- 

Photos © Photo press. 

scope, but rely upon the naked eye; in much 

the same way as a user of the microscope 

keeps both eyes open, but still sees only the 

object under the microscope. The eye which 

is not looking through the microscope is 

.sub- conhciously rendered, as it were, blind. 

Professor Cheshire, lately president of 

the British Optical Society, who was present 

at these demonstrations, stated that a 

man sitting at the transmitter was very 

clearly seen on the receiver in another laboratory 

in the same building, in perfect relief, 

showing the facial delineation and expression; 

and declared also that these experiments 

promise considerable development 

and importance in their practical application. 

41 

Televentures, Telewitticisms 

WITH the first public demonstration 

of successful television, on however 

modest a scale, the press has taken 

up the task, in a spirit of humor blended 

with seriousness, of accustoming itself and 

its public to the new conditions which must 

be met. As with the telegraph, the telephone, 

the electric light, the moving picture, 

the airplane and the radio broadcast 

system, all of which have successively 

emerged from the laboratory in an unperfected 

condition, to develop into public utilities 

of the most commonplace nature, so it 

is to be with television. 

A certain amount of gibing at the present 

unperfected nature of the invention alternates 

with half- serious prophecy of what 

it will be when it has reached its fullest 

growth; in many cases, no doubt, the reality 

will outrun the joke. 

"Moving pictures by radio," remarks H. I. 

Phillips in "The Sun Dial" of the New York 

Sun, "are soon to be a household commodity. 

The time may come when every radio set 

will carry a chart giving Charlie Chaplin's 

wavelength, the number of kilocycles it 

takes to get Toni Mix and the right type 

of bulb to use to give perfect reception to 

Douglas Fairbanks." 

"Probable complaint to radio service station: 

'This set you sent me is no good. I 

can't get Famous Players or Metro - 

Goldwyn.' " 

"The owner of a two -bulb set soon will 

be able to get everything a picture house 

can offer except the ultra -polite ushers, the 

lobby statuary and the liar outside the box 

office who tells you there are 'plenty of 

good seats inside.' " 

"The radio is making it more and more 

unnecessary to leave home for diversion. 

All that is needed now is announcement 

from some genius that lie has found a way 

for the family to make its week -end automobile 

trip by radio and for all men to go 

to work by television." 

THE INVENTOR'S CHANCE 

More conservatively and sedately, as ever 

its editorial wont, the New York Times 

looks at the present experimental stage of 

the art: 

"Probably the tinkering televisionary will 

never be as ubiquitous as was the 'listener- 

and the Televocabulary 

in' in the heyday of home -set building. The 

construction of a television apparatus in the 

garret demands an equipment and a skill 

beyond the average amateur. At best the 

'televised' images must be coarse and 

barely recognizable, with an almost uncontrollable 

tendency to shift from the screen. 

It must not be forgotten that the brilliant 

demonstrations by the American Telephone 

and Telegraph Company were possible only 

with the aid of a score of trained engineers 

who knew their technical roles as well as 

the actors of a theatrical company know 

their lines. 'Fading,' one of the bugbears 

of radio, causes unpleasant distortion of the 

image, and so does poor synchronization of 

the transmitting and receiving apparatus. 

Radiatioh of faces on a lavish scale is at 

present a technical impossibility because 

each television transmitter requires an excessively 

wide channel in an ether already 

overcrowded. 

"Clearly, the development of television 

belongs to the engineer. British and German 

authorities view his task with misgivings 

and even doubt if it will be possible 

(Continued on page 466)



The Jenkins "Radio -Movie" Reception Methods 

Some Operating Hints Which Will Be Valuable to Television 

Experimenters in Constructing Their Receiving Apparatus 

REGULAR schedules of radio movies 

have been established by the Jenkins 

Laboratories, 1519 Connecticut Avenue, 

Washington, on 46.72 meters (6,420 kilocycles) 

with 48 -line pictures. They run from 

8:00 to 9:00 p. m., E. S. T., on Monday, 

Wednesday and Friday nights (or 0100 to 

0200 GMT on Tuesday, Thursday and 

Saturday mornings). When a sufficient number 

of amateurs have shown that they are in 

position to receive these, the broadcasts will 

be made nightly. Preliminary announcements 

are made from the station, whose 

call is 3XK, in both code and phone. At 

the end of each picture the letters END 

are shown, to indicate that it is time to 

return to reception by ear. 

The transmitting system, which was described 

in RADIO NEWS for August ( "Radio 

Movies and Television for the home," page 

116) operates to send silhouette images, 

which are printed on standard moving -picture 

film. Scanning these with a very small 

beam of intense light gives an impulse much 

sharper than that obtained in televising 

faces, clothing, etc., by reflected light. The 

images are sent out at the rate of 15 a second, 

or 900 per minute. 

While the Jenkins laboratory -model receiver, 

described in the article above mentioned, 

is of very high -grade workmanship, 

and too complicated for home construction, 

the television experimenter will find it possible 

to receive the radio movies on a 48 -hole 

lisc running at 900 revolutions per minute. 

TRACKS 

NEON TUBE 

IDLE MOTOR 

Later, it is promised, "halftone" or 

shaded motion pictures will be sent, when 

it is to be expected that the technique of 

the receiving amateurs has improved. For 

the present, a gradual progression in the 

complexity of the images is being attempted; 

the earliest film transmitted was 

only that of a dancing figure, comparable 

with the "zoetrope" toys, which were the 

forerunner of the moving picture. Elaborate 

subjects and later actual stories followed. 

The broadcasting has been in charge of 

Stuart Jenks and Paul Tomsen. 

"We have disaivered," says Mr. Jenkins' 

announcement, "that stories in silhouette 

are as entertaining as movie cartoons in the 

theater; plus, also, the appeal of the mystery 

of movies by radio. 

BEGINNING A NEW INDUSTRY 

"Picture subjects and picture stories in 

silhouette are easier for the amateur to pick 

up at first; and obviously the width of the 

picture- frequency band is very much less 

and, therefore, greater latitude is available. 

"Our immediate interest in the broadcasting 

of radio movies is to enable the amateurs 

of America and Canada to become familiar 

with the principles involved, in the belief 

that they will assist in this development. 

'l'he American radio amateur has shown his 

remarkable cleverness in the development of 

`worthless frequencies' below the 200 -meter 

band, as is now generally and officially ac- 

today. 

I- 

NEON 

-TUBE 

TUBE 

SOCKET 

FRAME 

FRICTION 

DRIVE 

DRIVING 

MOTOR 

BRACKET 

SLOT 

knowledged. I expect as great a surprise 

when the amateur takes up this new work. 

"This is the beginning of a new industry 

-a new form of radio entertainment. With 

these motion- picture broadcasts we are hoping 

to contribute to its rapid development. 

Your reports on our signal strength, fading, 

echo images and quality of picture reception 

will greatly help. 

"Ultimately, this pantomine story -teller 

will come to all our firesides as a fascinating 

teacher and entertainer, without language; 

Literacy or age limitation; a visitor 

to the homestead with photoplays, the 

opera, and a direct vision of world activities, 

without the hindrance of muddy roads, 

or snow blockades." 

While the radio movies are vision only 

at second -hand, in contrast to the true television, 

the mechanism reproducing them is 

the same as that required for television; 

and it is quite possible that they will 

find places in television schedules even after 

the perfection of television, even more so 

than mechanically- reproduced music does in 

the radio broadcast schedules of the world 

For instance, many events of great 

interest in the world take place at hours 

when the inhabitants of distant lands are 

busy or sleeping; and their repetition by the 

radio movies a few hours later, with or 

without an accompanying sound broadcast, 

will be a desirable news service. 

(Continued on page 492) 

DISC 

DRIVING 

MOTOR 

NEON 

TUBE 

DISC 

FRAME 

IDLE 

MOTOR 

DRIVING 

MOTOR 

TOP VIEW 

THREADED 

ROD 

SIDE 

SUPPORTS 

FRONT VIEW 

BOTTOM OF 

FRAME 

SIDE VIEW 

1" STRIP ABOUT 

12" LONG 

THICK 

1" STRIP 

NUTS SOLDERED 

TO ROD 

BRASS L 

SLIDE 

NUT SOLDERED 

TO L 

KNOB 

1= 

SET 

RUBBER 

DISCS 

WOOD SCREW FOR 

TIGHTENING SUDE 

DETAILS OF SLIDE 

AND TRACKS 

STOP OF 

FRAMEWORK 

RIGHT END 

OF SLIDE 

FRAMEWORK 

DETAILS OF 

ADJUSTING MECHANISM 

THREADED 

BRASS ROD 

BRASS L 

MOTOR 

SHAFT; 

DETAILS OF 

FRICTION DRIVE 

The three upper drawings show the arrangement of the parts of an 

'excellent television or "radio- movie" receiver; the support for the 

disc may be an idle motor or a small polishing head. Mount the 

neon tube so that it is not affected by the vibration of the driving 

motor. In assembling the adjusting mechanism, drill out: the upright 

arms of the L- shaped brackets so that the threaded brass,rod will revolve 

in them easily. Once the proper position for the slide has been 

found, turn in the wood- screw, so that the motor will not "walk."


Radia News for November, 1928 421 

Successful DX Work 

nADIO experimenters who are contemplating 

the construction of television 

or "radio-movie" receivers will 

be interested to learn of the splendid 

reception that is being obtained by 

others who have already assembled the scanning 

machinery and its supplementary apparatus. 

Such successful reception should 

encourage hesitant constructors to proceed 

with their own receivers without delay, so 

that they also will experience the great thrill 

of "seeing by radio." 

One of the most active television enthusiasts 

in the East is James Millen, of 

Malden, Mass. Although Mr. Millen is a 

professional radio engineer in, the employ 

of a large manufacturing concern, he is an 

amateur dabbler at heart and spends a great 

deal of time in his own home laboratory, 

pictures of which are shown on this page. 

He constructed a simple television receiver 

using a twenty -four-inch disc, a neon -gas 

glow -lamp and an adjustable -speed motor, 

and has had unusually good luck in receiving 

the Jenkins "radio movies" on 46.7 

meters. 

A letter received from him lately by 

RADIO News reads as follows: 

FIVE -HUNDRED-MILE RECEPTION 

"You will, no doubt he interested to know 

that for the past week I have been able to 

receive all of the Jenkins 46.7 -meter broadcasts 

on a rather simple outfit built up at 

home in one evening. While the pictures are 

not as good as those .Jenkins himself demonstrated 

in Washington, I think they are very 

fine when one considers the iliaance involved 

-somewhere around 500 miles. During a 

local thunderstorm last Friday (This letter 

Marks "Radio- Movie" Transmissions 

.11r. James Millen 

was written at the end of August.- EDITOn), 

when reception on the broadcast band was 

almost impossible, we received the entire 

silhouette broadcast, and had no difficulty 

in following the movements of the girl 

bouncing the ball and seeing the ball itself 

bounce up and down. 

"The outfit comprises the standard National 

short -wave kit, a three -stage trans - 

former- coupled amplifier operated from a 

'B' socket -power unit, and the scanning de- 

vice. The amplifier used was from a broadcast 

set, with one 'haywire' stage ahead. I 

had no trouble in using a 'B' supply unit for 

both the glow -lamp and the receiving tubes 

on this short wave." 

THE RECEIVING APPARATUS 

That Mr. Millen finds it possible to use 

a transformer -coupled amplifier for satisfactory 

reception of images is rather surprising, 

as practically all television engineers 

have considered resistance coúpling 

to be necessary, because of its comparatively 

smoother amplifying characteristics. 

Mr. Millen s transformers are exceptionally 

large and heavy ones, which may account for 

his success with them. 

A picture of the amplifier is shown below; 

it comprises two straight amplifier 

stages and one of push -pull. Resistance - 

coupled audio amplifiers will, in most cases, 

give more reliable images. However, the 

experimenter owning a high -grade transformer 

amplifier should by all means try 

his available apparatus first, before spending 

money on additional equipment. 

The general layout of the apparatus employed 

appears below. The clock -like instrument 

on the right side of the scanning - 

disc box is a speed indicator; this is a 

rather expensive device but is, of course, a 

great help in adjusting the speed of the 

disc's driving motor properly. 

The short -wave receiver used by Mr. Millen 

was assembled from a commercial kit, 

but experimenters desiring to build one like 

it are invited to write for RADIO News Free 

Blueprint No. 62. This blueprint shows the 

construction of a receiver of practically 

identical design; this employs a screen -grid 

tube as an R.F. amplifier, and is a very fine 

all -rood short -wave outfit. Remember, the 

blueprint is free for the asking. 

At the right: The "breadboard" 

three -stage transformer - coupled 

amplifier used by Mr. Millen for 

his reception of the Jenkins 

"radio movies." Below: A general 

view of the television re. 

triver. The short -wave tuner is 

the apearatu s with the small 

panel, the scanning apparatus 

is in the box on Nue right. The 

clock -like instrument connected 

to the scanting disc is a speed 

indicator. 

Below is a rear view of Mr. 

Jlillen's scanning apparatus. 

The neon -.gas glow -lamp is 

mounted upright on the narrow 

upper shelf behind the scanning 

disc. The scanning disc's driving 

motor is an alternating -current 

machine of the condenser type. 

designed especially for television 

work. This receiver is, it will 

be seen, very much like the one 

described on page 422 of this 

issue. 

i


422 


How to Make Your Own Television 

Receiver 

IN order to pick up and reproduce the 

television images now being broadcast 

by WRNY and W2XAL, you need 

only a modest assembly of instruments, 

some of which you probably already have on 

hand, and some of which you will have to 

buy. 

First, since the television images are 

transmitted simultaneously on 326 and 30.91 

meters, by WRNY and W2XAL, respectively-, 

you need either a regular broadcast 

tuner or a short -wave tuner. If you live 

in or near New York, and obtain satisfactory 

loud -speaker results from the regular 

WRNY transmissions, all you require is a 

separate audio -amplifier of the resistance - 

coupled type, and the scanning mechanism, 

to be described later. If you are already 

using a resistance -coupled amplifier, as 

ninny radio fans are, you will need only the 

scanning apparatus. 

If you cannot hear WRNY's 326 -meter 

wave very well, the best thing to do is to 

install a short -wave set, in order to pick up 

the 30.91 -meter wave of W2XAL. You 

will require the audio amplifier also, however. 

Happily, short -wave receivers are 

very inexpensive and can be built very 

easily, so you should assemble one without 

delay. It will enable you to pick up, not 

only W2XAL's television signals, but also 

the "radio- movies" of station 3XK (using 

the Jenkins system), and musical programs 

from short -wave broadcast stations in many 

parts of the world. We can particularly 

recommend the set described in the RADIO 

NEws Free Blueprint No. 62. This uses an 

R.F. amplifying stage, has only one tuning 

control, and costs very little to assemble. If 

you do not already own a short -wave receiver, 

just drop us a card and we will 

send you Blueprint No. 62 free of charge. 

In making this receiver, do not install the 

single stage of audio amplification. Leave 

out the audio transformer and the third 

tube, and simply provide two binding posts 

for the wires that are shown connected to 

the primary posts of this transformer. The 

detector is then easily connected to an external 

resistance -coupled audio amplifier. 

H. Gernsback, Editor of RADIO News, receiving the television broadcasts from WRNY at his 

home in New York City, with the simple apparatus described in this article. For purposes of the 

test, the neon tube and loud speaker were connected in series temporarily, with successful 

operation simultaneously. 

If you are able to use your regular broadcast 

receiver for WRNY, you will not use 

for television reception the present audio 

amplifier if it is of the transformer type. 

Simply run a wire from the plate (P) post 

of the detector tube to the top input post 

of the resistance -coupled amplifier shown in 

Figs. i and 3, unhook the "B+Det" wire 

running to the power unit or "B" batteries, 

and bring this saine wire to the other input 

post of the audio amplifier instead. With 

this arrangement, the detector will be feeding 

directly into the resistance- coupled 

amplifier. 

RANGE OF FREQUENCIES 

"Why can't a regular transformer amplifier 

be used? Why is a resistance amplifier 

necessary ?" you may ask. 

The answer is that resistance- coupled amplifiers 

amplify audio -frequency impulses 

ranging from 50 to 5,000 cycles snore uniformly 

than do most transformer -coupled 

amplifiers. The television impulses broad- 

cast by WRNY - 

W2XAL and others 

cover this frequency 

range, and they must 

be reproduced faith- 

.,,.,,,,,,.,.,,,,,,,,. 

A commercial three -stage 

amplifier which may be 

purchased already assembled 

is convenient and 

compact. The 171 -type 

tube in the output is best 

suited to the characteristics 

of the neon tube. 

fully at the receiving 

end, without emphasis 

on any particular register, 

in order to create 

a recognizable 

image. Most, transformer amplifiers possess 

slight irregularities in their response characteristics 

but, when voice or music is be- 

ing reproduced, these are not very noticeable 

to the ear. When television images 

are being reproduced, even the slightest irregularity 

will cause the already crude 

images to break up and assume peculiar 

shapes. The general experience of television 

experimenters has been that resistance - 

coupled amplifiers are more satisfactory for 

both television transmitters and receivers, 

at least in this stage of the art. 

above statements should not be interpreted 

as a condemnation of the transformer 

amplifier. There has long been raging 

in technical circles a controversy over 

the respective merits of the transformer and 

resistance systems for the amplification of 

voice and musical signals, with the radio 

experts evenly divided between the two 

camps. At the present time, however, it is 

easier to get good pictures from the latter 

system, so we recommend resistance coupling. 

However, it is entirely possible to 

obtain satisfactory results from a high - 

quality transformer arrangement; witness 

the work being done by James Millen, of 

Malden, Mass., whose experiments are described 

briefly on page 421 of this issue. 

A good three -stage resistance -coupled amplifier 

can easily be assembled on a wooden 

board, about five -inches wide and twelve 

inches long. A completely- assembled one 

can be bought for about ten dollars, but a 

home -made one will not cost so much. After 

you finish it, you will have a fine amplifier, 

not only for television impulses, but 

for regular broadcast programs as well. 

DESIGN OF AN AMPLIFIER 

S -oil will need the following parts, arranged 

and connected as shown in Figs. 1 

and 3: a wooden baseboard; three UX -type 

tube sockets, V1, V2, V3; three 4-ampere 

filament ballast resistors, R4; two double - 

resistor mountings; four 0.5 -mf. fixed condensers 

of the by -pass type, C; one 1.0 -mf. 

condenser, Cl; a special high -value grid



TO PLATE OF 

DETECTOR e 

TUBE 'I 

R1 

TO "B'+ 

DETECTOR 

R3 

0 

V1 V2 V3 

- 

R3 

al 

r .ig 

- 

R4 

F 

i 

eL2 

II o 0 

o o 

180 -VOLT 

"B" BATTERY 

_L 

R5 

NEON 

TUBE 

DISC 

MOTOR 

R6 

SWITCH 

SWITCH 1 MF. 

DOUBLE - 

CIRCUIT JACK 

R7 

- + B- C+ C- C- B-- 

A 1 -3 40 180 

VOLTS VOLTS VOLTS 

FIG. 1 

110 VOLTS 

A. C. 

Vitte this arrangement, sufficient amplification for good signals is 

obtained by the use of two "high -inn" tubes and a 171 -type in the 

last stalle. When the speaker is plugged into the jack, the neonlamp 

tube is disconnected automatically from the amplifier. 

impedance, LI; an output choke of 30 

henries, L2; a filament switch; eleven binding 

posts; fixed resistors of the following 

values: one 100,000 -ohm, R1; four 250,000 - 

ohm, 112 and 113. 

The grid impedance unit LI is used instead 

of a grid Irak in the last stage, as 

The cabinet of the reproducer with the front 

removed, showing the lamp and the motor with 

its regulating condenser. The "B" blocks are 

conveniently located beneath. 

shown in Fig. 1. In this position it overcomes 

the tendency of the amplifier to 

"motorboat" when used with a "B" socket - 

power device. The tubes Vi and V2 are of 

the 240 ("high-mu") type, while V3 is a 

171A. 

The wiring of the amplifier is simple, and 

should give no trouble. The hook -up is that 

of a perfectly straightforward resistance - 

coupled system, with an output filter consisting 

of a choke coil (1.2) and a fixed condenser 

(the last of those marked C). 

BUILDING THE TELEVISOR 

With the amplifier finished, the next step 

is construction of the scanning mechanism.. 

For this you will need the following parts: 

a neon -gas glow -lamp, which fits in a 

standard UX -type socket; a scanning disc 

24 inches in diameter, drilled with a spiral 

of 48 round or square holes; a universal or 

a condenser-type motor, of not over 1/8_ 

horsepower; a variable resistor, 0- 10,000 

ohms, I15; a rheostat, 100 ohms, Rî; a rheostat, 

0 -10 ohms, R6, and a pear -shaped hand 

switch. 

The neon -gas glow -lamp is described in 

detail in another article in this number (see 

page 427) ; so nothing more need be said 

about it here. 

The scanning disc is merely a flat disc 

of aluminum drilled with a spiral of holes 

about 3/64 -inch in diameter, as shown in 

Fig. 4. Now please accept a word of kind 

advice: don't try to make your own scanning 

disc unless you have available a lathe 

and a power drill- press, and have had some 

years of experience as a mechanic on precision 

work. We are showing the details of 

the disc as a matter of interest, and not 

with the expectation of having our readers 

make it themselves. Buy a disc -there are 

a number of inexpensive ones now on the 

market -and you can then expect to see 

good images. 

For a motor to turn the disc, you can get 

either a condenser -type machine designed 

especially for television work, or a universal 

motor such as are used by the thousands 

for electric fans, vacuum cleaners, coffee 

grinders, etc. The speed of the motor must 

be capable of adjustment by an external 

rheostat; for it must be slowed down to 450 

revolutions per minute for WRNY- W2XAL, 

or 900 for the Jenkins 

radio -movies f r o m 

The scanning disc, to 

show the image in correct 

arrangement, must revolve 

in the direction opposite 

to those of the hands of 

a clock. 

3XK. A synchronous 

motor, revolving at 

1,800 r.p.m., can be used only if it is geared 

to the disc by 1 :1 or 1':2 reduction gears, for 

WRNY and 3XK, respectively. The 1/4- 

horsepower size of motor is widely available, 

and is just` right. A special condenser -type 

motor was used in the particular television 

receiver shown in the accompanying illustrations, 

and proved exceedingly satisfactory 

because its speed can be controlled 

very smoothly by a hand rheostat. 'l'liis 

motor has a half -inch shaft, on which the 

Mounting flange of the disc fitted snugly. 

If you happen to pick up a motor with a 

shaft smaller than IA-inch, you can buy for 

a few cents a bushing to adapt the disc 

to it. 

THE TELEVISOR BOX 

The idea is now to assemble the scanning 

apparatus so that the neon tube is mounted 

directly behind the disc and above the motor, 

with its flat plates parallel and as close 

as possible to the back surface of the disc. 

The tube should be placed along the vertical 

center line of the disc, at such a height 

that the outermost hole of the spiral sweeps 

,just under the top edge of the plates, and 

the innermost hole just above the bottom 

edge. Any strong, rigid framework that 

satisfies these conditions will serve the 

purpose. 

The drawings (Figs. 5 and 6) show an 

arrangement of excellent design. A simpb 

box 31 inches square and 12 inches deep k 

made up of 3/4-inch boards, securely fastened 

together with wood- screws. The corners 

are strengthened by additional 3 -inch 

strips about l/ inches wide. A shelf to 

'hold the motor is made of another piece of 

3 -inch stock about eight inches wide, and 

supported by two side and one center supports. 

No dimensions are given for the 

latter pieces because they naturally will depend 

on the size of the particular motor on 

hand. 

They should be cut so that the center 

of the scanning disc coincides with the center 

point of the box. 

The neon tube is suspended upside döwn 

from the top cf the box; its socket can lie 

spaced away trom the board with thin strips 

in order to lower the tube to the proper position 

with relation to the holes in the disc. 

The back of the box may be covered, or 

left open. A piece of beaver board, or 

The lower panel of the cabinet -which was 

solidly built -i,, place showing the controls, 

(R 5, 6, 7), switch, and lead from tue amplifier.


-lc 

I.1I111II 


similar TA-inch board used for partitions, 

will be most suitable for the purpose. 

'l'he front of the box should be covered 

with two pieces of this hoard, one 21 inches 

high and the other 10 inches. From the 

larger piece cut out a hole 1 inches 

square, directly in front of the square plates 

of the neon tube. On the small board mount 

the three variable resistors R5, 116 and R7, 

and two pairs of binding posts, as shown in 

Fig. 6. .1 telephone jack may also be 

mounted on this panel; this device is optional 

and its uses will be discussed later. 

To facilitate experimentation with the 

disc, motor and the neon tube, do not permanently 

screw down these front panels at 

first; but merely turn one or two screws 

into each, to hold them in position. 

It is well worth while to construct a lox 

like this, as it will afford absolute protect 

ion against the rotating disc. The latter is 

far less dangerous than any ordinary ' B'' 

power device but, as a matter of safety. 

revolving machinery of any kind should be 

enclosed. If you do not want to make anything 

as elaborate as this heavy box, use 

lighter material for the sides, or make upright 

supports of broomsticks and cover the 

sides with cloth. At any event, be sure that 

the motor is securely fastened, and that the 

neon tube is not shaken by its vibration. 

CONNECTING THE TELEVISOR 

With all the mechanical work done, you 

can now start with the electrical end. As 

explained by many articles in RADIO NEWS, 

the neon -gas glow -lamp has the same function 

in a television receiver that the loud 

speaker has in a music receiver. It trans - 

lates back into light -impulses the modulated 

electrical impulses created at the transmitter 

by the photoelectric cells. (See the first 

article in this issue for a fuller explanation.) 

It is connected in exactly the same* 

place in the audio circuit that the loud 

speaker ordinarily occupies. 

The best arrangement is shown in Fig. ]. 

The two output posts of the resistance - 

coupled amplifier are led to a double- circuit 

telephone jack, which may be mounted on 

LI 

SINGLE. POLE, 

DOUBLE - CONTACT SWITCH NEON TUBE 

C- 

40V 

TELEVISION 

MUSIC 

C 

OUTPUT FILTER 

L2 =30 HENRIES 

C = 0.5 MF. 

DISC 

LOUD 

SPEAKER 

FIG. 2 

MOTOR 

An alternate arrangement for the output of the amplifier shown in Fig. 1. 

the lower panel of the box holding the scanning 

apparatus. The inner springs run to 

the connection posts of the neon tube, across 

which are connected also the resistor R5 

and a separate 180-volt "B" battery. Resistors 

Iì6 and R7 are in series with each 

RADIO NEVs 

FREE 

BLUE PRINTi 

ARTICLE 

No. 67 

Large blueprints of 

the diagrams in this article, 

containing information 

for the construction 

of a television amplifier 

and reproducer as 

illustrated here, will be sent postpaid 

on request. Write to the Blueprint 

Department on a sheet of paper separate 

from any letter to other departments; 

print your name and address 

legibly and ask for No. 67. (See also 

page 449.) This will avoid possible 

delay. 

R6 

AC 

R7 

SWITCH 

other in the 110 -volt A.C. circuit. A six - 

foot length of flexible cord is run from the 

pear switch (which is nothing more than a 

push button in a small wood case which can 

be held comfortably in the hand) to the 

resistor R6. 

Now turn on your receiver, tune in 

WRNY or W2XAL with the loud speaker 

plugged into the double- circuit jack, and 

adjust the set to give a clear, loud signal. 

Turn up the resistor R5 until the neon 

tube breaks out into a bright pink glow. 

The glow should take place on the plate 

facing the disc. If it appears on the opposite 

plate, reverse the battery connections 

to it. Further details on the characteristics 

and operation of the glow -lamp 

will be found in an article on page 427 of 

this issue. 

Turn on the alternating current to the 

motor, and adjust 117 so that the latter 

turns at about half its normal speed. Turn 

off all the lights in the room. The instant 

the buzz -saw note of the television signals 

comes through the loud speaker, pull out 

R1 

o v C 

SOCKET 

o 

¡ 

'' 

F.l 

F... 

E- .,. 

O 

TO DETECTOR 

O 

SWITCH 

0.5 MF CONDENSERS 

r 

F. 

t 

E C 

0 C SOCKET 

0 C 

_ 

OUTPUT 

R3 Ni j R2 

V2 R2 

V3 CHOKE 

1 

0 0 1 .0 0 

L1 

oo 

oo 

o) oO 

\oO oO 

RESISTOR MOUNTINGS R3 SOCKET 

GRID C'; v 

IMPEDANCE 

1 

ÍIJR4 - 

BATTERY BINDING POSTS 

R4 

FILAMENT 

BALLASTS 

0o 

O °0 

OUTPUT 

OO O O O O O WOOD BASEBOARD 

A simple layout for an amplifier such as that shown in Fig. 1. It 

uses straight resistance coupling in the first two stages (see preceding 

pages for values), a grid impedance coil, and an output 

FIG. 3 

R4 

C1 

" POSTS 

choke. The output may be connected as in Fig. 2, above, for 

.greater convenience. It is possible, also, to have the tube and 

speaker in series, with a slight additional "B-}-" voltage.


,- 

í 

Radio. News for November, 1928 425 

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the speaker plug and start playing with 

the motor rheostat, R7. 

OPERATING IS SIMPLE 

If you have no tachometer (speed indicator), 

the only thing to do is to run the 

motor up and clown the scale. When you 

hit 450 r.p.m., the crazy criss -cross lines 

that are shooting back and forth and up 

and down the surface of the disc in front 

of the neon tube should melt into a rough 

image of a man's face, or other distinguishable 

object. You will notice that, with no 

signal being fed to the neon tube, the square 

of pinkish light you observe through the 

disc is streaked with fine dark lines. The 

instant the audio signal is turned on, this 

even glow will be modulated by the fluctuating 

currents. When you hit 450 r.p.m. and 

the image of the man's face literally uncurls 

itself from the hodge -podge you saw 

before, you will experience a thrill that will 

make all the effort well worth while. You 

probably received a big "kick" from your 

first successful broadcast receiver but, 

when you see your first television image, 

you will know what a real thrill is. 

In the absence of any synchronizing system, 

the images will tend to wander out of 

view but, by carefully manipulating the control 

rheostat R7, you can find the proper - 

setting for 450 r.p.m. The use of the smaller 

rheostat R6, with its switch, is more or 

less incidental. Set R6 to about half its 

value, and just press the switch for an in 

stant when the images start to run off. This 

will cause the motor to jerk and speed up 

for a second. 

If you are using a universal motor, you 

can disregard 116 and its switch altogether 

and depend on 13.7 for the speed control. 

The images you receive may be upside 

down, or the WRNT televised card may 

read backward. To correct these conditions, 

follow the operating hints given in 

the article on pages 428 -9. 

OTHER ARRANGEMENTS 

An alternate circuit arrangement is 

shown in Fig. 2. Here the neon tube is connected 

directly in series with the plate circuit 

of the last audio tube, with a single - 

pole, double- contact switch to shift the output 

of the tube. The rest of the amplifier 

and motor circuit is exactly like that of 

Fig. 1. This is a simple hook -up; but its 

main disadvantage is that the voltage applied 

to the "13-1-" post must be at least 

300 volts, as there is a drop of about 150 

volts across the neon tube itself, and V3 

is a 171A, which operates on 180 volts. As 

no "B" power unit designed for 171 operation 

will supply more than about 220 or 

250 volts, it will be necessary to connect 

one or two 45 -volt "B" battery blocks in 

series with the highest voltage lead from the 

unit you have. At least, this will be cheaper 

than using four 45 -volt blocks for the hookup 

of Fig. 1. 

Several experimenters have used a "B" 

power unit for the neon -tube illumination 

with good success, but separate batteries 

are really the cheapest, easiest and most 

satisfactory source of supply. 

The audio amplifier need not be limited 

to a 171A for the output stage. A 210 -type 

power amplifier will work perfectly well, 

but in this case the shunt -feed scheme of 

Fig. 1 should be used. The series arrangement 

of Fig. 2 will strain the power pack 

and the neon tube is likely to be burned up 

by the high plate current. With the Fig. 2 




Synchronized Broadcast Joins Images and Music 

Wire Transmission of Image- Frequencies and Radio Reception of 

Sound Enable Audience to See as Well as Hear Miniature Drama 

A 

JitETASTE of the radio television 

of the future, accompanied as it 

will be by radio "teleaudition," was 

given to radio fans in Newark, N. J., 

during the week of August 19, when a 

demonstration of "wired television" synchronized 

with musical radio reception was 

presented at the huge department store of 

L. Bamberger & Co., owners of station 

WOR. On its sixth floor the transmitter 

and receiver, linked together by short wire 

lines, had been installed 1w their manufacturer, 

the Daven Radio Corporation of the 

same city; and two -hour marionette performances 

were daily enacted before the 

transmitter and reproduced before the eyes 

of the radio spectators in synchronism with 

the music broadcast at the saune time from 

WOR. The little dance of the puppets was 

repeated each two minutes during the period 

of the demonstration; as the limitations of 

the lamp and screen used in the receiver, as 

in other present- moment television apparatus, 

prevent the image from being seen 

by many at once. 

"It is our belief," said a representative 

of WOR, explaining the reason for holding 

the demonstration at this time-that of giving 

the public a basis on which to found an 

idea of the coming importimce of television 

in radio programs of the comparatively near 

future -"that television broadcasts will 

eventually be combined with the simultaneous 

transmission of speech and music; but 

this is impracticable at the present moment, 

from the viewpoint of both transmission and 

reception: However, by the use of a wire 

line, we are able to present the effect of 

synchronized reception of a radio program 

consisting of simultaneous music and television." 

THE SYSTEM EMPLOYED 

The "wired -television" apparatus employed 

is similar in principle, of course, to 

other installations recently demonstrated 

over radio channels, both short and long - 

wave. The transmitter comprises a 48 -hole 

scanning disc, 24 inches in diameter and 

rotated at 1,000 revolutions per minute by 

its motor, and four 7 -inch photoelectric 

cells. A 900 -watt tungsten lamp produces 

the light bean which the scanning disc 

causes to "explore" the field of its subjects 

a trifle over sixteen times a second. A condensing 

lens aids in this task of illuminating 

the miniature stage. 'l'he light reflected, 

spot by spot, from the surfaces covered by 

the dancing beam emitted by the lamp is 

converted into electrical pulses by the photoelectric 

cells; and these signals are passed 

through a six -stage resistance -coupled amplifier 

of special design to handle the combination 

of audible and supersonic fre- 

quencies which makes up the television band 

'l'he arrangement of the apparatus appears 

in the illustration; the scanning disc man 

be seen directly in front of the demonstrating 

engineer, and the source of illumination 

is housed in the hood behind the disc. 'l'he 

frame before the disc contains the four 

photoelectric cells and the first five stages 

of the amplifier. The final stage of 210 - 

type tubes, in push -pull, is contained in the 

small box on the table at the right, and the 

"B" power -supply unit is in the larger box 

beside it. 

RECEPTION ADJUSTMENTS 

Since the range of frequencies required 

by the television dramas ran far beyond 

available broadcast channels, the transmitter 

was connected directly .by wire to the 

receiver on the same floor. The latter apparatus 

also is standard; it is housed in a 

wooden cabinet, approximately 30 inches 

high and wide, and 8 inches deep. The assembly 

comprises the conventional scanning 

disc with its motor, and the neon -filled glow - 

tube. The controls on the front of the 

housing include a resistor governing the 

speed of the motor, a switch turning it on 

or off, a rheostat regulating the direct -current 

voltage across the plates of the neon tube, 


Set up of the television transmitter used at IVOR during the synchronized transmission. The puppets' "stage" is nt the 

extreme left; the apparatus is of the usual type.



The Neon Tube Television's "Loud Speaker" 

How This Marvelous Device Makes Possible the Distant Reproduction 

of Moving Scenes Simultaneously with Their Occurrence 

0 

NE of the essential components of 

a television receiver is the glow - 

lamp; this and its associated scanning 

device serve the sane purpose 

in the television apparatus that the loud 

speaker serves in the radio set. 

This remarkable device, as most success - 

fully developed, utilizes neon gas as the 

luminous element, and is the only lamp yet 

known which, without prohibitive cost, can 

be made, satisfactorily, to meet the requirements 

of the present television systems; in 

which there is required a light -source, of 

uniform intensity over a large area, which 

will instantaneously vary in brilliancy with 

variations in the television signals. The 

television lamp most strikingly differs from 

the familiar electric lamp, in that it gives 

off a soft orange "glow" from a large surface 

which may be looked at without hurting 

the eyes, rather than the dazzling white 

"spot" of an incandescent tungsten filament. 

The color of this glow may be readily controlled 

in manufacture by variation in the 

kind and quantity of gas employed within 

the bulb. 

As will be seen from Fig. 1, the construction 

of the television lamp is apparently 

quite simple; although this simplified appearance 

has been secured only after a 

great deal of research work with gaseous - 

conduction tubes and neon lamps of all 

types and for many different uses. Indeed, 

the development and refinement of this 

device has involved a review of many rare 

gases, a deep study of atomic structure, 

and a long process of reasoning out the 

acrobatics of electrons. The highly intricate 

action taking place in the miniature universe 

of the gas contained in the television lamp 

is, therefore, not at all in keeping with 

the utter simplicity of the mechanism and 

electrical features of the device; yet we 

must master the first before we can enjoy 

the second. 

ITS ACTION A PARADOX 

The "glow" takes place uniformly over 

the surface of either one or the other of 

the two flat and parallel plates (P and PI, 

Fig. 1) ; the effect depending upon which 

plate is connected to the positive and which 

to the negative side of the power supply. 

The two parallel plates are so placed with 

respect to each other as toT utilize the principle 

of "short- path'-insulation in order 

to prevent "glow" between the plates which, 

of course, would not be very desirable. 

The "short- path" prinçiple is one of 

those scientific truths that are stranger than 

fiction. Briefly, in a gaseous conducting 

nteditms, if we have oppositely -charged 

metallic bodies of sufficiently high potential 

difference, the gas between will "break 

down" or "ionize," and conduction will take 

place from one to the other. However, 

move these same conductors very close to 

each other, and the gas between is no 

longer ionized; Which is apparent from the 

fact that there is no longer a glow present 

in the tube. Current ceases to flow from 

" Raytheon Manufacturing Company 

By D. E. Replogle 

one to the other. An excellent insulator is 

now presented by the intervening gas. Why? 

The explanation is steeped in academic 

science, which is usually far beyond the 

realm of the layman. Furthermore, no one 

has ever seen atoms or electrons; hence cold 

logic steps in to explain things which man 

may never see for himself. However, if 

we may be permitted to make a free translation 

into lay language, of a theory by 

C. G. Smith, inventor of the "S" tube, the 

story runs about like this: 

The facing charges of electricity are 

bound to produce action. Some loose electron 

in the gap between the charged conductors 

is coaxed toward one or the other, 

and rapidly accelerates its rate of travel 

until its speed is sufficient to smash those 

atoms obstructing its path. The collisions 

result in ionization, or the breaking down 

of the gas, which then becomes a fair conductor 

of electricity; or, to put it another 

way, there is now a wholesale movement 

of electrons. It is evident, then, that the 

electron needs a good running start, so to 

speak, in order to smash things up in 

general. Failing in a good running start, 

the electron does no smashing, ionization 

cannot take place, and there is no electrical 

conduction; the gas, under such circumstances 

is a good insulator. Some gases 

require a longer path for ionization than 

others, which is another important consideration. 

Helium is especially ideal in 

this respect, having an exceptionally long 

free path. 

CONSTRUCTION OF THE GLOW LAMP 

The "short- path" principle, then, is 

adopted merely to prevent electrons from 

getting a gtiod running start; it is practically 

applied in insulating the inner surfaces 

of the two electrode plates most effectively. 

- 

Glass spacers are arranged at the top - 

edge of the plates in order to maintain this 

separation at just the right value, while the 

supporting rods between the stem and the 

lower edges of the plates serve the same 

purpose at the bottom. The cross rod at 

the top of the plates is merely to prevent 

the plates from being bent away from their 

normal vertical plane, as a result of jars 

during transportation. This brace serves 

also to prevent vibration of.the plates when 

the tube is mounted on the sanie framework 

as the scanning -disc motor, as frequently is 

the case. 

The bull) surrounding the two plates is 

of particularly clear glass, to permit the 

radiation of the maximum amount of light. 

'fhe tube contains neon gas, at a low pressure, 

together with certain alkaline substances 

which increase the speed of operation 

imd the intensity of illumination. 

The tube is fitted with a standard UX 

base. The luminous plates are placed in a 

plane at right angles to the axis of the 

socket pin. In a television receiver, therefore, 

the pin should point directly either to 

or away from the scanning disc, in order 

that the glow -lamp's plates may be parallel 

to the disc. Connections are made to the 

plate, and one of the filament, prongs of the 

socket. 

CIRCUIT CHARACTERISTICS 

As with all types of gas -discharge tubes, 

the neon lamp has a very pronounced "negative- 

resistance" characteristic and a stabilizing 

resistor must always be used in series 

with the lamp and the supply voltages. 

(This is just a technical way of saying that 

the internal electrical resistance of the lamp 

decreases as the current through the lamp 

is increased. Thus, if no current -limiting 

resistor were to be used in series with the 

The steps in the assembly of a glow lamp: A, glass stem and wire supports, ready for the 

plates. B, plates mounted in position. C, plates completely assembled, with top wire supports. 

D, tube ready for evacuation. E, completed tube ready to work.

428 

tube, the current would tend continually to 

increase and, as it increased, the resistance 

of the tube would automatically decrease, 

causing still further current increase and so 

on; until an excessive current value was 

reached and the lamp destroyed.) A resistor 

which is smoothly variable through a 

wide range (0- 500,000 ohms) will be found 

very convenient for this purpose; as not 

only does it stabilize the tube operation, hut 

it serves also as a ready means for adjusting 

the current through the lamp, and thus 

its brilliancy, to the desired value. 

As will be seen from Figs. 2 and 3 a D.C. 

voltage of 180 is required for proper operation. 

By means of the series variable resistor, 

the current through the lamp may 

then be controlled between 5 and 20 milliamperes. 

With a current of less than 5 

milliamperes, the glow on the plates is not 

uniform and, therefore, not satisfactory for 

television use. As the current is increased 

in intensity from 5 to 20 milliamperes, the 

glow remains very uniform and increases in 

intensity. Currents in excess of 20 milliamperes 

should not be passed through the 

tube or its life will be materially shortened. 

As will be seen, either a separate D.C. 

source (which may be either batteries as 

in Fig. 3, or a good "B" power unit), of else, 

in some instances, the plate current of the 

power tube itself, as in Fig. 2; may be used 

to light the lamp. In case the regular 

power -tube plate supply is used, the plate - 

to- filament resistance of the power tube 

serves as the stabilizing resistor and the 

plate voltage must be increased from the 

normal value (180 volts in case of the 

UX -171 type) by an amount equal to the 

drop across the lamp (about 150 volts). 

71 TUBE 

VARIABLE 

RESISTOR 

11111111 

300 VOLTS' 

GLOW -LAMP 

Fig. 2 

64- 18o V. 

While the impedance of the neon lamp is 

quite low -500 ohms -it should. be operated 

directly in the output circuit of the power 

tube (either UX -171 or UX -210) without 

using any impedance -adjusting device. Such 

an arrangement is used because the television 

lamp is a current -operated device 

rather than a power -operated device; therefore 

the most desirable output circuit arrangement 

is one which provides for a maximum 

of current change in the plate circuit 

of the power tube in which the lamp is 

connected. 

REVERSING THE COLOR EFFECT 

It has already been mentioned that 

changing the D.C. connections to the tube 

changes the "glow" froid one plate to the 

other. Interchanging the A.C. connections, 

on the other hand, reverses the character of 

the image, in the reception of television. 

Thus one connection will give a positive 

picture, and the reverse a negative. 

That 

such a condition is possible will readily be 

seen if we consider the instant at which 

one A.C. lead is positive and the other negative. 

If these leads are so connected to the 

electrode plates that the A.C. " +" lead and 

the D.C. " +" lead are on one plate, and the 

A.C. " -" and the D.C. " -" lead on the 

other, the "instantaneous" current through 

the tube is equal to the instantaneous A.C. 

value plus the steady D.C. value and the 

instantaneous brilliancy of the illumination 

is greater than normal. 

If, on the other hand, however, the A.C. 

leads have been interchanged with respect 

to the D.C. leads, the instantaneous value 

of the alternating current opposes the direct 

current and, as a result, the brilliancy of 

Fig. 3 

A higher "B -I-Max 

voltage is needed in Fig. 

2, where the power tube's 

plate current lights the 

neon tube; while in Fig. 

3 the additional batteries 

are across the latter only 

(Sec page 423). The 

value of the coupling condenser 

is not critical. . 


P1 

P 

Fig. 1 

GLOW-LAM? 

SYMBOL 

PIN 

FRONT REAR 

PLATE 

P 

PLATE 

P1 

END VIEW OF BASE 

SHOWING CONNECTIONS 

The details here show more clearly the arrangement 

of the neon tube's elements. The article 

explains why the glow is on the outside 

of the plates -not between them, as might be 

expected. 

illumination will be below, rather than 

above, normal. See Fig. 4 on the next page. 

Thus, in the first instance, a signal impulse 

results in the illumination of the tube 

getting dimmer, and in the other brighter; 

which in turn, results in a positive picture 

in the first instance, and a negative in the 

second, providing the polarity of the signal 

voltage is the saine as it was at the transmitting 

end. In the case of some amplifiers, 

however, the instantaneous polarity of the 

signal voltage may be reversed by the time 

it reaches the television lamp; this is the 

case with a "grid leak- condenser" detector 

working into an even number of resistance - 

coupled audio stages. In such an instance, 

a reversed or negative image would always 

be obtained if it were not possible to correct 

matters simply by reversing the lamp connections. 

How to Adjust the Television Receiver for Operation 

THE first step in the reception of a 

television image is the locating of the 

signal on the receiver dials. This 

is best done with the aid of headphones 

or a loud speaker connected in place 

of the neon tube. Do not fail, however, to 

have a fixed condenser of about 1 mf. capacity- 

in series with the phones when connected 

in place of the neon tube or across 

-its terminals. 

The television signal has a distinctive 

sound but, unfortunately, the short -wave 

band contains several signals that. may 

easily be mistaken for television. For instance, 

the high -speed code transmissions 

of such stations as WIZ and WQO are 

quite like a television signal because of the 

"flutter," or what may be called a "group 

frequency." On the broadcast band, in 

which WRNY operates, this trouble will 

not be experienced. 

In addition to a low "group frequency," 

which is the rate at which complete pictures 

are transmitted and which is around 

18 to 20 cycles (per second), the television 

signal contains high- frequency- notes whose 

character depends upon the nature and 

the position of the subject before the transmitter 

pick -up. 

The experimenter will hear a signal 

which sounds at first like a flutter and will 

then note that this flutter is really the rapid 

repetition of a high-frequency note. The 

nature of this note and its loudness constantly 

change as the subject before the 

transmitter moves or is changed. For instance, 

a newspaper rolled up and held in 

a vertical position produces a distinct note 

which is very clean cut. A hand does not 

produce so clear a note, yet the signal is 

of the same general nature. 

. "CRAZY" IMAGES 

The television experimenter may, upon 

his first attempts, be puzzled to find his 

received images either turned upside down, 

or else reversed as when looking through a 

photographic negative the wrong way. Both 

of these faults can be corrected quite easily. 

It is quite obvious when an image is upside 

down, and the correction of this fault 

is equally obvious. The subjects before the 

transmitters at most stations broadcasting 

television are scanned from top to bottom 

during one rotation of the disc. Accordingly, 

if the receiving disc is so rotated 

that the plate of the neon tube is scanned 

from the bottom to top, the picture will be 

inverted. 'ro reverse the manner in which 

the neon lamp plate is scanned vertically, it 

is necessary either to reverse the rotation of 

the disc or to remove the disc from the 

driving motor and turn it around. The 

latter operation may involve the removal of 

the hub and remounting on the opposite 

side of the disc. 

Whether or not the received image is reversed 

horizontally, is impossible to tell 

unless one happpens to know the scene being 

transmitted, or unless distinctive char- 

acters are held before the transmitter pickup. 

For example, one of the objects often


Radio, News for November, 1928 

placed before the transmitter pick -up at 

station WLEX, in Boston, is a microphone 

stand with the station letters mounted 

on it. If the image of the microphone stand 

and letters is received with the object erect 

but reversed (so that the letters read 

"XELW") then the scanning disc is being 

so rotated that the holes pass the glowing 

plate of the neon tube in the wrong direction. 

The correction of this fault is not so 

obvious. It is plain that whether the experimenter 

scans the plate from top to bottom 

or from bottom to top, makes the difference 

between the picture being rightside 

up or upside down. Similarly, whether 

the experimenter scans the plate from left 

to right or from right to left makes the 

difference between seeing the image correctly 

or reversed. 

How can we make the holes pass the plate 

in the opposite direction and still progress 

from top to bottom? Reversing the rotation 

of the disc alone will turn the image 

upside down. The disc must also be turned 

around on the shaft of the motor. Thus 

if the image is right -side up but reversed, 

we must reverse the direction of rotation 

of the disc, and also remove the disc from 

the shaft and turn it around with the other 

side out. 

In spite of the fact that these two factors 

make three wrong combinations and only 

one correct one, the wrong combinations 

provide perfectly recognizable images whose 

worse fault is to be upside down. 

Should the image obtained be a negative 

instead of a positive, the trouble is due 

to reversed A.C. connections to the neon 

tube. Interchanging these connections will 

correct the trouble. 

In the experimental work at WLEX it 

has been found that the television signal 

may be almost submerged in noise and yet 

provide an image. This fact will undoubtedly 

be of interest to those who are already trying 

to receive the signals from WGY and 

WRNY and who think that reception is 

Fig. 4 

lrhen the image is negative, as shown at the 

right, the .4.C. signal is working against the 

battery. Reversing the leads to the lamp is 

the simplest remedy. 

hopeless, because of the noise caused by 

daytime electrical disturbances and the 

static of warm weather. 

It is true that, when we are interested in 

listening to a signal, the noise level is an 

important determining factor; but in the 

case of television, the noise level may be 

high -in fact, so high as to make speech 

429 

transmission hopeless -and still a fair image 

can be received. Of course, noise does 

not help matters; it produces a mottled 

background and tends to speckle the picture 

itself. Extreme noise will produce 

dark lines of varying width across the field 

of the image. But in spite of this, the 

picture is there and, since noise is non - 

periodic unless introduced by vibration front 

the motor and disc, the speckle and dark 

lines are continually shifting their positions 

while the image remains generally stationary 

or moves in an orderly fashion. 

Therefore, if in the experimenter's attempts 

to receive television images, he finds 

the signal more or less accompanied by 

noise, he should not judge the noise by 

speech broadcast standards, but go right 

ahead and try the signal on the disc. It 

goes without saying that the minimum of 

noise should be introduced by the set itself. 

Loose connections in the microphonic 

tubes, noisy resistors, and other causes of 

noises should be avoided. 

When a good television signal is being 

received, it sounds quite like a slowly -revolving 

circular saw which is slightly off 

center. In other words, one hears a high - 

pitched note which might correspond to the 

tooth frequency, and broken up into groups 

whose frequency corresponds to the rate 

at which the saw (the disk) rotates. The 

latter we have referred to as the group 

frequency while the high -pitched note is 

the modulation introduced by the scanning 

spot. If the dlise speed is high and the signal 

is weak, it may easily happen that the 

only sound audible in a pair of phones will 

be the group frequency. Even so, this is 

no indication .that a fair image cannot be 

received. 

Television Teems with Trials for Telexperimenters 

Editor, ltADto NEWS: 

In the interest of the science please allow 

me to make this suggestion: get the broadcast 

stations and the experimenters in television 

together and confine their experiments 

to the same type of scanning discs 

and same speed. You can well see the 

trouble that is sure to arise, with every 

different station using a different number 

of holes and .with different -speed motors. 

As yet I have not tried to receive any 

pictures from these stations on account of 

atmospheric conditions and the distance 

from the televisor; having confined my experiments 

to a simplified method of synchronism. 

I can get a stable speed on one 

frequency but, when shifting from one 

speed to another, great difficulty is experienced; 

and of course the layman will have 

even more trouble when he attempts this 

adjustment. Then too, how many television 

receivers do you suppose can be sold when 

the user is told how many discs will have 

to be changed before tuning from one stalion 

to another? 

Please accept this criticism or rather this 

suggestion in the same spirit it is given. 

WII.VER N. BARNES, 

1120 No. 22 Street, Waco, Tex. 

graphs and the like seem to call for such 

activity on the part of an enterprising experimenter 

as our imaginative artist has 

portrayed. 

However, the thing to be remembered is 

that all these transmissions are still, so 

o 

0 

o 

far as the working details are concerned, 

very much in the stage of experiment. The 


A DAY-AND-NIGHT TASK 

From one standpoint, our correspondent's 

good -natured protest may seem well justified; 

the numerous systems now projecting 

radio television, radio movies, radio photo- 

The paradise -or will it be purgatory ? -of the radio experimenter who tries to 

keep up with everything new in radio imagery. (Drawn front imagination.)

Pullman. 



List of Broadcast Stations in the United States 

Radio 

Call 

Letters 

n 

211 Radio 

BROADCAST STA. éi Call 

Location 3g fr.X Letters 

at ; q 

BROADCAST STA. 

Location $3 

Radio 

Call 

Letters 

BROADCAST STA. eö óñ 

Location t! a.3 

Radio 

Call 

Letters 

.1 eII 

BROADCAST STA, q XII 

Location E C3 

KD KA last Pittsburgh. Pa.. 316 50000 

KO LR Devils Lake. N. D 231 15 

K O YL Salt Lake City. Utah 234 500 

N EJK Los Angeles. Cal 252 250 

KELW Burbank. Calif 229 500 

KEX Portland, Ore 278 2500 

KFAB Lincoln, Neb 319 5000 

KFAD Phoenix, Aria 322 500 

KFAU Boise, Idaho 286 2000 

KFBB Havre, Mont 275 50 

K F B K Sacramento. Calif 275 100 

KFBL Everett. Wash 224 50 

KFBU Laramie, Wyo 484 500 

KFCB Phoenix. Aria 244 125 

KFCR Santo Barbara. Calif 211 100 

KFDM Beaumont, Texas 484 500 

KFDX Shreveport. La 236 250 

KFDY Brookings. S. D 545 500 

KFEC Portland. Ore 214 50 

KFEL Denver. Colo 227 250 

KFEQ St. Joseph. Mo 231 1000 

KFEY Kellogg, Idaho 232 10 

KFGQ Boone, Iowa 210 10 

KFH Wichita, Kan 246 500 

KF HA Gunnison. Colo. 250 50 

KFI Los Angeles, Calif 468 5000 

KF IF Portland. Ore 229 50 

KFIO Spokane, Wash 246 100 

KFIU Juneau. Alaska 225 10 

KFIZ Fond du Lac. Wis "268 100 

KFJB Marshalltown. Iowa 248 100 

KFJF Oklahoma City. Okla , 273 5000 

KFJ I Astoria. Ore 250 50 

KFJM Grand Forks. N. D 333 100 

KF JR Portland. Ore 240 500 

KFJ Y Fort Dodge. Iowa 232 100 

KFJZ Fort Worth. Texas 250 50 

KF KA Greeley. Colo 250 500 

KF KB MUford. Kansas 242 1500 

KF KU Lawrence. Kansas 254 505 

KF KZ Kirksville, allmoUrl 225 15 

KFLV Rockford, Il. 268 100 

KFLX Galveston. Tuns 270 100 

KF NF Shenandoah,lowa(day) 461 20ÓÓ 

KFOA Seattle. Wash 447 1000 

KFON Long Beach. Calif 242 1000 

KFOR Lincoln. Neb 217 100 

KFPL Dublin. Texas 275 15 

KFPM Greenville. Texas 231 15 

KFPW Sulphur Springs, Ark 263 50 

KFPY Spokane. Kash 248 250 

KFQB Fort Worth, Texas 333 1000 

KFQD Anchorage. Alaska 345 100 

KFQU 1101y City, Calif 220 100 

KFQW Seattle. Wash 217 100 

KFQZ lioli wood. Calif 232 250 

KFRC San Francisco. Calif , 454 1000 

KFRU Columbia. Missouri 250 . 500 

KFSD San Diego, Calif 441 500 

KFSG Los Angeles. Calif 252 500 

KFUL Galveston. Texas 258 500 

KFU M Colorado Spgs., Colo , 488 1000 

KFUO ?Clayton. Mo 545 1000 

KFUP Denver, Colo 227 100 

KFUR Ogden, Utah 225 50 

KFVD Culver City. Calif 216 250 

KFVG Independence. Kan 225 50 

KFVS Cape Girardeau, Mo 224 50 

KFWB Los Angeles, Calif 353 1000 

KF WC Ontario. Calif 248 100 

KFWF St. Louts. Mo 214 100 

KF W I Sao Francisco, Cal 268 500 

KFWM Oakland, Calif 236 500 

KFWO Avalon. Calif 300 250 

KFXD Jerome, Idaho 204 15 

KFXF Denver. Colo 283 250 

KFXI tEdgewater,Colo.(near)210 50 

KFXR Oklahoma City. Okla 224 50 

KFXY Flagstaff. Aria. 205 25 

KFYO Breckenridge, Tex 211 100 

KFYR Bismarck, No. Dak 250 250 

KGA Spokane, Wash 261 2000 

KGB San Diego. Calif 248 100 

KGAR Tueson, Aria 234 100 

KGBU Ketehikan, Alaska 400 500 

KGBX st. Joseph, Mo 288 100 

KGBY Columbus, Nebraska 222 50 

KGBZ York. Nebraska 213 100 

K G C A Decorah, Iowa. 248 10 

KGCB Oklahoma City. Okla 216 50 

KGCH Wayne, Nebraska 294 250 

KGC1 San Antonio, Texas 220 250 

KGCN Concordia, Kansas 208 50 

KGCR Brookings, So. Dak 208 15 

KGCU Mandan. No. Dak 240 100 

KGC X Vida. Montana 244 10 

KG DA 

Dell Rapids, So. Dak 

(daytime) 254 15 

KG DE Barrett. Minn 205 50 

KG DM Stockton. Calif. 217 10 

KG DP Pueblo. Colo. 224 10 

KGDR San Antonio. Texas 207 15 

KGDW Humboldt. Neb 294 100 

KGDY Oldham. So. Dak 207 15 

KGEF Los Angeles. Calif 263 1000 

KGEK Yuma. Colo. (day) 263 50 

KG EN El Centro. Calif 225 100 

KGEO Grand Island. Neb 205 100 

KGER Long Beach. Calif 216 100 

ROES Central City. Neb 204 10 

KGEW Fort Morgan. Colo 219 100 

KGEZ Kalispell. Montana 294 100 

KG FF Alva. Oklahoma 205 25 

KG Oklahoma 

Glendale, Calif Okla 263 250 

KGFI San Angelo. Texas 220 15 

KGFJ Los Angeles. Calif 213 100 

KGFK Hallock. Minn 224 50, 

KGFL Raton, N. M 222 50 

KGFW Ravenna. Neb 297 10, 

KGFX Pierre. S. D. (day) 254 200 

KGGF Ficher, Okla 207 100 

KGGH Cedar Grove. La 213 50 

KGHA Colo 210 500 

KG H B HonoluPueblo, lu, Hawaii 227 250 

KGHF Pueblo, Colo 210 250 

KGHG 

McGehee, Ark 

KGHI Little Rock, Ark 261 15 

KGHL Billings. Mont 222 250 

KGHX Richmond, Texas 52 

KG IF (portable) Nebraska 217 8 

KGJF Little Rock, Ark 250 

KG KB Gotdthwaite, Texas 280 

KG KO Wichita Falls, Texas '... 250 

KGO 

KGRC 

KGRS 

KGTT 

KGU 

KGW 

KG Y 

KHJ 

KHMC 

KHQ 

KICK 

KJBS 

RJR 

KKP 

KLON 

KLOS 

KLRA 

KLS 

KLX 

KLZ 

KMA 

KMBC 

KMED 

KM IC 

KMJ 

KM WI 

KMO 

KMOX 

KMTR 

KNRC 

KNX 

KOA 

KOAC 

KOB 

KOCH 

KOCW 

KO IL 

KO IN 

KOMO 

KORE 

KO W 

1 

Oakland, Calif "384 

San Antonio, Texas... 220 

Amarillo, Texas 244 

San Francisco, Calif 220 

Honolulu, Hawaii 270 

Portland. Oregon 492 

Lacey, Wash 246 

Los Angeles, Calif 400 

Harlingen, Tex 236 

Spokane, Wash 370 

Red Oak, Iowa (day) 322 

San Francisco. Calif 245 

Seattle, Wash 349 

Seattle, Wash 203 

Blytheville, {irk. (day) 286 

Independence, Mo , 270 

Little Rock, Ark.... 204 

Oakland, Calif 246 

Oakland. Calif 508 

?Dupont. Colo 353 

Shenandoah, Iowa 395 

see KLDS 

Medford. Oregon 270 

Inglewood. Calif 224 

Fresno. Calif 366 

Clay Center, Neb 286 

Tacoma. Wash . 254 

tSt. Louis, Mo 300 

Los Angeles. Calif 516 

Santa Monica, Calif 375 

Los Angeles. Calif 337 

Denver, Colo 326 

Corvallis Oregon (day) 270 

State CollegeN ew Mex :395 

Omaha. Neb 258 

Chickasha. Okla 252 

Council Bluffe. Iowa 319 

?Portland. Oregon. 319 

Seattle. Wash 309 

Eugene, Ore. "00 

Denver. Colo 219 

5000 

250 

50 

500 

1000 

10ÓÓ 

100 

1000 

100 

100 

2500 

15 

15ÓÓ 

50 

250 

500 

1000 

1000 

50 

25Ó 

250 

500 

5000 

500 

500 

500 

5000 

7000 

502(100 

250 

5000 

1000 

1000 

250 

WBAK Harrisburg, Pa. (day). 300 500 

WBAL ?Baltimore. Md "286 5000 

W B A O Decatur, Ill 268 103 

WBAP Fort Worth, Texas 500 5000 

W BA W Nashville. Tenn 240 5000 

WBAX Wilkes Barre, Pa 250 100 

WBBC Brooklyn. N. Y 227 500 

WBBL Richmond, Va 234 100 

WBBM ?Glenview. Ill "389 5000 

WBBR Rossvile, N. Y....., 256 1000 

WBBW Norfolk, Va 236 100 

W B B Y Charleston, So. Car 250 75 

W BC N Chicago, Ili 288 500 

WBES Salisbury, Md 265 100 

WHET Medford, Mass 288 500 

WBIS See WNAC 

WBMH Detroit, Mich 211 100 

WBMS Union City. N. J 200 100 

W B N Y New York, N. Y 236 500 

W BO Q Richmond Hill. N. Y 309 500 

WBO W Terre Haute, Ind 208 100 

WBRC Birmingham, Ala 303 250 

WBRE Wilkes Barre, Pa 250 100 

WBRL Tilton, N. H 232 500 

WBSO Wellesley Hills. Mass. 384 100 

WBT Charlotte, No. Car 258 1000 

WBZ ?Springfield, Mass. -.333 15,000 

WBZA Boston, Maas 333 500 

WCAC Mansfield, Conn 535 500 

WC AD Canton, N. Y 244 500 

WC AE Pittsburgh, Pa 461 500 

W CA Columbus, Ohio 234 250 

WCAJ Lincoln, Neb. (day) 380 500 

WCAL Northfield, Minn 286 500 

WC AM Camden. N. J 224 500 

WCAO Baltimore, Md 244 250 

WCAP Asbury Park, N.J 240 '500 

WCAT Rapid City. So. Dak 248 100 

WCAU Byberry, Pa 261 1000 

WC A X Burlington, Vermont 254 100 

WCAZ Carthage, Ill 250 5o 

list will be superseded on November 11, 1928, 

THIS 

by a new 

allocation. The new apportionment, as officially confirmed, will 

appear in RADIO NEWS for December, and should be consulted 

by readers at that time for new wavelengths, etc. 

KPCB Seattle, Wash 231 100 

KPJM Prescott. Aria 214 15 

KPLA Los Angeles. Calif 288 500 

KPO San Francisco. Calif 422 1000 

KPOF ' Denver, Colo 201 500 

KPPC Pasadena. Calif 316 50 

KPQ Seattle. Rash 231 100 

KPRC Houston, Texas 294 1000 

KPSN Pasadena. Calif 316 1000 

KQV . Pittsburgh. Pa. 270 500 

K Q W San Jose. Calif . 297 500 

KRE Berkeley. Calif. 231 100 

KRLD Dallas. Texas 461 500 

KRMD Shreveport, La 220 50 

KRSC Seattle. Wash 273 50 

KSAC Manhattan. Kansas 333 500 

KSBA ?Shreveport, La 268 1000 

KSCJ Sioux City, Iowa 244 '500 

KSO St. Louis. Mo 545 .500 

KSEI Pocatello. Idaho 333 250 

KSL Salt Take City. Utah 303 5000 

KS MR Santo Maria. Calif 273 100 

KSO Clarinda. Iowa 227 500 

9(500 Sioux Falls, So. Dak 210 250 

KSTP Westeott, Minn 220 3500 

KTAB Oakland. Calif 230 500 

KTAP San Antonio, Texas 229 250 

KTBI Los Angeles. Calif 275 1000 

KTBR Portland. Oregon 229 500 

KTHS Hot Springs, Ark 500 '1000 

KT NT Muscatine. Iowa 256 2000 

KTSA San Antonio. Texas 265 2000 

KTUE Houston. Texas 213 5 

KTW Seattle. Wash 395 1000 

KU Longview. Wash 200 10 

KU OA Fayetteville. Ark 297 1000 

KUOM Missoula. Mont 461 500 

KUSD Vermillion, So. Dak 484 250 

KUT Austin. Texas 232 500 

KV I Tacoma. Wash 283 250 

KVL Seattle. Wash 273 100 

KVOO Tulsa, Okla 949 .5000 

KVOS Bellingham. Wash 210 250 

KWBS Portland. Oregon 200 50 

KWCR Cedar Rapids, Iowa. 240 100 

K W EA Shreveport. La 213 100 

KWG Stockton. Calif 345 100 

KWJJ -. Portland. Ore 250 50 

W K St. Louts. Mo 234 1000 

K W KC Kansas City. Mo 222 100 

K W K H Kennonwood, La 395 3500 

K W LC DMorah, Iowa 248 50 

K W SC . Wash 395 500 

KWTC Santa Ana. Calif 273 100 

K W W G Brownsville, Texas 278 500 

KXA Seattle, Wash 535 500 

KXL Portland. Ore 220 250 

KXRO Aberdeen. Wash 224 50 

KYA San Francisco, Calif 361 1000 

KYW Chicago, Ill 534 2500 

KIM Oakland. Calif 231 100 

NAA Arlington. Virginia.. 434 1000 

WA A D Cincinnati. O 231 25 

WAAF Chicago. Ill 389 500 

WA A M Newark, N. J 268 250 

WAAT Jersey City. N. J 246 300 

WAAW Omaha, Neb. (daytime)441 500 

WA BC Richmond Hill, N. Y 309 '2500 

WABF Kingston, Pa 205 250 

WABI Bangor. Me. (Sundays) 389 100 

WA BO See WHEC 

WABY Philadelphia, Pa 248 50 

WABZ New Orleans, La 238 50 

WA DC Akron, Ohio 238 1000 

WAFD Detroit. Mich 231 100 

WAG IA Royal Oak, Mich 225 50 

WA 1U ?Columbus, Ohio 283 5000 

WALK Willow Grove. Pa 201 50 

W A P I Auburn, Ala 341 1000 

WASH Grand Rapids. Mich 256 250 

WBAA West Lafayette, Ind.. 273 500 

*Allowed higher daylight power Sta dard or constant -frequency transmission. I Remote Control. 

WC BA Allentown, Pa 222 100 

WC B D Zion. III 345 5000 

WCBM Baltimore, Md 225 100 

WCBS Springfield, IB 210 250 

WCCO ?Minneapolis, Minn-m.405 5000 

WCDA Cliffside, N..1 213 250 

WC F L Chicago, Ill 484 1500 

WCGU Brooklyn, N. Y 219 500 

WC LB Long Island City, N.Y 200 100 

WC LO Kenosha, Wise 227 100 

WCLS Joliet, Ill 216 100 

WC MA Culver, Ind 261 500 

WC OA Pensacola, Fla 250 500 

WC OC Columbus, Mies 231 500 

WCOH Greenville, N. Y 211 250 

W C R W Chicago, Ill 224 100 

WCSH Portland. Maine 366 5000 

W CSO Springfield, Ohio. 256 504. 

W C W K Fort Wayne, Ind 214 100 

WCX See WJR 

WDAE Tampa Fla 268 500 

WDAF Kansas City, Mo 370 1000 

W DAG Amarillo, Texas 263 1000 

WDAH El Paso, Texas 234 100 

W DA Y Fargo, No. Dakota 545 250 

W D BJ Roanoke. Va... 231 250 

WDBO Orlando, Fla 288 '500 

WDEL Wilmington, Del 297 250 

WDGY Minneapolis, Minn 286 500 

W DO D Chattanooga, Tenn 244 500 

W D RC New Haven, Conn 283 500 

WDSU New Orleans 1227 250 

WDWF-WLSI Cranston, R. I 248 250 

WDZ Tuscola, Ill. (daytime) 278 100 

WEAF ?Bellmore, N. Y "492 50.000 

WEAN Providence, R. I. 275 500 

WEAO Columbus, Ohio 283 750 

WEAR Cleveland, Ohio "400 1000 

WE BC Superior, Wie 242 1000 

WEBE Cambridge, Ohio 248 10 

WEB Q Harrisburg, Ill 224 15 

WEBR Buffalo, N. Y 242 200 

WEBW Beloit, Wis.:.. 258 500 

WEDC Chicago, Ill 242 100 

WEDH Erie, Pa 219 30 

WEEI Boston, Mora 508 500 

WE HS Evhnston, Ill 216 100 

WEMC Berrien Spas., Mich 484 1000 

WENR see WBCN 

WEPS Gloucester. Mass 297 100 

WEVD Woodhaven, N. Y 246 500 

WEW St. Louis, Mo. (day) 353 1000 

WFAA Dallas. Texas 545 500 

WFAN Philadelphia. Pa 224 500 

WFBC Knoxville, Tenn 234 50 

WFBE Cincinnati, Ohio. 246 250 

WFBG Altoona, Pa 268 100 

WFBJ Collegeville, Minn 273 100 

W FB L Syracuse. N. Y 258 750 

W FB M Indianapolis. Ind 275 1000 

WFBR Baltimore, Md 244 250 

W FC I Pawtucket, R. I 242 100 

WFDF Flint, Mich 273 100 

WFI Philadelphia, Pa 405 500 

W F I W Hopkinsville, Ken 261 1000 

WFJC Akron, Ohio 227 500 

WFKD Philadelphia. Pa 248 50 

WFLA Clearwater. Fla 517 750 

WGAL Lancaster. Pa 252 10 

WGBB Freeport, N. Y 246 155 

WGBC Memphis. Tenn 229 10 

WGBF Evansville. Ind 236 255 

W GB I Scranton. Pa 231 250 

W GBS ?New York, N. Y 349 500 

WGCM Gulfport. Miss 222 10 

WGCP Newark. N. J 268 250 

WGES ?Chicago, Ili 242 500 

WGHP ?Fraser, Mich 278 750 

WGMS Minneapolis, Minn 246 500 

WGN -WLIB Chicago Ac Elgin, I1141615.000 

W GR Buffalo, N. Y 303 750 

W CST Atlanta, Ga 270 500 

W HA Madison, Wise 333 750 

W HAD Milwaukee, Wise 270 500 

WHAM Rochester, N. Y '280 5000 

WHAP ?Carlstadt, N. J 236 1000 

W HAS Louisville, Ky 322 500 

W HAZ Troy, N. Y. (Monday) 306 500 

W H B Kansas City. Mo 341 500 

W H BC Canton, Ohio 236 10 

W HB D Bellefontaine, O 222 100 

WHBF Rock Island, Ill 222 100 

WHBL Sheboygan. Wis 204 250 

WHBP Johnstown, Pa 229 250 

W HS Q Memphis, Tenn 232 100 

WHBU Anderson, Ind 220 15 

W HB W Philadelphia. Pa 220 100 

W HB Y West De Pere, Wks 250 50 

WHDI Minneapolis, Minn 246 500 

WHEC -WA BO Rochester, N.Y. 254 '250 

WHFC Chicago, Ill 216 100 

WHK Cleveland, Ohio "265 500 

W H N New York, N. Y 395 500 

WHO Des Moines. Iowa 535 5000 

W HPP Englewood. N. J 205 10 

W HT ?Chicago. Ill 306 5000 

W IA Philadelphia. Pa 288 100 

W IAS Ottumwa. Iowa (day) 322 100 

WIBA Madison, Wle 240 100 

WIBG Elkins Pk..Pa.(Sund'ys)441 50 

W 180 ?Chicago, 111 306 5000 

W IBR Steubenville, Ohio 250 50 

W IBS Elizabeth, N. J 204 250 

WIBU Poynette, WO 217 20 

W I B W Topeka. Kan. 204 250 

WIBX Utica, N. Y. ..... 238 150 

W IBZ Montgomery. Ala 231 15 

W ICC Easton, Conn 265 500 

W IL St. Louis. Mo 258 250 

W INR Bay Shore, N. Y 211 500 

W IOD Miami Beach, Fia 248 1000 

W IP Philadelphia Pa 349 500 

W ISN Milwaukee, Wie 270 250 

W IVA Norfolk, Va 210 100 

WJAD Waco, Texas 333 500 

WJ AG Norfolk, Neb 286 250 

WJAK Kokomo, Ind 234 50 

WJAM Cedar Raplds.Iowa 240 250 

WJAR Providence, R. I. 484 500 

WJAS Pittsburgh, Pa... 270 500 

WJAX Jacksonville. Fla. 341 1000 

W J A Y Cleveland. Ohio 227 500 

WJAZ ?Mt. Prospect, Ili 263 5000 

WJBB Sarasota, Fia 238 250 

WJBC LaSalle, Ill. 227 100 

WJBI Red Bank, N. J. 263 100 

WJBK Ypsilanti, Mich 220 15 

WJBL Decatur, Ill 213 250 

WJ BO New Orleans, La 263 100 

WJBT Chicago, III. 389 500 

W J B U Lewisburg, Pa. 214 100 

WJBW New Orleans, La 238 30 

WJB Y Gadsden, Ala 234 50 

WJJD Mooseheart, Ill "366 1000 

WJ KS Gary, Ind 232 500 

WJR -WCX ?Pontiac, Mich 441 5000 

WJZ ?New York, N. Y "45430.0í0 

WKAQ San Juan, Porto Rico 322 500 

WKAR East Lansing, Mich 278 500 

W KAV Laconia, N. H 224 50 

W KBB Joliet, Ill 216 100 

W KBE Webster, Mass 229 100 

WKBF Indianapolis, Ind 252 250 

WKBH La Crosse, Wis 231 590 

W KB 1 Chicago, Ill 216 50 

W K B N Youngstown, Ohio 214 50 

WKBO Jersey City, N. J 219 250 

WKBP Battle Creek. Mich 213 50 

WKBQ New York, N. Y 219 250 

WKBS Galesburg. Ill 217 100 

WKBT New Orleans, La 252 50 

WKBV Brookville, Ind 219 100 

W KB W Amherst, N. Y 217 5000 

W K BZ Ludington. Mich 200 15 

W KEN Y 207 750 

WKJC 

er, Pa 252 50 

LancastsBUffalo, 

W KRC Cincinnati, Ohio 246 500 

WK Y Oklahoma CttyOkla 288 150 

W LAC Nashville, Tenn 225 5000 

W LAP Louisville, Ky 268 500 

WLB Minneapolis. Minn 246 500 

WLBC Muncie, Ind .. 210 50 

W LBF Kansas City. Kansas.. 210 50 

W LB Petersburg, Va 214 100 

WLBH Farmingdale. N. Y 232 30 

WLBL tStevens Point. Wise 333 1000 

WLBO Galesburg, Ill 247 100 

WLBR Rockford, Ill 248 15 

WLBV Mansfield Ohio 207 50 

W LB W Oil City. $a 294 500 

W LB Long Island City, N.Y 204 100 

WLBY Iron Mountain, Mich 210 50 

WLBZ Dover- Foaeroft, Me 208 250 

WLCI Ithaca, N. Y 248 50 

WLEX Lexington, Mara 218 50 

WLIT Philadelphia, Pa -405 500 

WLOE Chelsea, Mass 211 100 

WLS ?Chicago Ill "345 5000 

WLSI See WDWF 

WLTH Brooklyn N Y 256 250 

W L W ?Cincinnati Ohio 428 5000 

W L W L ?Kearny. N. J.. 370 5000 

WMAC Caaenovia, N. Y 225 500 

WMAF So. Dartmouth. Mass 428 500 

W MAK "Martinsville, N. Y 545 750 

W MAL Washington, D. C 242 500 

W MAN Columbus, Ohio 234 50 

WMAQ 'Chicago, Ill "447 2500 

W M A Y St. Louis. Mo 234 100 

WMAZ Macon, Ga 270 509 

WMBA Newport, R. I 204 100 

W MBC Detroit, Mich 244 100 

W M B D Peoria Heights. Ill 205 239 

W MBF Miami Beach, Fla 384 500 

WMBG Richmond. Va 220 50 

WMBH Joplin, MO 204 100 

WMBI ?Addison, Ill 263 5000

I 


Ocean 

105.90 


Radio 

BROADCAST STA. (e 

Location ;f Oa 23 

Radio 

Latter 


Location 

'« 

3f 

;ÿ 

¿; 

Radio 

Call 

Letter 

BROADCAST STA. oe 

Location 3 ¿= 

O. 

Radio 

Lett n 

BROADCAST STA. 4. l¡ 

Location 3f :; 

WMBL Lakeland, Fla 229 

WMBM Memphis, Tem 210 

WMBO Auburn. N. Y 220 

WMBQ Brooklyn. N. Y 204 

WMBR Tampa, Fla 252 

WmBS Lemoyne, Pa 234 

wMC Memphis. Tenn 517 

W MCA tNew York. N. Y 370 

LAMES Boston. Mage 211 

WMPC Lapeer. Mich 234 

WMRJ Jamaica, N. Y 207 

W MSG New York, N. Y 236 

WNAC -WBIS Boston, Mass,.,, 461 

WNAD Norman. Okla 240 

WNAT, Philadelphia. Pa 288 

WNAX Yankton. S. D. (day) 303 

WNBF Endicott, N. Y 207 

WNBH New Bedford, Mass 261 

WNBJ Knoxville, Tenn 207 

WNBO Washington, Pa 211 

WNBQ Rochester, N. Y 205 

WNBR Memphis. Tenn 229 

WNBW Carbondale, Pa 200 

WNBX Springfield. Vt 242 

WNBZ Saranac Lake. N. Y 232 

WO Newark, N. J 268 

WNOX Knoxville, Tenn 265 

WNRC Greensboro. N. C 224 

WNYC New York. N. Y 526 

WOAI San Antonio, Tex 280 

WOAN Lawrenceburg, Tem 240 

wOAX Trenton, N. J 240 

ans 

100 

10 

100 

100 

100 

250 

5000 

500 

50 

30 

10 

500 

500 

500 

100 

1000 

50 

250 

50 

15 

15 

100 

5 

10 

10 

250 

1000 

500 

500 

5000 

500 

500 

1s 

WOBU Charleston R. Va.... 268 250 

WOC Davenport, Iowa 375 5000 

WOCL Jamestown, N. Y 224 25 

WODA Paterson. N. J 294 1000 

WOI Ames, Iowa 265 1000 

WOKO Beacon, N. Y 216 500 

WOMT Manitowoc. Wis 222 100 

WOOD tGrand Rapids Mich 261 500 

WOQ Kansas City. Mo 341 500 

WOR tKearnY, N J 422 5000 

WORD tRatavia, III 252 5000 

WOS Jefferson City, Mo 422 500 

WOV tNew York. N. Y 294 1000 

WOW Omaha, Nebr 508 1000 

WOWO Fort Wayne, Ind 229 2500 

WPCC Chicago, Ill 224 500 

WPCH tNew York. N. Y 326 500 

WPG Atlantic City. N. J 273 5000 

WPRC Harrisburg, Pa 210 100 

WPSC StateCollege, Pa. (day) 300 500 

WPSW Philadelphia, Pa 207 50 

WPTF Raleigh. N. C 545 1000 

WQAM ML.mt. Fla 384 750 

WQAN Scranton, Pa. 231 250 

WQAO -WPAP tCliffslde. N. J 395 500 

WQBC Utica, Mies. (day). 216 225 

WQBJ Clarksburg. W. Va 40 05 

WQBZ Weirton, W. Va 250 60 

WRAF Lanorte. Ind ?fig 100 

WRAK Erie, Pa ?19 30 

WRAW Reading, Pa ... 238 100 

WRAX Philadelphia. Pa 213 250 

WRBC 

WRBH 

W RBI 

WRBJ 

WRBL 

WRBQ 

WRBT 

WRBU 

WRB W 

WRBX 

WRC 

W REC 

WREN 

WRHF 

WRHM 

WRJN 

WRM 

WRK 

WRN Y 

WRR 

WRUF 

WRVA 

WSA I 

WSAJ 

WSAN 

WSAR 

WSAZ 

WSB 

WSBC 

WSBF 

WSBT 

WSDA 

WSEA 

Valparaiso. Ind 238 

Manchester, N. H 

Tifton. Ga 222 

Hattiesburg Miss 250 

Columbus, Oa 258 

Greenville, Mies..,, 275 

Wilmington, N. C 227 

Gastonia. N. C 

Columbia. S. C 

Richmond. Va 

Washington, D. C 468 

tMemp ls, Tem 250 

Lawrence. Kan 254 

Washington.D.C.(day) 322 

tMinneapolis, Minn 261 

Racine, Wie 248 

Urbana, I0. 273 

Hamilton. Ohio 205 

tNew York. N. Y 326 

Dallas, ex 461 

Gainesville, Fla 203 

Richmond, Va 254 

tCinclnnati, Ohio 361 

Grove City, Pa 224 

Allentown, Pa 222 

Fall River, Mass 213 

Huntington. W. Va 250 

Atlanta. Ga 476 

Chicago, Ill 232 

St. Louis, Mo 258 

South Bend, Ind 400 

See WSGH 

Portsmouth. Va 263 

Allowed higher daylight power. Standard or constant -frequency transmission. tRemote Control 

LIST OF CANADIAN BROADCAST CALLS 

CFAC Calgary. Alm 435 500 CHCT Red Deer, Alta 357 1000 

CFBO St. John. N. B 337 50 CHGS Summetsslde, P. E. I 268 25 

CFCA Toronto, Ont 357 500 C H LS Vancouver, B. C 411 50 

CFCF Montreal, Que 411 CHMA Edmonton. Alta 517 250 

CFCH Iroquois Falls. Ont 500 1250 CHML Mt. Hamilton, Ont 341 50 

CFCL Toronto, Ont. (Sunday) 517 500 CHNC Toronto. Ont 517 500 

CFCN Calgary, Alta 435 1800 CHNS Halifax, N. 5. ...... 322 500 

CFCO Chatham. Ont 476 500 CHRC Quebec, Que 341 5 

CFCT Victoria, B. C 476 CHWC Regina. Sask 312 15 

CFCY Charlottetown. P.E.L. 312 

Chililwack, B. C 248 5 

CFJC Kamloops. B. C 268 

Montreal, Que 411 750 

CFLC Prescott, Ont 

297 

Toronto, Ont..517-357- 312 500 

CFMC 

CFNB 

CFQC 

CFRB 

CFRC 

CHCA 

CHCK 

CHCS 

Kingston, Ont. 268 

Fredericton N. B 248 

Saskatoon. Seek 330 

Toronto, Ont 312 

Kingston, Ont..... 268 

Calgary. Alta 435 

Charlottetown. P.E.I 476 

Hamilton. Ont. 341 

100 

15 

50 

20 

25 

500 

1 

250 

500 

CHWK 

CHYC 

CJBC 

CJBR 

CJCA 

CJCJ 

CJGC 

CJ G X 

CJHS 

CJOC 

CJOR 

Regina. Sask 312 500 

Edmonton. Alta 517 

Calgary, 

250 

London, Ont 330 500 

Yorkton. Sask 476 500 

Bask 330 250 

Lethbridge Sethbridge Alm 268 50 

Sea Island, B. C 291 50 

CJ R M Moose Jaw, Sask 297 

CJRW Fleming, Sask 297 

CJSC Toronto, Ont 517 

CKAC Montreal, Que 411 

CKCD Vancouver. B. C 411 

C KCI QJebee. Que 341 

C KCK Regina, Soak 312 

CKCL Toronto, Ont 517 

CKCO Ottawa. Ont 435 

CKCR Brantford, Ont 297 

CKCV Quebec, Que 341 

CKFC Vancouver. B. C 411 

C KG W Bowmanvllle. Ont 312 

CKLC Red Deer, Alta 357 

CKMC Cobalt. Ont 248 

CKMO Vancouver, B. C. 411 

CKNC Toronto. Ont 517 

CKOC Hamilton. Ont 341 

250 

500 

50 

10 

50 

100 

50 

50 

15 

_a 2 0 

500 

500 

750 

150 

1050 

50 

500 

100 

500 

500 

5000 

10X: 

5000 

250 

100 

250 

100 

1000 

100 

250 

500 

500 

WSGH Brooklyn, N. Y 227 50 

WS IX Springfield Tenn 250 15 

WSKC Bay City. Mich 273 25 

WSM Nashville. Tenn 337 500 

WSMB New Orleans, La. 297 76 

WSMK Dayton, Ohio..... 297 20 

WSPD Toledo. Ohio 240 250 

WSRO hllddletown. Ohio 236 10 

WSSH Boston, Mass 288 10 

WSUI Iowa City. Ia. day) 476 50 

WSUN St. Petersburg. la 517 75 o 

WSVS Buffalo. N. Y 204 5 0 

WSYR Syracuse, N. Y. 294 50 O 

WTAD Quincy, Ill 236 25 0 

WTAG Worcester, Masss 517 250 

WTAM Cleveland. Ohio... 400 350 0 

WTAQ Eau Claire, Wis 254 50 p 

WTAR- WPOR Norfolk. Va 236 50 

WTAS See WGN 

WTAW College Station, Tex 484 50 

WTAX Streator, Ill ... 248 5 

WTAZ Richmond. Va 220 1 5 

WTFF Mt. Vernon Hills. Va 20310,000 

WTFI Toccoa, Ga 210 00 

WTHS Atlanta, Ga 227 _ 0(I 

WTIC Hartford, Conn 535 500 

WTMJ Milwaukee. Wle 294 1000 

WWAE Chicago. III 227 500 

WWJ Detroit, Mich 353 ] 000 

WWL New Orleans, La 246 500 

WWNC Asheville, N. C 297 100 

WWRL tWoodelde. N. Y 200 10 

WWVA Wheeling. W. Va 517 25 o 

500 CKOW 

500 CKPC 

500 CKPR 

1200 CKSH 

LIST OF SHORT -WAVE STATIONS OF THE WORLD 

U. S. Short- Wove Stations wilt prefix their experimental calls with W or K after October 1, 1928; and others 

with their allotted national totters on or before January 1, 1929. 

50 

23 

500 

500 

100 

50 

50 

50 

5000 

1000 

100 

500 

100 

Toronto, Ont. 357 5n0 

Preston Ont 298 

Midland. Ont 268 0 

St. Hyacinthe Que. 297 b0 

CKUA Edmonton. Alta 517 55' 

C K W X Vancouver. B. C 411 100 

C K Y Winnipeg, Man 384 500 

CNRA Moncton, N. B 976 500 

C RC Calgary. Alta 435 500 

CNRE Edmonton, Alta 517 5'0 

C NR NI Montreal. Que 411 1600 

CHRO Ottawa. Ont 435 550 

CNRQ Quebec. Que 341 50 

C RR Regina. Sask 312 500 

CNRS Saskatoon, Sask 330 500 

C N RT Toronto. Ont 357 500 

C RV Vancouver. B. C 291 500 

CNR W Winnipeg. Man 384 500 

Radio 

Call 


Location 

Radio 

Call 

Letten 


Location 

Bad.- 

Call 

Letters 


Location 

la 

¡LO 

2BL 

2FC 

2ME 

SAR 

3AR 

3LO 

6AG 

LATH 

EB4A2 

CF 

CJRX 

EKaZZZ 

7MK 

7RL 

15W 

2NM 

CBS 

Radio LL 

FBAV 

Radio Vitus 

Radio Lyon 

YN 

FW4 

AFI 

AFT 

AFU 

AFK 

H EA 

AGC 

AGJ 

AGK 

LA 

POF 

POZ 

AFRICA 

Johannesburg, U. S. Akira_ _ 3 (Ó.O00 

Nairobi, Kenya 

h 

AUSTRALIA 

Sydney 32.50 

Sydney 32.00 

Sydney 28.50 

Melbourne 55.00 

Melbourne.. 55.00 

Melbourne 32.00 

Perth. West Australia 32.90 

AUSTRIA 

Vienna 37.00 

Vienna 22.20 

4.000 

BELGIUM 

Brussels 42.00 300 

CANADA 

Drummondville, Quebec 32.00 

Winnipeg, Man 25.60 2,01X1 

DANTZIG - 

Dantzig . . . . . - - . 40.00 

DENMARK 

Copenhagen 32.90 'd10 

Copenhagen 42.12 and 84.24 250 

ENGLAND 

Chelmsford 

24.30 15.01x) 

Catcrham 32.50 

Rugby 24.40 

Paris 

Nogent 

Paris 

Lyons 

Lyons 

Nancy 

Ste. Astise 

FRANCE 

61.00 

80.00 

37.00 

40.00 

8.00 

15.50 

24.50 

GERMANY 

Konigswusterlumsen 14.00 

Xonigswusterlansen 14.00 

KonllSwusterbaustn 14.00 

Berlin 45.30, 93.12, 41.50 

Nauen 11.00 

Nauen 1350 

Berlin 17.20 

Nauen 56.70 

Nauen 11.00 

Langenberg 43.90 

Nauen 11.00 

Nauen 

auen 18.10 

Konlgswusterhausen 52.00 

Stuttgart 41.00 

500 

51X) 

1,500 

50 

3,x0 

'00 

HOLLAND 

PCI, Eindhoven 31.4 30,0000 

PCKK Kootwllk 16.00 

PCLL Kootwllk 18.10 32.000 

PC PPM Kootwwilke 16.50 

PCRR Kootwilk 37.00 

PCTT Kootwijk 21.00 

PCUU The Hague 37.00 

ITALY 

iAX Rome 45.00 

IA Y Rome 45.00 

IMI Milan 45.00 

J FAV 

JHBB 

J IPP 

JKZB 

IAA 

..... ,:.:,,:,::,,:,,:,,:,,:,,:,,:,,:,,:,, :,,::,:,,::,:,,,,,,,,,,.,,, ,,,,,,,:,,::, ,,,,,,,,,,,,,,, 

THIS list of the short -wave broadcast 

stations throughout the world is not 

complete, although we bave endeavored to 

list every station of whom we have heard 

reports; since in many Cases reliable information 

about the programs, wavelength 

and power of the stations cannot even be 

obtained from the stations themselves. 

(See page 456.) 

JAPAN 

Taipeh. Formosa 

Ibarakiken 

Tokio 

Tokio 

Iwatsuki 

JAVA 

Malabar 33.00 

ANE Bandoeng 15.93 

ANF Malabar 56.00 

ANH Bandoeng 17.00 

Batavia 46.50 

MEXICO 

XC51 Mexico City 44.00 

MOROCCO 

AJN Casablanes 51.00 

NORWAY 

LCHO Oslo 33.00 

U. S. S. R. (RUSSIA) 

39.50 

37.50 5.000 

20.00 

20.00 

40.00 

RDRL Leningrad 28.50 

RDW 

Moscow 

RFM Knabarovak (Siberia) 7020 12,000 

RA19 Tomsk (Siberia) 37.00 

SPAIN 

LAM Madrid 30.70 

RAE55 Barcelona 1 

SAJ 

SMHA 

Karisborg 

Stockholm 

SWEDEN 

47.00 

41.00 

SWITZERLAND 

EH90C Berne 3200 

EH9XD Zurich. 85.00 and 32.00 

UNITED STATES 

KDKA (6XK) East Pittsburgh, Pa.... ... 62.50 40,000 

(8X8, SEP- portable) 

42.75 

KEJK (CRAN) Loe Angeles, Calif . 250 

KEWE Bolinas. Calif 14.10 

KFPY (7XAB) Spokane. Washington 105.90 100 

KFQU (6XBH) Holy City, Calif 31.00 50 

53.00 

63.00 

106.00 

KFQZ (6XAL) Hollywood. Calif 108.20 .50 

KFVD (6XBX) Culver City. Calif 105.00 50 

KFWB (6XBR, auto) Los Angeles, Calif 105.00 50 

40.00 

KFWO (6XAD) Avalon, Calif 53.07 100 

KGER (6XBV) Long Beach, Calif 48.86 

KGB San Diego, Calif 65.18 

KGDE Barrett, Minn 40.00 50 

KGO l6XAX, 6XN) 10 to 40 10,000 

KHJ (6XAU) Loe Angeles. Calif....... 104.10 50 

KJBS (SXAR) San Francisco, Calif.... 61.00 50 

KJR (7XC, 7X0) Seattle, Washington 105.20 250 

KMOX St. Louis, Mo. .... 49.00 15 

KMTR Lott Angeles, ('alit 108.20 250 

KNRC (6XAF) Santa Monica. Calif..... 108.20 100 

KNX (6XA) Los Angeles. Calif 107.10 100 

KOIL (9XU) Council Bluffs, Iowa 61.06 500 

KWE -KEWE Bolinas, Calif ....... .. 14.10 

KWJJ (7XAO) Portland, Oregon 53.54 100 

WAAM (2XBA) Newark, N. J 65.18 0 

WABC (2XE) Richmond Hill, N. '1' 58.50 500 

(Yacht 111U -1, 2XAO) 

WAJ Rocky Point, MY 22.48 

WBRL (1XY) Tilton, N. H 100.00 250 

WCGU (2XBH) Brooklyn, N. Y 54.00 150 

WCSH (1XAB) Portland, Maine 63.79 250 

WCX Pontiac. Michigan 32.00 75 

WEAJ Rocky Point, N. Y ' 2.48 

WEAO (9XJ) Columbus, Ohio 54.02 25 

WGY (2XAF) Schenectady, N.Y.. 31.401 

(2XAD) Schenectady, N. Y 21.96 

WHK (8)(F) Cleveland. Ohio 66.04 500 

WJR -WCX (CXAO) Pontiac, Michigan 32.00 

WIZ New Brunswick, N. J 43.45 

WJZ (3XL) New York, N. Y 59.96 30,000 

WLW ($XAL) Cincinnati, Ohio 52.02 25 

49.061' 250 

WNAL (9XAB) Omaha. Neb 105.00 50 

WNBT Elgin. Ill. (Time Signals) 35.50 500 

WND Township, N. J 46.48 

- 

WOR (2XAQ) Kearny N J 65.40 50 

WOWO Fort Wayne. Ind 22.80 1,000 

WRNS* (2XAL) New York, N. Y 30.91 500 

WTFF Mt. Vernon, Va 56.00



JT was a tense moment for the thousands 

gathered there in the great bowl of 

the Coliseum -those thousands of intrepid 

film fans who had risked crumpled 

fenders, crushed hats, comfort, and 

almost life itself, simply to gain a glimpse 

of that great man who is not only the chief 

idol of the film fans of the world, but a 

far -famed philanthropist as well. It was an 

equally interesting moment for millions of 

happy families everywhere, who, through 

the agency of television, were seeing with 

equal clearness from the privacy of their 

own homes every detail in the spectacle 

which was taking place in Los Angeles' 

great amphitheater. The palpitating hearts 

of countless devoted film fans throbbed in 

unison to realize that the deep, vibrant, 

resonant chest tones issuing from the loud 

speaker were the voice of him whom a 

whole world idolizes as one of supreme daring, 

of unsurpassed generosity, and of a 

breadth, depth, and thickness of character 

that mark him as the biggest and best 

film hero in the industry. The eyes and 

cars of;the whole world were turned toward 

that little platform in the blaze of a hundred 

spotlights, where Harold Dare, Flicker 

Films' famous favorite, was concluding the 

few well- chosen remarks with which he was 

bestowing upon Southern California a boon 

'for which generations to come would ever 

'bless :Iris name. 

. 

: furo you, Mr. Mayor, as representing the 

peóple of the Southland, I present this key - 

the key..-to progress, the key to prosperity, 

the Ivey to that great future which shall be 

Southern California's. May this be merely 

the beginning of a long advance, onward 

and uípward, bigger and better, toward that 

world supremacy which is the goal of every 

true booster. Here is power, Mr. Mayor. 

lay it ever be used for the greatest good 

to the greatest number." 

- Amid a thunder of applause, the Mayor 

took the little gold key and held it up before 

the eye of the televisor that all the 

millions in that vast outside audience might 

see. In n long eulogy of fulsome tribute, 

he traced for his audience the progress of 

Harold Dare's activities in this latest manifestation 

of the great screen star's boundless 

benevolence and whole -souled public 

spirit. He told how Harold Dare, ever 

watchful of the public welfare, ever lead- 

ing in everything that was bigger and better, 

had realized that Southern California 

faced a future power famine if means of 

expansion were not provided; how he had 

initiated and backed the movement for a 

great public -owned power system; how at 

every step he had been hampered by the 

insidious machinations of a certain power 

corporation, which saw in this project 

dangerous competition; and how, even after 

an overwhelming majority at the polls had 

demonstrated the public's confidence in the 

project, material had mysteriously disappeared 

from the site, important shipments 

had been unaccountably delayed or sidetracked, 

and a host of sinister occurrences 

had demonstrated powerful influences at 

work to undermine the screen star's great 

work of public benefaction. But that same 

indomitable courage and unswerving devotion 

to the public weal that have made 

Harold Dare the outstanding world figure 

that he is, had ever sustained him through 

all these crises and carried him onward and 

upward to his goal. Success was his at 

last! This key, when turned in the little 

lock on the control panel before the speaker's 

table, would send out an electrical impulse 

over many miles of copper wire, 

through the city and across desert wastes, 

over plain and mountain, to a structure of 

concrete and steel located among the desobate;, 

ragged- fastnesses of the high Sierras. 

Her'; at the head of a great blue lake feci 

from the melting snows, tons of water held 

chained by man's masterful mind would be 

released to do his bidding. 'Down from 

the great turbines whirled by the enslaved 

giant.wòuld coúrse a cataract of power, of 

electrical energy which, guided by three 

tiny threads..of copper flung across gorge 

and river, would speed the wheels of industry 

to an activity heretofore undreamed. 

"To you, Mr. Dare," concluded the Mayor, 

in a final burst of eloquence, with a sweeping 

gesture which summed up all the admiration, 

_respect, and : gratitude due so 

great a public benefactor, "Southern California 

owes a. debt it can never repay! 

"On behalf of the citizens. of the City of 

Los Angeles and of all Southern California 

as well, I accept this key; to their benefit, 

and that of posterity, I hereby dedicate the 

new Wolf Creek power line." 

He inserted the little gold key in the 

lock switch. A buzzer sounded; all the 

lights winked out, except a single brilliant 

spotlight trained upon the speaker's platform; 

upon three monitoring television 

screens suddenly appeared a vista -of huge 

dynamos against a background of switch - 

studded panels jewelled with control lights; 

and in the loud speakers rose an ascending 

whine as tons of water, surging through the 

great turbines, whirled the mighty generators 

faster and faster. 

The radio audience now beheld a strange 

sight. Down the middle of the television 

screen ran a narrow line, separating two 

distinct pictures. On the left, the Mayor 

and Harold Dare were acknowledging the 

storm of applause which swept the Coliseum; 

on the right appeared a panorama of switchboards 

and controls, at which operators 

were bringing up the Wolf Creek line into 

phase; while from the loud speaker issued 

a hum of busy dynamos against a background 

of frantic applause. The Dare technicians 

had scored another succes. By 

masking opposite halves of the fields of 

two television transmitters, one at Wolf 

Creek and another at the Coliseum, and by 

combining the currents as they were fed 

into the transmitter broadcasting the event, 

the two scenes were reproduced side by 

side upon the receiving- screens, much as 

in the double exposures common in motion - 

picture photography. The sound currents 

were simply superimposed upon one another, 

the relative proportions being regulated by 

operators at the conventional gain controls. 

The television circuits had required many 

days of careful balancing and adjustment 

before the synchronization had been perfected; 

the ultimate success was indeed an 

engineering triumph. 

Suddenly Harold Dare, bowing and acknowledging 

with matchless ease the tremendous 

clamor of applause of that enormous 

audience, sensed that something was 

wrong. He turned -and stood transfixed. 

The applause of thousands suddenly died; 

the smile of the Mayor faded from his face; 

for the silver screen of the televisor flickered 

and was dark. 

For a few endless seconds, Harold Dare 

and the Mayor stared, amazed, aghast, incredulous. 

An operator hurried over from 

the control box and spoke a few words in 

a low voice. The Mayor gasped and paled; 

but dauntless Harold Dare stepped calmly 

to the front and addressed the puzzled 

audience.



"Friends, there is no use in keeping the 

truth from you. The Wolf Creek line is 

dead." 

it murmur of amazement, mingled with 

indignation, swept the great gathering. Harold 

Dare raised his hand for silence. 

"Friends, before you judge or blame, let 

me tell you a few facts about the construction 

of the Wolf Creek line. The wires 

are run in duplicate -two complete sets 

upon each tower. If an insulator should 

fail, or a wire break, the other circuit would 

still maintain service. There is not one 

chance in a million that both lines should 

fail at the saute moment -and of all tuo- 

'meats, the very moment when failure would 

mean the greatest personal blow possible, 

a spectacular debacle calculated to shake 

the confidence of the public in this project 

and turn the admiration of the world to 

ridicule. Let me remind you, ladies and 

gentlemen, that although this line, strung 

from sturdy towers founded upon eternal 

rock, is made to withstand the ravages of 

the centuries, a single blast of dynamite 

might easily send one massive tower toppling 

into a ravine, doing damage it would 

take days to repair. As you all know, 

there are forces bitterly opposing this great 

project; they could have chosen no better. 

time to strike than now. No apology I 

could make would suffice; yet I promise 

you that I shall not sleep nor rest until 

the fiendish perpetrator of this crime against 

humanity is brought to justice!" 

The ovation these words received was 

tremendous. The thousands went forth with 

the warmest sympathy for the heroic stand 

of their great friend and protector. Not 

a woman but sighed a little in admiration 

for this fearless hero who thus smiled coolly 

in the very face of disaster; not a man but 

clenched his fist and protruded his jaw 

with just indignation toward the unprin- 

cipled persecutors of the public's dauntless 

champion. 

Who might be behind these dark and 

devious deeds? One none was whispered 

about with steadily growing persistency. 

Remembering the countless similar outrages 

perpetrated in the past by the monster, 

the public intuitively suspected Dandy Diavolo, 

that arch super -villain of the Flicker 

Films, who had ever pursued Dare with 

increasing relentlessness through the superlative 

Flicker Films, and in real life as well. 

Dare himself did not doubt that his archenemy 

was behind this plot, but his detectives 

were unable to find any trace of 

the villain, who had left for parts unknown 

to spend a short vacation between pictures. 

At two o'clock the next afternoon cante 

news that rocked all Southern California. 

The trouble in the Wolf Creek line had 

been located. Three insulators of the six 

on a single tower located on the edge of 

a cliff above a deep valley had shattered, 

allowing the wires to fall and short- circuit 

both lines. Working in continuous shifts, 

repairmen replaced the insulators in a few 

hours. 

The new insulator liad lasted hardy ten 

minutes. The startled linemen had scarcely 

gathered up their tools when a terrific arc 

rent the air. One huge insulator, then a 

second, shattered into a'thousand pieces, 

as if struck by a giant's hammer. Two long 

cables swung together and were welded 

into one; then as the intense heat melted 

the stranded copper, the severed wires 

traced tattered shreds of flame as they 

slipped along the steel tower to the ground. 

New insulators were rushed from the 

nearest supply station. Engineers hastened 

to the spot to make observations. While 

it was ostensibly their opinion that both 

insulators had developed flaws, possibly 

through strain while being hoisted to their 

433 

position several hundred feet in the air. 

in their hearts was developing a fear that 

some error had been made in the design. 

The insulators used had been tested under 

conditions so much more severe than any 

met in practice that . failure was unthinkable. 

Yet nothing seemed to stop the mad 

surge of half a million volts across this one 

apparent weak spot in the whole Wolf 

Creek line. Frankly, they were baffled. 

The new insulator was hoisted to its place 

under the strict scrutiny of world- famous 

electrical engineers. It had been given a 

thorough test and was apparently electrically 

perfect. 'l'he voltage was applied gradu- 

ally. At Wolf Creek station, a group of 

engineers watched tensely the meters registering 

line conditions, while at the tower 

itself, motion- picture cameras, equipped with 

telescopic lenses, made slow- motion pictures 

of the insulator from various angles. At 

length the line was carrying its full load. 

For moments the engineers watched, while 

reel after reel of film ran swiftly through 

the cameras. 

Suddenly the meters at Wolf Creek quiv- 

ered. As suddenly the needles shot across 

the scale; great circuit -breakers tripped; 

an arc flared and was quenched; and the 

generators whined at high speed as the 

load was removed from the line. The 

frightened engineers stared helplessly at 

one another. The Wolf Creek lines were 

dead! 

It was an old story the engineers saw 

re- enacted before their eves as a few hours 

later they sat in the projection room of 

the Dare laboratories at Hollywood. A 

tongue of flame suddenly bridged the gap 

between a cable and the tower. It grew 

to a broad ribbon, and slowly two great 

strings of bell- shaped insulators separated 

from their mountings amid a shower of 

large fragments of porcelain. As if in 

sympathy, another insulator on the other 

side of the tower also burst hito splinters 

of porcelain and the three floated leisurely 

to ground, while the cables tangled, melted. 

and dropped out of sight in the canyon. 


"d million people gazed horror -stricken; for to 

the topmost cross -arm of the /rge tower clung 

two lining skeletons- skeletons whose hands 

clutched pliers, skeletons that shouted hoarsely 

for lights!"



f 

j 

- 

a 

eer,,, 

9 0 

a s New -1 1 

ün a 

Ì f 

; 

Two -Way Regulator Corrects 

Line -Voltage Variation 

THE small box -shape device illustrated 

in this column is a voltage regulator for 

use in connection with radio receivers. It 

tential to 110 volts for the operation of 

the radio receiver, regardless of whether 

the line -voltage is above or below this value; 

whereas resistors are capable only of reducing 

the voltage. Secondly, the unit 

has a sufficiently wide range to cover all 

conditions; it will increase the voltage to 

normal value from as low as 90 volts, or it 

will decrease the voltage to normal from 

as high as 130 volts. Thirdly, there are 

eight voltage taps, thus providing a ver,v 

close adjustment. And fourthly, it is highly 

efficient, as it regulates the voltage by reactance, 

rather than resistance. 

The appearance of the device is clearly 

shown in the accompanying picture; it is 

housed in a metal box 41/4 x 414 x 3'''% 

inches and weighs 3 pounds. It is provided 

with a cord and plug for connection 

to the lamp socket, and also with a 110 - 

volt receptacle for the plug of the power 

transformer; the only adjustment is a knob 

which operates an eight -point switch. 

The way in which the unit is connected 

is shown in the schematic wiring diagram. 

Another illustration shows the mechanical 

construction of the combination switch 

which automatically connects the voltage - 

indicating buzzer when the voltage regulator 

is being adjusted. It will be noticed 

that the shaft turned by the adjustment 

knob is connected to the contact arm of 

SW1 and that, as the shaft is turned to 

the right, the contact arm of SW1 is turned 

and the switch SW2 is closed. However, 

as soon as pressure is removed from the 

knob, It spring opens switch SW2, thus 

disconnecting the buzzer. 

Manufacturer: R. B. 3!. Manufacturing 

Company, Logansport, Ind. 

To obtain 110 -volt current from a variable or 

non -standard lighting supply, plug the receiver's 

power -unit lead in at B on this device, 

and insert C in a light -socket. Adjustment is 

made by knob A, as shown in the diagram at 

the right. 

has been designed to correct the housesupply 

voltage to 110, the potential usually 

required by electric sets. It will operate 

in any A.C. circuit, provided the voltage 

is not greater than 130 nor less than 90, and 

it has an output of 60 watts, which is ample 

for the operation of the average set. 

It is not difficult to appreciate the importance 

of an A.C. line -voltage regulator, 

for the chief cause of dissatisfaction with 

electric receivers has been due to the short 

life of the tubes. It was first thought by 

the experimenters that this condition resulted 

from poorly -designed .tubes, but investigation 

has shown that variations in 

the 110 -volt house -supply current usually 

are responsible for overloading the filaments 

and reducing tube life. A. majority of the 

power transformers available for heating 

tube filaments are designed for 110 -volt 

operation and an increase in the input voltage 

will cause a proportional increase in 

the output. Therefore, in cities where the 

house potential rises to 120 and 130 volts 

during the evening, the tube filaments operated 

with A.C. are dangerously overheated. 

On the other hand, insufficient power is 

frequently the cause of poor reception. 

The voltage- regulating device illustrated 

on this page provides the broadcast listener 

with a very simple method of regulating 

the input voltage to a receiver. It is a 

simple auto-transformer, equipped with a 

special A.C. buzzer which vibrates when 

the potential applied to the receiver reaches 

110 volts. The interesting feature of the 

regulator is that the voltage- indicating buzzer 

operates automatically during adjustment, 

but is turned off by the removal of 

the operator's hand from the adjustment 

knob. 

Among other advantages it possesses, this 

regulator will correct the house -supply po- 

5W 2 

VIBRATOR 

5W 1 

TO 110V. A. C. 

SPRING 

5W 2 

-m41 

} 

110-V. RECEPTACLE 

FOR POWER TRANS- 

FORMER. 

T he auto -transformer steps the voltage either 

up or down, as required. The correct setting 

is indicated automatically by the buzzer; SW2 

functions only during the operation of adjustment. 

New Short -Wave Plug -In Coils 

Small and Rugged 

A well -known manufacturer of short -wave 

receiving equipment has developed some 

new plug -in coils which are small and of 

very rugged construction. The coils are 

sold in sets of three, as shown in the illustration. 

They provide a receiver with a 

wavelength range of 15 to 130 meters. 

A complete set of these coils consists of 

three interchangeable coils, a suitable base 

and an adjustable primary, which is 

mounted on the base. In each case the 

interchangeable coils have two windings, a 

secondary and tickler. The coils may be 

used in the standard fixed- tickler, capacity - 

controlled regenerative circuit, with a 140 - 

mmf. variable grid -tuning condenser and a 

250 -mmf. variable feed -back condenser. 

With this arrangement the smallest coil 

provides a wavelength range of 15 to 33.5 

meters, the next largest coil has a range 

of 31.5 to 68 meters, and the largest coil 

has a range of 57 to 133 meters. Also, coils 

of the same design are available for higher 

and lower wavelengths. 

The picture immediately below clearly shows 

the skeleton construction of the coils. The 

The compactness and convenience of these coils for the short -wave operator may be readily seen. 

The secondary- tickler coil at the left is for the 15 -33.5 -meter range, and that at the right for 

3L5 -68 meters. The 57. 133 -meter coil is shown plugged into the base; to which the primary is 

permanently attached, as it is the some in all combinations.



secondary winding consists of the necessary 

number of space -wound turns of enameled 

wire. The tickler winding is self -supporting 

and is wound with cotton -covered wire. The 

adjustable primary coil is also space -wound 

with enameled wire. 

Manufacturer: Aero Products, Inc., Chicago, 

Ill. 

Sturdy New 110 -volt Switches 

for Electric Receivers 

WITCHES of improved design have rel../ 

cently been placed on the market for 

use in connection with A.C. -operated receivers. 

Electrically, these switches are 

identical with those previously available, but 

their mechanical design has been changed 

to render them better suited for front -panel 

mounting. They are of the standard 110 - 

volt type, and may be operated with knobs 

of the type used for other radio apparatus. 

Their electrical rating is 3 amperes at 250 

volts. 

There is a considerable difference in construction 

between switches which are used 

in battery sets and those which must be 

used for A.C. receivers. In battery sets 

any single -pole switch may be used, as the 

potential in the filament circuit is never 

greater than six volts. On the other hand, 

in A.C. receivers the switch is connected in 

a 110 -volt circuit, and the only switches 

approved for this purpose are snap switches 

having a heavy spring which makes or 

breaks the circuit rapidly. Because of the 

high voltage in the circuit this type of construction 

is necessary in order to prevent 

arcing between the poles of the switch. 

Of necessity snap switches are quick in 

action and, for this reason, the usual radio 

knobs have not been used for their opera- 

tion. Most of the 110 -volt switches which 

have been available are of the toggle type, 

and this has disappointed many set constructors 

who have attempted to balance 

the arrangement of apparatus on their front 

panel. 

The switches illustrated on this page are 

of the usual toggle type, but there have 

been added to theist ingenious mechanical 

devices which permit operation by either 

a knob or plunger or in connection with a 

rheostat knob. In the case of the rheostat 

combination, as the knob of the unit is 

turned to the òff" position the switch turns 

the set off, and vice versa. The drawing 

shows the switch turned on, and dotted 

lines indicate the "off" position. In the 

knob -operated switch a ball- and -socket connection 

joins the shaft with the switch 

and, in the central switch, a knee joint 

couples the plunger with the contact arm. 

Manufacturer: The Hart and Hegentan 

Mfg. Co., Hartford, Caul. 

The power switch shown 

above is co, trolled from the 

panel of a set by its knob: 

which is of conventional appearance, 

but whose action, 

however, is to flip the sturdy 

toggle which controls the input 

from the lighting mains. 

The combination of rheostat and 

switch shown at the right differs 

from the usual one in that the 

switch is a heavy -duty one. built 

to make and break circuits carrying 

full house -lighting voltages. 

and therefore suitable for use in 

the power line fredinn the Unit. 

4=+ 

Radio Outlets Attractive 

For Home Wiring 

THE convenient radio outlets pictured on 

this page will be appreciated by fans 

who are anxious to improve the appearance 

of their installations. One outlet is equipped 

with tip jacks for the aerial and ground 

connections and the 

other is provided with 

a seven -wire jack and 

plug for the battery 

cable. Both outlets 

are made of lacquered 

brass and are the 

sane size as standard 

110 -volt power outlets. 

With the battery - 

wire outlet the jack -is 

mounted on the frame 

and the plug is free 

for connection with 

the battery cable. The 

plug is made in two 

parts and may be 

taken apart for convenience 

in soldering 

the seven wires of the 

battery cable to its 

terminals. Wires are 

soldered to the jack 

for connection to the 

batteries. 

It is not necessary 

to elaborate extensively 

on the ways in 

which these outlets 

may be used, as they 

are very convenient 

for a number of purposes. 

Of course, the 

way in which they 

may be employed in 

the individual installation 

depends largely 

on the arrangement 

of the radio appa- 

The outlets shown in this illustration 

are similar in finish to 

the wall plates used for lighting 

fixtures, and enable a room to 

be wired attractively for radio. 

The tip jacks shown above are 

intended for concealed lead -in 

and ground connections. The 

cable -plug receptacle below makes 

more cono,ient the operation of 

a receiver from either batteries 

or separate power unit, which 

may be conveniently located for 

set operation in several positions. 

ratus. A radio experimenter might mount 

them in the with or on the top of a worktable 

to enable him to quickly connect batteries 

when testing receivers. They are just 

as valuable to the radio listener who may 

wish to wire his house so that the set may 

be moved from one room to another quickly 

and easily; and for many other purposes 

which will readily occur to the user. Such 

wiring is especially desirable during new 

construction of residences and apartments. 

Manufacturer: l'axley Manufacturing 

Company, Chicago, Illinois. 

The switch ,drown in the 

center differs only in being 

operated by a shove or 

pull of the knob, not a 

tarn, 

435 

Battery -Cable Connector 

Handy for Builder 

IMPROVEMENTS and refinements are 

possible in all manufactured products, 

including such simple items as battery -cable 

plugs as well as more complicated radio 

parts. Although the usual cable connector 

is quite satisfactory for the purpose for 

which it is intended, a device of improved 

design which possesses several new features 

has been recently developed and placed on 

the market; it is illustrated in the drawings 

on the following page. 

In electrical design, the cable connector 

under discussion does not differ greatly 

front the usual product of this type. The 

cable consists of seven wires which are of 

different colors to permit identification; a 

seven -contact plug is soldered to the wires 

at one end of the cable and this plug fits into 

a receptacle which is mounted on. the baseboard 

or panel of the receiver. The contact 

prongs of the plug are split so that 

they make good contacts in their respective 

sockets in the receptacle unit. Also, a lug 

and notch have been placed in the plug and 

the receptacle, respectively, to insure that 

the plug must always be inserted in the 

correct position. 

An interesting feature of the cable connector 

is that it is available with either of 

two mounting receptacles, one of which is 

designed for baseboard mounting and the 

other for panel mounting; the construction 

of the two is shown in the drawings. Both 

types are made of molded Bakelite, and the 

color of the wire to which each soldering 

lug connects is engraved on the back of the 

receptacle. The baseboard -type receptacle 

unit is fitted with a base and may be

the 


436 

CABLE 

CONTACT PLUG 

PANEL MOUNTING 

RECEPTACLE 

BASEBOARD MOUNTING 

RECEPTACLE 

:In attractively- designed battery cable and receptacles 

of two types designed for use in 

connecting its plug to a receiver. 

mounted in a vertical position. A hole 1/ 

inches in diameter is required to receive the 

panel -type receptacle unit; . unit is 

mounted on the rear of the panel and the 

plug is inserted in the hole. The design of 

both receptacle units is such that there is 

easy access to the lugs with a soldering 

iron, and the lugs have been tinned and 

slotted to facilitate the connection of wires. 

The plug unit also of the cable connector 

is of molded bakelite, and is in three sections; 

the plug proper, an insulating separator, 

and a cap which protects the soldered 

connections. The connections of the 

plug are insulated carefully with bakelite 

partitions, so that a short- circuit of the 

wires is practically impossible, and a soft - 

rubber coupling prevents, any abnormal 

strain on the wires. Also, if an open circuit 

should occur, the plug unit may be disassembled 

and a new battery cable soldered 

in place. 

Manufacturer: Herbert II. Frost, Inc., 

Chicago, Ill. 

A Handy Time -Conversion Chart 

for th e Short -Wave DXer 

THE United States Department of Commerce 

recently has developed an international 

time chart which will prove to be 

a very useful article for radio listeners, par - 

ticularly those who are interested in long - 

distance, short -wave reception. The chart 

is being printed by the Government and 

may be obtained at a cost of ten cents 

(coin, not stamps) by writing to the Superintendent 

of Documents, Government Print- 

ing Office, Washington, D. C. It is made 

of heavy cardboard and is reproduced in the 

next column. 

Knowing the standard time and the longitude 

at any place on the earth, the corresponding 

standard time at any other place 

can be read directly from the chart. The 

inner circle is marked with the hours of the 

day, the white half for forenoon (a.m.) 

and black half for afternoon (p.m.); while 

the outer circle is marked off in degrees 

east and west of Greenwich. The inner 

circle may be revolved and by comparing 

the two scales, it will be seen that the time 

changes one hour for every 15 degrees 

change of longitude. 

To obtain the time at any place in relation 

to the time at any other place, it is 

necessary only to set the time on the inner 

circle to the longitude of the place where 

the time is known and to read the time 

indicated at the longitude of other place. 

It should he noted that the 180° meridian 

corresponds to the international date line. 

In going across this line from east longitude 

to west longitude, a day is lost; in the 

other direction, a day is gained. That is, 

a place just east of this date line is one 

day later than is a place just west of this 

line. 

For an example of the use of the chart: 

it is desired to.know the time in Alaska, in 

India, in Japan, and in New Zealand when 

it is 9.15 a.m., March 2, in Washington, 

D. C. 

Washington, D. C., is in the eastern -time 

zone of the United States and takes the 

time of the 75th meridian west. Setting 

the 9 on the white half of the inner circle 

so that it coincides with 75° west longitude, 

we are ready to read off the time in the 

other countries. Following the outer circle 

until the longitude; of Alaska is reached, it 

will be found the 4 on the white half of the 

inner circle coincides with this line, which 

indicates that it is 4.15 a.m., March 2. In 

the same way India is found half -way 

between 7 and 8 on the black half of the 

inner circle, which indicates 7.30+.15 or 

7.45 p.m., March 2, as the corresponding 

time for India. Likewise, the time indicated 

for Japan is 11.15 p. m., March 2. 

DEPARTMENT OF COMMERCE 

BUREAU OF STANDARDS 

GEORGE IL BURGESS, DúeM 


New Zealand is found coincident with 1.30 

on the white scale, which indicates forenoon, 

and since we have already passed the 

180° meridian, the time indicated is that 

of the next day or 1.45 a.m., March 3. 

Map Makes Handy Record 

of Continental Reception 

ACONVENIENT departure, from the 

usual wall -size map heretofore available 

to the radio fan for logging purposes, 

is to bé found in a new copyrighted radio 

chart of the United States, Canada, Mexico 

and the West Indies. It is niounted on a 

substantial sheet of heavy drawing -board 

and measures only 18 x 12 inches; so that it 

may be laid on the table or held in the lap. 

This map is furnished with 100 colored 

markers to record stations heard; and near 

the names of each "city the calls of the various 

broadcast stations located there are 

printed in such an arrangement that a separate 

marker may be used for each station 

without undue crowding. 

Manufacturer: Radio Map Company, Los 

Angeles, Calif. 

STANDARD TIME CONVERSION CHART 

4141M1'- 

FÚF 

PY 

. wESTcEAST 

Uncle Sam's handy calculator somewhat reduced. 

s 

(Directions for use on reverse side) 

4 

Miscellaneous Publication 

No. 64 

J 

;;e 

, .. ttte 

P.:« te..bt. 

The circle of hours is pivoted in the center. 

l



437 

PUTTING T11E AERIAL IN SI1AFE FOR WINTER 

Fig.. -. Lary men should replace frayed halyards 

before they break. It's a good deal easier then. 

NO'I'WITI- ISTA\DING the number 

of indoor aerials and loops now 

used with ultra- sensitive radio receivers 

there are many more outdoor 

aerials, good, bad and indifferent. Almost 

anything will do in fair weather, so 

long as it hangs fairly steady and keeps 

dry; but winter weather, with its gales, 

snow, sleet and ice often wrecks even the 

best aerial systems and renders the receiver 

useless until the wires can be put back in 

order. Consequently, it behooves the radio 

owner to put up a good aerial and keep it 

in order so that wild winter 

weather will not ruin it in the 

first gale. To do this and to 

insure good reception throughout 

stormy periods, the following 

hints should be followed and 

every effort made to see that 

insulators are inserted properly 

and halyards are strong, and 

PULLEY 

Fig. B. Only weight counts in this 

position. Fig. C. One piece of wire for aerial and lead -in 

may be fastened as shown here and in Fig. A. 

chief trouble with the latter is that its 

effectiveness is limited by its elasticity while 

the counterweight will allow the halyards to 

contract or stretch as much as needed without 

disturbing the tension of the aerial. 

Either one or the other idea is practically 

necessary to overcome the tendency of the 

halyard to snap during extreme high winds, 

wet and dry weather and similar disturbing 

influences. 

ONE PIECE OR TWO 

While it is always preferable to have the 

aerial and lead -in wire in one piece to do 

INSULATOR 

IQ 

SPIRAL SPRING O 

_mtnvevkvtN --sad 

6H A LYARD 

LEAD -IN 

HALYARD 

INSULATOR 

INSULATOR TUBE 

TIPPED UP AT ANGLE 

r 

SNOW COVERS 

LEAD-IN 

Be sure to do a thorough job of soldering, 

however, and one that will not eventually 

allow the joint to corrode. 

Avoid letting the lead -in hang over a flat 

roof or enter the room just above a window 

stool or ledge. (The diagrams in Fig. 3 

illustrate why) ; this, of course, if the wire 

is bare. With insulated wire the chances 

for leaks are considerably less unless the 

insulation becomes broken. 

No matter what the lead -in may be or 

how it entérs the room, provide aun insulator 

that will tip up through 

the wall and arrange a "drip - 

bend" at the entrance. With a 

tipped -up insulator the worst 

driving storm cannot blow up 

and under into the room; whereas 

one that tips down may lead 

to a stream of water eventually 

running over the wall or floor. 

At (1) and (2) we have optional 

methods for a safe anchorage of the 

aerial: see Fig. B above. The wrong 

tray to bring the lead -in down is shown 

at (3): obvious, why didn't we think 

of it before.' The connection at (4) 

will avoid lots of tranble. 

that all connections are clean and 

eliminate leaks and losses. 

First of all, do not secure the 

outer end of the aerial to a tree 

if it can be helped. Trees naturally 

bend and lash in high wind 

and. unless some efficient compensating 

device is inserted, the 

aerial is sure to break. Of 

course, a big tree can he usu with 

more or less success; but it is wise to have 

a stayed mast if possible. If a tree must 

be used, take up the backlash and the 

shrinkage with either a spiral spring in the 

halyard, between the pulley and the insulator, 

or a counterweight at the bottom 

of the halyard. Either is good but the 

writer prefers the counterweight; this can 

be composed of any old junk metal slightly 

heavier than the weight of the aerial, so that 

it keeps the latter taut, as shown in Fig. 1. 

Fig. 2 illustrates the spring method; the 

RAIN DRIP 

d 

CUT 

B 

STORM GUARD FOR THE LIGHTNING ARRESTER 

OIL 

SOAKE 

RAG 

away with splices, there are offsetting reasons 

why a splice may be the lesser of two 

evils. In winter a bare lead -in ruins every 

chance of becoming imbedded in the snow 

or sleet deposited on a window -sill or in 

a crevice, and thus short -circuiting the signals 

to the ground. It happens many, many 

times that, when signals have died out during 

a snowstorm, it is later found that the 

lead -in has been grounded in some such 

way. Now, by having the lead -in of heavily 

insulated wire and soldered securely to the 

aerial, such grounding is made impossible. 

The diagrams at (5) show three stages 

of the manufacture of a serviceable 

storm -guard for the lightning arrestor, 

which must be kept dry. The trick 

shown at (CO makes it possible to 

lubricate the aerial halyards conveniently. 

Prevention is always 

cheaper than repairs. 

'l'he drip -bend in the lead also 

tends to allow all accumulated 

water on the lead to drop to 

the bottom of the loop and be 

blown off. This arrangement is 

shown in Fig. 4. 

SHORTS IN THE ARRESTOR 

Watch your lightning arrestor; 

it can cause much trouble -shooting because 

of a short between the contacts inside. This 

is especially true of arrestors with an open 

back or other way by which rain or melting 

snow can creep inside. If you hear a 

click -click- click -during the height of a 

rain, but no such sound during dry weather, 

you can make up your mind the lightning 

arrestor is at fault. Even a sealed one 

can short with water across the terminals. 

A nice little hood is shown in Fig. 5 and 

can he quickly made from heavy roofing 




Electrodynamic Speakers Become Popular 

(14164 

N who has made the slightest 

attempt to follow radio developments 

during the past year is aware 

of one outstanding trend which is 

the cause of considerable discussion at the 

present moment; namely, the greatly increased 

popularity of the electrodynamic 

speaker. Less than one year ago a majority 

of the broadcast listeners in the United 

States had never heard the term electrodynamic 

used in connection with a piece of 

radio apparatus, whereas today it is on the 

tip of every radio fan's tongue. Further 

evidence of the sudden change which has 

taken place in the loudspeaker field may 

be gained from the fact that last year at 

this time only three manufacturers were 

making electrodynamic reproducers, and toclay 

they are being sold by two- thirds 

(thirty-two) of the larger manufacturers of 

receivers and by twenty -one speaker manufacturers. 

After giving the above statistics it is 

hardly necessary to explain that the electrodynamic 

loud speaker is a superior repro- 

ducer of radio music. It may be said that 

this loud speaker is capable of. reproducing 

a radio program with less distortion than 

any other type available at the present time. 

Also, these speakers are able to handle great 

volume without overloading and without distortion. 

Those who are inclined tobe skeptical 

of these claims are referred to accounts 

of the sound- transmission demonstrations 

conducted in New York City a few 

months ago under the auspices of the Bell 

How This Reproducer Differs Electrically and Mechanically 

From Other Horns and Cones, and the Necessary 

Conditions of its Operation 

By Fred H. Canfield 

Telephone Laboratories (see RADIO NEWS 

for April, 1928). Electrodynamic speaker 

units were used for these transmissions, and 

listeners on the New Jersey shore of the 

Hudson River were able to hear clearly a 

voice which was projected from a giant 

horn installed atop a New fork office building, 

three miles away. Of course, such performance 

cannot be expected from the usual 

speaker, but the experiment shows what may 

be accomplished with specially -built electrodynamic 

units. Also, it may be pointed out 

that such a feat has never been approached 

with electromagnetic speakers of the type 

usually used for radio reproduction. 

NOT A NEW INVENTION 

The electrodynamic speaker is not a new 

invention, although the suddenness with 

which great numbers of these speakers have 

appeared on the market has caused many 

persons to consider it as such. The fact is 

that the electrodynamic principle has been 

known and thoroughly appreciated by engineers 

for a number of years, and at least 

one speaker of the type has been on the 

market since the early clays of broadcasting. 

Also, it has been known that these speakers 

were capable of providing better results 

than the usual design of "electromagnetic" 

speakers. They have not been used generally 

because their construction is necessarily 

moré elaborate and complicated than 

other types, and because the quality of 

reproduction obtainable from the average 

set in previous years did not warrant the 

4*(0 

Fig. C. 

This picture shows an electrodynamic speaker 

cabinet of usual design. The grille. backed 

with a light cloth, conceals the opening for 

the cone, and thé cabinet itself serves as a boxtype 

baffle. The rear of the cabinet is open, 

but covered with a wire mesh. 

use of a better speaker than those available. 

Before continuing further with this article, 

the meaning of the terni electrodynamic, 

when applied to a loud speaker, will 

be explained. In this connection it should 

be understood first that the word refers to 

the electrical principle upon which the 

speaker operates, and not to the construction. 

From this it may be seen that any 

of the popular types of speakers, such as 

the cones, horns, stretched- diaphragms, etc., 

may be electrodynamic or permanent -magnetic 

in principle; the only difference between 

the two being in the loudspeaker 

unit. It so happens that a large majority of 

the electrodynamic speakers on the market 

are of the free -edge cone type, because this 

is considered the most practical design for 

these speakers. 

Fig. B 

Two electrodynamic horn speakers are shown above; that to the left is a small 

cabinet -size exponential horn which has been designed for home use. The 

speaker at the right is a large double exponential horn intended for use in theaters. 

in connection with the presentation of talking moving- pictures. It is five 

by six feet in cross -section at the opening. 

WHAT THE DIFFERENCE IS 

The chief difference between the permanent- 

magnet and electrodynamic speaker 

units is in. the source of magnetic force. 

As the name indicates, the first type employs 

a permanent magnet to produce the 

necessary lines of magnetic force; but in 

the case of the electrodynamic speaker, an 

electromagnet is used for the same purpose. 

Electromagnets have many advantages over 

permanent magnets, but they require a 

source of direct current for their operation. 

These magnets consist of coils of many 

turns of wire wound over cores of soft iron. 

With magnets of this type it is possible 

to produce a field of great strength, such 

as is required for the reproduction of 

strong radio signals. 

The second difference between the two 

types of speaker units is in the method of 

producing vibrations of the diaphragm. In


Radio News for November, 192Y 

the permanent-magnet unit the modulated 

current from the radio receiver flows 

through coils wound over the magnet, and 

a diaphragm is located so that it is separated 

a fraction of an inch from the pole 

pieces of the magnet. The modulated current 

causes changes in the magnetic force 

and these cause the diaphragm to vibrate. 

On the other hand, in the electrodynamic 

speaker a moving coil is freely suspended 

in the field of the electromagnet, and this 

coil is fastened directly to a free -edge cone. 

The modulated current from the receiver 

IRON CASE 

FRAME 

MOVING COIL SPRING 

IRON 

CORE 

MAGNETIC PATH 

ro ricco EICIT,Nc 

CURRENT SUPPLY 

TO RADIO OUTPUT 

TRANSFORMER 

MOUNTING HOLE 

Fig. 6 

AMOIS 

FELT 

NSULATION 

The mechanical construction of an electrodynamic 

speaker unit for a free -edge cone is 

illustrated in this cut -away drawing. The paper 

cone, to which the moving coil is attached, is 

non- rigidly supported in position by a spring 

at the apex and a strip of chamois at the 

opening. 

passes through this coil, causing it to move 

in its field with each pulsation; and as the 

free -edge cone is fastened directly to the 

coil, it vibrates and sets up the sound 

waves we hear as voice or music. 

ADVANTAGES OF TILE DYNAMIC 

The outstanding electrical advantage of 

the electrocl-nt speaker unit over other 

designs is found in the fact that the forces 

on the moving coil are dependent only upon 

the current in that coil. The magnetic field 

of the speaker is of great strength and 

the coil in the field has no effect upon the 

reproduction. Also, there is no iron armature 

to saturate. These facts result in 

complete freedom from distorting harmonics 

introduced by the speaker itself. 

The mechanical construction of- the electrodynamic 

speaker unit results in additional 

advantages. From the drawings it 

will be noticed that the motion of the moving 

coil is parallel to the pole pieces instead 

of between them; as a result, the danger of 

hitting the pole pieces is eliminated. Secondly, 

the usual driving rod, which is apt 

to bend and vibrate, has been eliminated by 

attaching the moving coil directly to the 

cone diaphragms; in this way another cause 

of distortion has been eliminated. Thirdly, 

IRON CORE IRON CASE MOVING COIL CONE 

Ililli1111i 

.w_..-.- 

11 

TO FIELD EXCITING/. TI O RADIO O UTPI 

CURRENT SUPPLY 

TRANSFORMER 

Fig 5 

Th's schematic diagram clearly illustrates the 

electrical design of an electrodynamic speaker. 

the small moving coil offers almost a pure 

resistance load to the tube. These three 

factors, combined, stake it possible for the 

speaker to provide great volume without 

distortion, and allow the unit to provide 

uniform reproduction on all frequencies. In 

addition, the driving unit itself does not 

have a definite resonance frequency. 

Another interesting feature of the electrodynamic 

speaker is that it will not 

weaken with use or ages; for there are no 

permanent magnets to become weak as they 

lose their magnetism. 

APPLICATIONS OF THE UNIT 

Early. in this article it was stated that 

electrodynamic speaker units may he employed 

for the operation of any standard 

type of loud speaker, but that the free -edge 

cone speaker is now being used almost exclusively 

in connection with these units. 

The mechanical construction of a speaker 

of this type is shown in Fig. 6, and a picture 

of the unit is given in Fig. A. 

In these illustrations it will be seen that 

the electrodynamic unit is much larger and 

heavier than the permanent- magnet type. 

The field winding consists of thousands of 

turns of wire wound over a solid -iron core; 

this coil is housed in a heavy cast -iron case 

at least four inches long and four inches 

in diameter. The frame for the cone is 

attached to one end of this case, at the end 

of which there is an opening for the moving 

coil. The paper cone is non -rigidly attached 

X -Y EFFECTIVE SIZE OF BAFFLE 

WOODEN BAFFLE' 

ELECTRODYNAMIC UNIT 

MOUNTING HOLE 

BRASS 

BRACKET 

SUPPORTING 

BLOCK 

WOODEN 

BASEBOAR 

Yf 

Fig. 4 

This drawing slows the method usually employed 

in attaching an electrodynamic free - 

edge -cone speaker unit to a baffle of the flat 

type. The baffle board should be approximately 

three feet square, and the frame of the 

speaker should be securely fastened with Tvood 

screws to the baffle at the opening. 

to the iron frame with a strip of chamois 

at the large end; at the apex a flexible 

spring holds it in position. Therefore, it 

may be seen that the cone is perfectly free 

to vibrate. The moving coil is attached to 

the apex of the cone, and this coil fits over 

the iron core of the magnet. Connection is 

made to the moving coil with flexible wires, 

as shown. 

'l'tvo methods are provided for mounting 

the usual electrodynamic cone. A bracket 

is fastened to the case for mounting the 

unit on a baseboard; the input transformer 

of the speaker is usually mounted on this 

sauce bracket. Also, holes are drilled in the 

cone frame for fastening the baffle board 

rigidly in place. In addition, it will be 

noticed that the front of the frame is covered 

with a felt pad in order to insure an 

air -tight connection between the frame and 

the baffle. 

439 

Electrodynamic speaker units are made 

also for exponential horns. 'l'he electrical 

construction of these units is identical with 

that of the cone type, but the mechanical 

construction is changed somewhat. The 

frame for the cone and the cone itself are 

eliminated, and the moving coil is attached 

to a diaphragm. The picture, Fig. B, shows 

a large double exponential horn with two 

electrodynamic units attached. This horn 

has a bell five by six feet in cross section, 

and was designed for use in theaters in 

connection with talking moving pictures. 

i lowever, electrodynamic units for use with 

smaller horn speakers are available. 

A smaller speaker of this type, designed 

for use in a console cabinet, is also illustrated. 

THREE TYPES OF SPEAKERS 

Thus far in this article the various advantages 

of electrodynamic speakers have. 

been considered. However, there are many 

interesting things regarding the operation of 

these speakers which must be explained. The 

first is supplying the current for the field 

winding, and the following paragraphs will 

describe the various systems which may be 

used. 

The electrodynamic speakers on. the market 

are of three general types, viz: those 

which require a high- potential supply for 

the field winding, those which require a low - 

potential supply, and those which obtain 

direct current for the field winding front 

an alternating- current supply. 'l'he latter 

type of speaker is merely plugged into a 

110 -volt A.C. light socket and a transformer 

and rectifier, built -in as part of the speaker, 

convert the A.C. into a low -voltage 

U.C. of the value required for the operation 

of the instrument. (See Fig. 3.) The 

first two types of speakers require an external 

source of direct current. 

Speakers requiring a high -voltage supply 

mar- be operated with D.C. developed 

by a standard "B" power unit, and the 

field winding may be employed as an A.F. 

choke coil in the filter circuit at the same 

time, thus improving the operating char- 

acteristics of the power unit. There are 

several different ways of connecting the 

field winding in the power -supply- circuit. 

Practically all of the speakers having 

high -potential field windings require approximately 

50 milliamperes at 110 volts. 

'l'he selection of this value of current for 

Fig. A 

.4u A.C.-operated electrodynamic speaker unit 

of the free- edge -cone type is slow', above. 

711e instrument mounted on the left side of 

the base is the input transformer, and the 

parts at the right of the base are the step - 

down power transformer and the dry-electrolytic 

rectifier.


440 

the field supply is very fortunate, as 110 

volts corresponds to the usual drop in voltage 

across a choke coil in a "B" power unit, 

and the amount of current required by the 

average five- or six -tube receiver with a 

power tube in the last stage is about 50 

milliamperes. Therefore, the field winding 

of the speaker may be substituted for one 

of the choke coils and no other adjustments 

are necessary. However, it is always wise 

to insert a milliammeter in series with 

the circuit to make sure that the speaker 

is receiving approximately the correct value 

of current. 

In receivers which employ more than six 

tubes, and sets which have a push -pull 

power stage, the plate current is frequently 

greater than the current required by the 

loudspeaker field winding. When this is 

the case, the method described above cannot 

be used without danger of burning out 

the field coil. However, there is a very 

simple solution to the problem; the filter 

circuit of the power unit is not disturbed 

and the field winding of the loud speaker 

is connected after the two choke coils in 

series with the positive wire. The plate 

current for the push -pull power tubes is 

then taken from the positive wire at a point 

between the second choke coil and the field 

winding of the loud speaker. The advantage 

of this circuit is that the plate current 

of the power tubes does not pass through 

the field winding of the loud speaker, and 

also the plate current supplied to the low - 

potential tubes of the receiver receives 

additional filtering. 

COUPLING SPEAKER AND TUBE 

The second thing to consider in connection 

with operating electrodynamic speakers 

is the method of connecting the moving coil 

to the plate circuit of the last audio-amplilier 

tube. It should be explained that a 

step -down output transformer must be 

used, and the impedance of the secondary 

winding of this transformer must be 

matched to the impedance of the moving 

coil. The output transformer for these 

speakers is usually built into the speaker, 

Ind is sometimes supplied for external con- 


Fig. i 

This diagram shows a combination "B" socket -power unit and last -stage A.F. 

amplifier, with the field winding of an electrodynamic speaker connected in place 

of one of the usual filter choke coils. When this arrangement is used the 

speaker receives field current, and the field winding acts also as a choke coil. 

nection. In either case this transformer 

must be used, and the regular output transformer 

or output filter in the receiver disconnected. 

When it is desired to use an electrodynamic 

speaker in connection with a push - 

pull amplifier, another problem presents 

itself, as the output transformer supplied 

with the speaker is not of the push -pull 

type. The most satisfactory solution to 

this problem is to connect a center -tapped 

output impedance unit in shunt with the 

primary winding of the transformer, and 

to connect the two outside terminals of 

the impedance to the plates of the two 

tubes. Then, the high -voltage supply for 

the push -pull tubes is connected to the 

center -tap terminal of the output impedance. 

If desired, it is possible to insulate 

the output transformer from the high -voltage 

supply by connecting a large by -pass condenser 

in each of the two wires from the 

primary of the transformer to the impedance 

unit. These condensers are not essential, 

but when the wires from the set to the 

speaker are exposed, they serve as a protection 

against accidental contact with the 

high voltage. 

Fig. 1 shows the complete circuit of an 

electrodynamic speaker connected with a 

standard full -wave "B" power unit and a 

power amplifier using a single tube in the 

output circuit. Ti and V'1 are the usual 

povi'er transformer and the full -wave gaseous 

rectifier tube, with Cl and C2 buffer 

condensers having a capacity of 0.1 -mf. L1 

is a standard single filter choke; the field 

coil of the speaker (L2) replaces the sec- 

ond filter choke. The condensers, C3, C4 

and C5, are the usual filter condensers, 

and CG and C7 are 1 -mf. by -pass condensers. 

In the amplifier circuit, T2 is a 

standard A.F. transformer, VI is the power 

tube and T3 is the output transformer, 

which is supplied with the loud speaker. 

The output transformer, it will be noticed, 

is connected to L3, the moving coil of the 

loud speaker. 

Fig. 2 

When the total plate current of a socket -power unit exceeds a certain value the 

circuit shown in Fig. 1 cannot be used for the operation of an electrodynamic 

speaker without danger of burning out the field winding. The above circuit provides 

a satisfactory solution to the problem, as the plate current for the power 

tube is tapped before it reaches the field winding. 

OBTAINING PROPER FIELD CURRENT 

In arranging a circuit in this manner, 

it is important to make sure that the field 

winding of the speaker receives the proper 

current, and if the current in the circuit is 

insufficient, it will be necessary to change 

the characteristics of the voltage- dividing 

resistor, R1. For example, the instructions 

supplied with the speaker may state that a 

field current of from 40 to 70 milliamperes 

is required, and a milliammeter connected 

in series with the field winding may show 

that the current passing in the circuit is 

only 35 milliamperes. Under these conditions 

the speaker will not operate at maximum 

efficiency, and it will be necessary to 

use a voltage -dividing resistor of a lower 

total resistance. It is possible to correct 

this condition by connecting a resistor in 

shunt with the voltage divider or by redesigning 

the resistor, as described in an 

article entitled "Applying Ohm's Law to



á 

e 

6 y~j 

ó 

The socket- operated electrodynamic speaker 

uses a dry -electrolytic rectifier R to convert 

the stepped -dawn A.C. current into 6 -volt direct 

current for the field winding LI. This arrangement 

may he used by the constructor 

with a speaker of the D.C. type, or a trickle 

charger may be employed. 

Radio Apparatus," which was published on 

page 1348 of RADIO NEWS for June, 1928. 

However, in a great majority of cases it 

will be found that the current passing in 

the circuit will satisfy the requirements of 

the speaker. 

Fig. 2 shows the method of connecting 

the speaker to a "B" power unit used in 

connection with a large set employing a 

push -pull amplifier. In this case the total 

current consumed by the set is so heavy that 

it would be apt to burn out the winding 

of the speaker, and, therefore, the plate 

current for power tubes is tapped before 

it reaches the speaker's field winding, which 

is connected as part of the voltage divider. 

In this circuit all the wiring and parts on 

the left side of the "13 +JIax." wire is standard, 

but on the right side of the line several 

changes have been made. Part of the voltage 

divider must be removed from the circuit 

to compensate for the drop in potential 

which takes place across the windings 

of the loud speaker, and probably the remainder 

of the voltage divider will have to 

he redesigned to permit a flow of current 

sufficient to operate the field winding of the 

speaker. For data on redesigning the voltage 

divider the reader is again referred to 

the article in the June number of RADIO 

NEWS. The circuit also shows the method 

of connecting the output circuit of the push-. 

pull amplifier with the moving coil of the 

speaker. L5 is a standard center -tapped 

output impedance unit, and T3 is the output 

transformer of the speaker. 'l'he condensers 

C9 and C10 are not absolutely 

necessary, but, if used, -should have a capacity 

of 2 to 4 mf. - 

With the low -potential electrodynamic 

speakers, the field coil is operated usually 

by a storage battery- connected to the winding, 

but it is also possible to employ A.C. 

operation, as shown in Fig. 3. ln this circuit 

T1 and R are a step -down transformer 

and a full -wave dry -electrolytic rectifier, respectively, 

which deliver direct current at 

6 volts and / ampere. A standard trickle 

charger may be used to supply this current. 

WHAT IS A BAFFLE? 

The baffle is the next subject for consideration 

in connection with the operation 

of electrodynamic speakers. The baffle is 

a board on which the speaker is mounted; 

itit is absolutely essential in order to obtain 

good reproduction from electrodynamic 

units of the free -edge cone type. In speakers 

of this type two distinct sets of sound 

waves are set up, one from the front and 

one from the rear of the cone. These sound 

waves will alternately neutralize and rein- 

T2 

force each other if the proper precautions 

are not taken, and it is the baffle which 

prevents such interference. Also, the size 

of the baffle determines the lowest frequency 

which the speaker will reproduce with full 

Baffles are of two general types: the flat 

baffle and the box baffle. 'l'he two are 

equally effective, but the box -shaped baffle 

may be much smaller for equivalent results. 

The rule which applies in this case is that 

the lowest note which the speaker will reproduce 

at full volume is - the one whose 

quarter wavelength is less than the distance 

from the front to the back of the cone 

around the edge of the baffle. Therefore, 

the baffle should be as large as conveniently 

possible, but considerable latitude is permissible. 

To determine the wavelength of a note 

it is necessary to divide the speed of sound 

in air by the note's frequency. To find 

the wavelength of a 100 -cycle note, for instance, 

it is necessary to divide 1120 feet 

(the speed of sound in air) by 100 cycles, 

and the result is 11.2 feet. As it is the 

quarter wave which is the important figure, 

it is next necessary to divide this figure by 

4, and this gives us 2.8 feet, or 33.6 inches 

for the quarter wavelength of a 100 -cycle 

note. 

Provided a baffle is flat, there is no limit 

to its desirable size. Speakers have been 

inserted in the wall of a room, which is 

practically the equivalent of a baffle of infinite 

extent, with excellent results. However, 

under average conditions a 100 -cycle 

baffle is entirely satisfactory, although better 

results could be obtained if it were still 

larger. A baffle of the flat type having a 

100 -cycle cut -off frequency will consist of 

a board approximately 35 inches square 

with a hole cut in the exact center for the 

cone. 

BUILDING INTO A CABINET 

In general, the box -type baffle is used 

more frequently than the flat type because 

it is more conservative in space require- 

ments. As the effectiveness of a baffle is 

determined by the shortest air -wave distance 

between the front and back of the 

cone, it may be seen that a box baffle is 

the approximate equivalent of a flat baffle 

of much larger size. Therefore, the lower 

compartments of radio console cabinets 

often serve as very efficient baffles for electrodynamic 

speakers, as indicated in Fig. i. 

One objection to the box baffle, however, is 

its tendency to resonate or "boom." 

the box is shallow from front to back, 

though high and wide, this effect is not 

noticeable. If the box is deep from front 

to back, while small in its other dimensions, 

the effect will probably be objectionable. 

To overcome this trouble, holes should be 

bored in the sides, top or bottom; or the 

sides should be lined with felt, or other 

sound- absorbing material. In general, with 

a box less than 18 inches square and deeper 

than one foot from front to back, some 

precautions should be taken to prevent 

resonance. Any box, the back of which 

is not almost entirely open or which lacks 

some other outlet of equivalent size for 

the sound from the back surface of the cone, 

will resonate badly unless a great deal of 

felt is used. A grille, covered with a light 

cloth, is usually the equivalent of an opening 

for the purpose. 

The remarks made above regarding the 

tendency of box baffles to resonate should 

not discourage the set builder from employing 

this type of construction. From a 

If 

4.41 

practical viewpoint, the box baffle is much 

more satisfactory and, if it is properly designed, 

no trouble should be experienced. 

The size of the battery compartment of 

most radio cabinets is such that satisfactory 

results are assured. However, if it is desired 

to construct a 100 -cycle box -type 

baffle, this should be approximately 16 

inches square and 10 inches deep. 

In constructing a baffle there are several 

things which should always be remembered. 

First, it should be made of heavy wood, so 

that it will not vibrate excessively on its 

own frequency. Secondly, the frame of the 

speaker should make an air -tight joint with 

the baffle at the opening which is cut for 

the cone. Thirdly, no holes should be cut 

in the front of the baffle other than the 

opening made for the cone. Lastly, the entire 

construction should be as rigid as possible. 

When the speaker is located in the sanie 

cabinet as the receiving tubes, great care 

must be taken to prevent its vibrations 

from causing the microphonic sounds which 

so often ruin reproduction. For this reason, 

both the speaker and the receiver should 

be mounted on a sound -insulating material, 

such as soft rubber. Special brackets are 

sold for mounting speakers on a soft rubber 

cushion, and rubber pads may be placed 

under each corner of the sub -panel of the 

set to insulate it mechanically from the 

speaker. As an additional precaution, the 

sockets used in the set should be of the 

cushion type, and the tubes should be fitted 

with heavy ballast caps. 

Very often, after unsuccessful attempts 

to eliminate microphonic noises, it is found 

that poorly- constructed apparatus used in 

the receiver is responsible. If it is suspected 

that the tubes are not the cause 

of the trouble the next parts to examine are 

the variable condensers. If condensers with 

unduly thin plates are used the vibrations 

set up in them may sound like tube noises 

in the speaker. 

Fig. 7 

.4 convenient method of mounting an electrodynamic 

speaker in a console cabinet is shown 

here. The lower part of the cabinet is thus 

converted into a baffle box, and the speaker 

should be so mounted that it comes in the 

exact center of its compartment. It should be 

provided with rubber feet to avoid vibration of 

the shelf on tchich the set rests.



1'lt:a \SFOn is a device for 

transferring electrical energy from 

one alternating- current circuit to 

another, and for changing the voltage 

from one value to another. The usual 

transformer consists of two coils of 

wire wound on an iron or soft steel "core." 

The coil through which the current is 

supplied to the transformer is called the 

"primary," and the coil from which the electrical 

power is taken is called the "second- 

ary." The alternating current traveling 

through the wire in the primary causes 

the iron core to become magnetized. This 

produces a varying magnetic field in the 

core, and because of the movement of this 

field, a corresponding voltage and electrical 

current is produced in the secondary by 

"electromagnetic induction." 

It is necessary to use alternating or 

fluctuating current in a transformer. 

A steady direct current in the primary 

winding would magnetize the core and 

thus produce a magnetic field, but this 

field would be stationary and it is the 

movement of the field that induces the 

current in the secondary coil. Alternating 

current is continually changing, rising to a 

certain value, then falling to zero, rising in 

the opposite direction and reversing again. 

Because of this continually varying action, 

the magnetic field is also varying, and the 

form of the voltage induced in the second - 

ary winding corresponds to that of the voltage 

in the primary. It is not absolutely 

necessary to have a primary current 

change its direction periodically, as alternating- 

current does; it is only necessary 

to have its value change continually. A 

fluctuating direct current in the primary of 

a transformer will induce a fluctuating current 

in the secondary. 

Some Facts About Transformers 

By C. Walter Palmer 

TURNS RATIO 

The entire purpose of a transformer is 

to transfer energy from one circuit to another, 

and, if desired, to change the voltage 

of the secondary to a different value from 

that in the primary. The voltage across 

the secondary of a transformer is proportional 

to the ratio of the number of turns 

in the primary to the number in the secondary. 

If we have a transformer operating on 

a 100 -volt supply and 500 turns of wire are 

used in the primary, a secondary containing 

100 turns would have approximately 

1/5 of the primary voltage, or 20 volts. 

There are three general types of transformers. 

The first has equal primary and 

secondary windings, and the secondary voltage 

is the same as that impressed on the 

primary. The second type has a secondary 

smaller than the primary, and the secondary 

voltage is lower than that of the primary; 

this is a "step- down" transformer. 

The third type has a larger secondary than 

primary and the secondary voltage is higher 

than the primary; this is a "step-up" transformer. 

The exact value of the voltage in 

the secondary depends upon the turns ratio, 

as explained. See Fig. 1. 

'l'here is a slight loss of power in a 

transformer, for'which there are a number 

of reasons. The windings present a certain 

resistance to the current, and some of the 

power is lost in overcoming this resistance. 

The core also presents a certain amount of 

heat loss, due to the currents which are 

set up in its laminations. The wire losses 

can be reduced by using heavy wire and 

the losses in the iron can be reduced by 

using a closed type of core. 

THREE TYPES OF CORES 

As you will notice in the accompanying 

illustration, Fig. 2, there are three general 

types of cores used for transformers. 'l'he 

first is the open -core type, which has the 

lowest efficiency of the three. The second 

is the closed -core type, which is used 

almost exclusively for small transformers. 

The windings on this type of transformer 

may be both on one arm of the core, as 

shown in Fig. 3; or the primary and secondary 

may be wound on opposite arms, as 

in Fig. 4. The third type of transformer 

is the shell type, with a completely closed 

core. This type of transformer is usually 

used when large currents are involved. 

Fig. 2 also shows an auto- transformer. 

An auto- transformer contains a single 

winding, with a tap somewhere along it. 

In the step -up type, the total winding is 

used as the secondary and part of the sanie 

winding (front one end to the tap) is 

used for the primary. In a step -down 

auto- transformer, the tap is placed in such 

a position that the ratio of the total winding 

to the section supplies the correct ratio 

of primary and secondary turns, for the required 

secondary voltage. The entire winding 

is used as the primary, while the tapped 

section becomes the secondary. In a step - 

up auto- transformer, the tapped section is 

the primary and the entire winding the 

secondary. 

WHY THE LAMINATIONS? 

In order to reduce the heat losses in tb. 

cores of transformers, they are almost invariably 

made of very thin sheets of iron, 

each one insulated electrically from the 

others. This arrangement prevents large 

induced currents from being set up in the 

core. In a closed -core transformer with a 

solid core, the core can be considered as a 

single turn secondary which would have a 

Transformer A is of the 1:1 type; primary and secondary hare an 

equal number of turns, and the secondary voltage is the same as 

the primary. Transformer B is of the "step-down" type; transformer 

C. of the "step -up" variety. depending on the "turns- ratio.'


I . 


PRI. 

SEC. 

SEC. 

PRI 

Olt 411011. 



Four commercial transformers sold for radio use. A, B and C are 

filament -lighting transformers, which step down the 110 -volt, 60 -cycle 

alternating house current to values between 1 and 15 volts. D is a 

combination unit which furnishes "B" voltage as well as filament 

current. Transformers are also available, which supply both fibcment 

and plate current, with one core. 

tion, or 450 volts maximum. This transformer 

is used with the filament type or 

gaseous- content type rectifying tubes to 

supply the plate current to the 171- and 

112 -types, as well as to the other tubes in 

the set. 

The other common type supplies current 

at about 500 volts and is of either the 

half- or full -wave type. This transformer is 

Used with the filament type of rectifier 

tubes to supply plate current to the 210 and 

250 power tubes. The current required 

from the secondaries of these transformers 

depends upon the type of rectifier tube employed, 

and the amount of current necessary 

for the receiver. It usually varies between 

60 and 150 milliamperes. This is a 

rather small current, since a milliampere is 

one- thousandth of an ampere. 

Besicles these two general types of transformers 

and the variations of each type, 

there are several combination transformers 

now being sold. These transformers have 

both large and small secondary windings, 

so that the filament and plate supply can 

be obtained from a single unit. A number 

of these transformers are wound with high - 

voltage, full -wave windings and either 

center -tapped or untapped windings to supply 

filament current. 

AUDIO -FREQUENCY TRANSFORMERS 

The problem of designing good audio - 

frequency amplifying transformers is very 

different from that of designing power 

transformers. In the latter, currents at 

only one frequency have to be considered, 

and the windings and core can easily be 

arranged to give the greatest efficiency at 

this figure. However, in amplifying transformers, 

a very wide band of frequencies 

must be covered with uniform efficiency, so 

that the signals and music will not be distorted. 

By referring to the chart of frequencies 

covered by common musical instruments 

that will be found on the preceding page, 

it will 

be seen that 

an average broadcast 

transmission covers a 

band between 30 and 

5,000 cycles. An ideal 

transformer should 

transfer currents of 

any frequency in this 

band equally well. 

Transformers f o r 

audio-frequency amplifying 

circuits can 

be divided into four 

types; the ordinary 

step -up, push -pull, auto- transformer and 

output. The problems involved in each of 

these types are approximately the same and 

a general discussion of these problems will 

be worth while. 

The purpose of the transformer used as 

a coupling device between two vacuum 

tubes in an amplifier is to receive the current 

changes from the preceding tube and 

Above: A, standard step -up transformer amplifier 

circuit. B, push -pull hook-up. C, auto -. 

transformer arrangement. 

Below: An amplifying transformer (left) compared 

in size with a "B" supply transformer. 

deliver them to the following tube with an 

increase in voltage. However, the compa r- 

ative voltage changes on the different signals 

must all be the same, so that natural 

reproduction will result. 

If the primary of the transformer is 

too small (if it has too low an impedance), 

the lower frequencies will pass through 

without affecting the secondary. The low 

impedance does not allow the current to 

magnetize the core or transfer the energy 

to the secondary, and the low frequencies 

are by- passed through the primary wind- 

ing. It has been found that the primary 

impedance should be two or three times 

the tube output resistance in order to fully 

amplify the lower notes. 

OBTAINING CORRECT IMPEDANCE 

In order to obtain the correct primary 

impedance, it is better to use a large core 

rather than increase the number of turns in 

the primary. If a small core is used, the 

primary 'must contain a great number of 

turns and naturally this also means an unusually 

large secondary coil in order to 

get the step -up ratio between the two coils. 

'l'he use of a very large secondary will also 

have a bad effect, since it has a tendency 

to increase the capacity between the turns 

of wire in the secondary. This value is 

known as the distributed capacity, and 

when it is increased, the higher frequencies 

are by- passed by it and are not properly 

amplified. 

It is generally considered that, the 

larger the core of a transformer, the more 

uniformly it will tend to amplify both the 

high and low frequencies. The core must 

be made of special magnetic material with 

a high magnetic value, or permeability. 

'/'here are two currents flowing through 

an audio- frequency transformer. The 

first is the alternating current which constitutes 

the signal and the other -is the 

direct current of the "B" supply. In a 

transformer with a small core, these two 

currents together may 

be sufficient to saturate 

the iron. In 

other words, the core 

is not large enough to 

handle all of the magnetic 

field produced 

by the primary winding. 

This condition 

may cause the production 

of harmonics 

of frequencies which 

(Continued on. page 

486)



SHOULD BE GOOD 

'SERVICE MAN (after 

listening to local in- 

/ terference in re- 

, ceiver): "I am afraid, 

madam, that it is your 

location which is to 

blame. The set is 

working all right." 

OWNER (justly indignant) : "I'll have 

you know, young man, I have as good a 

location as anyone in this town. I pay $80 

a month rent here !"-S. O. Taylor. 

LOOKED LIKE PHONES 

It was so cold that 

day that the traffic 

cop stationed at the / 

1 

school corner had to + - 

wear muffs over his 

ears. But he was 

slightly surprised 

when one little tad 

stopped to look at him 

carefully and then 

came up close and inquired, confidentially: 

"Say, mister, what station are you getting 

now ? " -Mollie Zacharias. 

THE LOST ART 

A local (Providence) 

station ended 

a morning talk for 

housewives with the 

promise of a free 

cook -book to those 

listeners who would 

call at certain chain 

stores. One young housewife who had 

purchased baked beans, salmon, condensed 

milk, canned tomatoes, etc., inquired as an 

afterthought for the cook -book offered by 

radio. "Lady," said the clerk, thoughtfully, 

"you don't want a cook -book; just a can - 

opener."- Theodore .4. Monahan. 

NEED ANY 

ASSISTANTS? 

W I F E (awakening 

her husband) : "T h e 

early morning radio 

setting -up exercises 

are on! You left the 

radio turned on when 

you went to bed! 

TIRED DX FAN 

(after a liard night): "Please be quiet. I'm 

doing my daily dozin' ."-A. H. Rodiek. 

HIS DX WAS NB (NEAR -BY) 

FIRST RADIO FAN: "What sort of a set 

has Joe got ?" 

SECOND Dirro: "Well, you don't need a 

radio log with his receiver. All you need is 

a splinter. "-A. H. Rodiek. 

page is devoted to humor of purely 

THIS radio interest; and our readers are invited 

to contribute pointed and snappy 

jokes -no long -winded compositions -of an 

original nature. For each one of this nature 

accepted and printed, $1.00 will be 

paid. Each must deal with radio in some 

of its phases. Actual humorous occurrences, 

preferably in broadcasting, will be 

preferred. Address Broadcastatics, care 

RADIO NEWS, 230 Fifth Avenue, New 

York City. 

PUSHING THE SCOTCH TOO FAR 

What is the difference between a storage 

battery and a native of Aberdeen? 

The storage battery can be overcharged! 

-From The Saveloy (house organ of the 

British Broadcasting Co.) 

SHADOWED TO HIS DOOM 

FAN No. 1: "Say, why are you so interested 

in getting a television 

set working ?" 

FAN No. 2: "I want 

to see what Old Man 

Static looks like, so 

I'll know him. Then 

1'11 get him and get 

him good, too!" 

-George Jess. 

COUNT 'EM AND SEE 

CITY BOARDER 

(watching F a r ni e r 

Timothy milk the 

cow): "Oh, yes, that 

set has four tubes, 

hasn't it 

RUNNING DOWN HIS 

BATTERIES 

JUNIOR FAN (entering 

hastily from outdoors 

at night) : "O 

papa! The cat's tubes 

are lit! I saw his 

panel lights !"-Philip 

Tracy. 

EDISON'S GREAT RIVAL 

CASEY: "My static eliminator was invented 

by an Irishman!" 

JONES: "What was his name ?" 

CASEY: "Pat Pending." 

-Billy R. Meredith. 

NO KEYHOLE WORK 

RADIO SALES ?IAN: 

"Good morning, 

madam. With this fine 

six -tube radio you can 

listen in on what all 

the world is doing." 

COLORED PROSPECT: 

"No, sah, ah believes 

in minding mall own 

business, sah r' 

-Wilfred Anderson (Bermuda). 

CHEAP ENOUGH 

A resident of Melbourne 

recently had a 

radio set installed,' 

and when his bill was 

presented this aston 

fishing item was at the 

.end of the account: 

"For hanging aerial 

aid myself-22 shillings."-Arthur 

Russell (.Australia). 

RADIO RHYMES No. 13 

THERE'S JUST ONE THING- 

I'D LIKE TO KNOW 

THAT'S QUEER TO ME IN 

RADIO - 

I WONDER wHV EACH 

TUNEFUL 51-12 AIN 

LIKE ANESTHETIC , DRUGS 

THE HRAIN I. -. 

THeN O'ER 'mu 'DROWSY NO DOUBT THE SCiENT15tS 

FEELWGS CREEP. WILL CLAIM 

AND LULL YOU TO PRO- 1-I -105E ETHER WAVES 

FOUNDEST SLEEP. MUST BE To BLAME!



How to Construct the "Pre- Selector" 

A Receiver Accessory Which Provides Extreme Selectivity 

Without Loss of Sensitivity or Additional Controls 

By S. Gordon Taylor 

TIIERE has always been a strong demand 

for an accessory that could be 

connected to any standard radio receiver 

to improve its selectivity. In 

general, such devices have fallen into one of 

two classes. 'l'he first is the well -known 

wavetrap, by means of which a single interfering 

station may be trapped out, either 

partially or completely; the second class includes 

what amounts to an additional stage 

of radio -frequency amplification built as a 

separate unit and connected ahead of the 

receiver. 

Both of these accessories have the disadvantage 

of adding one or more tuning 

controls and both, therefore, tend to complicate 

the operation of a receiver. They 

have also individual faults. The wavetrap, 

for instance, is not always capable of entirely 

cutting out even the single interfering 

station for which it is adjusted and, furthermore, 

it frequently reduces the intensity 

IT volume of the desired signals. The added 

stage of R.F. amplification almost always 

tends to make the receiver unstable by increasing 

undesirable feedback. To prevent 

oscillation in such a combination it is usually 

necessary to turn back the volume control, 

or the sensitivity control of the receiver, 

with the result that the over -all sensitivity 

of the combination is often actually less 

than that of the receiver alone. Most radio 

experimenters have tried devices of both 

hinds and have recollections of these facts. 

SOLVING THE PROBLEM 

In spite of these faults, there are thousands 

upon thousands of these two classes 

of accessories in use today. Such being the 

case, it seemed well worth while to devote 

some attention to the development of a unit 

that would really provide the maximum 

practical degree of selectivity but which - 

(1) Would not decrease volume or signal 

strength; 

(2) Would not 

complicate tuning or 

operation; 

(3) Would not tend 

to make the receiver 

unstable, and, 

Fig. C 

"PreSelector" has 

The 

an attractive appearance: 

its controls supersede entirely 

those of the receiving 

set, which may be 

placed elsewhere. 

(4) Would be applicable 

to the general 

run of receivers 

in use today. 

It was decided that these conditions could 

not be met without providing some degree 

of amplification in the accessory unit to 

make up for the losses which are bound to 

result from any method that might be used 

to increase selectivity; this meant that at 

least one tube would have to be included 

in the unit. Furthermore, either the receiver 

or the unit would have to be untuned 

if we were to avoid adding tuning controls. 

Finally, the tube circuit or circuits in the 

unit could not be tuned to the same frequency 

as those in the receiver because the 

TAYLOR 

PRE -SELECTOR 

--(5 

Gl Ca Cz 

addition of a resonant tube circuit would 

upset the stability of the receiver. 

In the face of all these requirements, it 

became obvious that the only possible 

method of securing the desired results 

would be through the use of a heterodyne 

system. An experimental unit which included 

a "first detector" and oscillator was, therefore, 

built up. With this arrangement, the 

tuning controls of the receiver proper could 

be set at one wavelength and left there at 

all times, and the new unit would act as a 

frequency -converter to alter the frequency 

of any incoming signal to the frequency 

(wavelength) to which the receiver was 

tuned. The wavelength selected for the 

receiver was one ,just above the broadcast 

band, 560 meters to be exact. This scheme 

worked out admirably as far as selectivity 

is concerned. It also simplified operation, 

because all tuning is accomplished with the 

two controls of the unit instead -of the three 

controls of the receiver proper. The combined 

outfit is also stable -even more stable 

than the receiver alone, because the receiver 

is now permanently tuned to such a high 

wavelength. 

Fig. B 

The aerial coupling of LI is automatically varied with the wavelength by the movement of CI, 

which tunes the first- detector input. L2 comprises the oscillator coils and coupler. 

Ranto NEWS Free Blueprint Article. No. 68. 

IMPROVING THE DESIGN 

The only drawback found in this experimental 

unit was that it did not provide quite 

as ereat over -all sensitivity as with the receiver 

alone. Further experimental work 

was carried on. therefore, to overcome this 

objection. First, by increasing the antenna 

coupling in the unit, greater input -signal 

voltage was obtained and this has the same



447 

SW2 

ivxw- 

R2 

TC7 

GND 

0 

AER. 

P 

C5 

SW I 

A- 

C4 

R3 

C6 

L3 

L2 

,C2 

V2 

) 

DL 

A+ B- B+ OUTPUT A- 

45V. RECEIVER 

Fig. 1 

The schematic diagram of the "Pre-Selector," above, shows it to be actually the frequency - 

changing end of a superheterodyne, for whose amplifier any tuned -R.F. set may be used. The 

effect as would increased amplification. 

'l'hen regeneration was added to the circuit 

of the "first detector." These two changes 

both increased the pickup, and increased 

amplification was obtained. Thus the last 

requirement was more than satisfied. 

Next, a good deal of time and effort was 

spent in further refining the device. It was 

found, for instance, that when the input &- 

chit of the unit was tuned to certain wavelengths 

the unit did not function as eliciently 

as at others. Also, under certain 

conditions, the tuning of one dial tended to 

alter the setting of the other. It was decided, 

therefore, that variable coupling between 

the antenna and the unit is necessary 

and the coupling coil was redesigned to provide 

automatically variable coupling. This 

arrangement consists of gearing the primary 

of the antenna coil to the shaft of the 

tuning condenser; so that the antenna 

coupling increases and decreases as the con-. 

denser is tuned for high and low waves, respectively. 

Careful design of the oscillator 

pick -up coil also helped to improve the 

results. 

The next refinement consists of a switch 

which is incorporated in the unit for the 

purpose of turning a receiver's filaments off 

and on, together with the filaments of the 

two tubes in the unit itself. For this purpose 

a combination rheostat and switch is 

included in the unit. The former controls 

the filaments of the two tubes and, when it 

is turned off, opens the switch which controls 

the receiver filaments. 

REMOTE- CONTROL APPLICATION 

first detector is regenerative. 

A very important possibility, and one 

which had not been thought of in the beginning, 

was that of employing this unit as 

a remote- control device. Inasmuch as the 

input frequency is changed during its progress 

through the unit, there should be little 

chance for feedback from the output to the 

input (aerial) lead. Therefore, there is no 

good reason why the unit cannot he placed 

some distance from the receiver. Experiment 

proved this theory to be correct and 

no difficulty was encountered in operating a 

receiver in the next room, approximately 

20 feet away from the aerial lead and the 

new unit. This experiment brought up another 

requirement ---that of controlling the 

volume at the unit rather than at the receiver; 

a special high -resistance potentiometer 

was therefore included in the antenna 

circuit. Thus, not only the tuning 

and all filaments, but also the volume, were 

entirely controlled without going near the 

receiver proper. 

Finally, the unit was considered deserving 

of a name and it was informally christened 

the "Pre- Selector." 

The Pre -Selector has been tried out with 

-a great many receivers, both commercial 

and home built. Of all which were tried, 

the only sets with which it did not perform 

in the usual manner were certain super - 

heterodynes and some receivers which employ 

only a regenerative detector and audio 

amplification. In every case where the receiver 

employed one or more stages of tuned 

R.F. amplification, the results were excellent. 

With receivers which employ a regenerative 

detector without R.F. amplification 

preceding, the Pre -Selector changes the input 

characteristics of the regenerative circuit 

sufficiently to prevent proper regeneration. 

In some superheterodyne receivers the 

double- heterodyne action will result in harmonics 

and "birdie" whistles. This is not 

true of all superheterodynes ; because in 

some cases the Pre -Selector has been found 

just as satisfactory with receivers of this 

type as with tuned R.F. outfits. 

HOW THE PRE -SELECTOR FUNCTIONS 

The Pre -Selector is connected between 

the aerial and the "Aer." binding post of 

the receiver with which it is to be used, and 

the tuning controls of the receiver arc adjusted 

to resonance at any wavelength above 

the broadcast band; usually around 560 

meters, for this is as high as most standard 

receivers will tune. The Pre -Selector may 

be connected to the batteries employed by 

the receiver or may have its own set of batteries, 

whichever is more convenient; more 

will be said about this later. 

The left dial of the Pre- Selector is the 

wavelength or tuning adjustment; it controls 

the variable condenser CI which times 

the secondary of the antenna coupler L1 in 

the input circuit of the first tube VI. This 

coupler includes a center -tapped primary 

winding mounted on a movable carriage 

which, in turn, is geared to the rear end of 

the shaft of condenser Cl by means of the 

cans- and -pin arrangement, supplied with 

the coupler. Thus, the primary coil is 

moved in and out of the secondary coil to 

vary the coupling according to the wavelength 

to which the circuit is tuned. 

In series with this secondary winding of 

the antenna coupler is the small pick -up 

coil which constitutes part P of the oscil- 

lator coil, L2. By means of this pick -up 

coil part of the oscillator energy is impressed 

upon the detector grid circuit along 

with the incoming signal from the broadcast 

station that has been tuned in. 

The detector combines these two frequencies 

to form a third, which is equal to 

L3 5 

Fig. A 

This view from above shows how direct are the leads employed in wiring the Pre -Selector. AU 

wires arc run above the wooden baseboard. Two methods of connecting to batteries appear in 

Figs. 2 and 3.


448 

the difference between the two frequencies 

present in the grid circuit. By tuning the 

oscillator circuit this third frequency may 

he wade equal to that, say 535 kilocycles 

(560 meters), to which the receiver proper 

has been tuned preciously and the signal 

from the broadcast station will be amplified 

in the receiver and heard in the loud 

speaker. 

From the foregoing explanation it is apparent 

that an installation, which includes 

a timed -R.F. receiver and the Pre -Selector, 

really amounts to a superheterodyne receiver; 

in which the Pre -Selector functions 

as the so- called "first detector" and oscillator, 

while the R.F. amplifier of the receiver 

proper serves as the intermediate 

amplifier of the combination. 

FEATURES OF THE CIRCUIT 

The tremendous selectivity afforded by 

the Pre- Selector is due largely to the frequency- 

changing process involved. In addition, 

the Pre- Selector combination provides 

better selectivity than the average 

superheterodyne receiver; because the R.F. 

amplifier of even a very broad -tuning broadcast 

receiver is tuned much more sharply 

than are the coupling transformers ordinarily 

employed in the intermediate stages 

of a regular superheterodyne receiver. 

Regeneration in the detector circuit of 

the Pre- Selector is not required for the 

sake of selectivity, but is used solely for 

r 

30 TURNS 

TAPPED 15?" TURN. 

#30 D.S.C. PRIMARY 

116= DIAMETER. 

-Id- 

N 

IÌI 

114 TURNS SPACED 

%28 D.S.C. SECONDARY` 

2 "- DIAMETER ) 

64 TURNS *36DSC. 

TICKLER 11/2."-DIA. LI 

ri 


47 TURNS 

Z8 D.S.C. 

2 "- DIAMETER 

12 -TURN# 36 D.S.0 

PICK -UP 

14.-DIAMETER 

47 TURNS 4128 D.S.G. 

2 "- DIAMETER 

Fig. 4 

Details of the coils; the primary of L1 is mounted on a slide, which is moved out 

of the secondary by a cam on the tuning condenser Cl as the rotor plates rise. 

the amplification it provides. Ordinarily 

the regeneration control, C4, is left with 

its knob set at zero. It is only in the case 

of reception from very distant stations that 

regeneration is required and, for such re- 

ception, the knob is turned up to a point 

just below that at which the detector goes 

into oscillation. The regeneration is ob- 

R1- 

SW1 

IIIIIIIIIIIIIIIIIII 

C4, 

TO FRAME 

OF CONDENSER 

Illllllllllllllllr 

+ 

V2 

J' 

i- 

IlPnnnnuq m 

I :,, n'lll ... 

. 1 

1 

=°ï' 

° 

Illla IIc : M ' 

Imïlüüiüiüilddlau nu 1 IIII 

L2 

MOUNTED ON 

FRAME OF 

CONDENSER C2 

I1 

r 

si 

aÌÍÍÌÍIIII 

l 

I 

JIM PIPIT !I 

ailíi.!IiI 

ii: 

11 

1 r- 

!lgtIIIIII 

SOLDER TO 

BRACKET 

A- OUTPUT B+ B- A+ A- SW2 AER. 

RECEIVER 

45V 

Fig. 5 

Complete wiring layout of the "Pre- Selector;" the apparatus is 

*lightly spread apart in the picture to show the connections. 

COIL LI MOUNTED ON FRAME 

OF CONDENSER Cl 

GND 

1



T-1 

2 

3' 

N 

14' 

3/g DRILL 

5 HOLES 

} 

5/32 DRILL AND 

COUNTERSINK, 2 HOLES 

3' 

1 

/g DRILL 

6 HOLES 

5/32 DRILL 

3 HOLES 

10' 

542 DRILL, B HOLES 3/g DRILL 

Fig. 6 

Drilling details of the "Pre- Selector" panel and binding -post strip. 

waveband. This a decided convenience, 

particularly when tuning for weak, distant 

stations. 

CONSTRUCTION AND WIRING 

The diagrams and photographic reproductions 

provide practically all the data required 

for the construction of the Pre - 

Selector; the only point that needs be 

touched upon is the mounting of the coils. 

Both LI and 12 are mounted directly on 

the frames of their respective tuning condensers. 

L2 should be mounted in a vertical 

position with the small pick -up coil at the 

top. A tapped hole will be found in the 

rear of the frame of condenser C2, and a 

6/32 screw passed through the hole in the 

brass mounting bracket of the coil and 

screwed into that in the condenser provides 

a convenient and substantial means 

for mounting. 

The curved brass bracket which comes 

with LI should be mounted on the frame of 

the coil by means of the two small screws 

provided. Its position should be that, when 

the coil is mounted in the position shown in 

the top view (Fig. A), the slotted lug on 

the bracket should be toward the panel and 

pointing down. Next, mount this coupler 

on the rear of condenser Cl by means of 

the screw provided. When in proper position, 

the notch in the lug of the mounting 

bracket should be astride the rib on the 

back of the condenser frame. 

tamed through the use of a feed -back coil 

mounted in a fixed position inside of the 

secondary of the input coupler, I.I. 

It will be noted from the diagram,Fig. 1, 

that a switch, SW2, has been included in 

the ground side of the antenna circuit. This 

switch is required, not for its effect on selectivity 

but rather to permit the smooth 

and consistent control of regeneration. 

Where a very large antenna is employed, 

with the full primary winding in the circuit, 

the absorption effect is so great as to make 

regeneration ineffective. In such a case the 

switch is set so that only half of the winding 

is in the antenna circuit, thus reducing 

the absorption effect to overcome this difficulty. 

The by -pass condenser C7 has been included 

in the ground circuit of the Pre - 

Selector, simply as a safety measure, to prevent 

any possibility of short- circuiting the 

"A" current in cases where the same device 

is used to provide the filament current 

for both the Pre -Selector and the receiver. 

The only other circuit feature not covered 

is that which employs the small adjustable 

condenser, C3. The purpose of this condenser 

is to permit enough capacity to be 

RADIO MEWS 

FREE 

BLUE PRINT 

ARTICLE' 

No. 68 

d set of large blueprints 

and a list of parts 

used in the construction 

of the "Pre- Selector" 

shown here will be sent 

postpaid to any applicant. Write to 

the Blueprint Department; write your 

name and address and "No. 68" legibly 

on a sheet of paper separate 

from letters to other departments. 

We regret to inform our correspondents, 

especially abroad, that U. S. 

postal regulations do not permit sending 

blueprints with magazines; nor 

can we undertake to accept blanket 

requests for "all blueprints." 

added to the tuned oscillator circuit to 

cause the two tuning -condenser dials to 

read alike. When it has been adjusted so 

that the two tuning controls read alike for 

a given wavelength, their readings will remain 

alike throughout almost the entire 

SUPPLY AND INSTALLATION 

If it is used with a battery -operated receiver 

the same set of batteries may be used 

for the Pre -Selector. Or, if the receiver 

uses a `B" socket -power unit, that may also 

be used to provide the plate current for the 

Pre-Selector. If the receiver employs A.C. 

tubes, it will then be necessary to provide a 

set of three standard dry cells to supply the 

Pre -Selector's filament; one set of batteries 

will provide approximately 200 hours of 

actual service. The rheostat (R1) included 

in the filament circuit of the Pre -Selector 

is of resistance sufficiently high to permit 

these tubes to be operated safely from a 

six -volt source. With the supply voltage the 

rheostat should be turned on half -way to 

provide proper operating voltage for these 

tubes; if the supply source is 4/ volts the 

rheostat should be turned on three -quarters. 

When dry cells are used the three -quarters 

position is correct while the cells are new; 

but the rheostat must be advanced as the 

cell voltage drops. 

In some cases as, for instance, where the 

"B" socket -power unit is built permanently 


-BATTERY HOOK -UP WHERE BOTH 

RECEIVER AND 

PRE - SELECTOR USE SAME 'A' AND 'B" BATTERIES- 

BATT 

0 0 0 

-B- 

BATT. 

BATT 

- BATTERY HOOK -UP WHERE PRE - SELECTOR 

IS EQUIPPED WITH SEPARATE BATTERIES - 

TO - (NEG.) TERMINAL 

0 0 0 

'B BATTERY 

45%, - 

OF RECEIVER 'A' BATTERY. 

TO RECEIVER 

'AER' TERMINAL 

TO RECEIVER 

'GRD' TERMINAL 

'B'- TERMINAL 

MuJSI BE LEFT 

UNCONNECTED. 

PRE - SELECTOR 

A- AER. A+ B+ B+ B+ B- ONO 

45V. 90V. 135. 

OR /BO V. 

NORMAL CONNECTIONS TO 

RECEIVER TERMINALS. 

PRE - SELECTOR 

TO 'A- TERMINAL 

# OF RECEIVER 

NOTE ; THIS CONNECTION IS MADE 

FOR USE ONLY WHEN RECEIVER 

FILAMENTS ARE TO BE TURNED OFF 

AND ON BY SWITCH SI OF PRE - 

SELECTOR. IN MAKING THESE 

CONNECTIONS REMOVE NORMAL 

CONNECTION BETWEEN RECEIVER 

-A-' AND BATTERY 

2. Here the "B -" connection is left unused, to avoid a short across 

the filaments of tic 199 -type tubes. 

Fig. 3. 

Even though separate batteries are used, the connection shown 

makes remote control of the receiver easy.



Magneto - Striction 

An Interesting Field for the Radio Experimenter; 

to Build a Magneto -Striction Oscillator 

By M. J. Cztttler 

RADIO NEWS LaGoratories 

ccERROMAGNETIC" substances 

(such as iron, cobalt, nickel and alloys 

into which those metals enter in 

considerable proportion) possess 

"magneto- strictioe" properties; which means 

that they undergo slight mechanical alterations 

of shape, and some of their physical 

properties change when they are subjected 

to the influence of a magnetic field. This 

action of the magnetic field on such sub 

stances is manifested in a series of effects 

discovered at different epochs and known 

under various names. 

The oldest among these is the "Joule effect," 

discovered by Joule about 1847; this 

is the variation of the length of a ferromagnetic 

rod exposed to a magnetic field. 

Let us consider an iron rod freely suspended 

inside of a long solenoid; an electric current 

of constant intensity flowing through a 

solenoid creates a magnetic field which is 

practically uniform within the solenoid over 

n great part of its length; provided that the 

ratio between the length and diameter is 

sufficiently high. This is illustrated in Fig. 

1. The field strength within the coil is proportional 

to the intensity of the current, and 

the variation of the field may be governed 

through the regulation of the magnetizing 

current. 

AN ALTERNATING ACTION 

Let us now examine what happens to the 

iron rod if the field inside the solenoid is 

varied from zero upwards. First, an elongation 

will take place. This will continue 

until the field's strength reaches a certain 

value, after which any further increase of 

the field will cause a contraction; the rod 

then becomes shorter, will again reach its 

FIG.1 

The magnetic field within a solenoid is prac, 

Orally uniform in distribution, as illustrated 

herewith. 

11r. Outlier is shown here testing the magnetostriction oscillator described 

in the accompany article. 

original value, and will then continue to contract 

until a saturation point is reached. 

Any further increase of the field strength 

will have no more effect on the length of 

the rod. 

The behavior of other ferromagnetic substances 

under the same conditions will .be 

different. Nickel, for instance, continuously 

decreases in its length; while cast cobalt, in 

contrast to iron, first contracts and then expands, 

reaches its original length and continues 

to elongate until saturation occurs. 

The relation between the strength of the 

magnetic field and the variation of the 

length is shown clearly in Fig. 2. (Both 

figures are taken from an article on magneto 

-striction by S. R. Williams, published 

in the Bulletin of the National Research 

Council, August, 1922. 

Other ferromagnetic substances may respond 

differently, but one thing is common 

to them all; they vary in length (whether 

positively or negatively) with a rising field 

strength, and reach a point where saturation 

occurs, after which a further increase 

of the field has practically no effect on their 

length. 

An important remark is to be made here; 

the Joule effect is dependent on the direction 

of the field. As the extent of the variations 

in the length of such rods is extremely 

minute, their measurement is a matter of 

great difficulty; the utmost care must be 

taken to avoid temperature variations and 

changes in other physical conditions, which 

may conceal the real values. 

Various ingenious arrangements have been 

used for such measurements; Fig. 3 gives a 

schematic layout of the method used by 

Professor Williams. The method of operation 

is self -explanatory; the expansion or 

contraction of the rod under test is converted 

into angular rotation of the mirror 

by means of the lever. 

CORRESPONDING PHENOMENA 

To the Joule effect corresponds another 

phenomenon which is its opposite; the "Villari 

effect." The forcible lengthening of a 

ferromagnetic rod located in a magnetic 

field is accompanied by a variation in its 

magnetization or its permeability. As we 

have seen in the Joule effect, various substances 

behave differently under the same 

conditions; but there is a relation, for each 

metal, between its Villari effect and its 

Joule effect. An investigator (Nagaoka) 

who followed Joule, has confirmed his supposition 

that a magnetic field has an influence 

on the volume of a ferromagnetic 

substance. 

Another very interesting phenomenon 

which belongs to the same group is the 

"Wiedemann effect" and its two inverse effects. 

The Wiedemann effect is the twisting 

of a rod under the influence of a combination 

of two fields, one longitudinal and 

one circular. Suppose a magnetic rod is 

clamped at one end inside of a long solenoid; 

then a current passing through the 

solenoid produces a uniform longitudinal 

field inside of it. If, at the same time, 

another current flows through the rod, a 

circular field will be created around it. If 

one of these currents is kept constant while 

the other is varied, or if both currents are 

varied, a rotation of the further end will be 

observed. 

The two corresponding inverse effects are: 

first, a circular field is created when a rod 

which is located in a magnetic field is sud- 

These curves show how various metals change 

in length under the influence of a magnetic 

field.


Radio Newts tor Novelnbe,. 1928 

SOLENOID 

SAMPLE UNDER 

TEST 

ROTATING SHAFT 

TILTING MIRROR 

FIG.3 

FRAME 

BRONZE RIBBON 

CLAMP 

BRASS 

HOLDERS 

KNIFE 

LEVER 

FBALANCING 

WEIGHT 

11 OW the change in length of a rod is observed. 

.45 the rod varies, it unbalances the lever, which 

tightens or loosens the bronze ribbon. This 

causes the shaft to turn the mirror, the movement 

of which is readily observed. 

lenly twisted. A sensitive galvanometer 

connected across the rod will indicate a flow 

of current. Second, a longitudinal field is 

created along a rod to which a sudden twist 

is given, if an electric current is passing 

through it. A galvanometer connected to 

the terminals of the solenoid will show the 

existence of a current. 

The schematic layout of the method used 

to measure the Wiedemann effect is shown 

in Fig. 4. Here, again, the rod is clamped 

at one end inside the solenoid.- To the free 

end is attached a protruding brass extension 

which carries a small mirror. If the magnetizing 

current of the solenoid is constant, 

a rotation of the mirror will be observed 

when the electric current passing through 

the rod is varied. 

There are many other phenomena belonging 

to the same group. Those of our readers 

who are more interested in this subject, we 

refer to the excellent and very clearly - 

written article on magneto -striction by Professor 

Williams, in the May, 1927, issue of 

the Journal of the Optical Society of America. 

Besides the general theoretical considerations 

and methods of measurement, the 

reader will find there a most complete 

bibliographical notice on this subject. 

DESIGN OF THE OSCILLATOR 

'l'he Joule effect has been very ingeniously 

applied by G. W. Pierce, director of the 

Cruft Laboratory at Harvard University, in 

a series of electrical devices for which a 

British patent has been recently granted. 

Among them, the single -tube magnetostriction 

oscillator deserves the most attention. 

(By the way, Professor Pierce is the 

inventor of the single -tube piezo-electric 

oscillator, a device which is of almost universal 

use in broadcast stations, and of 

growing popularity among radio amateurs.) 

The fundamental circuit of the nickel 

oscillator is shown in heavy lines in Fig. 5. 

The dotted part of the drawing represents 

an amplifying stage, which is not essential 

for the operation of the oscillator. As may 

be seen from the sketch, the essential element 

of the circuit is the ferromagnetic rod, 

which is clamped at its middle point. The 

two coils Ll and L2, of equal inductance 

value, are connected, respectively, to the 

grid and plate circuit, and surround the rod 

without touching it. The variable condenser 

C is connected to the grid and plate, and 

completes an oscillatory circuit. Disregarding 

the presence of the rod, the circuit is 

identical to the Hartley oscillator, with the 

exception that the coils are connected in the 

opposite direction. 

When the oscillatory circuit is tuned by 

the variable condenser to a frequency which 

is close to the natural longitudinal frequency 

of the rod, a sudden rise in the plate current 

is observed in the milliammeter, and 

the rod begins to vibrate. If the frequency 

falls within the audible range, this vibration 

of the rod may be heard very distinctly. 

The frequency of the current generated by 

the tube is now the same as the natural frequency 

of the rod. 

A CONSTANT -FREQUENCY CIRCUIT 

If all elements are properly selected, the 

capacity of the tuning condenser may be 

considerably varied without having any disturbing 

effect on the frequency of the tube, 

which is now controlled exclusively. by the 

vibrating rod. Similarly, it is not influenced 

by either a variation of the filament current 

or any reasonable change in the plate voltages. 

If the ferromagnetic substance used 

is of such a nature that the natural frequency 

of the rod is not affected by small 

The circuit of the magnetostriction oscillator. The dotted portion indicates an additional amplifying 

stage. F.M.R.. ferromagnetic rod; Cl, 1 -m(.; C, tuning condenser; Ll, L2, inductors; .4, 

plate milliammeter; P, telephone receivers; K.S., knife switch; L3, 800 -turn honeycomb coil; 

L. IV.3f.. long -wave wavemcter. 

431 

How the twisting of a rod under the influence 

of two magnetic fields is observed. One field is 

created by the solenoid; the other by the current 

passing through the rod and indicated by the 

ammeter A. 

temperature fluctuations, the generated frequency 

is of remarkable constancy, and may 

be used as a standard for calibrating purposes. 

This type of oscillator will cover a relatively 

wide range of frequencies, from a 

few hundred cycles up to 300,000 cycles per 

second and, as a standardizing device, fills 

in a gap between the range of the vacuum - 

tube- driven tuning fork and that of the 

piezo- electric oscillator. On the other hand, 

it may find a very wide field of application, 

in connection with synchronizing devices 

used in television and transmission of pictures 

over wireS or radio. 

THEORY OF OPERATION 

We will now try to explain briefly the 

operation of a magneto-striction oscillator. 

Let us consider a ferromagnetic rod 

clamped at its middle point and surrounded 

by a coil through which an alternating current 

is passing (we assume that the coil 

does not touch the rod). During a complete 

cycle, the field strength inside of the coil 

varies from zero to maximum, from maximum 

to zero, again to maximum (in opposite 

direction) and conies back to zero again. 

As the Joule effect is independent of the 

direction of the field, the variation of the 

length of the rod during the same period 

will pass through zero to maximum, zero, 

maximum, and zero again. In other words. 

to each cycle of the magnetizing current will 

correspond two cycles of the variation of 

the length of the rod; that is to say, the rod 

will vibrate with a frequency which is twice 

that of the magnetizing current. 

Suppose now that, simultaneously with the 

alternating current, a direct current flows 

through the coil. If the intensity of this direct 

current is higher than the amplitude of 

the alternating current, the resulting current 

will vary, but will never become zero. 

During one cycle, it will pass from minimum 

to maximum and come back to minimum 

once; and so will the magnetizing field. Accordingly, 

the length of the rod will vary in 

the same way and, to each cycle of the alternating 

current, will correspond one cycle

I 


452 


x 

Z-s 

11Ju 

o? 

LL 

i 

ALTERNATING CURRENT 

A 

A1I 

I 

1 

® 

I 1 

1 1 

/NI/III 

ONE CYCLE: 

M--- N 

FIG.6 QA 

I 

lA 

I 

Alik 

of the variation of the length of the rod. 

The rod will vibrate now with the same frequency 

as the alternating current. Those 

two cases are illustrated in Figs. 6A and 

6B. 

We will now return to the oscillator. To 

simplify the case, we will assume that there 

is no tuning condenser across the coils. 

(Such an oscillator may operate provided 

the amplifying power of the tube is high 

enough. A single tube may be replaced by 

an amplifier having several resistance - 

coupled stages.) One coil is then inserted 

into the grid circuit of the first stage, while 

the other is connected to the plate of the 

last stage. (One form of Professor Pierce's 

patent application.) 

Suppose, now, that the rod is at rest and 

that the plate current has a constant intensity, 

which is determined by the characteristics 

of the tube and the applied volt- 

ages. The rod becomes magnetized under 

the influence of the field created by the 

second coil. This magnetization is not uniform, 

as the field strength along the rod is 

not uniform. 

Should there happen a sudden variation 

of the plate current (due, for instance, to 

an exterior cause) a tendency in the rod to 

expand or contract, due to the Joule effect, 

will be caused instantly. The situation is 

somewhat similar to the case in which a 

shock is given to the rod in the line of its 

length. The particles of the metal are 

thrown out of balance, and longitudinal 

oscillation will take place in the rod under 

the action of the two forces of elasticity 

and inertia. 

FREQUENCY OF THE ROD 

The fundamental frequency of the rod 

may be found by dividing the velocity of 

sound in the substance of which the rod is 

composed, by twice its length. During the 

longitudinal oscillation of the rod, variation 

in its magnetization will occur (V Mardi effect). 

An oscillatory electromotive force 

will be created in each of the two coils; 

those electromotive forces will have the same 

fundamental frequency although, as a general 

rule, they will differ in their other elements. 

A variation of the plate circuit then will 

cause the appearance of two electromotive 

dorces in the grid coil; one due to the mutual 

ONE CYCLE ¡ 

A 

Fig. 6.4 illustrates the 

Tonle effect. For each 

complete cycle of the magnetising 

current, the rod 

within the magnetic field 

of that current vibrates 

TWICE: that is, the frequency 

of vibration of 

the rod is equal to twice 

the frequency of the al 

tcrnating current. If, as 

in Fig. 6B, a direct current 

is added to the alternating 

one, the rod will 

vibrate at the frequency 

of the alternating current. 

I-PURE A.C. 

II'RESULTING CURRENT 

A 

inductance between the two coils, and the 

other as a result of the Joule effect and its 

opposite. The resulting emf. will cause the 

plate current to fluctuate with the natural 

frequency of the rod. Ordinarily, the vibrations 

of the rod produced by a shock, or any 

other momentary disturbance in the internal 

balancing forces, would not continue indefinitely; 

as they are damped by the losses 

of energy and would die out very quickly. 

But here the conditions are different; if the 

elements are properly selected and the circuit 

is connected in the right way, the decrease 

in the amplitude after each oscillation may 

be compensated by the current in the tube, 

and a sustained longitudinal oscillation will 

take place in the rod. The rod will be driven 

by the tube. (Something similar we find in 

the oscillation of a pendulum maintained by 

the driving force of a weight or a spring, as 

in a dock; the energy of the pendulum after 

each complete cycle is restored to its original 

value by a release of corresponding 

amount from the driving mechanism.) 

Simultaneously with the vibration of the 

rod, an oscillatory current, the frequency of 

which is controlled by the rod, will flow 

through the plate coil. 

Tuning one of the coils with a condenser 

or both together (Hartley circuit) does not 

alter the fundamental principle of operation 

in this type of oscillator. 

SELECTION OF APPARATUS 

The above simplified theory gives us some 

ideas about the elements to be used and 

their constants and characteristics. 

(1) The tube should be of the "high -mu" 

type, although satisfactory results may be - 

obtained with other types. 

(2) The substance of the rod is of the 

highest importance. It must have sharply - 

pronounced magneto -strictive properties 

and, preferably, should not reverse the direction 

of the change in its length during a 

single half -cycle of the magnetizing force. 

Comparing with Fig. 2, the characteristics 

of iron, cast cobalt and nickel, we find that 

the latter is the most suitable material of 

the three. 

Some of the nickel alloys, such as invar 

(30% nickel, 63.8% iron and 0.2% carbon), 

nichrome (60% nickel, 12% chromium, 26% 

iron), or monel metal (66% nickel, 33.5% 

copper and 0.5% iron), have been found to 

require excessively long rods. For the purpose 

of obtaining low frequencies, the ends 

of a shorter rod may be loaded with weights. 

Also, we may use a tube made of a magneto- 

strictive substance which is filled out 

with a metal having a low sound -velocity; 

for instance, lead (4,025 feet per second, as 

compared to 16,315 for nickel). 

(3) As to the shape and the inductance 

values of the coils, more complicated and, 

to a certain extent, contradictory, considerations 

enter. The plate coil has to be designed 

in accordance with the direct -current 

component of the peak current and the mag- 

The complete magnetostriction oscillator as constructed in the RADIO News Laboratory. 

The "loatd speaker" resting on the vibrating rod is merely a rolled sheet of 

writing paper. Note the simplicity of the whole oscillator.



neto-strictive characteristics of the substance 

employed in the rod. A field so 

strong as to cause saturation (with regard 

to the Joule effect) must be avoided. On 

the other hand, an equal variation of the 

plate current will cause a larger Joule effect 

in the rod when a coil of larger inductance 

value is used. A similar consideration may 

be applied to the grid coil. 

The dimensions of those coils lie within 

relatively large limits and the most desirable 

values may be obtained only through a complicated 

mathematical analysis, connected 

with a considerable amount of experimental 

work. 

CONSTANTS OF A SET -UP 

The photographs reproduced here show a 

magneto- strictive oscillator built in the 

RADIO NEWS Laboratories. The designers 

had no particular frequency in mind and no 

special parts were constructed; they used 

parts under hand, from which it was expected 

to obtain some results. 

di- 

The monel -fetal rod is /-inch in 

The tube 

ameter and 7 -13/64 inches long. 

is of the standard 201A type, and has 90 

volts on the plate. The method of clamping 

the rod between two knife -edges is clearly 

shown in Fig. 7. Three sets of different 

coils were used, with no very appreciable 

difference in the results. The coils shown 

in the pictures are wound on hard -rubber 

tubing, / -inch in diameter and 2 -3/16 

inches long. There are 26 layers of approximately 

60 turns each of No. 30 S.C.C. copper 

wire. Each coil has an inductance of approximately 

25 millihenries. The secondaries 

of an intermediate- frequency iron -core 

transformer formed another set which was 

tried. 

This oscillator is not powerful; nevcrthe- 

illn stration above sbous just how the ferromagnetic rod of mancl or other suitable metal is 

rhunped is place, without damping its vibrations. Any similar arrangement will be suitable; the 

base may be of wood half an inch thick, or more. 

453 

less its operation could easily be detected, 

either by the milliammeter in the plate circuit, 

or by sound of a very high pitch. The 

acoustical effect can be amplified by the use 

of a small paper cone with a pin glued to 

its apex, as shown. Still better results were 

obtained with a paper drinking cup playing 

the role of a loud speaker. 

A 13,000-CYCLE NOTE 

The dotted part of Fig. 5 shows the 

method used to measure the frequency of 

current. A 1,000 -turn honeycomb coil was 

inserted in the plate circuit of the amplifying 

stage, and the frequency was measured 

by a General Radio No. 224 wavemeter. 

This was in close accordance with the computed 

natural frequency of the rod. By 

Newton's formula, we calculate the velocity 

of sound in monel metal to be approximately 

4,760 meters per second. Having 

divided this value by 0.366 (which is twice 

the length of the rod, expressed in meters), 

we found the same number, 13,000. 

The phones in series with the honeycomb 

coil were short -circuited during the frequency 

measurements. 

'rhe tremendous penetrating power of 

such a high note is surprising. Although 

the intensity of the sound in the neighborhood 

of the rod was not very great, it could 

be heard distinctly in the adjoining rooms, 

separated by wood and glass partitions. 

Some of the members of the editorial staff, 

without suspecting the source, had complained 

of being annoyed by a hissing, "drilling" 

sound. 

The construction of such an oscillator involves 

no great difficulties nor expense. The 

essential elements of success in experimenting 

are thoughtfulness, care and a knowledge 

of what is going on; and those of our 

readers who will build such an apparatus 

will certainly discover a large field for interesting 

experimental work, and perhaps 

valuable practical applications. 

Ways of Sensitizing the R. F. Amplifier with Stability 

THE popular tuned- radio -frequency circuit 

of late has been improved by the 

widespread introduction of two methods of 

stabilization: namely, plate- voltage control 

and grid suppression. In fact, these methods 

have come to replace in large measure the 

previous potentiometer stabilizer which figured 

in early R.F. circuits, and, to a lesser 

extent, the neutralization method which 

played an important role a few years ago. 

Few radio enthusiasts, even at this late 

date, seem to appreciate the significance of 

plate- voltage control. They take it for 

granted that 90 volts is approximately the 

correct voltage, and let it go at that. Of 

course, 90 volts will give results in R.F. 

amplification, but so will 67% and 135, if 

necessary. The radio- frequency tubes may 

be operated at maximum efficiency if provided 

with the proper plate voltage to meet 

existing conditions in the individual receiver. 

Thus the old -time potentiometer stabilizer, 

which serves to make the grid positive, may 

be dispensed with if the R.F. tubes have 

the precise plate voltage to keep them just 

a shade under oscillation. In the neutrodyne 

circuit the neutralizing condensers may he 

removed and the R.F. amplifier controlled 

by precise plate voltage, with a marked 

gain in sensitivity. 

The potentiometer -stabilized set today is 

no longer efficient with the closely- packed 

wavelengths. It tunes too broadly, due to 

making the grid positive. It draws too 

heavily on the plate supply. It even intro - 

(Continued on page 4.82) 

At A we have an "old -fashioned" 400 -ohm -pote ,tiometer arrangement. which regulates the action 

of the tube by varying its grid bias ( "Eg" in ne characteristic curve). The circuit shown at B 

is a modification which varies the plate voltage ( "Ep ") and thereby produces the desired regulation 

more satisfactorily. In this case the resis or El should have a range up to 500,000 ohms. 

Condensers and chokes arc omitted for simplicity.


All 

454 


A Way to Mount a Home -Made 

Scanning Disc 

experimenting with television, who 

FFANS are making their equipment, find it quite 

difficult to mount the scanning disc on the 

shaft of the motor; particularly in view of 

the fact that the disc must run perfectly 

true in order to give good results. If the 

disc is home -made, the job is much harder 

than when a manufactured disc is used; 

but, in either case, the bushing must be 

quite large in order to prevent the disc from 

wobbling. 

A satisfactory hushing for a television 

disc may he made from an old radio dial 

as illustrated in Fig. 1. First the hole in 

the center of the dial is drilled all the way 

through and, if necessary, it is enlarged to 

fit the shaft of the motor. Next, fromtwo 

to four holes are drilled at equal distances 

around the riot of the dial. The dial is now 

placed in the exact center of the scanning 

disc, and used as a template for drilling 

holes in the scanning disc, which correspond 

with those drilled in the rim of the dial. 

After this has been accomplished it is necessary 

only to mount the dial on the scan - 

ing disc, with from two to four machine - 

screws. 

When selecting a dial for this purpose, it 

is important to make sure that it is made of 

good bakelite. Many of the inexpensive 

dials are made of other compounds which 

do not have sufficient mechanical strength. 

-Contributed bp Albert Baez, Jr., East 

Orange, N. J. 

Handy Current -Supply for 

The Experimenter 

EXPERIMEXTERS who desire to build 

and test all kinds of radio apparatus, 

yet at all times have one receiver which may 

be operated, are always faced with the question 

of power supply. Many have found it 

necessary to maintain two complete sets of 

batteries or power units, one for the house- 

hold music maker and the other for experiments; 

while others have tried various 

PLUG I,3, 

NUT 

SOLDERED 

JOINT 

Fn:. 2. 

WIR 

LUG 

/JACKS, 

methods of using the same batteries for both 

purposes. However, in a large percentage 

of the cases where a single set of batteries 

is to be used for more than one purpose, the 

frequent reconnections are considered more 

of a nuisance than the saving is worth. 

Many systems for rapid change -over of 

batteries from one set to another have been 

suggested and many of these are very satisfactory. 

In most cases, the instructions 

call for batteries to be mounted permanently 

under the work -table or in some other 

convenient location, and the binding posts of 

the batteries are connected to a terminal 

strip mounted on the work -table. With this 

system, any receiver may be connected easily 

with the binding posts on the terminal strip 

and there is very little danger of short -circuiting 

the cells. However, the task of 

fastening wires to the posts of the terminal 

strip requires considerable time, each time 

a set is connected. 

A system which the writer has found very 

satisfactory for this purpose is illustrated 

in Fig. 2, below. It will be noticed that the 

MOTOR 

SET SCREW 

METHOD OF ATTACHING 

SCANNING 

MOTOR 

SHAFT 

OLD RADIO DIAL 

SCREWS 

NUTS 

DRILL HOLES WIDTH 

OF SCREWS 

DISC 

FIG. 1. Plain bakelite dials make strong bushings 

to attach a disc centrally to a motor shaft. 

batteries are connected to a terminal strip 

in the usual manner, but the terminal strip 

is equipped with tip plugs instead of the 

usual binding posts. When this arrangement 

is followed, a tip plug is fastened to 

each wire of the battery cable leading from 

the set, and a number of connecting wires 

A- A+ B- B+45 V. B+90 V. B+135 V. 

t% . 0 0 

BLACK YELLOW GREEN BLUE MAROON RED 

CONNECTING 

TERMINAL STRIP 

?2?'2c»'tL2«X24.: 

COLORED WIRES 

BATTERY CABLE 

This handy system makes it easy to plug is the battery cable of any one of several sets, 

or to connect on experimental hook -up to the proper voltages. 

i 

a re prepared; each with a tip plug on one 

end and a connecting lug or spring clip on 

the other end. 

: á1, 

HOLE MUST BE DRILLED SO 

THAT SCREW ON CLAMP ABOVE - 

MAY FIT EASILY 

THE LITTLE SCREW WHICH 

FITS IN THIS HOLE WILL INSURE 

A GOOD CONNECTION WHEN 

SET IS IN USE 

TO+0F'A 81NDING POSTS ON SET 

T' 

I 

caË 

TAPE 

METAL 

CLAMP 

M1G. 3. The movement of the phone's automatic- 

switch hook can be used to cut off the 

loud speaker during conversation. 

To facilitate connecting the receiver to 

the terminal strip, a strip of paper may be 

pasted in front of the tip jacks and the 

color of each wire of the battery cable may 

be marked in front of the particular jack 

with which it connects, as indicated. When 

connecting other apparatus to the batteries 

the separate connecting wires are used for 

the purpose. The connecting lug of each 

wire may be fastened to any binding post, 

and the tip plug may be inserted in the 

proper jack on the terminal strip. 

Only seven tip jacks are shown on the 

terminal strip illustrated, but there is no 

reason why a greater number of plugs could 

not be used. For a complete work -table, 

the experimenter might include also jacks 

for the aerial, ground, loud speaker, and 

110 -volt A.C., as well as lower A.C. voltages 

for filament supply. -Contributed by 

E. L. Gibson, Atlanta, Ga. 

Telephone Automatically Cuts 

Off Radio Set 

IN radio -equipped homes the loud speaker 

usually is considered a nuisance when 

trying to talk on the telephone. If loud 

signals are being received, it is necessary 

either to turn off the radio set or ask the 

person at the other end of the wire to re- 

peat almost everything he says. Both of 

these things are annoying, but they may be 

eliminated easily with the simple device 

illustrated in Fig. 3. This device is a homemade 

switch which automatically disconnects 

the radio receiver when the telephone 

receiver is removed front the hook. 

The construction of the switch is illustrated 

clearly in the drawing; it consists of 

two contacts, one of which is fastened to 

the receiver hook and the other to the vertical 

support of the telephone just below 

the hook. The contacts are placed so that 

they touch each other when the telephone 

receiver is on the Itobk; but so that the 

circuit is opened when the telephone re-



45 

ceiver is removed. Both contacts should 

be carefully insulated from the telephone 

itself. 

As suggested in the illustrations, the 

switch may be disconnected in the filament 

circuit of the set, thus turning off the tubes 

when the telephone receiver is picked up. 

However, this system is not very satisfactory 

unless the telephone is near the 

radio set; for long wires in the filament circuits 

tend to decrease the efficiency of the 

set. But the switch will give equally good 

results when connected in series with a 

loud -speaker wire. -Contributed by Francis 

Piscitelli, .A':c York City. 

STRONG 

SPRING 

WOODEN 

FRAME 

LINEN - 

DIAPHRAGM 

ltttttttftttt 1111t11Mttf 

SPEAKER 

UNITS 

DRIVING 

ROD 

ADJUSTING 

-NUT 

l'i,.. 4. By taking up the springs, it is made 

casier to join the two diaphragms; and they 

are easily balanced with the aid of the nuts 

at the corners. 

Spring Mounting Adjusts a 

Linen Speaker Easily 

DTHING the past year the linen -dia- 

phragm speaker has become one of the 

most popular -types in use. This speaker 

is rather bulky, in comparison with other 

types, but it provides very uniform reproduction 

over the entire frequency -range 

when properly adjusted, and is particularly 

satisfactory for low notes. There is another 

advantage which also must be considered 

in connection with these speakers; and that 

is, their design is such that they may be 

constructed at home. 

Fans who have built linen- diaphragm 

speakers have found that satisfactory reproduction 

is obtained only when the proper 

tension is applied to the diaphragms. Also, 

for best results this tension must be very 

great; thus, as the quality is improved, the 

construction becomes increasingly difficult. 

This is because of the fact that in building 

the speaker the diaphragms must first be 

separated to the proper distance, and then 

the centers of the diaphragms must be 

brought together. 

In a linen -diaphragm speaker of the type 

illustrated in Fig. 4, ninny- of the difficulties 

experienced with the usual device of this 

type have been eliminated. In this speaker 

the usual wooden frames for the diaphragms 

are used, but the two frames are separated 

by springs instead of wooden spacers. The 

springs, which must be unusually strong, 

may be purchased at large hardware stores. 

They are placed over bolts which join the 

two frames. 

In building the speaker, when the diaphragms 

are to be drawn together, the nuts 

on the bolts may be tightened in order to 

compress the springs and reduce the distance 

between the two diaphragms. This 

makes it very much easier to join the 

diaphragms, and after this has been done 

the nuts may be loosened as much as needed. 

It will be seen that, as the nuts are loosened, 

the springs will expand and the tension on 

the diaphragm will increase. The use of the 

springs also greatly facilitates the adjustment 

of the receiver after it has been 

placed in operation. Contributed by J. A. 

Johnson, Knapp, llrisconsin. 

Plug -in Tips Facilitate 

Condenser Trials 

DURING experiments with new circuits, 

it is often necessary to change a fixed 

condenser frequently until the proper value 

is found. In most cases, changing a fixed 

condenser means disconnecting two soldered 

joints and making two new soldered connections. 

This operation requires a considerable 

amount of time, thus making it 

difficult to compare the results obtained with 

the two condensers. However, the problem 

would be simplified greatly if plug -in fixed 

condensers were used; as with this system 

it would be possible to make a change almost 

instantly. 

Fig. 5 shows how a standard, molded 

fixed condenser may be converted easily into 

a plug -in condenser. The two terminal 

screws of the condenser should be removed 

and two standard tip plugs may he screwed 

into the threaded holes of the condenser. 

The plugs which are on the market have 

mounting screws which will fit into the 

threaded terminal holes of most of the 

FIG. 5. Condensers of different values are 

readily tested at any place in a circuit with 

this arrangement. 

molded condensers but, if the thread of 

the condenser is too large, the plug may be 

soldered in place. 

After the condenser has been prepared 

as described above, it is necessary to make 

: 

I 

I 

o NEWS has received from read - 

R ADIO so many letters and ballots 

requesting more "Wrinkles" that it 

has been decided to re- establish the 

department. A year's subscription to 

RADIO NEWS will be given in compensation 

for each accepted item. If the 

author of the wrinkle is already o 

subscriber, his subscription will be extended 

one year or he may accept a 

one year's subscription to Science and 

Invention or Amazing Stories, both 

published by the Experimenter Publishing 

Co. 

a receptacle. For this purpose a small Bakelite 

panel 1 x2 x 3/16 inches is used and 

two tip jacks are mounted on it, at the 

proper distance apart. Also, two extra 

holes are drilled at the ends for mounting 

screws. For experiments, the receptacle is 

connected in the circuit and various sizes 

of plug -in condensers are inserted until the 

proper value is found. -Contributed by 

Morris Dorsey, Atlanta, Ga. 

Home -Made Gauge Saves Time 

in Construction 

WHEN you are drilling the front panel 

of a radio receiver, it is important to 

know the exact size of each hole required 

before starting to drill: If the set builder 

guesses at the size of the drill needed, the 

hole is apt to be too large or too small. If 

the hole is too large the mounting screws arc 

apt to loosen up after the set has been in 

use for a short time; and, so far as small 

holes are concerned, it is always more trouble 

to enlarge them than it is to drill them 

to the correct size in the first place.. 

The amateur who has only a few drills 

available will find the device shown in Fig. 

(i a great aid when drilling a front panel. 

A small piece of Bakelite or hard wood, 

about 3 x î x 3/16 inches, is selected and in 

this one hole is drilled with each drill in the 

tool box. The various holes in the order of 

their size should be drilled in straight lines, 

about 1 inch apart. Next, the number on 

the shank of the drill should be marked in 

front of the corresponding hole for identification. 

When making a set, it will be convenient 

to use the device described above to select 


7 

I _ 5:6 ° 

3 

8' 

3-52' 73 

32 T 

1 

_ 

4 

32 

G =ai - 

;_AÀ'/,á 

I 

íi. i w \\ I _ 1- 

Ir-, 

-I- - -1 

1,- 

1 

__ -. A,V3 

-Ill; 

9 t, JJ 

--T: 

I 

g -'6 4,,1z - I{ammor3" 

Fla. 6. 

A gauge prepared in this way will prevent many mistakes in drilling. 

r I 

4='`

- meters. 


456 

en The 

fiori Vaves 

i 


RADIO NEws roill welcome any definite information 

from our readers about unlisted 

stations which you may hear putting 

on programs, only if you hear the call or 

the announcement of location. Please give 

the wavelength as closely as you can estimate 

it. Because of the number of experimental 

transmissions by amateurs and 

others, we cannot undertake to list such 

stations in the short -wave broadcast list on 

another page. unless confirmation is received 

of their having a regular schedule; 

but all definite information received will 

be published here. Please consult data 

we have published before writing for information; 

we hare no way to identify 

a station by its program or language, since 

many foreign stations transmit in several 

languages; nor even by its approximate 

wavelength, unless it is one of the larger 

and best -known transmitters. 

WHO IS THIS ARGENTINO? 

Editor, RADIO NEWS: 

On April 20th I heard a station on about 30 or 

32 meters, from 6.25 to 9:15 p. m., E. S. T. 

There were selections in German, Spanish and 

English. At 8:25 the announcer said (in Spanish) 

it was Buenos Aires, Argentina. I held on until 

11:20, but they had probably signed off. I will 

appreciate any information your readers can give 

me. 

JOHN J. HANNIGAN, JR., 

35 Maple St., Norwood, Mass. 

NEW WINNIPEG STATION 


The Winnipeg station, operating on 27 meters 

and heard by your correspondent, Norman Wiswell, 

was not CKY, but IIC, owned by James Richardson 

and Sons, Limited. Tests were broadcast for several 

days by the Marconi engineer who installed 

the equipment. The regular wavelength will be 

25.6 meters and the call letters CJRX have been 

applied for, to take effect at the end of the present 

year. - 

The tests were very successful. Reports of loudspeaker 

reception have been received from the 

Yukon, from all' corners of the North American 

Mr. Tompkins' short -wave set in its old -style, 

but attractive, cabinet. 

continent and from Australia, New Zealand and 

British New Guinea. 

If this should catch the eye of your contributor, 

Mr. E. Blake. whom I had the pleasure of meeting 

in London some years ago, I hope he will listen 

in and try to hear us. We shall tie CJRX in 

with our regular broadcast station CJRM at Fleming, 

Sask., each afternoon, from 4:30 p. m. to 

7:00 p. m., Central Standard Time. This schedule 

will be extended in the near future. 

D. R. P. COATS, 

Radio Station CJR.II, 1018 Grain 

Exchange Building, Winnipeg, Can. 

COSTA RICA STEPS OUT 

Editor, RADIO NEws: 

I have been getting a strange station in Costa 

Rica (Central America). He is generally on 

Saturdays, Sundays and Wednesdays, sometimes 

other nights, from 10 to 11 p. m. Central Standard 

Time. He was first on about 38 meters, but of 

late is using 30. 

He announces in English and 

Spanish; just what city and who owns the station, 

I do not know, but would like to find out. 

1 would like to thank RADIO News for introducing 

me to short waves; it is a great pleasure 

to listen in at the bottom of radio. 

CHARLES J. SCHROEDER, 

3125 No. Spangler St., Philadelphia, Pa. 

(Mr. Schroeder writes later: "I know for a fact 

it is not the Costa Rican government at San Jose, 

because the announcer says that he is an amateur 

station. I received him again Sunday night at 

10:15 E. S. T. At 11 he said, I believe, '9:00 

C. S. T., at Heredia, Costa Rica.' The next night 

he mentioned that his wavelength is 30.5 meters. 

I can't seem to get his call or name. 

I would like 

to get his address, as I get him at times R5 to R6 

with two tubes. ") 

.11e. Tompkins' short wave receiver, described 

below, compactly built and including two extra 

stages of transformer- coupled audio. 

A NEAT RECEIVER 


The photographs show a short -wave set that I 

have been using for about three months. It is of 

the same style as the "Junk- Box," but I have put 

in an aerial coil and find that it cuts out dead 

spots. The housing is an R.C.A. No. 5 cabinet, 

made of solid brass, into which I have built a 

sub -panel to mount my four sockets; under them 

are my two audio transformers and the choke coil. 

You can see that this little outfit is very compact. 

It works wonderfully well on a "B" power unit, 

with 200 volts on a 171. I can get enough volume 

to hear a block away on KDKA. NVA111C, etc. 

CHARLES B. 'TOMPKINS, 

220 Broad St., Waverley, N. Y. 

JAVA FOR BREAKFAST 


I have heard Bandoeng, Java, on my RADIO NEWS 

Short -Wave receiver, from my previous location at 

St. Johns, Michigan, and have just received a confirmation. 

(The letter says, "Yost heard us testing 

on duplex telephony with Kootwijk- PCLL-on 18 

We are broadcasting Wednesdays from 

1240 to 1440 G. M. T. Would you report us? 

-Studio Radiodienst, Bandoeng. ") 

FERRIS W. FITZPATRICK, 

Hq. Sect., Chanute Field. Rantoul, Illinois. 

Mr. Dobyns at the microphone (shielded from 

the wind by boxes) of his short -wave station 

6XBV, announcing the progress of the regatta 

from the official barge. 

SHORT -WAVE SPORTING ANNOUNCEMENTS 

Station KGER, owned by C. Merwin Dobyns, of 

Long Beach, Calif., has also a short -wave phone 

transmitter 6XBV. During the recent Pacific 

Southwest Exposition regatta held in Long Beach 

harbor, this was used to transmit a description of 

the races to the main transmitter working on 

215.7 meters, Owing to the carrying power of 

the short waves on 48.86 meters, it is quite possible 

they were heard much further than the higher - 

power transmissions of the broadcast station. 

RIGHT IN THE MADDING CROWD 

Editor, RADIO News: 

I have received -a letter from PCJJ dated July 

25th, stating they are now on the air from 1600 to 

2000 and 2300 to 0200 G. M. T., Tuesdays (11 

to 3 and 6 to 9 E. S. T.); 1600 to 2000 Thursdays: 

and 0400 to 0700- and 1400 to 1700 Saturdays 

(from 11 p. m. Fridays to 2 a. m. and from 9 

a. m. to noon E. S. '1'.) on 31.40 meters. 1 am 

situated at Third Avenue and 52nd Street, New 

York City; there as a power house around the 

corner which always causes noise on the short 

waves, and the "L" causes interference. I am 

using a 50 -foot aerial of No. 12, and when reception 

is bad, I use an R.C.A. AG814 loop. 1 can 

receive PCJJ on Tuesdays and Saturdays. 1 

would like to hear from other fans located in the 

middle of large cities how they get distance. 

WILLIAM MORITZ, 

843 Third Ave., New York, N. Y. 

SHORT -WAVE ON SUPERHETS 


In commenting on the communication from Baron 

von Iloyningend-Iuene, you ask if other owners of 

standard superheterodynes have received short -wave 

signals. 

When the L -2 Ultradyne was announced, I assembled 

the set with considerable success but did 

not receive any short-wave signals. However, 

that was before broadcasting on short waves was 

as commonplace as it is now. 

Last winter I assembled the Magnaformer 9 -8 

to operate with A.C. tubes, at our winter home 

in south- eastern Florida. As an A.C. set it was 

a failure (as I anticipated it would be if built in 

accordance with the published instructions) so 1 

rebuilt it to work on D.C. battery. 

I tried it only one day working on A.C. and



the last program received was a musical number. 

I do not remember the call letters, but the announcer 

was very distinct in saying "located at 

Bound Brook, New Jersey and broadcasting on a 

frequency of 5,000 kilocycles." This was the only 

time I ever had this experience but it shows that 

it is possible for some supers at least to pick 

up and reproduce short waves with good volume. 

A. B. GARDNER, 

511 Green St... Dowagiac, Michigan. 


Re Baron v. IIoyningen- Heune's letter, are either 

or both of his tuning coils reversed in the Ultra - 

dyne? Reversing the primary coil lessens the 

effectiveness of the set, of course, but makes it 

very interesting to handle. 

HOWARD T. BEATON, 

Iroquois Falls, Ontario, Canada. 


During the winter of 1926, I picked up one of 

KIJKA's short-wave broadcasts, on an ordinary 

Pressley superhet. This was one of their Far 

North programs, broadcast for Alaska and Northern 

Canada, and came in on a dial setting that would 

correspond to a wavelength of about 260 meters. 

There was present the usual rapid fading, and 

the announcement stated that the broadcast was 

from KDKA's short -wave station, but I did not 

get any statement as to which wavelength was 

being used. I never did pick them up in this manner 

again, and I think possibly the reason they 

came in so strongly on this occasion was perhaps 

due to their using the limit of their power. There 

was nothing faint about their signals in this case: 

they came in on the speaker with plenty of volume. 

At present I am using a super built up from the 

Silver -Marshall Lab. circuit. using their coils, but 

having Scott World's Record intermediates. Using 

the plug-in coils, I can get down to about 26 

meters. I think I must have been one of the first 

to pick up RF \I in this country. I got them sometime 

last December, and played them regularly for 

several weeks before I found out who they were. 

I have been able to get KDKA on two wavelengths, 

WGY the sane, but not a thing from 

\\'RNY or WLW, though 1 am always trying. 

Short waves may carry well with low power, but 

there is no doubt that plenty of power helps a lot. 

W. WALLACE CLENDENIN, 

Culver City, Calif. 


I have built several Ultradyne circuits. I found, 

a few months ago, that by turning the condenser 

tuning the antenna cod completely 'out, I could 

tune in SUFI\ on their 62 -meter wave during 

the afternoon with the oscillator condenser alone. 

The tuning was very sharp, and there was rapid 

fading, but it could be done day after day. Our 

reception of KDKA is very uncertain on their 

broadcast wavelength; I don't believe we average 

anything like good reception on two nights a week, 

in summer. But as long as I used an Ultradyne, 

I could get their short -wave broadcasts in the 

afternoon. 

B. J. SANFORD, M.D., 

Clare, Michigan. 

FOR SCOUTMASTERS AND SCOUTS 


Now that good radio weather is about to open 

up, maybe some scoutmaster might start a radio 

club that could work with the one I have started 

here, and also have the real "kick" of talking to 

some American Scout who is in a foreign country. 

Personally, I think it would be about as fine a 

training as any Scout could receive, and 1 would 

be very glad to send my ideas or rather suggestions 

to any scoutmaster who is willing to work. 

I have had' some wonderful results from the different 

radio manufacturers, and they have all 

expressed a desire to help the good work along. 

Also, a lot of other letters have been received; but 

I have been too busy to take much time away from 

business to answer any but the. ones from Scouts. 

Will you return the enclosed letter (printed below) 

to me, as I want to use it as an incentive for 

my boys to keep on trying. 

GEORGE O. HOWARD, 

109 Tulsa Bldg., Tulsa, Oklahoma. 

Dear Mr. Howard: 

Having seen your letter in RADIO NEws, I would 

like to write in commendation of your idea in 

teaching radio to the Scouts and getting them interested. 

I am a "harm" of three years experience 

and certainly did not have the ease in starting 

that the fellows in the States enjoy. At present. 

after trying, and tedious, unsuccessful times with 

long -wave sets, I have reverted to short waves and 

can get plenty of good musical programs (barring 

the fading) as well as code. 

I also am a Scout, 16 years of age, and would 

be glad if you could put me in touch with two or 

three Scouts also interested in radio. It has been 

pretty hard here to keep pounding the old brass 

when nobody else is interested in that line; but 

once in a while a brother "ham" has come along, 

and we have a pretty good time. Don't get the 

idea that I'm lonely, though; the fellows all have 

a respect for the work I've done, and I have plenty 

of pals. The only thing that I sure would like is 

to have someone in the old country to talk things 

over with -chew the rag, so to speak. 

\\'ell, GB till the next mag comes in. I would 

be glad to tell the fellows anything they want to 

know. 73 to you. 

EARL A. NOOSE, JR., .-IC 2 AJ, 

American Bible Society, Pekin, China. 

USE OF SHORT -WAVE ADAPTER 


On June 19 I received a Submariner and attached 

same to my Norde -Hauck Super 10, which has 

four audio stages, with a power tube in the last. 

The results were very gratifying. Each night I 

get the programs of SSS wonderfully and on 

Sundays also, from 10:00 a. m. to 9:00 p. m., 

Central standard time. 2 XAF comes in one week 

daily and the next on Tuesday, Thursday and 

Saturday. 

Your program from 2XAL on July 31, from 

7:30 to 7:50 p. m., containing your talk about 

flying rockets and the orchestra numbers was 

heard but with severe fading. 

PCJJ, Holland, broadcasts every Tuesday front 

7:00 to 8:15 p. m. and on Fridays I enjoy the 

Spanish program from 7:45 to 9:00 p. ni. It 

comes in exactly between 2X: \L and 2XAF; the 

readings on the Submariner are 19, 1934 and 20. 

ORESTES CENA, 

Tuxpam, Vera Cruz, Mexico. 


Station PCJJ, that of the Philips 

company at Eindhoven, Holland 

(transmitter at Hilversum), which 

so many of our readers have 

heard, is probably the most 

powerful transmitter in the 

world putting out short-wave 

broadcasts. Its total power is 

about 15 kilowatts in the aerial, 

and it works now on 31.40 meters. 

The illustrations which we 

reproduce show the compactness 

of this installation; at such high 

frequencies, care must be taken 

that leads do not introduce oscillatory 

circuits, as regeneration 

of 1 /20.000th of the power would 

cause difficulty. This is minimized 

by changes of the fre- 

quecy. The piezo- electric control 

crystal is contained in the 

box at the left in the center 

(uppermost) picture. It is 

ground to a frequency corresponding 

to a wavelength over 

180 meters, and the unit puts 

out 50 watts on Une second harmonic 

of this. In the middle 

section of the transmitter, shown 

at the louver left, the frequency 

is tripled and the output raised 

to 3 kilowatts. At the right of 

titis picture. and the left of the 

third, is shown the 25 -kw. tube 

which feeds the aerial -a single 

bronze Loire. The remaining apparatus 

of the louver right comprises 

the modulators and their 

cooling system.



The Radio Constructor's Own Pages 

Wherein Custom and Home Set Builders and Experimenters 

All Over the World Swap Experiences and Suggestions About 

Hookups and Accessories 

REJUVENATING AN OLD -TIMER 

.Editor, RADIO NEWS: 

A short time ago, I got hold of one of the old 

Westinghouse receivers consisting of a type RA 

tuner and a type DA detector -amplifier. This set, 

as you may know, uses three tubes of the WD -12 

type, which I decided to replace with the present 

UX type. I replaced the three sockets with UXtype 

sockets and used a UX -200 in the detector 

socket and UX -201A tubes in the two audio stages. 

The second audio transformer was burned out, so I 

replaced it with a Thordarson with a turn ratio 

of 6:1. The grid leak and condenser I replaced 

with a .00023 Sangamo condenser and a 4- megohm 

grid leak. I used 45 volts on the detector plate 

and 90 volts on the plates of the audio tubes. For 

a loud speaker I used the Saal eccentric cone which, 

in my opinion, is about the best speaker I have yet 

heard for torte quality and its ability to handle 

great volume without blasting. 

My aerial is about 150 feet long and 40 feet high 

and is of the single- strand type. My ground system 

is somewhat out of the ordinary, in that one 

connection is made to a water pipe while two other 

connections are made to two groups of three 1 -inch 

pipes driven into the ground; the groups are spaced 

about 23 feet apart at right angles to each other. 

With this layout I have been able to get what I 

consider surprising results, considering the fact 

that we in the Hawaiian Islands are located over 

2,000 miles from the mainland. 

I have only been using this set for the last three 

days, but I am convinced that it outperforms a 

certain well -known 6-tube set which I happened to 

be using on trial; it outperforms it, not only in 

range, but in volume as well. The volume put out 

by this set is truly amazing; it not only fills my 

room but can be heard distinctly all over the house. 

In the short time I have been using it I have already 

logged the following stations: KGU, KGO, 

KFC, KPO, KHJ, KFSD, KOIN, KFI, KPLA, 

(COIL, KF \VB, KNRC, KYA, KNX, KMTR, 

KOMO, 4QG, 2BL, besides some others which I 

could not make out because of fading. I am looking 

forward to enlarging this list considerably in 

the very near future, even though this is claimed to 

be the worst season of the year for radio reception. 

Since this set employs the regenerative circuit, 

tuning must be carefully done to prevent marring 

the neighbors' reception; but my experience has 

been that it is very simple to tune if one keeps in 

mind the simple rudiments of tuning. I have noticed, 

however, that correct manipulation of the detector 

rheostat gives great flexibility. The amplifier 

rheostat, however, need not be touched in tuning; 

the best position is so that it is just turned 

on. In this position it gives maximum volume with 

a minimum consumption of current and a consequent 

lengthening of the life of the audio tubes. 

It is very likely that there are others who have 

one of these sets and would like to remodel it. It 

is for these that I decided to write you and tell 

of my experiences, and for that reason I hope that 

you will find it possible to publish this letter. 

O. F. STERNEMANN, 

Box 9, Hatei, Hawaii. 

M. :Uampc's triple speaker, viewed from the front of the baffle. 

FIRST X -RAY PHOTOGRAPHS OF RADIO 

SETS 


Under the heading "X- Raying the Radio Set to 

Show Its Insides," on page 206 of RADIO NEws 

for September, Baron Manfred von Ardenne is 

credited with the introduction of X -ray photography 

of wireless sets. 

Unless he did this before 1919, I believe I was 

the first to employ X -rays for this purpose. I 

showed an X -ray photograph (which I took in 

1919) of a wireless set to illustrate a lecture on 

wireless telephony to the Royal Society of Arts in 

London in 1920. (See. Wireless World," for July 

24, 1920). This radiograph, together with an ordinary 

photograph of the same set, is reproduced in 

my book, History of Radio Telegraphy and Telephony, 

published by Chapman & Hall, Ltd., London, 

1926. 

I shall be obliged if you will publish this letter 

in your excellent journal, to which I have been 

a regular subscriber for many years. 

G. G. BLAKE, 

8 -10 Onslow Road, Richmond, Surrey, England. 

MULTIPLE GROUND MAKES A FRIEND 


I always read your magazine with the deepest 

interest and get lots of good out of it. For example, 

"Encircling the World with a Two -Tube 

Set," in the March issue, made mention of using 

several grounds. This was tried by a friend of 

mine in Ottawa to whom I passed the magazine. 

The results were beyond expectation, and have 

made him a regular reader of your magazine. 

Others are to try the idea. With sincere thanks 

for the information contained in your recent letter. 

J. PRUD1OMME, 

139 Botcher Street, Ottawa, Canada. 

THANKING THE WRITER 


In keeping with your policy of giving us the 

latest and best, you have again conferred a great 

treat cn the Browning -Drake fans. In the August 

issue of RADIO NEws, you published an article by 

Mr. C. A. Oldroyd, of Barrow -on- Furness (England), 

"A Booster Unit for the Browning- Drake." 

I built one of the "Boosters" and it has done 

wonders for that selective and wonderful DXgetter. 

The results are almost beyond belief. During 

this excessive heat and fearful static condition 

of the atmosphere, I have been able to bring 

in the Gulf State stations and the Atlantic coast, 

with greater volume than is ordinarily obtained 

during the fall and winter months. Also, I have 

been able to get a great many of the low- powered 

stations (some at quite a distance) which, under 

the best of conditions, are hard to bring in, and 

all of these on the loud speaker. 

It is true that we have one more tuning control, 

but the results more than compensate, and, as the 

dials "track" pretty closely, it is very little 

trouble. 

J. N. BACON, 

Oshkosh, Wisconsin. 

O. Mampe of Palisade, N. 1., 

opposite New York City, is a 

radio constructor who goes in 

for elaborate effects. He has 

built a speaker, with three electrodynamic 

-care units, whose appearance 

is shown here; the 

baffle board is 41 feet wide 

and 51 feet high, and made of 

h -inch wood. The three speaker 

units arc supported an shelves at 

the rear, as will be seen from 

the view in the third column; 

and other shelves are provided 

for the power supply and amplifier. 

The reproducer assembly 

is admirably adapted for high 

quality under control; though it 

is hardly suitable to be tined 

loose under frill power indoors. 

Constructors who desire to build 

a speaker with even one dynamic 

unit of this type are referred to 

',ages 438 -441 of this issue for 

information. 

MR. PORTER WILL BILL YOU 


I will send you and Mr. Porter my heartfelt 

thanks for the permanent hook-up of a phonograph 

pick-up to a receiver (page 53, July, 1928 RADIO 

NEws). I have a very expensive phonograph, and 

by a little expenditure and some of my own time, 

I have a neat job at a saving of about $500 compared 

with buying one of the new combinations. 

This is a feature which, I suppose, appeals to the 

majority of home constructors. I am using a 

SCIENCE AND INVENTION circuit of 1925, but it 

works fine. 

A. CARL CUTSINGER, 

960 East Orange Grove Ave., Pasadena, Calif. 

A rear view of 111r. Mampe's speaker, shoe. ing 

the three electrodynamic cones. 

LUCKY YOU WERE NOT FLYING 


Today I bought the June issue of RADIO NEws 

and read "The Port of Missing Airplanes. ' The 

story is indeed a good one, and I believe it is 

quite possible for a person to be overcome with 

dizziness by listening to a shrill note sent through 

a pair of headphones, as in the story. While listening 

to my set, I decided to change the grid 

leak, still wearing the phones. The set started 

to oscillate and the whistling made me dizzy. I 

am not telling you of this as a scientific experiment, 

but an actual happening. In closing, I wish 

to say that I greatly enjoy the stories printed in 

your magazine. 

NILS GJERDE, 

5612 Sixth Ave., Brooklyn, N. 1'. 

(Sonic of our readers are not in entire agreement 

as to tiro fiction which RADIO NEWS carries. 

However, the series of stories referred to is, in our 

opinion and that of many others, worth reading 

purely for the scientific considerations which it 

presents.) 

OUT IN THE WOODS 


I feel a great deal of credit is due the World's 

Record Economy Eight, as I built one of these 

sets. I am spending the summer here and our 

camp is in the heart of a large forest, and located in 

such a way that I cannot put the aerial above the 

trees. I am using 125 feet of aerial, including 

lead -in, and have received forty DX stations in 

one week's time with no overlaps or interference 

by other stations. Two of them are real DX at 

this time of year, I feel; they are KFI and WKAQ. 

I would appreciate your publishing this. 

CHESTER L. PRICE, 

Wanakena, New York.



SET BUILDING IN FRANCE 


Just a few lines of appreciation to yourself and 

RADIO NEWS, the current copy of which was a 

boon companion to me during an exceedingly violent 

electrical storm up here (at Holzleck, in the 

Vosges Mountains). I was far too deeply engrossed 

in your description of the Screen -Grid Strobodyne 

to notice such trifles as storms. I ha n 

taken RADIO NEWS since its first edition but, because 

of traveling all over the world, I had to 

plan with my newsdealer in New York to hold 

over my copies until my return. Now that I have 

a permanent address in Paris, I have at last become 

a subscriber. 

Here is something that would be of great assistance 

to me and undoubtedly to many other 

fans over here, and that is a table comuaring the 

relative sizes of wires between the American B & S 

gauge and the French gauge which is given in 

mils. I desire to build a Strobodyne a l' Americaine, 

but cannot do so until I know what size 

wire is equivalent to that given. (See below). I 

fell down on the construction of the RADIO News 

Short -Wave set on this account and am anxious 

to complete it and fish for good old \VRXY on 

the 30.91 -meter wave. 

We have not yet come to the screen -grid tube 

in France, but I have found that the "Metal 

Radio" factories are putting one on the market 

in the near future, and if it has similar characteristics 

to the 222, I shall build the Strobodyne 

S. G. as described. 

I am at present using a Strobodyne built by M. 

Chrétien, the originator of the circuit, but the 

American hook -up is way ahead of it. My set 

has coils for both wavebands (180 to 500 and 500 

to 3.000 meters) incorporated, and the change is 

made by a commutator on the panel. 

By the way, the relay of the Tunney- Ilceney 

fight over Daventry and 21.0 was wonderful. I 

received it in Paris clear as a bell. Absolutely 

no fading right up to R'GY's announcement of 

the time signal, when England acknowledged the 

defeat of her champion with silence immediate and 

profound. But that relay certainly spoke worlds 

of the future of radio from an international view - 

point; may good old RADIO NEWS stick and grow 

with it.. 

R. W. HuMPHRE.YS, 

57 Boulevard Suchet, Paris 16e, France 

Metric Measurements of Wire 

( Fiere arc the measurements of copper wire - 

the metal conductor only -in the metric system: the 

diameter in millimeters and the area in square 

millimeters. This may be of benefit to some of 

our other friends abroad. The gauge is Use familiar 

American Brown & Sharpe.- Eotroa.) 

Gauge Diam. Area Gauge Diam. Area 

14 1.628 2.081 28 0.321 0.081 

16 1.291 1.309 30 0.255 0.051 

18 1.024 0.823 32 0.202 0.032 

20 0.812 0.513 34 0.160 0.020 

22 0.644 0.325 36 0.127 0.013 

24 0.511 0.205 38 0.101 0.008 

26 0.405 0.123 40 0.080 0.005 

NO PANCAKES FOR BREAKFAST 


I attach a snapshot of two speakers made of 

scrap paper, a cone and a horn built along the 

lines of the model described in Chester Schenck's 

article in the June issue of RADIO NEWS. The 

horn was built around a form made from an old 

orange crate and some stiff cardboard; the forni 

Mr. Ste-wart, above, flanked on either side by 

a low -cost loud speaker made as described. 

It will be bard to lower his record unless you 

steal a unit. 

being well coated with talcum powder to insure 

its easy removal after the horn had thoroughly 

dried. For the material, I used all the old magazines, 

newspapers, wrapping paper and so forth 

that was available, and for paste a mixture of flour 

and water. The job was rather tedious; but, as 

L am not especially fond of work anyway, it came 

in handy to apply a layer or two a day and allow 

time for drying. The horn was finally built up to 

near / -inch in thickness, but is still too thin. Only 

one brace is used, that being made of four pieces 

of wood, )1 -inch square and about twelve inches 

long, nailed together in the form of a square and 

slipped down on the bell as far as it will go and 

pasted in position. The tone is as good as that of 

several manufactured horns I've heard, and better 

than some. 

The cotte consists of one layer of heavy brown 

wrapping paper with two layers of newspapers 

pasted on the outside, three layers in all. A circle 

36 inches in diameter was laid off out this and a 

V- shaped slice cut out. That gave me a cone 34 

inches in diameter and 7 inches deep. A loop of 

soft copper wire was pasted on the outer edge and 

the string used for mounting the cone in the 

square wooden framework was laced back and forth 

through the wire and to the frame. A 1 x 2 

bolted to the frame, supports a cigar box, which, 

in turn. supports the driving unit, one taken from 

a Musicone. The main item of expense in this big 

cone was five cents for the two bolts in the 1 x 2; 

the flour for the paste was stolen from the family 

larder, so cost nothing. 

The cone is by far the better of the two. Both 

reproduce well the bass and middle- register notes; 

but we have lots of static down in this hot country 

and it is not so objectionable on the cone as on 

the horn. The set driving these speakers is home - 

built, a Browning -Drake type, with a screen -grid 

R.F. stage, 200A detector, Thordarson Autoformer 

audio amplifier with a UX -112 in the last socket. 

\ olume amt quality de luxe! 

GtY STEWART, 

U opio, Texas. 

A SENSITIVE FOUR -TUBER 

Editor, RADIO NED S: 

I am sending my four -tube circuit, which was 

very much like Mr. McCormick's till the screen - 

grid tube came out. I think that the only real 

difference was that I changed my antenna coil 

by doing away with the fixed condenser and tapping 

at the twelfth turn from the filament end. 1 

have written Mr. McCormick, advis'ng him to put 

a screen -grid tube in his R.F. stage; it requires 

only a little changing and it is well worth the 

trouble. With his DX record, using a 201A, he 

certainly should step out with the screen -grid hookup 

for a few more miles. 

This circuit is very sensitive and selective with 

a short antenna, and the west coast comes in with 

plenty of volume. 

We have only from 7:30 p. m. until midnight 

to do any DXing, on account of the high -power 

naval station NSS here, which sends off a heavy 

mush or "back- wash "; so you can see ive do not 

have a shot at the foreigners. My most distant 

stations are California, Mexico, Cuba and Canada; 

but remember we have to do this early. 

This circuit was originally the "Reactodyne" published 

by RADIO NEWS its 1924. I hope you can 

interest a few others in this circuit. 

FRANCIS E. ENGLE, 

14 Cathedral St., Annapolis, .l(d. 

A SINGLE- CONTROL SHORT -WAVER 


I am enclosing a diagram of a "one-hand" shortwave 

receiver I have been using for about four 

months. I use Aero short -wave coils; with this 

arrangement I am able to set the feed -back control 

condenser for a given coil and sweep th,s whole 

range without any other adjustment until the desired 

signal is found. Then a little adjustment of 

the detector filament and I am all set to listen. 

No more "holes," etc. 

I am using special R.F. chokes. \\'hile an 

Aero No. 10 will work very well, a choke with very 

low inductance must be used on S. W. I use No. 

36 S.C.C. on a piece of round or square Vs -inch 

bakelite, about 6 inches long; start winding otoz 

end about 40 turns, space %-inch, then 60 turns, 

space 1/s -inch, 80 turns, and so on till the space is 

used up. I find the 112A tube the best detector 

for this receiver; the rest is standard. 

W. E. SMITH, 

Oak Forest, Illinois. 

MR. LOVELESS IS NOT SOLELY TO BLAME 


I was interested in finding in the article on the 

Loveless aerial the description of a circuit embodying 

the principle of my patent No. 1,668,261, 

issued to me by the patent office May 1, 1928; 

application for the same having been filed Dec. 27, 

1923. An examination of this patent will reveal 

the validity of my claim; for it will be there seen 

that specific claim is there made for aerial circuits 

together with a claim embodying the same principle 

in radio sets themselves. The discovery of the 

principle involved was made by me as far back 

as 1920, while engaged as professor of physics its 

the University of Santa Clara. 

(Rev.) RICHARD H. BELL, S. J. 

St. Ignatius College, 2130 Fulton St., 

San Francisco, Calif. 


47 

22D LC 

i j 

i j 

35T 47T 

26D.CC. 22 D.C[ 

2zz ¡ 2OI-A 201-A 

h 

, 

_ 

FiY 

áó 

°°fiV 

71-A 

Ir 

-.00015 MMF 

r 

- I I 2-A 

t 

b 

BND, A- C4 -A +B= 

O 6 

B+45v. 'C=4;V. '8". 90V. -C-27V. '8+135V. 

Mr. Engle's hook -up differs from the " Reactodyne" in its aerial circuit; the latter was 

very loosely coupled in the original. The primaries are wound fumble -fashion and placed 

inside the secondaries, which are on 3 -inch tubing. Transformers are 5.31 220s. Ile 

suggest a fixed ballast also in the 222's "A-." 

Mr. Smith's set is tot a reflex, as first glance might suggest, 

but a short -waver with two A.F. amplification stages. 

Our readers may test it to see if ease of operation is accompanied 

by necessary sensitivity and control.


460 


LAB(RATORCE 

e rneltsnco 

adïo News 

praforie5 

manufacturers arc invited to send to RADIO NEWS LABORATORIES 

RADIO samples of their products for test. It does not matter whether or not 

they advertise in RADIO NEWS, the RADIO NEWS LABORATORIES being an independent 

organisation, with the improvement of radio apparatus as its aim. 

/f, after being tested, the instruments submitted prove to be built according 

ro modern radio engineering practice, they will each be awarded a certificate 

cf merit; and that apparatus which embodies novel, as well as meritorious 

features in design and operation, will be described in this department, or in 

the "What's New in Radio" department, as its news value and general interest 

for our readers shall deserve. If the apparatus does not pass the Laboratory 

tests, it will he returned to the manufacturer with suggestions for improve. 

meats. No "write-ups" sent by manufacturers are published in these pages, 

and only apparatus which has been-tested in the Laboratories and found of 

good mechanical and electrical construction is given a certificate. As the sere - 

vice of the RADIO NEWS LABORATORIES is free to all manufacturers, whether 

they are advertisers or not, it is necessary that all goods to be tested be forwarded 

prepaid, otherwise they cannot be accepted. Apparatus ready for, or 

already on, the market will be tested for manufacturers free of charge. Apparatus 

in process of development will be tested at a charge of $2.00 per hour 

required to do the work. Address all communications and all parcels to RADIO 

NEWS LABORATORIES, 230 Fifth Avenue. New York City. Readers will be informed 

on request if any article has been issued a Certificate of Merit. 

AUDIO -FREQUENCY 

TRANSFORMER 

The "Type AX" audio -frequency 

transformer shown, submitted by the 

Sangamo Electric Company, Springfield, 

III., is of excellent mechanical 

and electrical design. The amplification 

of the transformer maintained 

a value almost constant from 32 to 

5,000 cycles, when used with the 

201A -type tube. The primary in- 

ductance, with a 

plate current of 

3 milliamperes, was found to be 

approximately 80 henries. The 

transformer has a ratio of three to 

rie; and excellent quality with great 

volume was obtained when it was 

used in the conventional audio am- 

plifier employing the 201A and 171 

tubes. The transformer is identified 

by a yellow spot. The core and 

winding are completely shielded by 

an iron housing of olive -green finish. 

The dimensions of the base are 2% 

x 2h inches, while the height is 3 

inches. 

AWARDED TI1E R. \DIO NEWS 

LABORATORIES CERTIFICATE 

OF MERIT NO. 2421. 

AUDIO -FREQUENCY CHOKE 

The "Type E" audio- frequency 

choke or "impedance" submitted by 

the same manufacturer, is of the 

same size and shape as their "Type 

AX" A.F. transformer illustrated 

above. It is used as an output impedance 

for the 171 -type power tube. 

in which case the entire inductance 

is employed. 

It may he used also 

as an output impedance for the 112 - 

or 210 -type power tubes, by using 

the portion of the winding between 

"T" and "B } "' It is designed to 

match the impedance of the modern 

power tubes and, for this reason, 

allows the lower frequencies to be 

better reproduced. When it is emrloyed 

in the output circuit, a blocking 

condenser external to the choke 

must also be used; this should have 

f rom 2 to 4 tuf. capacity, and be 

of voltage rating suitable to withstand 

safely the maximum voltage 

of the power stage. The inductance 

was found to be within 10% of 

the rated value of 30 henries, when 

measured at 60 cycles; the ohmic 

resistance is approximately 570. The 

metal case is finished in dark red 

and the device is identified by a 

"mandarin red "' spot. 

AWARDED THE RADIO NEWS 



AC- OPERATED RECEIVER 

The "Packard" 8 -tube radio receiver 

shown, submitted by the Packard 

Radio Co., 2161 No. California 

Ave., Chicago, Ill., is of the all - 

electric type, using five 226 A.C. 

tubes, one 227 A.C. (heatéd- cathode) 

detector tube, and two 171 power 

tubes; it operates directly from the 

110 -volt, 60- cycle, house- lighting circuit. 

The low -voltage A.C. current 

for the filaments of the tubes is 

supplied by separate windings of the 

power transformer, and the "B" 

voltages are provided by a full -wave 

rectifier of the 280 type in connection 

with an efficient filter system, 

the chokes of which are contained 

in the same metal housing with the 

power transformer. Three stages of 

tuned radio frequency of modern design, 

using 226 -type tubes, give ample 

selectivity and sensitivity. The 

tuning inductors are of the compact, 

small -field type, enclosed in indi- 

vidual shield cans. The radio -frequency 

stages are followed by a 

conventional 227 -type detector, which 

feeds into two stages of transformer - 

coupled (1:1 ratio) audio frequency, 

followed by a stage of push -pull 

power amplification of the 171 type. 

The speaker windings are protected 

by a balanced output choke. The 

tuning of the R.F. and detector circuits 

is accomplished by one control, 

which is .geared to the common shaft 

of the condenser rotors; the scale is 

of the drum type. A fine adjustment 

of tuning for DX work is accomplished 

by means of the levers protruding 

through the panel on each 

side of the tuning control. A power 

rheostat with a panel voltmeter is 

provided. to maintain the filaments 

of the tubes at the proper temperature. 

The control at the right of 

the set is provided for controlling 

oscillations and volume, and there is 

a sub -panel adjustment to balance 

out the hum in the R.F. and 1:1- 

ratio audio stages. The filament 

circuits of the detector and the 

power tubes are automatically balanced 

by center- tapped windings. The 

receiver is of attractive appearance, 

and its operation, with regard to 

sensitivity, selectivity, quality, volume, 

and elimination of the A.C. 

bum, is satisfactory. 




PHONOGRAPH PICK -UP 

The "Via-Rad" phonograph pick-up 

device shown, submitted by the 

Brooklyn Metal Stamping Corp., 

718-728 Atlantic Ave., Brooklyn, 

N. Y., is of the magnetic type and 

makes it possible to reproduce speech 

and music from ordinary phonograph 

records, when it is used in connection 

with an audio -frequency amplifier. 

It is of the balancedarmature 

type; the airgap between the pole 

pieces is adjusted in the factory before 

sealing. The magnets are of 

the bar type and situated on each 

side of the adjustable pole pieces 

in such positions that their fields 

assist. Their magnetic strength is 

great, resulting in a very sensitive 

and loud reproducer. The frame or 

base which supports the coil, armature, 

and pole pieces, the dimensions 

of which are 11/4 x 2 inches, is cast 

of aluminum alloy. The end of the 

balanced armature protrudes through 

the metal housing and carries at its 

end the socket and fastening screw 

for the phonograph needle. The device 

is fitted with a flange, designed 

to fasten over the tone arm 

of the phonograph after the usual 

reproducer has been removed. The 

over -all dimensions are 2j inches 

long, 2 inches wide, and 1g inches 

high; and the weight 8 ounces. The 

housing is of a gold - finish. 




PICK -UP VOLUME CONTROL 

The "Via-Trot" phonograph pickup 

device volume control shown, submitted 

by the same manufacturer, 

is of the graphite -and -powdered-mica 

compression type; it has a resistance 

range from 0 to 500,000 ohms and 

is to be shunted across the terminals 

of the phonograph pick -up device. 

This resistor is provided with cord - 

tip jacks, two on each side of the 

housing; the tips of the pick -up are 

plugged into one pair of jacks, while 

those of the receiving -set adaptor 

are plugged into the other pair. The 

case or housing is of brown molded 

bakelite of pleasing appearance, the 

top is of gold- finished die -stamped 

metal, and the adjusting knob is 

molded of the same colored bakelite. 

The diameter of the base is 21/4 

inches and the height over all 2V 

inches. The device has proved satisfactory 

in giving smooth control of 

volume when used with the pick -up 

manufactured by the same concern. 




PHONOGRAPH PICK -UP 

ADAPTOR 

The "Via-Tector" home broadcaster 

and pick-up adaptor device 

shown, submitted by the same manufacturer, 

is of the UX type and 

designed to be plugged into the detector 

socket of the radio receiver. 

If it is so desired, the detector tube 

may be plugged into the adaptor; 

thus utilizing this tube as an additional 

stage of audio frequency. 

Otherwise, the tube may be replaced 

by a jumper, which is plugged into 

the socket, thus allowing only the 

audio -frequency stages of the set to 

function. The device is of black 

molded bakelite and approximately 

the size of the standard UX tube 

base; it is provided with a four - 

foot extension cord, the tips of 

which may be plugged into the volume 

control described above. 




A.C.-OPERATED RECEIVER 

The "Model 801A" radio receiver 

shown, submitted by the Stewart - 

Warner Speedometer Corp., 1834 

Diversey Parkway, Chicago, Ill., is 

of the all- electric type and operates 

directly from the 110 -volt, 60 -cycle 

house current. The receiver uses 

four 226- types, one 227 -type, and 

one power tube, in three stages of 

tuned radio frequency, detector and 

two stages of audio frequency; the



power stage being of the 171 type. 

The "B" voltages are supplied by a 

full -wave rectifier of the 230 type, 

and smoothed well by an efficient 

filter system. The filament current 

is supplied by special windings on 

the power transformer. The compact 

tuning inductors are of the 

small -field type and located under 

the metal chassis. Four tuning condensers 

are arranged in tandem, 

with rotors fastened to a common 

shaft; the drum is calibrated in 

wavelengths as well as degrees, and 

controlled ' . kno'i on the panel 

of -the set. A volume control is 

provided, which serves also as an 

oscillation control on the shorter 

wavelengths. The receiver is provided 

with connections for long or 

short aerials or. if preferred, the 

110 -volt line may be used as the 

antenna. 

A cone speaker of the balancedarmature 

type, approximately 6 

inches in diameter and enclosed in 

a metal housing. is attached to the 

cover of the radio receiver, making 

the receiver entirely self -contained. 

The housing of the set and speaker 

is finished in a brown crystalline 

finish. The combination is small in 

size, lmt was found to be satisfactory 

in regard to sensitivity, selectivity, 

quality and volume. 




VACUUM TUBE 

The "Type 01B" vacuum tube illustrated, 

submitted by the C. E. 

Manufacturing Co.. Inc., 702 Eddy 

St., Providence, R. I., has the same 

general characteristics as the 201A 

tube, which it may be used to replace 

when provision is made for the 

lower filament consumption of '/s- 

ampere (125 milliamperes) at 5 volts. 

The amplification constant (taken 

from a set of four tubes) is approximately 

9, with a plate impedance 

at 90 volts of approximately 

10,000 ohms. The tube is equipped 

with a standard UN base and its 

operation as a detector or amplifier 

is found to be as satisfactory as 

that of the 201A -type tube. 




A.C.-OPERATED RECEIVER 

The "Metrodyne" eight -tube radio 

receiver shown, submitted by the 

Metro Electric Company, 2171 No. 

California Ave., Chicago, Ill., is of 

the electric type, using 6 -volt D.C. 

tubes, and operates directly from 

110 -volt, 60 -cycle current. The "A" 

current is supplied by a step -down 

transformer from the A.C. line to 

a rectifier of the dry type. The 

low -voltage, pulsating uni- directional 

current is then properly filtered until 

all trace of A.C. hum has been 

eliminated. A voltmeter and rheostat 

are provided, so that the filament 

voltage may be adjusted and 

maintained at the proper value. The 

"B" voltages are supplied by a full - 

wave gas -filled rectifier tube in connection 

with the necessary filter sys- 

tem. Three stages of tuned radio 

frequency with shielded coils are 

employed for selectivity and sensitivity. 

The oscillation control is 

placed on the panel so that maximum 

sensitivity may be obtained at 

all wavelengths. A tuned detector 

is followed by two stages of I:1- 

ratio audio frequency of the conventional 

type which feed the amplified 

impulses into a stage of push - 

pull amplification of the 171 power 

type. 

The speaker windings are protected 

by an output choke of bal- 

anced type. The tuning of the R.F. 

and detector circuits is accomplished 

by one control of the drum -scale 

type, which operates the common 

shaft of the condenser rotors; fine 

adjustment is obtained on the tuned 

circuits by the operation of levers 

protruding through the panel on 

either side of the tuning control. 

The receiver has an attractive appearance, 

and its operation with regard 

to selectivity, quality and volume 

is satisfactory. 




A.C. VACUUM TUBE 

The "No. 22" vacuum tube shown, 

submitted by the Arcturus Radio 

Company, 255 Sherman Ave., Newark, 

N. J., is an A.C. screen -grid 

tube of the indirect- heater type, employing 

a cathode emitter which is 

heated by a filament of carbon, whose 

filament consumption is 0.35- ampere 

at 15 volts. An amplification of 

400 at 1,000 cycles was obtained 

with the sample submitted for test; 

with 135 volts on the plate, 11/4-volt 

"C" bias on the control -grid, and a 

shield -grid voltage of 45, and using 

a plate load of 1 megohm. An 

amplification of from 25 to 60 at 

radio frequencies was obtained with 

output coupling impedances of different 

types. The measured conductance 

at 1,000 cycles was found 

to be approximately 445 micromhos, 

the plate impedance 900,000 ohms. 

The tube may be used successfully 

as an A.C. screen -grid R.F. or A.F. 

amplifier tube, a space -charge or 

screen -grid detector, or a space - 

charge audio amplifier. 




NEON TELEVISION TUBE 

The "Telion" neon tube illustrated, 

submitted by the F. & II. 

Electric Corp., 68 Springfield Ave., 

Newark, N. J., is designed especially 

for television' work. Its 

"striking voltage" as measured, was 

found to be approximately 180 volts. 

the current at the "dark point" 11 

milliamperes. The recommended 

safe average current is 50 milliamperes, 

although the maximum current 

may reach 125 milliamperes. 

The tube gave a uniform glow and 

did not become spotty with changes 

of current at high frequencies. It 

is fitted with a base of the UX 

type. The glow electrode has a surface 

1 -7/16 inches square, and is 

made of a special material to promote 

uniformity of glow with very 

small currents. 




MICA BALANCING CONDENSER 

The "Micrograd" small adjustable 

balancing condenser, submitted 

by the Pilot Electric Mfg. Co., 323 

Berry Street, Brooklyn, N. Y., is 

of the mica-dielectric type, designed 

for neutralizing or compensating 

radio -frequency circuits. It was 

found to have a variable capacity 

range between 6 to 50 micromicrofarads. 

The variation is accomplished 

through adjustment of the small 

knob, either by hand or by the use 

of a screw- driver; this compresses 

or loosens the curved spring -brass 

plates, which are separated by mica, 

thus increasing or decreasing capacity. 

The housing is of black 

molded bakelite and requires a sub - 

panel or base -board space 2 x 1 

inches. The overall height, with the 

adjusting screw at minimum. capacity, 

is approximately 11/4 inches. 




SPEAKER CONTROL SWITCH 

The loudspeaker control switch 

shown, submitted by the Fisch Radio 

Company, 1233 Hoe Ave., Bronx, 

N. Y., allows the listener to operate 

either of two speakers separately 

or both simultaneously, connected in 

series. This is advantageous when 

a speaker designed for reproduction 

of high notes and one designed for 

reproduction of low notes are used 

together. It is of black molded 

bakelite, 244 inches long, 11/4 inches 

thick and 21/4 inches high. On its 

curved top are found four holes for 

the insertion of the tips of the 

speaker cords. One terminal of each 

speaker is inserted in one of the 

holes marked 2, while the remaining 

two terminals of the speakers 

are connected into the holes marked 

1. The internal construction is that 

of a double -pole, double -throw rotary 

switch; contact springs are arranged 

along the top of the switch mounting 

to receive the ends of the cord 

tips, which pass through the molded 

housing. The operation of the switch 

was found to be satisfactory for the 

use designed. 




PLUG -IN COIL FORM 

The "plug-in 

coil" form shown, 

submitted by Silver -Marshall, Inc., 

846 W. Jackson Blvd., Chicago, Ill., 

is of the UY- or 5- prong -type, designed 

to be plugged into any Uy 

socket. Its over -all height is 2% 

inches and it provides 11/4 inches 

winding space on a tube 1% inches 

in diameter. The secondary winding 

space is threaded with 75 turns 

to the inch, which allows the construction 

of a space -wound plug-in 

coil of modern design. The lower 

end of the form is provided with a 

slot 1/16 -inch wide and 1 -inch deep 

for a primary or tickler winding of 

the bunched type. The five prongs 

provide for the use of the coil as a 

short - wave three - circuit coupler, 

when the filament and ground ends 

of the secondary and primary are 

made common to the cathode prong. 

The form is molded of black bakelite 

and provided with a reenforced rim 

at the top, to prevent damage to the 

completed coil when removed from 

the plug -in socket. 




SCREEN -GRID A.F. COUPLING 

UNIT 

The "Type -223 Hi-Mu" audio 

transformer shown, submitted by 

the same manufacturer, his been de- 

signed as an output coupling device 

for a screen -grid tube or 

other hi -mu vacuum tube. It pro. 




1:'ppl.tllllÍll 

RADIO NEWS readers send in every month an average of 5000 letters 

asking information on every phase of radio theory, construction and 

operation. We can only print the five or six replies which are of 

widest general interest. 

Other letters will be answered by mail, if inquirers observe these rules: 

BE BRIEF: TYPEWRITE OR WRITE LEGIBLY IN INK ON ONE SIDE OF THE 

SHEET ONLY ENCLOSE A STAMPED ENVELOPE ADDRESSED TO YOURSELF. 

Many letters are not readable. Simple questions will be answered free; 

Conducted by C. W. Palmer 

those asking for sketches, diagrams, data, etc.. should send TWENTY - 

FIVE CENTS FOR EACH QUESTION : failure to enclose this will cause delay. 

We cannot answer for this sum questions requiring original research, 

intricate calculation, or patent investigation; we cannot compare the 

merits of trademarked apparatus, or give constructional data on apparatus 

whose makers withhold it. We cannot undertake to answer more than 

THREE QUESTIONS 18 each letter. If you inquire concerning a Circuit 

which is not a standard, published one, enclose a diagram to save delay. 

BY- PASSING AUDIO AMPLIFIER 

(2307) Mr. R. W. Wilson, Portland, Maine, 

writes: 

(Q.) "I understand that most audio -frequency 

amplifiers can be improved by the correct use of 

by -pass condensers. .Can you explain where these 

condensers should be used, their values, and just 

what advantage they supply to an amplifier of this 

type ?" 

(A.) Audio -frequency amplifiers are often constructed 

in such a way that a common coupling is 

unavoidably formed by the power unit or common 

"B" battery. This coupling provides an excellent 

path for feed -backs, from which a large amount of 

distortion may result. This trouble may be reduced 

very easily by the proper use of by -pass condensers 

between the various circuits. These condensers 

provide a lower resistance path for the audio -frequency 

currents than the artificial coupling. Of 

course, the direct current passes through the usual 

circuits, since it is blocked by the condensers. You 

will find two diagrams showing how by -pass condensers 

should be used in an audio -frequency amplifier 

in Figs. Q. 2307A and B. The first represents 

any audio -frequency amplifier with transformer 

coupling, resistance coupling, or any type 

of "impedance" coupling. Condenser Cl is the 

usual by -pass condenser connected between the 

plate of detector V1 and the negative filament. The 

plate circuit of each amplifier tube is completed by 

connecting a 1 -mf. by -pass condenser between one 

of the filament terminals and the positive "B" 

terminal of the transformer. These condensers are 

shown at C3 and C5. A separate path is also 

provided for the grid currents by placing by -pass 

condensers of % -mf. or more capacity between the 

transformer secondaries and the filament terminals 

These condensers are represented at C2 and C4. 

The diagram in Fig. Q. 2307B represents the 

usual transformer -coupled audio -frequency amplifier 

and shows how the by -pass condensers should be 

A- A+ BI- 

C+ B- DETECTOR 

COUPLING TRANSFORMERS, 

RESISTORS OR IMPEDANCE UNITS 

G _ 

V2 

connected in order to improve the results. The 

condensers should be placed close to the transformers, 

so that the audio -frequency currents will 

not have to travel through much of the wiring in 

the amplifier or through any of the leads to the 

power units. 

REDUCING THE HUM IN A.C. SETS 

(2308) Mr. B. Brown, Miami, Florida, writes: 

(Q.) . "I am constructing a receiver with two 

stages of radio- frequency amplification and two of 

audio -frequency amplification, 

using the 226 tubes 

in the radio -frequency 

and first audio -frequency 

positions, a 227 in the detector 

and a 171 in the 

The voltage on the 

fila- 

ment alternates, except at 

its center, which is a 

"node" or point of uniform 

potential. On the 

"Wheatstone bridge" 

principle, a resistance 

shunted across this must 

contain a point of identical 

voltage, located by 

the sliding arm. 

last audio -frequency stage. I am rather puzzled 

about the grid returns and he methods of keeping 

the A.C. hum at a minimum. Can you give me 

any data on this subject ?" 

(A.) The method of balancing out the audio - 

frequency noises in an A.C. receiver is a rather 

puzzling problem for the average radio fan. The 

usual method of connecting the grid return directly 

to one side of the filament supply circuit is not sa - 

B+ 

AMPLIFIER 

V3 

P 

LOUD 

SPEAKER 

Q. 2307A 

Alternating impulses are kept out of the "B" battery, which is common to all circuits, by the 

use of suitable condensers which divert them to the grounded filament. Cl is an R.F. by -pass; 

C2 and C4 block the "C" voltage, and C3 and CS the "B" voltage from the filament while 

completing the A.F. circuits. 

isfactory with A.C. sets, since it unbalances the 

filament circuit and introduces a considerable bum. 

The grid returns for the 226 tubes may be connected 

according to several easy methods. The 

balancing consists merely of finding the exact electrical 

center of the filament circuit, so that no 

alternating voltage from the power supply will be 

impressed on the grid. Naturally, since this current 

is an alternating one, it must be kept entirely out 

of the grid circuit. 

Three methods of obtaining the electrical center 

of the filament circuit are shown in Fig. Q. 2308A, 

B and C; these methods are the most common in 

use at the present time. Fig. A shows the use 

of a resistor with a sliding contact which can be 

adjusted for the minimum amount of hum. This 

resistor usually consists of a potentiometer of about 

15 ohms shunted across the center of the filament 

transformer. This method is a very good one, since 

it is often found that the actual center of the 

filament circuit is slightly to one side of the 

theoretical center. 

Fig. B is similar to Fig. A except that a fixed 

center tapped resistor is used. This method is not 

quite as efficient as the one shown in Fig. A, since 

if the center tap of the resistor does not balance 

the secondary of the power transformer in reference 

to the ground, the filament circuit will be 

unbalanced. However, in most cases it is very 

satisfactory. Another method is shown in Fig. C, 

which has the same defect as the method shown 

in Fig. B. This method employs a center tapped 

filament transformer for the filament supply, but 

is also very satisfactory for general uses. 

It is best to use a separate resistor for each 

grid return rather than try to use one resistor for 

all of the tubes, since in this way, each tube is 

balanced in respect to its own filament circuit. 

The wiring to the filament circuits of the A.C. 

tubes should be done with twisted wires, well 

insulated and kept as far away from the grid 

circuits as possible. This wire must be quite heavy 

(No. 14 at least), to pass a considerable current. 

The use of resistors for the grid returns of tubes 

in a radio -frequency amplifier sometimes results in 

instability or oscillation in the amplifier. However, 

this difficulty can easily be overcome by connecting 

fixed condensers between the center tap 

of the resistor and each side. These condensers 

should have a value of .005 -mf. 

Grid Bias 

This is another point which causes considerable 

confusion in the construction of A.C. receivers. 

%Vlsen the negative grid bias for the radio -frequency



Schematic circuit of the arrangement in Fig. Q. 2307A when transformers are used. Cl may be 

from .001 -mf. up; C2 and C4 are usually 0.25 -mf., C3 and C5, 1 mf., though such values 

are not critical. 

amplifier and audio -frequency amplifier tubes in an 

A.C. set is to be obtained from the "B" power 

uit, a separate resistor may be used to supply 

the voltage to each grid or one common resistor with 

the correct taps may be used for the complete 

supply. When 226 tubes are used in a radio - 

frequency amplifier, the plate voltage should be 

135 volts and the negative bias 9 volts, in order to 

give the greatest amplification and the quietest 

operation. Because each of the tubes requires the 

same bias, a single resistor can be used for all of 

the tubes. The method of connecting this resistor 

is shown in Fig. Q. 2308D. It will be noticed that 

the center filament terminals of these amplifier 

tubes are connected to one side of resistor RI, 

while the other side and the grid returns connect 

to ground and to the negative "B" battery 

terminal. 

The value of resistor Rl can he easily determined 

with the aid of Ohm's Law, wherein R 

equals E divided by I. R represents the unknown 

resistance required, E represents the biasing voltage, 

and I the plate current of the tubes for which 

the grid bias is required. To give the least amount 

of hum, the plate current should be 3 milliamperes 

and the plate voltage 135 volts, for each tube. The 

correct value of the "C" bias for this plate voltage 

and current will be found to be 9 volts. If we 

have three 226 tubes requiring "C" bias, the total 

plate current will be 9 milliamperes, or .009 ampere. 

Substituting these values in the equation 

given above; R equals 9 divided by .009, or 1,000 

ohms, which is the correct value for the resistor 

RI. The condenser C6 in the diagram is used 

to by-pass the radio -frequency currents around 

resistor RI. This condenser should have a value 

of about 1 -mf. 

THE INSTITUTE OF RADIO ENGINEERS 

(2309) Mr. A. T. Kenny, Spokane, Washington, 

writes: 

(Q.) "I have frequently encountered the letters 

I.R.E. in electrical and radio publications and 1 

have wondered just what the Institute of Radio 

Engineers was founded for and what their aims 

are. 

Of course, I realize that every large engineer- 

ing profession has its society; but am particularly 

interested in this Institute and I would appreciate 

any information that you can give me." 

(A.) We have received a number of inquiries 

about this society, and because we believe that the 

data will be of interest to a number of our readers, 

we are reprinting part of the information contained 

in the 1928 Year Book of this Institute. 

"The Institute of Radio Engineers functions 

solely to advance the art and science of radio 

communication. It numbers among its members 

nearly all of the men who have been prominent in 

the development of "radio in the United States, as 

well as many noted engineers and scientists in 

other countries. 

"The membership of the Institute consists of 

those persons who are qualified for any of its 

several grades of membership, either through their 

interest in radio communication, or by practice 

of some phase of radio engineering as a profession. 

The eligibility of an applicant to membership in 

any grade is finally determined by the Board of 

Direction of the Institute, in most cases on the 

recommendation of the Committee on Admissions. 

"Through the presentation and publication of 

original papers, by affording its members the opportunity 

of meeting to discuss radio problems, by 

awards of honors and prizes, and in other ways, 

the Institute fosters and encourages the develop- 

ment of this important means of communication, 

and particularly aids in the exchange of radio information 

of a technical and engineering nature -" 

Membership 

"There are four grades of membership in this 

Institute; namely, Fellow, Member, Associate and 

Junior. All the benefits of membership are available 

at once to all new members of any grade, 

except that Juniors are not eligible to vote. Membership 

means, also, that one is enrolled with 

others having a similar interest in radio, and 

that one is on record as being among those who 

are interested and active in the development of 

this new and useful branch of the engineering 

industry. 

"The grades of Fellow and Member require a 

much higher degree of technical training and experience 

than the grade of Associate. In order to 

maintain a high standard of membership, the 

Board of Direction in each case very carefully 

scrutinizes the applications for Fellow and Member 

grades. 

"Before applying for membership in any grade 

the applicant should carefully read the Constitution 

of the Institute to ascertain for which of the 

several grades he is eligible. An extract from the 

Constitution dealing with admission, eligibility, fees, 

etc., is printed on the back of the application form 

obtainable from the Institute's headquarters. When 

filling in the application form, the applicant should 

submit the names of those persons who have knowl- 

edge of his professional experience, rather than 

those who have a high professional standing, but 

cannot vouch for him." 

History 

"Prior to the formation of the Institute of Radio 

Engineers, two other organized groups of radio 

enthusiasts held meetings in New York and Boston. 

These were the Wireless Institute and the 

Society of Wireless Telegraph Engineers. On May 

13, 1912 these two organizations were merged, 

taking the new name of the Institute of Radio 

Engineers. Headquarters were established in New 

York. The Society of Wireless Telegraph Engineers 

had a membership of eleven in 1907 and 

forty -three in 1912. The Wireless Institute had 

fourteen members in 1909 and twenty -seven in 

1912. The Institute of Radio Engineers, at the 

time of its foundation, had less than fifty paid -up 

members." lts membership is now about five 

thousand, four -fifths of them in the United States. 

Application blanks and information can be obtained 

by addressing the Secretary of the Institute 

at the Engineers' Building, 33 West 39th Street, 

New York City. 

ELECTROLYTIC "B" POWER UNIT 

(2310) Mr. H. A. Wilkins, Cleveland, Ohio, 

writes: 

(Q.) "Will you please supply me with instructions 

for making an electrolytic "B" power unit 

to operate on the 110 -volt 60 -cycle electric -light 

line? I do not wish to use a transformer in this 

unit as I require only about 90 volts' for the radio - 

frequency and detector tubes in my receiver. I am 

using a power pack with an audio -frequency amplifier, 

but the rectifier employs a 216B tube and will 

not supply sufficient current for the rest of the set." 

226 L2 226 L3 227 T1 226 

TO REST OF 

A. F. AMPLIFIER 

CI 

sss lsl 

OIMME. 

R2 ow R3 \ ONO R4 

C6 

R1 

2.5 VOLTS A.C. 

1.5 VOLTS A.C. 

0 8 

. 8+ DETECTOR 

o g+AMPLIFIER 

Q. 2308D 

A typical A.C. hook-up; the value of resistor Rl depends on the plate current 

of the two R.F. amplifiers and the first A.F. amplifier, which it biases. 

It keeps the center points of the filaments at, say, 9 volts above ground, to 

which the grid leads return, In the last stage a resistor must be used, of 

value suitable ta maintain Nie higher bias on the power tube. The floati, g 

circuit of the detector, which' uses a grid leak and condenser, is based on the 

cathode of Nie 227 tube. The value of the resistors R2, R3 and R4 is 

negligible in computing the voltage drop,

I 


The 

464 


o 

110 VOLTS 

A. C. 

Q 2310 

e 

11111 

CHOKE 

2MF. 

30 HENRIES 

2MF. 

11111 

CHOKE 

8MF. 

IMF 

B+ 90 

..*-100,000 

OHMS 

oBFOET 

og- 

Connections of a simple electrolytic recttficr, which will furnish up to 90 volts "B" supply without 

the use of a step -up transformer. The variable resistor regulates the detector voltage to any 

desired amount. 

(A.) Yod will find the diagram of a power unit 

of this type in Fig. Q. 2310. Four electrolytic 

rectifier jars are used, and two 30 -henry chokes 

with three filter condensers comprise the filter system. 

The rectifier plates are made by cutting strips 

of pure aluminum and lead, 2 inches wide and 5 

inches long. The aluminum plates are made of 

!e -inch extra pure or No. I commercial stock; 

you can obtain this from any good metal dealer 

or hardware company. 

Bend the plates over at a right angle, one inch 

from one end. Then hang them over the tops of 

the cells, which consist of four pint mason jars. 

Make the electrolyte by dissolving as much primary 

(acid) ammonium phosphate as possible in 

two quarts of distilled water. Add crystals until 

there is an excess which will not dissolve. Then 

pour off the liquid and place it in the jars. Next 

insert the aluminum and lead plates into the solution 

and connect them as shown in diagram Q. 2310. 

Before using the "B" power unit, the plates 

must be "formed." Connect a 25 -watt electric - 

light bulb across the rectifier, in place of the 

first 2 -mf. condenser, and leave the rest of the 

apparatus disconnected. This will place the bulb 

across the rectifier and will supply the necessary 

load. Next, connect the input or alternating current 

wires to the electric -light line and let the 

unit run for about 5 or 6 hours. This will be 

sufficient to "form" the plates and you can connect 

the condensers and chokes as shown in the 

diagram. High -voltage condensers are not required 

here. 

The output of the power unit will supply about 

90 to 100 volts, depending on the resistance of 

the choke coils. This is usually too great for the 

detector tube, so that a variable resistor (a regular 

100,000 -ohm carbon -type) is provided to reduce 

this voltage to the correct value. A 1 -mf. condenser 

is also connected between the detector 

tap and the "B-" terminal of the unit, to keep 

the output steady and by -pass any stray radio - 

frequency currents. 

In order to obtain satisfactory results with an 

electrolytic "B" power unit, you must use pure 

metal for the aluminum electrode and chemically 

pure ammonium phosphate for the electrolyte. Also 

use only distilled water, to be sure that it is pure. 

By pouring a layer of mineral oil over the surface 

of the electrolyte. evaporation will be reduced 

considerably; and this will also prevent 

sparking at the surface of the liquid to some extent. 

If the sparking is excessive, insulate the 

tops of the aluminum electrodes by placing rubber 

tubes over them or by coating them with celluloid 

dissolved in acetone. 

SIMPLE ONE -TUBE SET 

(2311) Mr. M. T. Lynch, Portland, :tlaine, 

writes: 

(Q.) "I am a beginner in radio and, although 

I have constructed several crystal sets, I have 

never attempted to build a tube set. I have been 

a reader of your publication for almost a year, so 

I am more or less familiar with the terms used in 

radio. I have looked over all the back issues that 

I have on hand, but I do not find a suitable set 

for my purpose. The receiver that I desire to 

build is one using a single tube. I do not like to 

make a set that would interfere with my neighbors, 

so I do not want a regenerative receiver: I 

want to get the greatest efficiency, though. Will 

you give me the diagram and specifications of a 

suitable set ?" 

(A.) We are printing the diagram of a single - 

tube reflex set, using a crystal detector, herewith. 

(See Figs. Q. 2311 A and B.) The parts required 

for the set are as follows: 

One 201 A- or 199 -type tube (VI); 

One tube socket; 

Two .0005 -mf. variable condensers (Cl, C2); 

One audio- frequency transformer, about 34 

ratio (AFT); 

One crystal detector (CE); 

This one -tube reflex circuit furnishes the maximum 

amplification available without making a 

"blooper." 

One 20- or 30 -ohm rheostat, depending on whether 

a 201A or 199 tube is used (Rl); 

One .001 -mf. fixed condenser (C3); 

Eight binding posts; 

One 7 x 12 -inch panel; 

One 8 x 12 -inch baseboard, % -inch thick; 

Two 3 -inch tubes 3 inches long for coils; 

No. 22 D.C.C. wire; screws; wire for ccaneetions, 

etc. 

The first point in constructing the set is to 

make the coils. . aerial coupler is wound 

with 12 turns of No. 22 double -cotton -covered 

wire ftë the primary and 48 turns for the secondary. 

The primary is wound on one end of 

the coil and a space of %-inch is left before the 

secondary is wound on. Both of the coils are 

wound in the same direction. The second R. F. 

coil (L2) is made the same as the first coil (L1). 

except that the primary contains 15 turns. In the 

aerial coil, the end of the secondary -farthest away 

from the primary is connected to the grid of the 

tube. In the second coil, the outer end of the 

primary is connected to the plate of the tube. 

The next step in building the set is to drill 

the panel for the condensers and rheostat. Place 

the parts approximately in the positions shown 

in Fig. Q. 2311 B. The positions of the Lodes 

depend on the particular apparatus employed and 

will have to be determined when the parts have 

been bought. After the panel has been drilled 

and these parts have been mounted on it. mount 

the other apparatus on the baseboard in the positions 

shown. Fasten the binding posts either 

directly to the baseboard or to small strips of hard 

rubber or bakelite mounted on the baseboard. Then 

wire the set according to either diagram, Fig. Q. 

2311 A or Fig. Q. 2311 B, as you find easiest, and 

check every connection. The connections to the 

audio -frequency transformer are indicated on both 

diagrams: although it may be found necessary to 

reverse the connections to the secondary coil in 

order to get the best results. 

The values of the "A" and "B" batteries de- 

pend on the type of tube used. If a 201A is 

employed, the "A" battery must be a 6 -volt storage 

battery; while, if a 199 is used, three dry cells 

connected in series will be sufficient. To put these 

batteries in series, connect the center terminal of 

the first battery to the outer terminal of the second. 

Then connect the center terminal of this bat - 

ery to the outer terminal of the third battery aml 

the two remaining terminals to the set. The center 

terminal of each cell is the positive ( " + ") 

and the outer one is the negative ("-") 

The "B" battery should have a voltage between 

45 and 90, for either type of tube, and since the 

current consumption is rather low, the small dry - 

cell batteries can be used. 

Operation 

The set is now ready for operation. Adjust the 

rheostat R1 until the tube lights up with its 

normal brilliancy; in a 20IA tube, this will be quite 

bright, while only a dull red glow will be noticed 


-r- --------- 12" ,. 

A- A+ B- B+ PHONES .001 MF 

8' 

e 

i 

¡ 

VUUUllIIIIIEIMM///p/p// 

Q23116 

C 

AERIAL 

IN. 

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Cl: : 

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EMI= 

The single -tube reflex circuit of the diagram above is shown here in pictorial form; the simplicity 

of the hook -up can be seen. The crystal detector may be of any type preferred; a Carborundum 

unit gives excellent results and requires little adjustment. This unit works with phones only; 

but an amplifier such as the "Extension" may be added to operate a loud speaker.


SJ 


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Ple.nsr .cav c a w 

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2161 -71 N. California Ave., Dept. 12 

Chicago, Illinois 

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a


466 


How to Make Your Own Television Receiver 

(Continued from page 425) 

hook -up, incidentally, it is a good idea to 

shunt the glow -lamp by a 0- 10,000 -ohm 

Variable resistor; this resistor should be so 

set that the tube lights nicely when there is 

no incoming signal. The 171A draws about 

20 milliamperes, which is the normal load 

limit of the glow -lamp; so the combination 

works out very happily. 

TRY YOUR LUCK 

Remember that television as we 

to -day is very crude. Do not 

expect perfect images, and do 

not forget that television on 

3,000 cycles was, until only very 

recently, held impossible altogether. 

Experiment with the 

have it 

To receive the .Jenkins radio movies, on 

46.7 ureters, you can use this sane apparatus 

with the disc speeded up to 900 

r.p.m. These "movies" are black and white 

silhouettes, usually of a little girl bouncing 

a ball, or playing with a clog. 

Next month we will publish more television 

"dope." Meanwhile, try your luck 

with this receiver; you will have a lot of 

fun with it. 

0 

Fig. 4 

1 Look for the 

on top of all 

Drilling layout of the 24 -inch disc 

used. .4 full -size template accompanies 

the blueprints -if you wish 

to try your luck making your own. 

neon tube and the motor's 

speed and try different output 

arrangements. Try putting an 

ordinary reading glass in front 

of the images, as shown in the 

cover illustration, and . see if 

you can magnify then[. Experiment, and 

let us know what results you have obtained. 

\ 

{ á t 

,p // 

RADIO / TUBES 

WHENWHEN you look inside of your 

be sure you see the 

monogram "C" smiling up at you 

on the top of each radio tube. 

Thirteen years of experience and 

tireless research, combined with a 

guarantee against mechanical and 

electrical defect, stand behind this 

simple monogram. 

Cunningham Tube quality has resulted 

in national leadership and 

public approval, two assets we 

zealously guard, and is your assurance 

of faultless modern reception. 

I 

Never use old tubes 

with new ones -use 

new tubes throughout 

E. T. CUNNINGHAM, INC. 

New York Chicago 

San Francisco 

Manufactured and sold under rights, patents 

and inventions owned and /or controlled by 

Radio Corporation of America. 

READERS will find interest and probable profit in the article, "Ho w to Build the 

'S & I' Television Receiver," in the November issue of SCIENCE AND INVENTION 

Magazine. This receiver may be readily built upon a fan motor, like the experimental 

set -up described in RADIO NEWS for September; and employs a very simple, but 

ingenious, visual ( "stroboscopic") method of determining its speed and obtaining 

synchronism. 

Televentures, Telewitticisms and the Televocabulary 

within a generation to broadcast to a whole 

nation such sights as a Reinhardt 'Miracle' 

or a tennis match. The optimistic American 

regards the surmounting of obstacles as the 

very essence of invention, and rightly. One 

has but to read the Federal 'Trade Commission's 

examination of radio patent monopolies 

to learn of the romance that lies 

in vaulting over technical obstacles -of fortunes 

paid to young engineers who made it 

possible for a farmer in carpet slippers to 

enjoy the Philharmonic Orchestra better 

than in a hard -boiled shirt in Carnegie Hall. 

To an inventor of imagination the difficulties 

that now beset the commercial realization 

of television are glittering opportunities, 

and it is in that spirit that they will 

be conquered." 

WHAT OF TILE DICTIONARY? 

With the vocabulary of even radio broadcasting 

quite out of the hands of the engineering 

profession, what is the puzzled 

maker of dictionaries to do about the new 

words which the art of television will require? 

The "glow lamp" and "scanning 

disc" may be soon used only in the past 

tense; but what shall we call the apparatus 

required for the transmission and reception? 

(Continued (rota page 419) 


Will both he "televisors "? And if not, which? 

"Television" is a word on which the language 

sharps look askance; like "automobile," 

it is a hybrid -half Latin and half 

Greek -and the public has even less Latin 

than the Bard of Avon, and no Greek. The 

editor of RAnlo NEWS, before the days of 

broadcasting; coined "television," and suggested 

for the apparatus "telephot," which 

is a better word from the dictionary stand- 

point than "televisor." Will we use "phots" 

or "visors"? 

An English writer has hinted 

of "teleopsis" and "teleoppers," to be shortened 

into "'oppers"; but this seems to lack 

the necessary seriousness to convince. 

What will be the title of the operators? 

We have "radiotricians" as specialized electricians: 

we will need a word of the weight 

of "televisticians.," which may do for the 

present. But a "'visionary engineer" seems 

impractical. 

Television transmissions require modulating 

frequencies, increasing with the size and 

detail of the image. While small figures 

suitable to the experimental receivers of the 

day are being reproduced front audio frequencies, 

the larger images of tomorrow will 

require wider bands and special amplifiers. 

These will be specially designated; "image-



The broadcast of 

the Army -Navy 

game last year toas 

enjoyed by hindredojthousands 

of fans all over the 

country. 

Phillips Carlin 

broadcasting 

at one of the 

big football 

games. 

The Big Game Conies Over__ 

BETTER CLEARER 

MILLIONS of enthusiastic football fans are 

listening this fall to the play by play broadcasts 

of America's greatest games. They are 

experiencing almost as keen enjoyment as if 

they were sitting in the stands. The voice of 

the announcer comes to them clearly and distinctly 

because their receiving sets are Aluminum 

equipped. 

Leading radio manufacturers are using Aluminum 

extensively for shielding, for condenser 

blades and frames, for chasses, sub -panels, 

front panels and for many other parts -because 

Aluminum so ideally meets the varied 

conditions that radio design presents. 

ALUMINUM COMPANY OF AMERICA 

ALUMINUM IN EVERY COMMERCIAL FORM 

2467 Oliver Building 

Pittsburgh, Pa. 

It combines remarkable shielding properties, 

high electrical conductivity, great strength 

and extreme lightness. 

Examine the set you contemplate buying. 

If it is Aluminum equipped you may rest assured 

that the manufacturer has done everything 

in his power to give you the finest possible 

reception. 

And if you are building, a receiving set use 

Aluminum for finest results. 

We will gladly send you the booklet,' Aluminum 

For Radio," which explains the varied 

radio uses to which Aluminum is adapted. 

"® Offices in 19 Principal 

ALUMINUM 

American Cities 

C >V 

ALUMINUM 

`?he mark of Quo /ity in Rodio 

Please say you saw it in RADIO NEWS


4Gì; 

The New Victoreen 

A. C. Circuit 

Is the Outstanding 

Success of the Year 

frequencies" seems most logical, but the 

"I. F." of the superheterodyne is already 

too well established. Perhaps we shall have 

"T. F." amplifiers for television frequencies. 

It is too early to start on the task of 

standardizing the vocabulary; but we must 

have an eye to the future and see that the 

newcomer in radio is not saddled with 

names that will be a burden in days to 

come. We must have, O philosophers, a new 

"teleology." 

Mr. H. Gernsback, editor of this publication, 

while addressing an audience at the 

New York University, at the occasion of 


WRN T's television inauguration, perhaps 

had in mind all this and more, when he 

stated that he could not refrain from beating 

the newspaper columnists at their own 

game when he suggested that hereafter, we 

will call an inventor, not "visionary," lint 

rather, "televisionary." Also, that we will 

not talk of a beautiful "vista" any longer, 

but it will, of course, surely be a "televista"; 

and, that certain females who are 

now called "perfect visions," are, of course, 

to become "perfect televisions "; and that 

finally, there will, of course, be a great 

many "telewisecracks." 

"Comforts of Home" 

Vital improvements in Victoreen R. F. 

Transformers, together with changes in 

the circuit itself, have still further perfected 

and simplified a "Super" which 

for years has had no superior. 

The New Victoreen is simply marvelous. 

Here you have A. C. operation 

at its best. Tone quality such as you 

have never heard before -selectivity 

such as you never dreamed to be possible 

-simplicity of assembly developed to 

the point where anyone can construct a 

set which is as nearly perfect as human 

ingenuity has been able to devise. 

The heart of this new Victoreen circuit 

is of course the world- famous 

Victoreen R. F. Transformer -greatly 

improved in efficiency, with binding 

posts located for maximum convenience 

in wiring. Each transformer is individually 

tuned to a precision of less than 

1/3 of one per cent by the Victoreen 

patented method. 

These new Transformers, together 

with the other Victoreen components 

which are used in this remarkable set, 

are literally years ahead of their time. 

To get the results which only Victoreen 

gives, either build, or have built for you, 

a Victoreen Super. 

BLUE PRINT FREE 

together with full constructional 

details. Write for it today. 

Victoreen "B" Power Supply 

Go6ght-r; 

---';, 

'NNS tN -... 

!RAM VQCfb`YDEa$ 

:l. 

TELEVISEN 

Supplies 45, 90, 180 and 450 volts, using 

a UX 210 or 250 in the last stage. Contains 

two voltage regulator tubes so that the 90 and 

180 volt taps are' supplied with a constant volt 

potential. It is the last word in "B" supply. 

For the most satisfactory results you must 

have it. 

FREE BLUE PRINT, with list of parts 

and complete assembly instructions, will 

be sent upon request. 

The George W. Walker Company 

Merchandisers of Victoreen Radio Parts 

2825 Chester Ave., Cleveland, Ohio 

Quality Radio Partsi 

Please 

-Clive Weed in New York Evening World 

Radio fans will sec that the mnnbcr of sound reproducers is somewhat too large; and the televisiphooe 

will probably be of a later model. gut the idea is clever, even though the 

"Television" is one -I'd. 

"C" Voltage Depends on "B" Voltage 

WHEN "B" batteries are used to supply 

the plate current for a receiver, listeners 

are cautioned to watch the voltage of 

the batteries and to discard them when the 

voltage of each 45-volt block runs clown 

to about 34 volts, or when that of each 

22/ -volt block runs down to about 17 

volts. 

Fans who employ- "B" batteries therefore 

usually test them at regular intervals to 

determine whether the batteries are still 

good for further service. 

A matter of vital importance which is 

often overlooked, however, is that of providing 

a proper relation between the grid - 

bias voltage and the plate voltage. 

It is generally known that, while "B" bat - 

say you saw it in. R.4DIO 

teries run down with usage, the "C" battery 

will last for the entire life of the battery - 

without any appreciable loss of voltage. 

This means that when the "B" batteries 

are new, the proper grid bias is being used 

. for best results; but just as soon as the 

"B" battery voltage begins to decrease, the 

grid -bias voltage is greater than is needed 

for the lowered plate voltage. 

In such cases, if the grid -bias voltage is 

reduced in proportion, as determined byconsulting 

the tables showing the proper 

plate voltage- grid -bias voltage characteristics 

of the tube. the amplifying efficiency 

of the tube can be maintained at a high 

level in spite of lowered plate voltage front 

the "B" batteries. 

NEWS



Now-, 

4;:f 

a e ovr 

dfír 

ear as a 

^-1.uzth Ma rvelous11i'ew 

;!,. ,,,,1,,,",. 

Sub -Aerial 

Endorsed by Experts 

May Stti. 192S 

'I am very glad to state that after 

testing many Aerials in my Laboratory 

I lind your Su b-Aerial is the bust for 

clarity of tone and elimination of 

static also for greater Volume and 

caeetivity. 

Your Sub -Aerial will fill a long-felt 

want among the Radio Fans." 

A. R. Johnson, 

Radio Engineer 

Chicago. May 9th. 192S 

"Received my Sub- Aerial and it has 

botat Installed as Per directions. We 

are more than satisfied W theresults. 

The tune Is marvelously clear without 

static interruptions. We would not 

changing hack to an outdoor 

aensbler rial under any circumstances. 

M. H. Grey. 

1416 Junetray Terrace. 

GROUND .4 ER IALØ 

Get Amazing Distance- Greater 

Volume and Finer Selectivity 

Without Distortion 

Why go on listening to terrible static and other maddening 

outside noises? Now you can get the real music your 

present Radio is capable of giving, by hooking your set on 

to the clear, practically static free ground waves with 

Sub -Aerial. The air is always full of static and your overhead 

aerial picks it up and brings it to your speaker. So 

why stay in the air -when you can use the whole earth 

as a static and noise filter with Sub -Aerial? 

SUB -AERIAL is a scientific, proven system of taking 

the radio waves from the ground, where they are filtered 

practically free of static. It brings these filtered waves 

to your radio set clear of static and interference common 

with overhead aerials. The result is positively clear 

reception, remarkable selectivity and greatly increased 

volume. The overhead aerial is a thing of the past because 

it is the weak link in radio. SUB- AERIAL has replaced 

overhead aerials because SUB -AERIAL is 100°,ó efficient. 

How can you get good reception without one? 

Low Original Cost -No Upkeep Cost 

SUB -AERIAL costs no more than an overhead or loop 

aerial and less than many. Its first cost is the only one. 

SUB -AERIAL is permanent. No trouble -no hard work, 

or risking your neck on roofs. 

25 Year Guarantee 

SUB -AERIAL is guaranteed against any defects in 

workmanship or material and against deterioration for 

25 years. Any SUB -AERIAL which has been installed 

according to directions and proves defective or deteriorates 

within 25 years, will be replaced free of charge; and also 

we will pay $1.00 for installing any such new replacement. 

TRY IT FREE! 

We know so well the surprising results you'll get that we'll let you 

put in a Sub -Aerial entirely at our Risk. You be the Judge. Don't 

take down your overhead Aerial. Pick a summer night when static 

and noise interference on your old Aerial are "Just Terrible." If 

Sub -Aerial doesn't Sell Itself to You Right Then on Performanceyou 

needn't pay us a cent. Send for "all the Dope on Sub -Aerial." 

You'll be surprised. Do it NOW. 

Can Be Installed 

in a Few Minutes 

Undergroune Aerial Systems, Dept. 9 -P 

St. Clair :aids., cor. St. Clair and Erie Sts., Chicago, Ill. 

Send me complete information on Sub -Aerial, Proof and Free 

Trial Offer. No obligation. 

Name._ 

Address 

__________ ___ 

UNDERGROUND AERIAL SYSTEMS 

St. Clair Bldg., Dept. 

Corner St. Clair and Erie Sts., Chicago, III. 

GroundOutStatic 

',itiv,Sl16AERIAI 


P



Follow the Lead 

of the 

L E A D I N G 

MANUFACTURERS 

PAY MORE 

GET MORE 

with 

DUBILIER 

SOCKET POWER 

CONDENSERS 

After exhaustive tests, the engineers 

of the leading manufacturers, 

have standardized on Dubilier 

Condensers. They pay more 

for them -- but they have the 

assurance 

that their 

sets are go. 

ing to stay 

sold and 

they know 

thattheample 

factor 

of safety 

means long 

life. They 

can't afford 

to take a 

chance and 

save a few 

cents. And 

neither can 

you! 

You can forget the Condensers - 

Type PL-666 and PL667 are 

standard equipment on high 

voltage AmerTran. Samson, 

Thordarson and other power 

packsspecifyingUX 281 or CX 

381 type rectifier tubes. Type 

PL-666.... 2 mfd. 1000 volts - 

$6.50: Type PL-667-4 mfd- 

1000 volts -Price $11.00. 

if they are Dubiliers. 

Dubilier 

LIGHT SOCKET AERIAL 

If it does 

not work 

on your 

set -your 

money back 

And we mean it! If it 

doesn't give you smooth reception, 

reduce static and interference 

and give you plenty of 

volume the dealer will give you 

your money back within 5 days. 

Uses no current. Just attach to 

your set and plug in to a convenient 

light socket. Price $1.50. 

Write for free booklet 

Dubilier 

C O N D E N S E R 

CORPORATION 

4377 BRONX BLVD. NEW YORK 

Please 

PERHAPS IT WAS TELEVISION YOU HEARD 

Program of radio entertainment from the 

Providence Journal of August 5: "9:35 p. ni. 

Baseball scores. 's Lusky 4 oMaHwpluli. 

EAL nn nn m wwkwk." What is the use of 

trying to eliminate static when they arc 

actually broadcasting it this year! We surrender 

right now. -Chester H. Page. 

THE ORPHAN OF THE STORM 

Directions enclosed with tithes by S. S. 

Kresge Co.: "It is essential that a grid battery 

he used, otherwise the windings of the 

loud speaker will probably be TURNED out" 

Oh, Mr. Tube, have pity on a poor old 

speaker, who has no other place to lay his 

diaphragm, and don't drive him out into the 

cold. -A non yaaoas. 

IF SINNERS ENTICE THEE, 

CONSENT THOU - 

Perils to which radio parts are exposed - 

ntorally and otherwise -revealed by W. C. 

Braun's catalog: "The slightest inaccuracy. 

allows disastrous URGES to rush through to 

the tubes." We think the R.M.A. should establish 

a Big Brothers' league to keep young 

and innocent tubes from imitating the Monk 

of Siberia.- Rowlind Bohstedt. 

DOCTOR, WHEREFORE THESE TEARS? 

Court procedure for compulsory licensing 

under Marconi patents of Loewe multiple - 

tube sets elicits the fact, as reported by the 

London Star, that some of these tubes contain 

"two LAMENTS," making it possible to 

"get every European station to Moscow for 

a total price of £4 17s wholesale." 

Why 

the lamentation -unless it is for more continents 

to coriqucr ? -A. M. Gibbs (England). 

OH, THOSE POWER -HOUSE CHORDS! 

Affirmative reply by the New York Tinges 

of July 1 to the query, "Can I put a 

DvNAMO speaker in series with an ordinary 

cone' raises the question whether or not 

this combination, like Charity, will not begin 

to hum? As soon as we have a spare mo- 

ment, however, we may try it out with our 

M. G. John C. Heberger, 8AEC. 

say you saw it in RADIO N 

ATTENTION, BETTER BUSINESS BUREAU 

Suspicions of the Blue Sky bureau ver, 

aroused by advertisement of "3-foot double 

Cox 

speaker kit," in Hampton- 33"right'.s 

catalog. Mike, the fearless investigator, 

went out sleuthing, and detected this slippery 

speaker endeavoring to sell the Wheatstone 

Bridge to a couple of newly -arrived 

and innocent tubes. -Raoul Esca Hie r. 

BLAME THOSE ELECTRIC EELS! 

Advice to a set owner whose battery runs 

down too soon, from the Sydney San of 

Jul- 3: "It is possible there May he a partial 

short -circuit in the SEA." We think that 

a socket -power unit will be cheaper than a 

diver's suit, in that case. What do you say? 

-Sid H. Cox, (Australia). 

GO TO THE ANT, THOU SLUGGARD 

:Advice of Solomon put to practical use by 

new invention advertised in the Boston. Post 

of .Izane 15: "Johnson ANTOscsTic charger, 

$5." We suppose that the power of the industrious 

ants charges the battery; but we 

would have to catch an awful lot of them. 

The charger could he taken with a portable 

set to the next picnic, though. -Robert H. 

Lefkovich. 

REMODELED WHILE YOU WAIT 

Boon offered to the wearied experimenter 

by Hamilton -Carr s latest: "Sterling Power 

OtTFIT traensfornaer...$2.94." We have sent 

for this and will set it to work changing the 

old five -tuber into an A.C. screen -grid 

superhet with television attachment. While 

E 

one is transforming the outfit, the ,job might 

as well be an thorough one.-Ted E. Jocelyn.


Radio Nest's for .\ nz.cinbcr, 1928 

WHOLE' SALE PRICES 

fôrDeaiers, Cornmuniti Sei-Builders, General RepÉrmen 

and Acids! 

Be sure to get this great 144 -page book 

with net prices to the radio trade. 

Radio Specialty Company is radio's 

oldest radio parts mail order house in the 

country, and the new confidential prices 

on standard radio merchandise are the 

lowest of any radio house. 

We are ready now to appoint additional 

agents in all parts of the country. If you 

are contemplating making big money 

in radio merchandise, be sure to get in 

touch with us at once. 

devisioll 

is here! 

Radio Specialty, as usual, is first with 

all new things. Send at once for free 

booklet for lowest prices on all tele- 

vision parts which have been put on 

the market so far. (If you have 

Catalog No. 18, just ask for the 

Television Supplement.) 

?1eìi75 

OOKUpS 

500 

I LLU STRATIONS 

from 92adios Oldest tail OrderJlouse i 

We are the oldest established, exclusive radio mail order house in the country. teous service. We carry a larger variety of radio parts, radio instruments, 

All orders arc positively shipped within twenty -four hours; quick, prompt, cour- accessories and radio findings than any other radio house in the country. 

"RpSCOr`has iE 

You will find in Catalog No. 18 the largest assortment of radio merchandise in this country. Radio Specialty 

carries more radio parts and radio material than any other house in the country. You will find in this catalog 

positively the largest variety of radio merchandise. 

If you re in need of certain small radio parts that other radio and mail order houses do not bother to carry 

get the Rasco Catalog and you will find the small parts there. anything from a screw to copper ribbon, tele. 

phone diaphragms, as well as thousands of other small radio findings. Just to mention a few: 

Lugs. nuts, jacks, plugs, all kinds of knobs, cords, panels, screws, sliders, washers, selenium, tinfoil, switches. 

rystabs. cap nuts, Litz wire, cord tips, brass rods, resistances, binding posts, switch parts, carbon balls, 

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ANYTHING 

IN RADIO 

98W PARK PLACE, NEW YORK 

P l e a s e . c u r r n n s a m ti .1 IJ 1 1l .A' F_ f ls


Ir,' 

472 

¡Raytheonst-- 

K111,oLdnIP 

PARTS IN CONSERVATORY STYLE 

Floricultural fashion note in Sears, Roebuck 

tí Co.'s catalog for the coming season: 

"Heavy PorrEO transformers." Radio fans 

who are interested in decorative effects will 

jump at this chance to decorate the music 

room with transformers, instead of the old 

style palms and rubber plants.Rowlind 

Bohstedt. 


THE MONDAY -MORNING SIX 

Household convenience offered be Gardener 

cf 1Vhite, Detroit, Mich.: "Crystal 

Electric Washer, $120. TIIBES and SPEAKER 

priced extra." The Lux program is said to 

be extraordinarily effective on this instrument, 

which should indeed make washday a 

pleasure. But we hope that the static will 

not fray our collars or take the buttons off 

our shirts. J. S. Bevan. 

TWO PIONEER 


ACCESSORIES 

The Raytheon Laboratories 

invite correspondence 

from both engineers and 

amateurs in regard to these 

two accessories now in 

successful operation. 

Raytheon Kino -Lamp is 

the first television- reception 

tube developed to 

work on all systems. 

Raytheon Foto -Cell, an 

extra sensitive broadcasting 

tube, is supplied in 

either hard vacuum or 

gas -filled types. 

RAYTHEON MFG. CO. 

Kendall Square Bldg., Cambridge, Mass. 

fRaytheoif. 

Foto-Cell 

Please 

,1 

t i!ìd 

(' st. 

A SUNBURNT SCIENTIST'S THEORY 

Explanation of the "skip-distance" effect 

in the S,ydnerl herald of June 29: "The 

ionisation is caused by the ULTRA-VIOLENT 

light transmitted from the sun." Well, if 

we were a little hit of a wave, only a few 

meters long, we'd steer quite clear of the 

Ileaviside layer, where such dangerous traveling 

conditions prevail.-Robert F. Willie 

(Australia). 

RICHARD IS AN R.E. 

The new short -wave receiver described in 

the Boston Globe of August 5 is evidently 

operated by a mechanical man: "Tuning 

with the metallic DICK is accomplished by 

angular displacement." We understood that 

Mike is the iron man who steers ships: but 

it seems that Richard is the radio expert of 

the famih. -FI. .1. Albin. 

IF vos, sec any humorous misprints about Radio 

in the press, dip them on t and send then, to 

RADIOTICS. e/o RADIO Saws; send also the 

heading of the page, shooing name and date of 

publication of the paper or magazine. .add a few 

humorous words of comment; the best contributions 

teill be printed, in case two or more send in 

the same R.DIOT!C. For each one printed here, 

$1.00 will be paid. 

Radio As an Advertising Force 

D)ES radio advertising pay? Some 

radio advertisers, like 3I r. Henry 

Field, of Shenandoah, Iowa, have shown that 

the most direct kind of advertising floes pay, 

if it is suited to its prospective customers. 

Other advertisers who have used more indirect 

methods have evidently found that 

their sales sheets showed very encouraging 

trends. But what of the business which 

looks upon radio as a direct competitor - 

the great industry which entertains the public 

in person, and must therefore regard as 

a disturbing influence whatever makes the 

fireside armchair more attractive at the close 

of the day? 

Here is a most pertinent putting of the 

case by a third party in interest -a radio 

merchant to whom radio is but an incidental 

item, though a large one. 

This advertisement was published by 

Bloomingdale's, a concern operating a large 

department store on the upper east silk of 

New York City, as well as stores in Brooklyn, 

N. Y., and Newark, N. J., and takes the 

finnl of an open letter to a well -known figure 

in the great industry of selling ringside 

seats: 

"Think it over, 3Ir. Rickard! After the 

Tunney- Heeney fight the newspapers voted 

you as saying, Ì blame much of the failure 

to have out a paying crowd on the radio. It 

helped kill my business.' 

Are you absolutely 

certain that your loss is clue to radio broadcasting: 

As one of the leading radio stores 

in this country, we feel it to be our duty 

toward the millions of radio owners to point 

out a few interesting facts in the matter. 

"Before broadcasting -the biggest attendance 

was 40.000, the biggest gate receipt 

$450,000; after broadcasting -the biggest 

attendance was 165,000, the biggest gate resay 

you saw it in RADIO 

ceipt $2,650,000; an increase in attend - 

ance of 312% and in receipts of 539!,. 

"'These are the facts, Mr. Rickard ! They 

tell an altogether different story. They 

show that fighting came into its own with 

radio broadcasting. That both gate receipts 

and attendance reached their highest point 

at the peak of radio broadcasting ... Radio 

has raised pugilism to the dignity of a great 

national sport with a new following of millions 

of men and women. Think it over. 

Mr. Rickard. It may be that you even owe 

a debt of gratitude to the thirty million men 

and women -the `Ladies and Gentlemen of 

the Radio Audience.'" 

The detailed figures which accompany the 

advertisement only further exemplify the 

argument; but to date, 3Ir. Rickard's comeback 

has not been recorded. At any rate, if 

radio advertising entertains the stay -athomes, 

it certainly coaxes no small number 

out and into the throng of cash customers. 

IN STRICT CONFIDENCE 

VISITOR : "And what became of the radio 

set you had?" 

HOSTESS: "Oh, it didn't work right; so I 

got rid of it." 

"I couldn't meet my payments 

VISITOR: 

either: " -Rd core! Piranian. 

THE ULTIMATE ULTIMO 

SaiITtI: "If prizes were given for the 

laziest anon, Biggs would get the fur-lined 

bathtub." 

JONES: "IS Ile So la'Ly ?" 

SMITII: "Is he? He's so lazy, he'd rather 

listen to a bedtime story than turn the 

dial I "- Jloltie Zacharias. 

NEWS



473 

(Chemistry p..Vs t- .4. 

to success! 

Some people measure success in 

terms of money and others in degree 

of knowledge and culture. Chemistry 

is the one uncrowded profession today 

that offers both. America, always a land 

of amazing opportunities, is especially so 

now in the field of applied Chemistry. In- - 

dustries have developed within eight years 

more rapidly than the output of trained men 

to conduct them. Every big industry needs 

chemists and there is a real demand for them 

imnlcdi mtcly. 

Earn a Bigger 

Salary from now on 

Good Chemists Command High Salaries 

Not only are there boundless opportunities for amassing wealth in 

Chemistry, but the profession affords congenial employment at good 

salaries to hundreds of thousands who merely follow out its present 

applications. These applications are innumerable. touching intimately 

every business and every product in the world. The work of the chemist 

can hardly be called work at all. It is the keenest and most enjoyable 

kind of pleasure. The clays in a chemical laboratory are filled with 

thrilling and delightful experimentation, with the alluring prospect of a 

discovery that may spell Fortune always at hand to spur your enthusiasm. 

You can make yourself independent for life by unearthing 

one of Chemistry's undiscovered Secrets 

Do you remember how the tales of pirate gold used to fire your imagination 

and slake you want to sail. the uncharted seas in search of treasure and 

adventure? And then you would regret that such things were no longer 

done. But that is a mistake. They are done -today and every clay -not on 

desert islands, hut in the chemical laboratories throughout your own country. 

Quietly, systematically, the chemist works. His work is difficult, but 

more adventurous than the blood- curdling deeds of the Spanish Main. Instead 

of meeting an early and violent death on some forgotten shore, he 

gathers wealth and honor through his valuable contributions to humanity. 

Alfred Nobel. the Swedish chemist who invented dynamite, made so many millions that 

the income alone from his bequests provides five $40,000 prizes every year for the advancement 

of science and peace. Hernian Frasch, who showed how to extract sulphur, built 

tip a huge fortune. C. M. hall, the chemist who discovered how to manufacture aluminum, 

made millions through this discovery. 1'. G. Cottrell. who devised a valuable process for 

recovering the waste front flue gases, Jantes Coyle)... who showed bow to save enormous 

losses in steel manufacture. L. H. Baekeland, who invented Bakelite -these are only a 

few of the men to whom fortunes have come through their chemical achievements. 

YOU CAN LEARN AT HOME 

To qualify for this remarkable calling requires specialized training. 

Formerly it was 

necessary to attend a university for several years to acquire that training, but thanks 

to our highly perfected and thorough system of instruction, ;'ou can now stay at home, 

keep your position. and let us educate you in Chemistry during your spare time. Even 

with only common schooling you can take our course and equip yourself for immediate 

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EASY MONTHLY PAYMENTS 

You don't have to haveTeven the small price of the course to start. You can pay for 

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MAIL THE COUPON FOR FREE BOOK 

Your name and address on the coupon will bring you by return mail our interesting free 

book. "Ol'l'ORTUNITIES FOR CHEMISTS." and full particulars about the course 

and what it will to for von. You owe it to yourself to get this book. Send the coupon 

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and mail to us. But whatever you do, act today. 

SEIZE THIS OPPORTUNITY -MAIL COUPON NOW ! 

Chemical Institute of New York, Inc. 

Home Extension Division 1l 

16 -18 -R -East 30th Street New York, N. Y. 

/' s,' s r r , n u .i t. ,, i i u 

Just a Few Letters 

From Students Who llave 

Taken This Course 

You will probably be pleased to 

learn one of the lessons gave me 

an idea to turn niy chemical 

knowledge to profitable account. 

I am now staking a varnish and 

paint which undersells the other 

type products by $2.60 a gallon, 

in some cases more. Have been 

receiving gallon orders from paint. 

's during past week which has 

netted the a profit of 512.50 for 

my "spare-time chemical industry." 

\fang thanks for your 

training thus far. J. J. KELLY 

I am but half -way through your 

course and am certain that I have 

saved my Company molly antes 

the cost of the course and raised 

myself in t he shareholders' estimation. 

The knowledge obtained has 

its immediate prao leal application 

tuul I do not hesitate in saying 

your course and the personal attention 

you give Is im.luable to 

the practical man In any business 

'Microchemistry plays a part. You 

may use this letter and my name 

and address to the furtherance of 

your good work. 

JOHN WALTER. 

I have not written since r received 

the big yet. I can still say 

that it far exceeded my anticipations. 

Since I have been studying 

with your school I have been apchemist 

('oat Co.. all the coal and 

ssh by proximate analysis. The 

lessons are helping me wonderfully. 

and the interesting way in 

which they are written makes me 

wait patiently for each lesson. 

attai.ais COUZENS. 

T. O'CONOR SLOANE, 

A. B.,A. M .,L L. D., P h. D. 

N otedIust ructor,Lecturer 

and Author. Formerly 

Treasurer American 

Chemical Society 

and a practical chemist 

with many. well -known 

achievements to his 

credit. Not only has 

Dr. Sloane taught chemistry 

for years but he 

was for many years engaged 

in commercial 

chemistry work. 

EXPERIMENTAL EQUIPMENT FURNISHED 

TO EVERY STUDENT 

we give to every student, without additional charge, his chemical 

equipment, including fifty -two pieces of laborntmy apparatus 

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work of the course. The fitted heavy wooden box serves not only 

as a case for the outfit. but also as a useful laboratory accessory 

for performing countless experiments. 

CHEMICAL INSTITUTE OF NEW YORK, INC. 

Home Extension Division 11 

16 -18 -R -East 30th Street, New York, N. Y. 

Please send me at once, without any obligation on my part. 

your free book, "Opportunities for Chemists." and full 

particulars about the Experimental Equipment given to 

every student. Also please tell nie about your plan of payment 

NAME 

ADDRESS 

CITY 

R- N -I1 -2S 

R.11)1O . \'EII'.4' 

STATE


474 

LONGER 

LIFE 

Radio "Bugs" 

HE amazingly lifelike figures which our 

1 ingenious readers macle out of the eon - 

ventional figures of the schematic circuit 

arc not without honor abroad. European 

magazines are following the example of 

RADIO NEWS; and from our contemporary, 

Radiowelt of Vienna (Austria) we take 


quite oscillatory. Let us he thankful that 

it does not pass too close to our humble 

residence and receiving station. Just one 

more example, and this department closes 

again with acknowledgements to all its 

coadjutors. 

"Short Waves from Java on the l'eridyne" 

is the humorous title which henry 

Newhoff, of Chicago, applies to this ingenious 

sketch of a combined coffee pot and 

Perid-ne stage. We don't know ,just how 

/_ V C 

RADIO 

TUBES 

A i 

v`4 

6 

P O N O P N C E D 

1E - CO 

Racli®Tubes 

WHEN you install a set of 

CeCo Tubes in. your 

radio, you immediately notice 

the greater clarity of reproduction 

-the increased sensitivity 

and the better volume. 

But your greatest satisfaction 

will come with their longer 

operating life- making CeCo 

the most economical tubes to 

buy, and worthy of their 

slogan, "they cost no more, 

but last longer." This is made 

possible partly by the exclusive 

method of evacuation. 

To avoid disappointing results, 

make sure each socket 

is equipped with CeCo tubes. 

Whether for battery or A. C. 

operation, there's a CeCo for 

every radio need -including 

"special purpose" tubes that 

are not obtainable elsewhere. 

They are sold by leading dealers 

everywhere. 

Tune in Monday evenings to 

the nearest of the 18 Columbia 

Broadcasting Stations and hear 

the musical program of the 

CeCo Couriers -8 P. M. Eastern 

Time,7 P. M. Central Time. 

CeCo MANUFACTURING Co., Inc. 

PROVIDENCE. R. 1. 

these two fine specimens, which show that 

humor, like radio, is international. 

"Die Wcllenwalzer" -the dance of the 

waves, is expressive; even though the lady's 

skirt is. unusual, it strongly evidences that 

one touch of jazz makes the whole world 

kin: 

"Die I_uhalbahn von Itaulinpolis" will be 

relished by all cnnuuuters on the Blank, 

Dash and !!!? ßaiload; we do not specify 

more closely, on account of the libel laws, 

but you will recognize this as the train which 

is met by the Toonerville Trolley. 

Our own "Bug" ontest closed some 

months back, but we take the opportunity 

to give a couple of excellent sketches which 

have since reached us from Leo D. Keller, 

of Rochester, N. Y. "The Waveband Director" 

should be able to straighten out 

the radio concert; let us hope so. 

The troller ear shown here should be 

E 

say y o u 

saw it in R.'17) I Cl 

practical the idea is; but a milk ( ?) shaker 

makes a good shield, according to our 

Beginner's editor, and we wait to see an 

entry of this kind in the Monthly Construction 

Feature. 

If you have any more "Bugs," consult 

the corner druggist, or the community 

trouble shooter. The department of Radio 

Entomology is now a has -been, and some of 

our friends may hint that it is a never -was. 

Advertising or Subsidies? 

I.1ilstralia, radio set owners pay licenses 

which are used to support "Class A" stations; 

while "Class B" stations, owned in 

most eases by organizations which desire ai 

mouthpiece for their views, are not so favored. 

Since the Commonwealth's postal 

authorities have undertaken a coordination 

of the programs and activities of the "Class 

A" stations, a request has been presented 

on behalf of the "B" stations for either a. 

share of the license revenues or the exclusive 

right to accept paid advertising. 

In the 

latter case, the virtues of the sponsored programs 

might be fairly tried out -were it 

not that the Australian listener must pay 

the bills of the preferred stations, whether 

or not he prefers other programs. Our 

American system has still some advantages 

which will commend it to the listeners, even 

though there may be a few corresponding 

drawbacks. 

Brightness No Guide 

SET operators, who have been used to 

consider the brilliancy of tubes as a 

measure of their operating condition, encounter 

a new condition with the new A.C. 

heated -cathode tubes, such as the 227-type. 

The manufacturers explain that differences 

in the light emitted have nothing to do with 

the performance of these tubes. Only a 

portion of the heating element or filament 

is exposed, and changes in its brilliancy at 

this point do not imply that the temperature 

below is incorrect. These tubes will stand a 

very considerable overload on the filaments; 

though, of course, the wise experimenter 

will not subject them to the test. . 

AT T J{T 5


Rd1nY 


Television Trials 

(Continued from poye 439) 

Lest systems must be worked out Lry actual 

practice. Will transmission be easier, and 

reception clearer, on this waveband or that? 

Which mechanical system will be most satisfactory 

in the long run? 

We may compare the state of television 

and its kindred arts to that of transportation 

in 183g: it is no time as vet for 

standardization. The "Toot Thuutii' was a 

good locomotive in its da v, but railroading 

would have been at a sad pass if it had to 

be standardized on the basis of such machinery. 

So with television; it has yet a few 

years ahead of it in which to be perfected, 

and undoubtedly the final apparatus which 

will be used for home, as well as commercial, 

scientific and governmental reception 

will he as much superior to that with which 

we are now wuirking as the great passenger 

and freight locomotives of today exceed 

the "Tout Thumb" in efficiency. 

SPECIALIZED SYSTEMS FOIL ALL NEEDS 

It is probable that, even when television 

has become a perfected art, are shall be a 

lung ways from stnndardizilion. The problem- 

of the frequency bands which can be 

allotted for the purpose is one of the 

principal ones; even if broadcasting is revolutionized, 

it is probable that cnulparatively- 

Iiulited lemds will be used far the television 

transmissions which will he receivable in 

the house. INIuch more elaborate apparatus 

will he used to project pictures in theatres 

and other places where large groups of 

spectators are gathered. (Again, we need 

a new word in the language; perhaps a 

"televisence" will signify the gathering who 

are looking on thy screen of the televisor.) 

Other purposes will demand elaborate apparatus, 

operating proled ly on travel ands 

which are today useless even for experiment, 

hat which will yield a frequency range 

capable of carrying the most detailed images, 

of largest sizes. 

For the present, the most advanced televisionanies 

are vet in the kindergarten class, 

and every conceiva ire system ti ml arl'angenaent 

must undergo careful test by engineers 

and other experimenters; the field is 

too wide for any one man or group of men, 

with even the most elaborate equipment that 

scientific organizations possess. 'lime hone 

experimenter will have to nibble at this dish 

and that, for the banquet of television dainties 

trill present too many courses for one 

digestion. 

hIowever, ItAini News does sympathize 

with those of its readers who ae n' desirous 

of keeping fully abreast of all that is going 

on; and to the hest of its ability, it will 

present ideas for the use of apparatus with 

which it will be possilde to receive as many 

different systems as possible. Apparatus 

manufacturers, too, are keeping this contingency 

in mind; and, while different television 

systems permit of varying ranges of 

speed and detail of pictures, we shall undmuhtedly 

have soon combination dises which 

may be used, by simple adjustment, for reception 

of coarser or finer images, at different 

locations of the glow-lamp and scan- 

ning hood. And, too, we may before long 

find the scanning -disc system entirely superseded 

by more refined electrical devices. 

e a adio xpert 

xJ .Smifh 

I've trained hundreds of fellows at home 

in their spare time forl3ig PayRadio Jobs. 

i 

Has Made 510,000 More - 

In Radio 

"I can safely say 

that I haace made 

810,000 mom in Radio 

than I would 

have made If r bud 

continued at the old 

Job. alien I enrolled 

with you I 

didn't know a volt 

from an ampere. I advise all 

ambitious young men to get. 

Into Radin. There is no greater 

opportunit F " 

Victor L. Osgood. 

C'nnaford Ave.. 

Bronx, New York City.' 

5500 a Month 

When I enrolled with N. R. I,. I 

s :1 motorman on a trolley ear. 

Now 1 have a tine, fast growing 

Radio business. I have $2500 in 

the bank and about S300 worth of 

Radio stock. I made It all since 

graduating test than sis months 

ago.' 

Richard Huller. 

353.5 Shem,dd Si., 

Philadelphia, Pa. 

$3,000 a Year 

'T cannot give 

too much credit 

to the N. It. I. 

for what I Inter 

been able to ,lo 

in Radio.] have 

averaged 53000 

it year for the 

past to rd'Fetus. 

I ant in the Radio 

buslneas. I 

consider all the seeress 1 mime 

ohtnival u, tar due entirely to 

your training... 

Vox! A. Nichols, 

Hereford. Polo. 

4/.` 

amazing growth is making hundreds of big -pay 

RADIO'S lobs every year. Trained men are needed. You young, 

ambitious men, starting out, who are looking around for something 

really good, and you older men, who aren't satisfied but 

want more money -here's a field that is growing fast enough 

to bring success in a year or two. I have doubled, tripled, quad- 

My book points out the 

rupled the salades of men in one year. 

many jobs in Radio. Clip the coupon. Get a copy now. Why 

be satisfied with anything less than $50 to $250 a week when 

that's what Radio pays its good men? 

So May Opportunities -Many Begin Making $10 

to $30 a Week Extra Almost at Once , 

You don't have to wait one year, two years, not even six months 

to begin getting the extra money you want. I'll show you the 

plans and ideas that are making $10, $20 and $30 a week extra 

for my students -show you how to begin doing it too the first 

month if you study hard and follow my plans. G. W. Page, 

1807 21st Ave., S., Nashville, Tenn., made $935 in his spare 

time while taking my course. Earle Cummings, 18 Webster St., 

Haverhill. Mass., writes: "I have made as high as $375 in one 

month in my spare time." No need to worry about money. 

this is the famous course that pays for itself. 

A great training 

made greater' 

Tele vision 

now included 

Television ran quickly easily become ant] as big ans 

L to 

tala,-. 

whole Radin perd 

you That's 

ought wits 

about to know 

the all 

dtaen'ut 

mÌna sen,lln 

fiy8- 

ce .it.p 

ng for 

:are pietuns 

man -there 

hcttl. /rnkiñ, 

it' ÓI rtght 

ril:v, R;dnls ,aoley"s, 

:Vexund . 

tre eover,I methods 

in 

' nr u ßalin 

I to absolutely ttaininßW ¡¡Ì 

eompiere 

iah 

it f. 

I give you a home 

experimental 

laboratory. You can 

design and build loo circuita 

with it. Here are two 

This is Radio's Bi a 

Xthen you h,iok -u1, 

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est Year 

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Learn at Home 

Don't lose a minute from your job. All I 

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14, men up to 60 have finished my course 

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school education. Many of my most 

successful graduates didn't even finish 

the grades. 

You Must Be Satisfied 

The day you enroll I'll give you a contract 

agreeing to refund every penny of 

your money if you are not satisfied with 

the lessons and instruction I give you. 

Get This Book AT ONCE 

"Rich Rewards in Radio" shows where 

the big jobs are, what they pay, what 

others are making- It has started hundreds 

of fellows on the 

road to bigger money 

J 1 

Rad1O . 

ail Cou 

who thought success was 

not for them. Get n 

copy. Not the slightest 

Yt 

obligation. Do it Now. 

J. E. SMITH. PrraidrN, 

Dept. 3355. National Rada., In- itute. 

Washington. D. C. 

J. E. SMITH 

Presiden, 

Dept. 33SS 

National Radio Institute 

Washington, D.C. 

onNOW 

I)ear \Ir. Smith: Send me your hook. "Rich Itrw:trd: 

in Radin." I want to know about the money -making 

opportunities in Radio and your practical method 

of training warn at honte In their spare tine to become 

Radio experts. This request does not obligate me. 

Name 

. 

Address... 

City. 

..Age 

S1a:at, 

James Clerk Maxwell predicted the laws 

of radio in 1867. 

Please ,fuv t'i,a saw it in K. -IIJI(J .\'G11'.


widest 


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A recent development, which 

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The "A" Filter consists of a 

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TOBE "A" FILTER $18.00 

Just attach your Charger 

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to RADIO NEWS -$2.50 a year. Experimenter 

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ta 

Synchronized Broadcast 

(C'ottinued front rouge 426) 

and another switch opening and closing the 

television -lamp circuit. 

To maintain the scanning disc of the receiver 

in synchronism with that of the trans - 

mitter -a requisite to the production of a 

recognizable image -delicate adjustment is 

necessary. This, as in other manual synchronizing 

systems, is accomplished by the 

simple expedient Of varying the series resistor 

of the motor; this is a task quickly 

Mastered by the experienced operator, but 

one which requires continual attention. 

PROBLEMS YET FACED 

While this exhibition is in the - 

sense "television," it is not true radio vision 

- hearing exactly the same relation to the 

Latter that the "Wired Wireless" described 

in last month's RADIO NEWS has to the 

broadcasts picked up by the listener's aerial. 

'l'he problems of operating such a television 

system over wires are very similar to those 

of broadcasting; except that in the latter 

case modulation and demodulation of a 

radio frequency are necessary to obtain 

(listant transmission. And, at the present 

time, wide -frequency channels are acquiring 

n value comparable with that of the. Kohlmaw, 

which is har(lI' rarer. 

Whether the medium of transmission is 

ether or copper wires beam's but little on 

the main problems, of creating the. "vision- 

impulses" at the transmitting end with sufficient 

energy to impress them on a photoelectrical 

system distinctly, and of synchronizing 

the receiving mechanism until a clear 

image will remain in the field of sight. The 

problems of amplifying a "television-fre - 

quency" hand. wider than the audio bind, 

through many powerful stages, are also alike 

in either system; though broadcasting and 

wire -line transmission have also well -known 

specific problems of their own. In any event, 

we may look forward with confident expectation 

to a not far -distant day when we 

shall hear and see together from a single, if 

complex, assembly of receiving apparatus. 

"Ventilation" in the 227 -Tube 

Obtained by Mesh 

the mesh -plate instead of a con- 

WHY tinuous sheet of metal in the UY -227 

heated- cathode tube? Many users of this 

tube have wondered about the reason for 

this change in the design of the outer element. 

During the development of this type of 

tube, the laboratory engineers found that 

emission of electrons occurred, not only 

from the cathode, but also from the cylindrical 

grid and plate unless they were relatively 

cool. This would be an undesirable 

condition in the operation of a device of this 

kind, as it would set up conflicting currents 

in a radio receiver. 

To allow the plate to remain cool, and to 

eliminate undesirable electron emission, the 

use of a wire -mesh plate was adopted, thus 

allowing the escape of much of the heat 

generated by the heavy current through the 

filament; the wattage of the 2.27 -type heater 

is :3r4 times that of the 201A -type filament, 

and the generation of heat consequently proportional. 

Hertz discovered radio waves in 1887, 

twenty years after Maxwell calculated that 

they must exist. 

mie 

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Radio News for November. 1978 

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Radio _\'ewes for November, 1928 

"Rays of Justice" 

(CoNliuf it fen ua tua,le -1:;:S) 

Unanimously the engineers diagnosed the 

trouble as being caused by too -small insulators. 

Feverishly they set about to design 

a new insulator of huge proportions 

which no current under a million and a 

Half volts could possibly break down. This, 

the engineers felt, would by its sheer size 

alone render failure impossible. Yet all 

the time they were haunted by the uncanny 

way in which the two insulators had broken 

down -at identically the same point, at the 

same time, in the saute way. The laws of 

probability utterly forbade such coincidences. 

The interest in the proceedings was so 

widespread that the public- spirited I-Iarold 

Dare, at the suggestion of his thoughtful 

public- relations department, arranged for 

the broadcasting of the installation of the 

new insulator. As if going on location, a 

whole company of fechniciaos from the 

Dare studios set out from Hollywood, transporting 

with them all the equipment necessary 

for connection with the regular television 

channels. The power truck with its 

gasoline -driven generator outfit was placed 

behind a ledge of rock several hundred feet 

,away, lest its deafening noise spoil the 

audio part of the broadcast. At noon they 

came on the air through WROT, and 

throughout the afternoon continued to report 

the progress of the work to a thrilled 

citizenry touched anew by the thoughtfulness 

of Harold Dane, thrilled with the opportunity 

of witnessing this dramatic engineering 

crisis: 

It was not until dusk that the linemen 

were finally whipping the heavy cables into 

place, and huge daylight arcs were already 

flooding the ridge with light. The television 

pick-up device was sent aloft in a captive 

balloon to the level of the tower top. .\ 

spotlight played upon the linemen who were 

putting the finishing touches to the last 

splice. The tension tightened as the crucial 

moment approached when the Wolf Creek 

line would be put under test. 

Then Fate took a hand. Perhaps the 

strain was too much for the long span of 

cable which carried current from the generator 

to the half -dozen flaming floodlights. 

A wire sagged, broke; an arc crackled, and 

dankness plunged down over the ridge, 

while the thundering power machine raced 

wildly without as load. 

But the screen of the televisor was not 

dark. .. million people gazed horrorstricken; 

for to the topmost cross -arm of 

the Inge tower cline two living skeletons - 

skeletons whose hands clutched pliers, skeletons 

that shouted hoarsely for lights! 

It was but a moment until electricians 

had repaired the broken wire, and the light: 

flared forth again; but from their room 

in the Hollywood laboratories, Dare and 

his engineers had seen all. The great screen 

star reached for his telephone; a few words 

to the operator and his transmitter was 

switched into the microphone circuits of 

\\'ROT. ;\ moment later his voice was 

reassuring thousands of shocked and shaken 

radio listeners that all was well, that the 

strange mystery which perplexed the world's 

best engineering talent was on the point 

of solution, and that if they would have 

patience, all would be explained. 

Then mysterious telephone calls began 

to fly about Hollywood, and in answer, ears 

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came speeding from all directions to the 

sacred inner court of the Dare studios. 

At the Dare private flying field, a score 

of lien suddenly appeared; the doors of 

the hangars were opened, and two speedy 

pursuit planes roared forth and vanished 

into the night., And at Wolf Creek, a crew 

of linemen, acting upon mysterious orders 

that had come by telephone from certain 

high offices, worked for an amazingly long 

time at a simple task that should have required 

not more than twenty minutes. 

An hour and at half had passed when 

three ears with lights dimmed low sped tip 

the bare pretense of a road that led up to 

the scene of the engineering catastrophe, 

to discharge a grim group of nlen. At a 

word from their leader they separated 

into two groups anti set off in opposite directions. 

Then Harold Dare himself stepped 

out before the battery of floodlights and 

spoke into the microphone standing on a 

pedestal. 

"Friends," he said, in a low, earnest 

voice that found instant response in the 

heart of every listener, "there is one who 

has plotted for years to work my ruin - 

a veritable fiend in human form, whom all 

the world knows and hates. As principal 

stockholder in a certain power corporation, 

he has clone his utmost to hurt me by endangering 

the confidence of the public in 

me and my new power project. Dandy 

1)iaolo and his minions are responsible for 

the three successive breakdowns in the 

Wolf Creek line. What proof? See for 

yourself. Watch the three insulators which 

suspend the cables of the Wolf Creek line." 

-The crew of linemen scurrieddovn from 

their tower. One by one the floodlights 

dimmed. In the televisor was seen the 

group of large strings of insulators hanging 

from the cross -arms. 

"Now, operators at Wolf Creek are starting 

the turbines, sending half a million 

volts surging along those cables." 

A faint glow appeared about the ends 

of the insulators. Momentarily it grew. 

A tongue of light darted out from the cable, 

then spat across to the corona shield and 

vanished. A flickering halo encircled the 

tips of the insulators, gradually spreading 

into a luminous cone. 'l'hen suddenly a band 

of flame ripped across the gap. With a 

report as of a cannon, two huge insulators 

plunged downward. Two heavy cables swung 

sinuously out against the tower; two bursts 

of flame, a shower of chops of molten copper, 

and the line was dead. 

"Lights!" cried Dare. From the truck 

which had been backed to the edge of the 

cliff, two huge searchlights suddenly shot 

long shafts of light' downward into the 

depths of the valley below; and where the 

two accusing .fingers pointed,- the ttcgrld 

saW a group of swarthy,. cyilfnced -nten 

gathered about a truck almost entirely 

screened from view by the surrounding 

shrubbery. Even as they leaped to their 

feet, n dozen stalwart men stepped out of 

the darkness on all sides, guns in hand, 

and the henchmen looked into a circle of 

menacing muzzles. With one accord they 

raised their hands heavenward. 

'l'he operator of the televisor adjusted 

his instrument for a close -up. Upon television 

screens everywhere, a group of 

si range instruments :and glass tubes of 

peculiar shapes Were seen to cover the 

truck; and in the foreground glared the 

cruel, evil features of Dandy Diavolo. I -Ie 

shook his fist toward the brilliant bears 

say you sate it in RADIO 


WHITEHEAD 

EXPLAINS THE 

GAME OF BRIDGE 

World's Greatest Authority 

Reveals Secrets of Success 

Wilbur C. Whitehead, in his master 

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of light which sought him out; his features 

twisted into a typical Diavolo sneer, and 

as clearly as if in a sub- title, the watching 

world read the words the thin lips shaped: 

"Foiled again! Cur -r-rse you, Harold 

Dare!" 

* . 

- 

"The basis of my latest plot," said Dandy 

Diavolo in a public statement an hour later, 

as he was being swiftly transported in a 

cabin plane to Los Angeles, where the 

agents of justice awaited him, "was discovered 

by Hertz half n century ago, when 

he discovered that ultra- violet light facilitated 

the passage of a spark across a gap. 

It was later found that this was due to 

ionization of the air, and that the effect 

was intensified if waves of still higher fre- 

quency were used. In order to put the 

Wolf Creek line out of commission, I set 

up a bank of powerful X -ray tubes in the 

valley below a tower on the Wolf Creek 

line. The beams of X -rays thus projected 

upon the insulators ionized the air so that 

the high voltage easily ,jumped across over 

the insulators, which were already under 

severe electrical stress, as indicated by the 

corona. No matter how large an insulator 

had been placed on this tower, the current 

would still have broken it down. Only the 

long arm of coincidence saved Harold Dare, 

as always, from the working of my plot." 

"What have you to say as to the way 

in which the plot was foiled, Mr. Dare?" 

asked a reporter. 

"To set at rest the fears of my public 

regarding the skeletons which Were seen 

upon the tower, let me first assure them that 

they saw merely ordinary X -ray pictures 

of the linemen at work, exactly as if taken 

by a doctor's X -ray. The photoelectric cell 

used in the televisor responded to the N -rays 

from Dinvolo's tubes, which, traveling on 

through the linemen, threw shadows upon 

the television field. When the lights were 

on, these shadows were too faint to he seen; 

but when the power was accidentally disconnected, 

they came into prominence. Let 

me merely remind my public that this episode 

reiterates the great truth taught by 

every Dare super -special: namely, that in 

the end, right will inevitably triumph over 

wrong, and evil -doing will receive its just 

punishment. The long arm of coincidence 

is merely the agent of ,justice, which, acting 

also through the hand of Fate, always 

finally catches the wrong -doer in the clutch 

of circumstance. This time Dandy Diavolo 

has gone a step too far.' Retribution has 

overtaken him, and during the next score 

or more of years when he will sit in the 

stone cells of the penitentiary, he will have 

abundant time to meditate upon the truth 

of this statement." 

A BIG CONSTRUCTION JOB 

VAUDEVILLE FAX: "Which do you prefer, 

the Keith or Lorw circuit ?" 

RETIRED HAM: "I can't really say; I 

haven't built a set for some time." 

HE HAD A GRIEVANCE 

":4fv name is William Ransom Nathan 

Young!" roared the angry caller at the 

broadcast station. 

"What if it is?" asked the polite attendant. 

"What if it is!" thundered the caller. 

"Why, this station, without getting my permission, 

or even asking me, is using nay 

initials! "-Gut/ T. Ermax. 

(We advised him. 'to have it changed to 

Kasper De Koren Awberson.) 

nl ° ê 

The New Knapp "A" Power Kit 

se 

Greater 

Efficiency- 

This is the 'A" power after you hare asbled 

it. A professional job: Operates on 

105 to 120 volts, 50 to 60 cycle. AC. Supplies 

rippleless DC current for operating any set 

using Standard 5 or 6 colt tubes and power 

Improved Design and Appearance -Lower 

Price -Money -making Plan for Set -Builders 

You radiofans who made myttA" power the largest sellingttA "power 

last spring have made it possible forme to offer thefinestttA "Power 

ever developed -in Kit form -even more complete than before. 

Study the illustrations -read the improvements -and you will 

wonder how I was able to reduce the price. You are the answer. I 

sold 5 times as many "A "Powers as I expected to-and this season 

I am counting on you to help me again by buying even more. 

The 8 Improvements 

I. Larger Filter System -3 Elkon 

Condensers instead of 2. Ideal 

for Super Hets and Short Wave 

Sets. 

2. Improved Choke Coils 

3. Pendant Switch Controlling "A ", 

"B" Eliminator & Set 

4. Dial for regulating voltage 

5. Celeron Front Panel 

6. Baked finish 

7. Heavier gauge metal cover 

8. Die Cast Base Plate instead of wood 

COMPLETE KIT -EASILY 

ASSEMBLED 

Like my Kit last year, the New Knapp 

Kit is a tooled job -the parts seem to 

fall into place. Every hole is drilled - 

all that it is necessary for you to do is 

to put the screws and nuts in place 

and connect a few wires. Everything 

is supplied. Nothing for you to buy 

extra. The fool -proof instruction 

sheet makes it easy for anyone to 

assemble. 

sa,, rou Saw it in RADIO NEWS 

to 

THE SET- BUILDER TAKEN 

CARE OF 

You set -builders played with me (as 

the saying goes) and I ám going to 

continue to play with you. My engineers 

have designed an a "A" Power 

which is well -nigh perfect -my production 

men, based on tremendously 

large quantities have cut their cost. 

so that I can keep faith 

with you by reducing 

the cost. And regardless 

of what the established 

trade may think 

about it -I am going to 

continue to give you the 

maximum discounts. 

The coupon will bring 

you the full details of 

both the new"A "Power 

and the special discounts 

to set -builders. David W. Knapp, Pres. 

KNAPP ELECTRIC, Inc., Port Chester, N.Y. 

-Div. P. R. Mallory & Co., Inc.- 

r 

Mr. David W. Knapp, Presiders:, 

KNAPP ELECTRIC, Inc., 

400 Fox Island Road, Port Chester, N. Y. 

Kindly send me complete information on the 

Knapp "A" Power and your special discounts for 

Set- Builders. 

Name ............... 

Address


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State 

DABLE "B" BATTERY POWER 

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SEND NO MONEY -PAT EXPRESSMAN 

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Eavox 

Makers 

of high 

d 

quality 

resistors and 

condensers that are 

Built Better - to endure. 

Write for The Research Worker. 

A free monthly publication. 

AEROVOX WIRELESS CORPORATION 

68 Washington Stre t Brooklyn, N. Y. 

Please 

Sensitizing the R. F. Amplifier 


duces distortion. However, the potentiometer 

may be removed, the grid return 

changed from the movable arm of potentiometer 

to minus filament, and a variable 

resistor (of 200 -500,000 ohms range) inserted 

in the plate circuit. An increase in 

selectivity will be noted, while the plate current 

drain will be materially reduced. 

REMODELING THE NEUTRODYNEe 

The neutrodyne circuit may be rendered 

more sensitive by removing the neutralizing 

condensers and controlling the R.F. 

stages with a suitable variable resistor, 

placed in the plate circuit. Radio enthusiasts, 

anxious to secure real distance with 

neutralized sets, have sometimes replaced 

the fixed neutralizing condensers with tiny 

variable condensers, together with a suit - 

able indication to show the normal adjustment 

for each condenser. A simpler method 

is to employ variable plate voltage, as mentioned; 

for then a single control takes care 

of the entire R.F. amplifier. 

Lately the grid -suppressor method has 

come into wide favor. This comprises a 

200- to 1800 -ohm fixed resistor, depending 

on the circuit conditions and the tube, 

placed in the grid lead of each R.F. amplifier 

tube. The grid -suppression effect of 

a given resistor becomes more marked at 

higher frequencies, or lower wavelengths, 

which is a most desirable feature, since the 

tendency of most R.F. amplifiers to oscillate 

increases with frequency. 

WHEN TIME WAS MONEY 

LABaY: "They say it cost $1.15 a second 

to broadcast the Democratic National Con 

vention." 

SANDY: "Gee! what a.spendthrift that announcer 

was, with his "Stand by one moment, 

please' ! " -ITrm. G. Mortimer. 

HOME, JAMES 

There was an announcer named James, 

A favorite indeed with the dames: 

But they all had to smile 

Every once in awhile 

When they heard him pronounce foreign 

names. 

-Mrs. Fred W. Auroache. 

TO ERR IS í 

'NE LN00t 

RApAto tXOE0.T C. l 

tESTURECLTYou¢ / 

toa,lanplocme- ` t, 

% 

.;t1jl' 

ANO AFTtRNololNg You MIA/woo FOR AN NOuR WITN,HCOntTIOAL DET,M1r 

AE Acoto sets Tax 4t Wal NOW Slut A DtMON;TWNTION OF OM VET eAntV11- 

_,^ ` 

` , 

So 

_s 

(9 ) 

úEA \ 

-Ax0 AFy-n 101Cau /VW, aLTwN N RAt,Ñ TTjTut TUBES/ 

Oe NICE wt AE TINOS TuNT. 

l' 

nur 

Liatpae 

r 

r 

,77,, 

N 

Ns_ 

uFxJt2tEn.E-ÌAAT 6QAND ANS (fLORIOOS fEEl.IN6! 

-The Wireless Constructor, London. 

say you saw it in RADIO NEWS 

PF-250 

Power Transformer 

for 

UX 250 Power Tubes 

A husky transformer built for doing the 

job, not for looks. The PF -250 is rated at 

1200 -600 volts plate, 75h volts power tube, 

73i volts rectifier tube filament. Center 

taps are provided on each of the filament 

windings. Continuous rated capacity of 

plate windings, 160 MA., continuous rated 

capacity of each 755 volt winding, 

3 Amperes. DC plate output with 

two U X 281's full wave, up to 

450 volts with sufficient excess 

for "C" Bias. 

Ask for Bulletin No. 1033 describing 

fully the PF250. 

Price, each -- $30.00 

S'ghtly bigler aQ,t of Rod, Mnunr.in, 

American Transformer Co. 

Tas former Builders for more thon rt Ymir 

263 Emmet St., Newark, N.J. 

DYNATONE DYNAMIC AND 

MAGNETIC REPRODUCERS 

Write for information on the new Dynatone 

40 -cycle reproducer. Brings out bass and 

depth from any set. Full dynamic movement. 

Dynatone Electromagnetic Units ....$12.50 

Complete with 7 -in. Cone and Baffle. 18.50 

Sold under 10-day money -back guarantee. 

Send check or money -order in advance or 

pay postman. 

ALSO 

Complete set of blueprints and instructions 

for building your own DYNAMIC moving 

coil unit. with cone and baffle. New design 

makes home construction simple with few 

tools. Guaranteed to work. Sent postpaid 

anywhere upon receipt of $1.00. 

FANSPEAKER RADIO COMPANY 

74 DEY STREET - - NEW YORK, N. Y. 

Wholesale 

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Everything in radio -kits, parts, 

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711 W. LAKE STREET. CHICAGO


Radio .News for November, 1928 

The "Pre- Selector" 

(Ct.litinle flout jape 440) 

into the receiver, it may be necessary to use 

a "B" battery for the Pre- Selector plate 

supply. In that case two of the small 22%- 

volt blocks ordinarily used as "C" batteries 

will serve the purpose and their life will be 

about a year, due to the extremely small 

lilate current drain. 

The proper connections for the batteries 

are shown in Figs. 2 and 3. In these clia- 

_rauns both the Pre -Selector and receiver 

are shown connected to ground. In most 

eases it will only be necessary to ground 

one. The best plein is to try grounding each 

individually, and then both together, to determine 

the best arrangement. 

OPERATING THE PRE -SELECTOR 

.\fter the l're- Selector has been connected 

and really for operation, the necessary preliminary 

adjustments of the receiver proper 

should be made. First, adjust the receiver 

dials for a wavelength somewhere above 

the broadcast waveband; if the exact settings 

of the dials of a multi- control receiver 

are not known, adjust the dials as 

closely as possible. 'l'hen turn the receiver's 

volume control to the position for maximum 

volume. Also, turn on its filament switch; 

unless the receiver's filaments are to be 

turned on and off at the Pre -Selector, when 

the receiver's switch should be left turned 

on at all times. 

Next, turn on the filaments of the Pre - 

Selector and adjust the rheostat to provide 

them a voltage between 3 and 3.3. 'l'urn 

the Pre -Selector's "Volume Control" all the 

way to the right and adjust the "Sensitivity" 

control so that the plates of the 

midget condenser C4 are all out (minimum 

regeneration). 

With the left or "antenna selector" (wave- 

length) dial of the Pre- Selector at, say 40, 

slowly rotate the right -hand or "frequency 

selector" control knob until a station is 

heard. If none is heard, repeat the opera - 

t1/2n but with the wavelength control set at 

50. It is important that the "frequency selector" 

control be turned slowly in hunting 

for stations; because the tuning with this 

control is so sharp that stations may be 

skipped over easily. 

Once the first station has been heard, 

carefully readjust the two tuning controls 

of the Pre- Selector for maximum volume; 

then turn the "volume" knob back to reduce 

the volume to normal. The tuning controls 

of the receiver should now be readjusted to 

exact resonance, which is indicated by maxi - 

mum volume. Also, any other adjustments 

provided in the receiver should be made 

now for maximum reception. If there are 

two or more antenna terminals, for instance, 

the Pre- Selector's output lead should he 

connected to the one which provides maximum 

energy- transfer. It may be worth 

while to try also increasing the plate voltage 

on the R.F. tubes in an effort to increase 

the R.F. amplification. This will usually 

be found entirely practicable, bemuse of the 

greater stability of most receivers when permanently- 

tuned to a high wavelength. 

Turning back to the Pre -Selector, it will 

be found advisable to experiment a little 

with the switch, S\V2, and the regeneration 

control, in order to become familiar with 

their action and effect. Finally, adjust the 

small condenser C3 to bring the readings of 

the two tuning dials into line. 

Please 

New Admiralty Model 

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This great new Receiver is far in advance of competition. It is a 

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10 tubes used. Five 222 screen grid 

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Super -selective -10 lire. separation. 

Perfect quality of reproduction. 

Features 

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Removable R. F. Transformers for all 

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Simple to operate -only two major 

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A laboratory precision Instrument, built 

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Complete attractive illustrated literature sent upon request. Full 

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Write, telegraph or cable today. 

NORDEN- HAUCK, Inc., Engineers 

Marine Bldg., Philadelphia, Pa. 

Builders of the highest class radio apparatus in the world. 

Cable -Norhauck 

RESH MA 

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483 

RADIO SCHOOL 

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NEWS


464 Radio News for Nove,ulicr, 1928 

FANS: third big edition 

Don't 

MISS 

This 

Big 

Issue 

COMPILED BY THE STAFF OF 

RADIO 

NEWS Cdóóo 

Over 

150,000 

Copies 

Already 

Sold 

PUBLISHING CO 

4".." NEW YORK CITY 

Compiled by the Staff of RADIO NEWS 

Completely Revised-Up -to -the -Minute 

1001 RADIO QUESTIONS AND 

ANSWERS, the most sensational 

seller in the radio field, is now in its 

third new and revised edition. No one 

interested in radio should be without 

a copy. The staff of RADIO NEWS, 

the leading fan magazine, has striven to 

make 1001 RADIO QUESTIONS AND 

ANSWERS the foremost work of its 

kind available. There is a full and 

complete explanation of every worthwhile 

circuit that has appeared since 

the beginning of radio, not only the 

explanation, but also complete diagrams 

from which the set can be con- 

structed. Concise, authentic answers 

to every question that can possibly be 

asked concerning the many and varied 

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short -wave and broadcast bands. 

FANS! Don't hesitate! Get your copy 

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large magazine size 

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Please say you saw it in RADIO .\'TTVS


hadio News for .V ovcmbcr, 1928 

COUPLING ADJUSTMENT 

A final word regarding the adjustment 

of the automatic coupling arrangement may 

be required. 'l'he cam should be slipped 

over the rear of the condenser shaft, with 

the fiber can] toward the rear and with the 

fiat side uppermost. Now, with the con - 

denser plates all meshed, turn the cam until 

its toe is just level with the bottom side of 

the bakelite strip upon which the coil is 

mounted; then. tighten the set -screw in the 

collar on the cam. Next, loosen the setscrew 

in the brass pin on the lower rod of 

the coil carriage; let this pin slip along until 

it rests against the fiber cauu, and then 

tighten the set -screw. With these adjustments 

made, it will he found .that the primary 

coil moves as the condenser is rotated 

ant, when the condenser plates are entirely 

unmeshed, the pin should slide just to the 

point of the cans. This is the correct adjustment. 

In the event that there should he no reception 

when the Pre -Selector is first put 

into operation, and all connections and wiring 

are found to be correct, test the tube 

used in the oscillator socket, V2. The whole 

action of the Pre- Selector depends on the 

oscillator, and a poor or defective tube here 

will prevent proper reception 

APPARATUS. REQUIRED 

'l'he following is a complete list: 

One variable condenser, .00035-utf. (C1); 

One variable condenser, .00025-mf. (C2); 

One equalizer condenser, 2- 20 -uunf. (C3); 

One midget condenser, 50-mmf. (C4) ; 

One fixed condenser, .00025-mf., with grid - 

leak clips (C5) ; 

One fixed condenser, .0001 -mf. (C6); 

One by -pass condenser, 0.5 -mf. (C7); 

One antenna coupler, with provision for automatic 

coupling variation (L1); 

One R.P. transformer (L2); 

One R.F. choke coil, 85- millihenry (L3); 

One rheostat -switch, 50 -ohm (lt1-SW1); 

One volume -control potentiometer, 25,000 - 

ohm (112); 

One grid leak, 2- megohnl (R3) ; 

One aerial switch, single -pole double -throw 

(SW2) ; 

Two vacuum tubes, 199 -type (V1 and V2); 

Eight binding posts, push -type; 

Two vernier dials, illuminated -type; 

One front panel, 7 x 14 x 3/16 -inch; 

One binding -post strip, 1 x 10 x 3/16 -inch; 

One wooden baseboard, 13r /y x 7 x % -inch; 

Two angle brackets, 1 x %-inch; 

Two tube sockets, UN -type. 

Station 

Build 

Your 

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Pack 

Around 

the 

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THIS new Truvolt Divider 

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By dividing the filtered voltage into 

usable values, it eliminates all necessity 

of mathematical calculations in 

constructing a power pack. It does 

away with a great deal of wiring and 

the need of voltage regulator tubes. 

It makes it possible to build a power 

supply device which is universal in 

its application. 

board or sub -panel, or used as the 

front panel on a metal cabinet, at 

the same time providing binding posts 

for all "B" and "C" voltages. 

Price- $12.50 

Electrad Specializes in a Full Line of 

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ELECTRAD, INC. 

VA -il 

Dept. New York. N. T. 

St., N 

175 Varick copy of th' 

Please send me FREE my copy l and 

Electrad 

Truvolt 

Divider for Grien' 

on your mailing 

out 

Data and information. 

Case made of genuine bakelite, it will 

add a smart appearance to any unit. 

Five potentiometer type control 

..... 

knobs show values on a scale of high 

Address......... 

visibility. Can be mounted on base - 

.State 

City .............. 

Write for Free Circulars and Full Informa, 

E LECT RkQ 

Name ............. ..... 

., 

NEW YORK 

326 METERS - 920 KILOCYCLES 

and W2 %AL, 30.91 METERS 

is owned and operated by the 

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Our Editors will talk to you 

several tunes every week - 

See yourÌewspaper 

for details 

TUNE IN ON 

WRNY 

vLECHTNEin 

SUPERIOR CONDENSERS 

Best for power packs, power amplifiers, and 

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Complete Line from 250 to 3,000 Volts D. C. 

Trite for New Catalog 

A. M. FLECHTHEIM & CO., INC. 

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/'lease say you saw it in RADIO NEWS

486 

EwTone 

FOlk,OLD LIDIOS 

- with this Power Amplifier 

and "B" Supply 

Camera - like fidelity of reproduction - 

lowest notes clear and rich - music such 

as you thought your radio could never 

deliver! 

Three improvements -a new transformer 

principle, better use of the big 

power tubes, and stable plate and grid 

voltage supply - enable this unit to vastly 

better the tone quality of your present 

radio. 

Available in semi- completed form . . . 

requires but an hour or so to put into 

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works from lighting circuit ...coupon brings 

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R E M L E R 

Twin -Rotor 

CONDENSER 

For knife-edge tuning, use this famous 

twin -rotor Condenser. Specified in] circuits 

that demand extraordinary accuracy and 

efficiency. Price $5.00. 

REMLER 

D r u m 

D I A L 

Rigid, heavy construc- 

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illuminated. Drum 

fifteen inches in circumference. 

Removable calibration 

strips. 

Price $4.50 

Use the coupon befoul for full information 

on Remler Parts and Units. 

Remler Division. Gray A- Danielson aftg. Co. 

260 First Street. San Francisco, California. 

Gentlemen: Please send me: 

...Ml the "dope" on the Power Amplifier. 

...Bulletin service for professional set builders. 

Nance 

Address 

City 

Do you build and sell sets? 

State 

RN-11 

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4004 S. Figueroa, Los Angeles 

E.C.A. DRI -LINE 'A" Eliminator, 60 cycle. Ito V., output s 

Amiss, 6 V. No Battery- SILENT--$16.00; "8" Eliminators 

New Line R, 150 volt, 90 millamps, 4 tape, "C bias, with 280 

bulb. 310.00: Model KW, 180 volts, 60 mills.. 5 taps. 280 bulb. 

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one unit, 3 A., 6 V., "A" side.180 volta, 5 taps, 60 millampe. 

B: 4.5. 27, 40 V. , CT DRI -LINE type, complete, 820.60. 

2 amp. "Z" metal electrolytic charger. 86.50: 2 amp. DRI rectifier, 

screw base, 82.25. Underground Aerials -no lightning 

hazard, 3.3.00; Shield grid sets, parts. supplies. Dealers wanted 

Catalog 58. Above guaranteed 2 years, with 10 days' Vial 

Electra- Chemical Co. of America. Indianapolis, end. 

Facts About Transformers 


do not exist in the original signal, and naturally 

distortion will result. 

It can be seen that there are two opposing 

values which must be accounted for in 

designing a distortionless transformer. 'l'he 

first clanger is having too low a primary 

impedance, and the second having too high a 

secondary. capacity. There are several 

ways of reducing the impedance of the secondary 

winding so that a sufficiently large 

primary can be used. One of these methods 

is to use heavy insulation on the wire, 

and to space the layers of wire. This reduces 

the capacity of the winding. 

The lowest frequency to which a person's 

ears will respond is about twenty per 

second. The highest frequencies used in 

the average radio musical performance are 

about five thousand, although the harmonics 

and overtones reach frequencies higher 

than ten thousand per second. Broadcast 

stations . are limited, by law, to a maximum 

of five thousand cycles anyway. In 

order to give perfect reproduction, a transformer 

would have to respond to all of 

these frequencies. If only the second harmonic 

of the notes is reproduced, the tone 

will seem quite natural, since the higher 

harmonics do not appear to contribute 

very much to the naturalness of tone. 

CONSTRUCTION 

In the construction of transformers, the 

secondary winding is usually on the outside 

and the primary winding is placed 

next to the core of the secondary. 'l'he 

cores in practically all the iron -core transformers 

are made up of a number of thin 

sheets of transformer iron or steel. In an 

audio-frequency transformer, these laminations 

are usually very thin, and care is 

taken to insulate them from each other. 

The push -pull transformer is very much 

like the straight step -up type, except that 

the secondary is twice the size of the ordinary 

type and has a tap In the center, 

connected to the "C-" battery, which 

"biases" the grids of the push -pull power 

tubes. Similarly, the `B +" power lead is 

connected to a similar center -tap on the 

primary of the push -pull output transformer, 

or of the output impedance. 

The auto-transformer contains one long 

tapped winding, so that part of the winding 

comprises the primary while the complete 

coil is used as the secondary. The circuits 

of the three general types of transformers 

are shown in Fig. 6. 

The output transformer is used to prevent 

the direct current applied to the plate 

of the last tube from injuring the loudspeaker 

winding. It also has another important 

use in balancing the output resistance 

of the tube with the impedance of the 

loud speaker. In order to get the most 

undistorted output from a power tube and 

loudspeaker combination, the loud speaker 

should have the smile impedance as the 

plate circuit of the tube. The use of the 

transformer with the correct primary and 

secondary impedances will satisfactorily 

match these circuits when the tube and 

speaker do not match directly. 

It is necessary to use a transformer with 

a large core so that current in the plate 

circuit of the tube will not be sufficient to 

overload the iron magnetically, as explained 


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Ptease say you saw it in RADIO VEWS


487 

previously. In the straight output transformer, 

two windings are used; primary 

and secondary, in 1 -to-1 ratio. The priiuary 

is sometimes larger than the secondary, 

since the impedance of the tube is usually 

higher than that of the speaker. This is especially 

true of the electrodynamic speakers 

when a small actuating coil with a very 

low impedance is used. The push -pull output 

transformer is constructed like the 

lush -pull amplifying transformer; here the 

primary is tapped, so that the two tubes 

it the last stage may be coupled properly 

to the speaker. 

Smooth Power Dependent on 

Tube's Reserve 

I\ recent years g the trend in automobile 

design has been toward the use of engines 

having a greater number of cylinders 

and greater and smoother power. The 

fact that an engine can develop 75- horsepower 

or more or has the ability to drive 

a car at speeds in excess of eighty miles an 

hour is not the important consideration, because 

few car owners ever have need to 

drive their cars at such tremendous speeds. 

The important fact is that a car which 

has such reserve power is capable of much 

smoother action at speeds of 30, 40 and 50 

miles an hour than less powerful cars can 

hope to he at such speeds. 

In between the two extremes of the light 

car of small power and the big cars of tremendous 

power there are a number of cars 

of varying degrees of power and smooth 

running at different speeds. 

SMOOTHER PERFORMANCE 

'l'he same condition holds true in vacuum 

tubes. The maximum undistorted volume 

which can be obtained from a 201A -type 

tube in the last audio stage is comparatively 

very small. Better quality for any 

given volume can be obtained with a 112A 

tube. Still better quality for any given 

volume can be obtained by using a 171A 

tube with proper plate and grid voltages. 

If more undistorted volume is desired 

Than can be obtained with the tubes already 

mentioned, a 210 or a 250 tube may he used 

to provide undistorted reproduction at 

volumes which would overload the 201.1, 

112A or 171A tubes. 

In radio, as in everyday life, the same 

principle holds true-"Don't use a. midget 

for a man's size job." 

By- Passing the Grid -Bias 

Resistance 

many instances where a resistor is em- 

IN ployed for the purpose of obtaining "C" 

bias or "C" voltage from the "B" power 

unit, no by- passing condenser is employed. 

This is an important oversight, since audio - 

frequency currents must pass through this 

part of the tube circuit, with the resistor 

offering serious opposition to their flow because 

of its straight resistance, and, in the 

case of wire -wound resistors, the inductance 

or choke -coil effect as well. In fact, there 

is an appreciable loss of volume and tone 

quality in the absence of a by -pass. 

There will be an improvement in volume 

and tone when a by -pass condenser is 

shunted acróss any grid -bias resistor. This 

condenser should have a capacity of 1- or 

2 -mf., and may be of the low - voltage type. 

One with a rated operating value of 180 

volts is satisfactory. 

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489 

Radio Wrinkles 

(Continued from paye 455) 

the size of drill required. The mounting 

screw for which a hole is to be drilled is 

fitted into the various sample holes until the 

proper size is found; and then a drill which 

will fit this hole may be found by referring 

to the marking in front of the hole or by 

experiment.- Contributed by D. Goodenough, 

Richmond, Ind. 

A Neat Panel Light 

Easily Made 

ANS who have radio receivers using 

F 1. the old -type non -illuminated vernier 

dials are often faced with the problem of 

lighting the front panel of their sets. In 

this connection it should be pointed out that 

an inexpensive yet neat panel light may be 

made from a standard brass drawer -pull, a 

6-volt, 4- candle -power automobile lamp and 

a piece of sheet brass. 

The first step in the construction is to 

cut a mounting plate out of the piece of 

sheet brass; the mounting plate should have 

the same width as the drawer pull and 

should be about one inch high. 'l'hree holes 

must be drilled in the mounting plate; two 

have a diameter of 1/4 -inch and are located 

in the lower corners, so that they correspond 

to the holes in the drawer pull, and the third 

has a diameter of 11/16 -inch and is located 

in the center of the plate. Notches are 

filed on opposite sides of the large hole, to 

allow the pins of the lamp to pass through. 

Next, holes identical with those in the plate 

are drilled in the panel of the receiver; the 

mounting plate may be used as a template. 

ÇUNTING PLATE 

o 

AUTOMOBILE 

LAMP 

ANEL 

NOTCHES 

L/ o 

PANEL- LIGHT 

Fig. 7. This bit of hardware will be a teat 

addition to a home -made set which uses oldstyle 

plain dials. It will serte the purpose of 

illuminating the scale, as well as show that the 

set is turned on. 

After the holes described above have been 

drilled, the panel light may be assembled. 

First, the socket is slipped through the hole 

in the mounting plate and soldered in place, 

with the shell projecting through about 1/4- 

inch. The socket is slipped through the hole 

in the panel, and the lamp inserted in the 

socket. To complete the assembly, the 

drawer pull is placed in position and, together 

with the mounting plate, it is fastened 

to the panel with two machine-screws. 

The panel light may be connected in the 

filament circuit of the set so that it is controlled 

by the filament switch; thus making 

it serve as a pilot light as well as a panel 

light. If, after it has been placed in service, 

it does not provide sufficient illumination, 

the inside of the drawer pull should be 

painted with white enamel. -Contributed by 

George Harvey, Lebanon, Ind. 

OVe -. 

_ 

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The Eliminator received from you 

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Eliminator received from you year 

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Experimenter Publishing Co., 230 Fifth Avenue, N. Y. C. 


4038 LI

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BUILD YOUR OWN 

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1245 Jefferson Bldg. Peoria. III. 

Putting the Aerial in Shape 

(Contiluled frolla paye 437) 

paper. Cut a slot half-way clown the paper 

and then curve the uncut part in the center. 

Bend the two tabs up at right angles and 

push them up under clapboards or shingles; 

nail with a brad or two so that the guard 

will forni a roof over the lightning arrestor 

as shown. This will effectively keep water 

off the arrestor hut, if you are in doubt its 

to the latter's efficiency, buy a good one 

that is hermetically sealed. 

A squeaking or sticky pulley can be lubricated 

from the ground by tying a piece of 

oil -soaked rag to the halyard and then raising 

the rag to the pulley until the oil is 

squeezed into the wheel bearing. This is 

shown in Fig. G and is a simple remedy. 

A STRONG CONNECTION 

The proper way to keep the aerial and 

lead -in in one piece is shown in Fig. C. 

Pass a loop through the insulator and then 

twist this loop back over the aerial. A 

solid hitch is made, and one that will not 

chafe away the wire. The twist is shown 

in Fig. A, which illustrates the frayed condition 

of a halyard which should by all 

oceans be replaced with new rope. Such 

chafings are caused by too -tight pulleys, 

rough trees, rotting of the rope, and like 

causes. Put in new rope, all around, in 

the fall and you will not find the aerial 

lying in the snow some nice morning after 

the worst storm of winter. 

Remember that an efficient aerial must 

not sway, it must not leak its tiny power 

to the ground in any way, and it must have 

a sure metallic path of low resistance over 

its entire length. Give it an overhauling 

this fall, and your programs will not suffer 

from neglect later on. 

WRNY Television Programs 


At the receiving end the signals are 

tuned -in in the normal manner but, instead 

of being made to operate a loud speaker, 

are led after A.F. amplification to a neon - 

gas "glow-lamp" which is fixed behind a 

scanning disc identical in dimensions and 

arrangement of its holes to the- one employed 

at the transmitter. This disc also 

is rotated at the rate of 450 revolutions per 

minute. The glow tube produces a pinkish 

glow which varies in intensity in accordance 

with the electrical impulses fed it; just 

as a loud speaker produces sound in accordance 

with the variations of the current flowing 

through its windings. As the disc revolves, 

it allows the varying light of the 

glow lamp to pass through its holes, one 

at a tinge, with the result that a continuous 

series of 48 closely adjoining lines of light 

is, apparently all at once, visible to the 

onlooker. These lines are dark at each 

point corresponding to one where the scanning 

ray of light in the transmitter hits a 

dark spot on the subject, and light where 

the ray hits a light -colored spot. If the 

transmitting and receiving discs are in perfect 

step, or "synchronism," with the holes 

in the receiver flashing past the glow -lamp 

in exactly the same relative order that the 

holes in the transmitter flash past the arc 

light, a recognizable image of the subject's 

face and form will he visible apparently on 

the surface of the disc facing the plate of 

the glow -lamp. (See pages 428 -9.) 




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CORP RATION 

711 W. LAKE STREET, CHICAGO 



Publishing Co., 230 Fifth Ave., N. Y. C.



491 

A series of eight 48 -line images per second 

is built up, in the Pilot system. Although 

it has been generally thought that 

at least twelve are necessary to create the 

effect of "moving pictures," this slower rate 

produces the illusion very successfully. As 

long as the subject does not move back and 

forth too quickly, his movements are reproduced 

smoothly and with a barely perceptible 

jerk. The images certainly will. 

satisfy the radio experimenters, for whose - 

sole benefit the broadcasting is done. 

IMPROVEMENTS UNDER WAY 

As this issue of RADIO NEWS goes to press, 

Mr. Geloso has not quite finished his automatic 

synchronising system, so this will be 

described in the next number. 

Briefly, his arrangement involves the 

transmission of a single strong impulse, at 

the end of each rotation of the transmitter's 

scanning disc. In the receiver, this impulse 

will kick over a relay in the plate circuit of 

the last audio-amplifier tube and this relay, 

in turn, causes a magnetic device either to 

accelerate or to retard the receiver's scanning 

disc. With one stabilizing impulse every 

revolution, the disc will settle down to perfect 

synchronism with the transmitting disc; 

so that the received images will remain automatically 

"in frame." Without some such 

means of synchronization, and with only a 

variable -speed control on the scanning disc, 

the images have a tendency to wander out 

of view. For further discussion of receiver 

problems, see the article on page 422 of this 

number. 

' It must he understood that television today 

is only for the experimenter, who will 

find it more entrancing as a scientific hobby 

than radio broadcasting itself. Complete, 

foolproof television receivers for the public 

will not be ready for a long time but, meanwhile, 

the home experimenter can contribute 

as much to the art of television as he did to 

the art of broadcasting in the early days, 

from 1921 to 1924. 

The true television broadcasting being 

dune with the Pilot televisor, through 

WRNY and W2XAL, must he distinguished 

from the "radio movies" being transmitted 

by C. Francis Jenkins and also the "radio 

movies" recently demonstrated by the Westinghouse 

Company, described elsewhere in 

these pages. In the latter forms of broadcasting 

the pictures on a roll of motion - 

picture film are transmitted, not the images 

of a living person. Radio movies, however, 

offer also an extremely interesting field and, 

fortunately, the owner Of a 48 -hole television 

apparatus can reproduce the ,Jenkins 

pictures also. 

John Geloso, the chief engineer of the 

Pilot Electric Manufacturing Company, and 

the man responsible for the design, construction 

and successful operation of the 

Pilot -WRNY television apparatus, is only 

twenty -eight years old and has been in the 

United States only four years. He was born 

in South America, but has spent most of 

his life in Italy; is a graduate of the University 

of Genoa, where he studied electrical, 

mechanical and naval engineering and, 

before coming to the United States, he followed 

the profession of a naval engineer. 

Mr. Geloso has been with the Pilot company 

for the past three years; and five 

months ago he was assigned by Mr. I. Goldberg, 

president of the company, the staggering 

task of designing a practicable television 

transmitter that would stay within 

5,000 cycles. Within five [hays from the time 

Television- 

Jules Verne, in his famous "Twenty 

Thousand Leagues Under the Sea," 

written in 1870, accurately predicted 

television. Captain Nemo, the mysterious 

owner of the great submarine, 

had worked out the scientific application 

of seeing at a distance. 

Many years have passed since the 

novelist's prophesy. All that time 

scientists and inventors have been 

striving to make television a reality. 

Every now and then for the last two or 

three years you have probably met 

some one who had a friend who had 

witnessed television. Somehow or other 

you never saw the witness himself. 

The information was always secondhand. 

Now we have advanced. Television is 

being accomplished. You may have 

At First Hand 

seen it yourself and experienced the 

tremendous thrill which comes from 

seeing a weaving pattern of luminous 

spots of light shift and whirl, then suddenly, 

as the revolving disk reaches the 

proper speed, resolve themselves into a 

clearly defined moving image which can 

be recognized by everyone. This modern 

miracle makes you think of nothing 

so much as a great Genie of the Arabian 

Nights forming itself out of a cloud of 

smoke from a jar, just opened. 

First -hand television is here and 

available to all. 

National Company, Inc., has developed 

new and better equipment for the construction 

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audio amplifiers of the type required 

for successful, experimental television 

reception. Write today for Bulletin 

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he obtained suitable photoelectric cells, he 

had a complete transmitter and test receiver 

working in the Pilot laboratories in Brooklyn 

and, the first time he turned the apparatus 

on, a crude but recognizable image 

appeared in the receiver. 

With a regular television service now under 

way at WRNY, Mr. Geloso is perfecting 

numerous details of the system, such as 

automatic synchronization, proper coñtrol 

and mixing of the outputs of the photoelectric 

cells, the design of a small motor 

for the receiving disc, etc. Further news 

of his accomplishments will be published in 

forthcoming numbers of RADIO NEWS. 

Reception of the Jenkins 

"Radio Movies" 

(Continued front page 420) 

SIMPLE SYNCHRONISING DEVICE 

A very simple and practicable method of 

adjusting the speed of the scanning disc of 

a television receiver is suggested by the 

Jenkins Laboratories in a recent bulletin 

which they have issued to radio experimenters. 

The idea is to support the disc 

on any suitable set of bearings, and to drive 

it by the friction of a small wheel (attached 

to the shaft of a motor) pressed against its 

surface. By varying the distance between 

the friction wheel and the center of the 

disc, the experimenter can find a setting at 

which the disc turns at exactly the same rate 

of speed as the transmitting disc. At different 

positions on the radius of the disc, 

the circumference of the friction wheel 

bears different "reduction- ratios" to the circle 

of active contact; so, naturally, it drives 

the disc at different speeds. (See page 420.) 

In this arrangement, the driving motor 

should be run at its natural speed, without 

being 'controlled externally by a rheostat. 

Once the correct position has been found, 

the motor should be clamped in place, or at 

least the position noted accurately so that 

the proper setting can be made quickly. 

Using a 48 -hole disc, a television experimenter 

can find two positions of the motor, 

for 900 and 450 revolutions per minute (the 

former will be at half the distance from the 

center, except for slippage), and then will 

be able to receive either the Jenkins or the 

WRNY broadcasts, respectively, without 

other change. This scheme is considerably 

cheaper and more flexible than one involving 

the use of gears, which require accurate 

mounting and alignment. 

If you already have a scanning disc 

mounted on a motor, use the latter merely 

as a support for the disc and drive the disc 

itself with another small motor of 1/20- or 

1 /16- horsepower, say. A suitable mechanical 

arrangement of all the parts used in a 

complete television receiver is shown in the 

illustration on page 420. The details are 

all obvious; the actual dimensions of the 

wooden members supporting the motors and 

the glow lamp will depend, of course, on the 

particular apparatus the individual experimenter 

has on hand. 

CAREFUL ADJUSTMENT DESIRABLE 

The friction wheel may be made of two 

discs of rubber cut from an old inner tube; 

they should be about DA or 3 inches in 

diameter, and will work best if clamped between 

two brass or fron flanges, one of 

which fits over the motor shaft. The flanges 


CARE SHOULD BE 

TAKEN 

IN CHOOSING 

LOUD SPEAKER 

Acoustic Engineers Recommend 

Use of Book by Well -known 

Authority for Instruction 

"The necessity for care in choosing a loud 

speaker cannot be over -estimated," say 

acoustic engineers. A radio is but the vehicle 

used to bring in broadcast entertainment, the 

true reproduction of sound depends almost 

entirely on the speaker. It follows, if the 

loud speaker does not meet the requirements 

of the receiver, reception will not be at 

maximum. Consequently the entertainment 

of the listener -in is often unwittingly spoiled 

by failure to recognize the importance of a 

good speaker in getting maximum results 

from his set. 

Education of the public in speaker con -, 

struction and design is necessary according to 

these experts. They recommend "HOW TO 

BUILD MODERN LOUD SPEAKERS," 

written by Clyde J. Fitch, as being the most 

efficient source from which this information 

may be obtained. The book is written in a 

style that is not only tremendously interesting 

but also decidedly easy to read. "HOW TO 

BUILD MODERN LOUD SPEAKERS" is 

the most complete treatise of its kind avail- 

able. 

It thoroughly explains every known 

type of speaker and gives full instructions for 

building. It is well to remember that if the 

proper speaker is not used the enthusiast 

leaves himself open to all manner of distorted 

reception. Crackling noises, fryings, whistles 

and squeals -these disturbances, often laid 

to the set, can in reality usually be traced to 

the speaker. Also the fact that a speaker 

works well with one set and not with another 

is no reason to lay faulty reception to the set. 

"So," the experts point out, "you must understand 

the speaker if you are to receive the 

maximum results from your receiver." 

"HOW TO BUILD MODERN LOUD 

SPEAKERS," by Clyde J. Fitch, is not only 

the best source from which to obtain this 

essential information, but also probably the 

cheapest. Complete, dependable data on 

every speaker known in radio -full instructions 

for building. All this for only twenty - 

five cents, the price per copy of "HOW TO 

BUILD AIODERN LOUD SPEAKERS," 

by Clyde J. Fitch. Mail this coupon to 

Consrad Company, Inc. 230 Fifth Avenue, 


CONSRAD COMPANY, INC., 


Gentlemen: 

Enclosed find twenty -five cents. for which please send 

me a copy of "How to Build Modern Loud Speakers," 

by Clyde J. Fitch. 

Name 

Address 

City 

Please say you saw it in RADIO VEII'S 

State


. Stat' 

Radio. News for November, 1928 

should be only about one inch smaller in 

diameter than the rubber discs, in order to 

prevent the edges of the latter from folding 

over when they are pressed against the 

scanning disc. 

It will pay the experimenter to have these 

flanges turned out for him by the local machinist, 

or by the garage man if he has a 

lathe; they will cost only a dollar or so, and 

will be well worth their price. Unless these 

flanges fit the driving motor's shaft 

smoothly, the rubber discs will wobble and 

will make the scanning disc wobble also. 

Use any small induction or synchronous 

motor that is obtainable. Universal motors 

which spark excessively at the commutator 

should be avoided; as this sparking will affect 

the neon -gas glow -tube and cause spots 

to appear in the images. However, this interference 

can generally be eliminated by a 

pair of ordinary 0.5- or 0.1 -mf. by -pass condensers 

connected in series, and across the 

motor brushes, with the center connection 

of the condensers going to the ground lead 

of the radio set. 

Naturally, the only way to determine the 

proper position for the driving motor is to 

tune in the television or "radio- movie" signals 

from WRNY- W2XAL, or from 3XK 

(the Jenkins station on 46.1" meters), and to 

turn the adjusting screw shown in the diagrams 

until the images appear. A little 

patience is required for this adjustment; 

if you do not obtain pictures on the first 

trial, try again. 

On the Short Waves 


SHORT WAVES AND BROADCAST 

LISTENERS 


The letter entitled "Short-Wave Reception on a 

Standard Ultradyne" in Raoul NEWS for September 

(page 254) deals with a matter that is surely 

not new to anyone who has ever operated a super - 

het within a few miles of an amateur transmitter. 

The fact that most any superhet (and particularly 

the Ultradyne) has this failing is never mentioned 

in the "how -to- build" articles, probably due to the 

commercial slant of these articles. In many instances 

the publishers seem to deliberately connive 

with the advertisers to "work" the reader by failing 

to tell the whole story. However, the tendency of 

the Ultradyne to suffer from its own oscillator 

harmonics was mentioned in Q.S.T. at least three 

years ago. 

With my own superhet (just the ordinary nameless 

standard variety) I found some time ago that 

it was the third or fourth oscillator harmonic that 

was heterodyning the short -wave signal to the frequency 

of the intermediate transformers: and thus 

permitting the short -wave signals to "come 

through" on broadcast settings of the oscillator 

dial. Practically every superhet owner in this vicinity 

has the same complaint. 

There are a number of methods of partially overcoming 

the difficulty: 

(1) Suppressing the undesired S.W. signal in the 

loop by mounting a tunable absorption Circuit on 

the loop frame. (Who ever heard of a real 

superhet that required more than a loop for coast - 

to -coast reception ?) 

(2) Suppressing the undesired oscillator harmonic 

by surrounding the pick -up coil with a tunable 

absorption circuit. 

(3) Suppressing the S.W. interference at its 

source by applying the homeopathic treatment ( "like 

cures like ") to the amateur operator who persists 

ill going on the air before 11 p. m. or a Sunday 

afternoon while the rest of the city is enjoying the 

broadcast programs. Most anyone past the radio 

kindergarten "knows how." 

Only "one-way" communication soon sends the 

troublesome operator to bed and permits the rest 

of the city to again turn on their receivers. 

even simpler way is to make friends with the family 

next door to the "source" and arrange with 

them to turn on the vacuum sweeper upon phoned 

request. If they own a receiving set the phone 

call is unnecessary. 

(4) It has been claimed that reducing the oscil- 

P(ea.te 

An 

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lator plate voltage will reduce the intensity of the 

harmonics, but it has been the writer's experience 

that the fundamental is reduced in the same proportion. 

(5) The shorter the wavelength of the intermediates, 

the less the likelihood of annoyance from 

short -wave stations. This is a strong point in favor 

of the "neutrohet" recently described in RADIO 

NEWS, the description of which was indeed a genuine 

"how-to- build" article -an article written for 

the benefit of the reader rather than the advertiser. 

W. J. IC., Salina, Kansas. 

(The above calls for comment. The short waves 

are now being drawn upon by not only the amateurs, 

for whor the writer of the above "has it in." 

but also governments, commercial radio services, 

public utilities, broadcasters, televisors, and others. 

The high frequencies will be used at all hours of 

the day and night, extensively; the entire waverange, 

from the highest to the lowest, will be 

tilled. The broadcast listener must therefore soot 

be prepared to obtain a set which will twee exclusively 

to one tcavcrange, not merely one channel 

in each range: for the ether will be full of harmonics 

as well as harmonics. .4s for the amateur, 

the law which requires him to keep within 

his own definitely, and now more narrowly limited 

channels, also forbids and provides penalties 

for the creation of intentionl interference in the 

manner prescribed as his third recommendation by 

our correspondent. Our advice is, DON'T! - 

EDITOR.) 

NO SHOCK AT ALL -IT'S JUST LUCK 


I have built the "Junk Box" receiver described 

in RADIO NEWS for July (Blueprint No. 58) and 

this is to prepare you for a shock. The set was 

built as described about three weeks ago and is 

used very night with an adapter plugged into a 

two -stage amplifier. I get practically all the shortwave 

stations using phone and code. But every 

program is clear of static. I have tested the set 

during thunderstorms; and music, speech or code 

came through without the crashes usually heard 

from lightning. I want to know if this is usual 

or unusual for a short -wave set. 

This is a pretty broad statement. I expected 

less static on short waves; but cannot understand 

why I get none -not even lightning. 

L. E. PLATT. 

(Short waves are usually freer from static than 

the longer ones; wherefore the growing demand 

for short -soave stations and apparatus, especially 

in the tropics, where static was invented. Except 

for local disturbances, therefore, there is less static; 

but our correspondent i.s highly favored if he hears 

Mont at all. He fails to state what his antenna 

system is.- EDITOR.) 

A SHORT -WAVE SET WITH 

LARGE CAPACITY 


Enclosed find a diagram of the short -wave set 

I have constructed which I find to be quite efficient, 

'and has some new pointers. First, I use 

as a regeneration control, a resistance of 200 ohms 

to 30 megohms. This will have to be of the 

non -microphonic type and also be noiseless over 

the entire tuning range. The one used in my 

set was manufactured by the Pilot Electric corn- 

The hook -up of .)Jr. D'.4ngelo's set. A fixed 

regeneration condenser is employed, with a 

variable resistor as a control. 

pany. Second: Instead of the usual 7 -plate tuning 

condenser, a 23 -plate De Jur straight-line condenser 

of .00035 capacity was used. This gives 

me good volume with oscillations over the whole 

dial at all wavelengths, with little hand capacity. 

Third: Although my aerial wire is well over 200 

feet, no condenser is in series with it. 

The following are specifications of the parts 


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used: LI, antenna coil, 8 turns of No. 18 D.C.C., 

space -wound '' -inch apart, on 4 -inch tube for all 

wavelengths. Up to 50 meters, grid windings, 3 

turns of No. 28 wire on is-inch tube. Tickler coil 

same as above, wound directly over the other. 

From 50 meters on, 9 turns of No. 20 wire 

spaced 1/16 inch apart for secondary, and 8 turns 

for tickler on a 3 -inch tube; 

Cl, .00035 -mf, condenser; 

C2, (This must be accurate); 

C3, .0002-mf.; 

C4, .0001-mf.; 

Rl, from 200 ohms to 30 megohms; 

R2, 6 megohms; 

L2, 140 turns of No. 26 wire on a 1 -inch tube, 

4 inches long. 

67 volts on the plate will be needed for wavelengths 

up to 50 meters, Beyond that 22 volts 

will be required for the correct operation of the 

set. The tube is the usual 201- \. 

The following stations have arrived regularly: 

2NAL, 2XAD, 2XAF, 2XE, WI.W. KDKA, 

WHAM, CITY, 5S \Y, PCJJ, 3XL. and numerous 

others. Harmonics of \\'A.\T, WIIN and \CTFF 

and others were heard. Amateurs in Montreal, 

St. Louis and California were also logged. 

I would like to hear from builders of this set, 

and hope this information will be of interest to 

your readers. 

EUGENIO DAwGELO. 

69 -71 Dundas St. WP., Toronto, Ontario, Canada. 

THESE FUNNY WAVES 


Many thanks for blueprint No. 58, for the 

"Junk Box." I have just completed the set and 

given it a few days' tryout. Following are the 

results to date: 

2XE, good; very clear. 

5SW, at times very clear, but much troubled 

with body capacity. Better at 7 than at 5 p. m. 

"Big Ben" comes in fine at 7. 

2XAL, not so good. Music difficult to follow. 

Much distortion -still, many- thanks for an an- 

nouncer who announces the station often. At least 

one gets a chance to locate the station if he misses 

the letters, with the sentence which follows: 

"RADIO NEWS station, located at the Roosevelt 

Hotel." 

2XAF, heard once, when everything said and 

done was very clear. 

KDKA, at 42.95 meters, better reception than 

on lower channel. 

MAN' cernes in very clear. 

Besides these stations, I have heard, although 

very indistinctly, the gym classes between II and 

12 a. m. of WMCA; also a religious service from 

(I believe) WAAM. The singing was so dreadful 

that I tuned out without attempting to get the 

call letters. Now, this morning. I heard a band 

playing (very fuzzy) about \V LW's wavelength. 

Is it possible that these were the harmonics of 

W5113Q, Brooklyn, as the call sounded like these 

letters? (It is quite possible to get a harmonic, 

say the fourth, of a broadcast station in this 

manner; in the station's immediate field, harmonics 

as high as the thirteenth or fourteenth may be 

detected. The oddity of short -wave reception is 

thus indicated; our correspondent, living just across 

the city line of New York. gets London easily, Pittsburgh 

and Cincinnati clearly, Schenectady with 

difficulty, and New York City stations hardly at all. 

.I fern miles closer, he would be in their inductive 

field; and a few miles further away, he would 

probably be unable to net them at all. The quality, 

also, of the ground wave is undoubtedly affected 

by numerous reflections at short distances in the 

city.) 

I have not as yet succeeded in getting a squeal 

from the largest coil, No. 5. I propose rewinding. 

I have two aerials, one outdoors, and one indoors, 

strung under the room. Reception seems about 

the same with both; but by disconnecting the 

ground wire last night, while listening to WL\C, 

reception was improved very much, and static and 

hum notably diminished. 

I built this "Junk Box" set after working long 

with the hook -up which appeared in RADIO Neuts 

last October. With that I got PCJJ once at 

2 a. m.; the rest of the stations, when I could 

make them out, were very poor. I have certainly 

got better results with the "Junk Box." Once 

again, many thanks for the hook-up and blueprints. 

I trust you will give us more short -wave data. Perhaps 

your expert could give us a few tips as to 

how to get rid of howls and body capacity in the 

"Junk Box." 

O. STANLEY 1IEATON, 

Bandmaster, Leake & 

Watts Home School, 

Yonkers, X. 1-. 

(The best way to reduce body capacity in this 

set is to use extension handles on the condenser 

dials. Howling is usually a matter to be regulated 

by better tuning: EDITOR.) 

Please 

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CIRCUIT. The Electrophonic employs an 8 -tube circuit; three stages direct tuned . 

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SHIELDING. The Electrophonic is totally shielded. Complete inter -stage shielding 

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SOME DO NOT 

Editor, RADIO News: 

To the many thousands of short -wave set builders 

who have been as unsuccessful in logging far 

distant foreign stations as I have, I would like to 

give a "handshake." These boys need more encouragement 

than the successful ones do praise. 

I, for one, have built every short -wave receiver 

that has appeared in RADIO NEWS, as well as 

others. For six months I plugged faithfully away, 

never' "getting beyend New York, hearing 2XAD, 

2XAF, \VGY, once in a while WLW and \VABC. 

The "R.F. Short-Wave Receiver" was built, 

which was the best one for volume and quality of 

reception. The radio frequency was not successful 

for me; this was removed and a B -T detector 

unit mounted. This was a great improvement, 

but still no foreign station. 

I have corresponded with several short -wave 

set builders and have tried their suggestions -but 

to no success. For the amount of blueprints distributed 

by the RADIO NEWS, the number of successful 

"foreign getters" must be very few in 

comparison. 

I have spent several hundred dollars, at least 

three hundred dollars, and still I have lots to 

learn and receive. I eventually drove a fifteen - 

foot pipe in the ground and by using the ground 

for an aerial and no ground, I have been able to 

tune in every Friday night PCJJ, which is barely 

audible in the p!lones. Occasionally it can be 

heard in the loud speaker. One evening, between 

6:30 and 7.30 E. S. T., I picked up a foreign 

station on the phones that sounded like German. 

This was on about twenty meters. One afternoon 

at two I .picked up a phone conversation in Italian 

at about 17 meters. 

This is the limit too my success. \VGY and 

KDKA come in with enough volume to be heard 

a block away -but no foreign station calls at my 

house. 

I have just completed another set in the past 

two days, using a CX -322, screen -grid tube as a 

radio frequency amplifier. Last night was the first 

time I ever heard PCJJ on the loud speaker with 

sufficient volume that I did not have to strain every 

nerve. On the phones it was very fine. 

A local short-wave expert is now worl:ing on 

my set to eliminate body capacity. He has a set 

such that you can put your hand on the coils, tubes 

or inside of the coils and no body capacity is present 

nor does it reduce the volume. He uses three 

tubes and gives more volume than the R.F. receiver 

with push -pull amplification, day or night. 

By the elimination of the body- capacity effect he 

increases his volume more than double. 

Let's hear from some of the "failures" in the 

short -wave field as I have been. Perhaps some of 

the other boys can help them out. It is very disheartening 

to some I know and I would like to 

see these boys get a little recognition, for it is 

one of the most interesting fields of the radio and 

some may give ttp. 

Thanking you for this opportunity, I am, 

J. \V. MANNING, 

Daytona Beach, Florida. 

(There are differences between short-wave operation 

and broadcast methods, and RADIO NEWS will 

deal with them in a series of articles. It mutt 

be remembered that the distant short -wave stations 

have generally very small power, and that the 

energy received is very feeble in comparison with 

that in comparison from American broadcast stations. 

This necessitates great sensitivity in the 

short -suave receivers, whose res,nance point is very 

narrow; and it is therefore very easy to pass over 

a short -wave phone station many times if the ex- 

act adjustment is not tried. Slow, patient tuning 

is needful. It will be noted that there is nothing 

wrong with Mr. 3fanning's receiver. -EDITOR.) 

BYRD EXPEDITION CALLS 

Commander Byrd's ship, the City of New York, 

which sailed a few days ago for the Antarctic, has 

been assigned the call \VFBT, while its auxiliary 

portable transmitter is WFA. Smaller portables are 

KFK, 50 watts, WFD, 50 watts, and \VFE, 7% 

watts. The airplane Fairchild has the call WFS 

and the Floyd Bennett WFB. 

In addition to the ship frequencies between 600 

and 800 meters, the Byrd expedition may use these 

short waves: 91.2, 68.1, 53.57 (commercial), 53.10, 

45.59, 34.05, 26.78 (comm.), 26.55, 22.75, 17.945, 

17.857 (comm.) and 13.758 meters. 

OFFICIAL CORRECTION 

The Department of Commerce announces two 

corrections of the published list of new international 

call letter prefixes: CA is Chile and 

HR Honduras. Canadian amateurs will not use , 

CF for the present, but only VE. 

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"JUNK-BOX" SET BUILDERS 


1 am using 199s in the "Junk-Box," and I find 

them a poor type for short waves. Larger ticklers 

are required, "B" voltages are more critical, and 

what -not. However, I am not kicking; the set itself 

is great. 

1í1)R:\ and \VGV cone in around noon 

without an aerial. I have also logged WLW, 

K \VKII and 'WEIR:, Chicago; the latter two apparently 

harmonics. I would be grateful for any 

information on this. 

I am using 45 volts on the detector and 67% 

on the amplifier; a 5- megohm grid leak works best. 

I find also that a .00025 -mf. fixed condenser across 

the filament terminals of the coil socket helps with 

some of the coils. Body capacity is bad, but I 

have on the condensers small shields which lessen 

it somewhat. 

BERT VOGEL, 

1541 White Street, Dubuque, Iowa. 

I have made a few changes in the "Junk-Box" 

set which might be of interest to others who are 

building this circuit. I made a plug -in adapter 

for my present three -circuit tuner, in order to use 

my two -stage amplifier without rewiring. I found 

that, in doing this, I used the tickler coil of my 

three -circuit tuner as a radio -frequency choke, and 

it works O.K. - I also picked up an old neutralizing 

condenser and put it in the aerial circuit. 

didn't happen to have the .000032 condensers, so I 

used .000025s and they Work O.K. with the coil 

specifications. It works better than I ever had 

hopes for. 

WARREN B. BARNES, 

1532 Lincoln St., Hillsboro, Oregon. 

I am a "kid" fourteen years old, and a constructor 

of the "Junk- Box." When I first constructed 

it, I found that my leads were too long 

and the set would start to oscillate with a groan. 

I rebuilt it, and as the howling at the beginning of 

oscillation was still present, 1 put a .002-mf. fixed 

condenser across the "A +" and the "B+ Amp." 

Finding that the condition was not entirely- remedied, 

I took the wire off the ticklers, turn by turn, 

anti found that the following specifications are best 

for my set: ticklers, 6, 7, 9 and 16 turns, respectively, 

for coils 1, 2, 3 and 4. To date I have 

received WGV end KDKA on the speaker, and 

2X.\L, 2XE and WLW on the phones; I have 

received code stations as far as the Pacific coast. 

Being a DX hound, however, I am greatly interested 

in transatlantic reception. I would like 

to communicate with makers of this set who have 

had the thrills of transoceanic reception and ]earn 

of some details of their sets, such as shielding, 

antenna construction, etc.; and also with constructors 

interested in the Browning -Drake receiver 

and boosters for it. I will try to answer as many 

letters as I can. 

CHESTER TUCHOLSxI, 

1012 Bremen St., Milwaukee, Wis. 

CORRESPONDENTS WANTED 

Editor, 'RADIO NEWS: 

Our radio club desires correspondence with boys 

between the ages of 13 and 19 who are interested 

in DX work on both short and broadcast waves. 

We will answer every letter. 

LELAND J. GILLETTE, 

President, Midwest Amateur Radio League, 

7263 Coles Ave., Chicago, Ill. 

I would be grateful if I could correspond with 

some young short -wave ham in Switzerland; or 

some man of experience who would take interest 

in a boy. 

WAYNE. D. DUNN, 

1044 F .4ve., Nevada, Iowa. 

I would like to communicate with anyone who 

is interested in short waves. 

WILLIAM BUDINGTON, 

95$ State St., Springfield, Mass. 

The following will be of interest to all shortwave 

listeners. The transmitter of 3LO, Melbourne, 

Australia, is using 5,000 watts on 32 

meters every Sunday from 1530 to 2030 G.M.T. 

(1:30 to 3:30 p. m., E.S.T.). ANIL, Mt. Malabar, 

Java, 17 meters. has 40 kw. power. 9 amperes 

in antenna. :\NE, Bandoeng, Java. 15.93 meters, 

has 7 kw.; S amperes in antenna. Announcements 

of these stations arc made in Dutch, English, 

French and German. 

I world like to correspond with short -wave enthusiasts 

in foreign countries. 

WRAY GILLETTE, 

923 IP. Anderson Are., Ft. lIycrs, Fla. 

Please 

e 

THIS shows a medium power crystal controlled 

transmitter using UX2I0 crystal controlled tube 

feeding a UV203 -A power amplifier. Filament 

and plate voltages are to be obtained from Item 34, 

ope ting (rom either DC or AC house mains. The v Inge to the lamen, 

of the tubes is variable, either by the field recitan in the filament generator 

circuit [not shown] or by the resistance in the filament circuit of the UX210 

tube. Keying is done in the bias circuit of the 203 -A power ampli er. As 

the amplifier is NOT neutralized, the power amplifier must work on some 

harmonic of the crystal tube [preferably the second], for all operations in the 

20, 40 or 80 meter bands. A crystal having a fundamental of 160 met n will 

allow operation in all bands with best output in the 80 meter one An 80 

meter crystal is best for 40 meter operation and in like manner the 40 meter 

crystal would be best for 20 meter operation. Forty meter crystals arc hard to 

MnM 

get and blow up easily, so for 20 meten the 80 meter crystal is used again Both 

tubes obtain plate supply from the plate end of Item 34. the UX210 being sup. 

plied with not over 350 volts through resistente R. and the 203 -A taking the 

full 1000 volts 

ELECTRIC SPECIALTY COMPANY 

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WESTERN RADIO MFG. CO. 

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Ideal for use with Dynamic Speakers) 

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The UX -210 super 

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s a 4 v o lt san' it in RADIO NEWS


` Ç Radio News for November, 1928 

.`... 

The Radio Constructor 

f 

Build a 


Daven Television 

BETTER USE PHONES 


Receiver 

I made the Loveless antenna exactly as directed, 

Cn1111,1ete Essential Kit, $60.00 

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Complete Stages of Daven Television 

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Daven Television Receiver, Complete, 

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Damn Tele. Amp. T -3 

Daven Spec. Telev. Amp. T -4 for t Hi Mu Tubes and 

z power Tubes 171, rio, z5o Types 

Daven Telev. Neon Lamp, zo to So Milliamperes 

Stricking Voltage too Plate 1 jdj'n 

Daven Telev. Motor 

Daven Bushing to fit X', 54 and W. Motor Shafts 

Daven for 48 Aperture disc 

Daven Rheostat 

Daven Telev. Photo Elect. Cell 1' Bulb 

Daven Telev. Photo Elect. Cell 3' Bulb 

Daven Television Couplers. 

at Stage No. 4ux D -4zrax 

Ind Stage No. Ozu Doux 

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Glastors are used for Grid and Plate resistors 

1x Super Davohms in Plate and Glastors in Grid 

Daven AC 71 for output tubes in series with Television 

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Daven AC to (for brighter illumination).. 

Daven Mu to Hi Mu Tubes for Amp. Stages 

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Publishing Co., 230 Fifth Ave., N.Y. C. 

Please 

ceived was dead silence. I reversed the connections 

to see what would happen, and again received 

nothing, 

I threw off the ground connection of coil, and 

immediately received very weak locals. Catching 

hold of the ground and of the aerial, I found 

a great increase in the strength of signals if I 

squeezed the end; signals weakened if I merely 

touched the end. I tried this with an old two - 

tube Crosley connected to a three -tube Sonatron 

amplifier. I received WOR, WENR and KFI, 

stations I never had before. 

I took the antenna upstairs and connected it to a 

three -tube Bremer -Tully hook -up, and the result 

was again dead silence. Back to the basement, and 

the stations mentioned were again heard with the 

Crosley. 

I then tried the Loveless antenna in connection 

with a Freshman lamp- socket aerial at the "ground" 

end, and succeeded in rousing the whole house with 

\\-h:NR's new transmission. 

That ended the experiments, for wrathful noises 

began to emanate from the upper regions; my wife, 

who calls herself a radio widow, began a series of 

interferences with home -made static which sounded 

like: "Fancy having that going at 2:30 in the morning 

like a locomotive!" 

JAMES HATTON, 

107 Ennerdale Road, Fairbank, Toronto, Can. 

(Even discoverers must have some consideration 

for the neighbors. The latter occasionally need 

sleep. As to the Loveless antenna, variations in 

the resistance of the ground connection, as well as 

in the inductance and capacity of the device, are 

apt to produce very different results for different 

experimenters. However, like Mr. Hatton, they 

may get lots of faun trying. We suggest a test 

with a variable condenser across the two open ends 

of the windings.) 

I\NQ UIRIES for information not given 

here should be sent to the constructor 

direct; but he should NOT be asked to 

furnish data already published, here or 

elsewhere, or for instructions that an experienced 

builder should not need. 

This department is for free discussion to 

the extent that space permits; but RADIO 

NEws accepts no responsibility for the 

opinions of readers as to the relative merits 

of apparatus and circuits. 

A HALF -GALLON ANTENNA 


The article on Mr. Loveless' aerial caught my 

eye, and I had to have one like it. Instead of 

getting a large tube, I used two -quart Sealright 

containers and some No. 26 D.S.C. wire. I wound 

225 feet of wire on each of the tubes, both of 

which are 7 inches high. The outer is 354 inches 

in diameter; the inner was slit and lapped to reduce 

it to 3 inches. 

I have a six -tube T.R.F. set and a five -tube 

Freed - Eiseman and have had fine results on both; 

but lately radio reception here has been rotten and 

static awful. With the aerial as described on the 

T.R.P. I logged \VEAF, WJZ, WOW, WRR, 

KTHS, several Chicago and Cincinnati stations, 

Mexico City and Havana. The last two are almost 

impossible on an outside aerial in the summer 

here. When I connected the coils to my outside 

aerial, my volume increased fifty per cent. 

At present I am winding 300 feet of No. 26 

D.S.C. on the pint -size Sealright cartons, and will 

see what they will do. I have a 200 -foot outside 

aerial. It is 45 feet up at the lead -in, runs north 

and south 100 feet and then west to an oak tree, 

where it is about 90 feet high. In the winter I 

get wonderful results. I have also a sub aerial 

which I use during storms. 

I am anxious to see what can be done with shortwave 

reception on these coils, but will have to wait 

until my set is built. I.intend to experiment further 

with the coil antenna. 

J. M. FRANCIS, 

1507 Thirteenth St., Tuscaloosa, Alabama. 

(Simultaneously with the above, there arrived 

letters from other readers who had no success, and 

were inclined to be skeptical about the whole matter. 

The uncertainty about any radio circuit is, 

at least 90 %, in its aerial and ground circuit; 

there is no universal prescription applicable everywhere. 

One man will get excellent results with a 

certain peculiar antenna; another none. In one 

say you saw it in RADIO NEWS 

\ \ it;ll,' / % ' 

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The results from this very novel and simple unit 

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builder of Radio sets should have a few on hand. 

LISTENING THROUGH WALLS 

This Unit makes a highly sensitive detectaphone, 

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CONDUCTING' SOUND THROUGH 

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Make yourself a 

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12 -PAGE INSTRUCTION BOOKLET 

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PRESS GUILD INC. 

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14 -18 -R-East 30th St., Ness York, N. Y. 

Please mall me at once as many of the following items 

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..Sklndervlken Transmitter Units at 95c. for 1; 51.75 

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Items specified plus postage. 

Name 

Address.. . 

City 

State 

Please 

place a listener with two tubas will get .4 nstralia 

and England; in another it cannot to done with 

the best ten -nrbc hook-up. These are matters still 

in the realm of experiment.- Eoiroc.) 

A SMALL TUBE GETS RESULTS 

Editor. RADIO Nrws: 

I trier! out a small edition of Mr. Loveless' 

aerial. I simply wound a hard- rubber tube 3 

inches in diameter and 7 inches long full of loop - 

aerial wire, and another tube a little smaller full 

of the same, and put it on my 5 -tube set for an 

experiment. 

It brought in local stations 100% better, with 

slight loss of volume and a change of about 7 

points lower on the left -hand dial. When I tuned 

for DX, I brought in WSM, which I couldn't get 

on my regular aerial, but threw the left dial so 

far off (about 13 points above 45 on the dial, and 

from 7 to 10 points below this) that I didn't like 

it. So I just hooked both leads to the ".\er" post 

and found it to work much better on all stations 

than my outside aerial. With this connection I 

brought in approximately twenty -five stations on 

August 11th, including some I couldn't get any 

other way. Then I put it on the short -wave 

"Junk -Box" receiver and it worked better; so I 

left it on. I couldn't get anything without the 

ground. Do you suppose an "A and B" power 

unit would cause such a change in the settings.since 

the eliminator is grounded ? My groceryman is 

making a regulation Loveless aerial, so I'll try 

it out. 

I am pleased with the "Junk-Box," and if I 

had used best -grade parts, perhaps I would get foreign 

stations also: but being next to an ice -cream 

factory probably affects DX. I get 2XE and WLW 

regularly; but KDKA does not come in as regu- 

larly as I thought when I built the set, and I 

have not had 2XAF; though I have tried hard 

for it. 

E. C. HAVES, 

324 Plymouth .4re., Buffalo, N. Y. 

(Adding inductance to a tuned aerial coupler 

must, of course, alter dial settings, unless capacity 

is also rednced to make up for it. .4s for the power 

unit, its effect would depend upon the actual resistance-to 

ground -of the system.) 

WE SUGGEST ASBESTOS 

PHONES 


I write this listening to a concert from KFAD, 

Phoenix, with good loud -speaker volume, while 

the temperature is around 102 in the shade (Sorry 

O11). My longest reception is WGY at 4:30 p. ni. 

in the winter. As for night reception, all winter 

long I crawl out of the hay to pick up real DX. 

Here are verified receptions: JOAK, JOBK, 

Japan; JOD1c, Korea; 2BL, 2FC, 3L0, 4QG, 

5CL, Australia. (Not verified, JOBK, Japan; 

2YA, New Zealand.) All this on three tubes. 

From October to February, there was hardly a 

night I did not get JOAK and 2BL with good 

phone volume and loudspeaker volume that could 

he heard twenty feet away. 

I would like to get in touch with DX fans 

who are using small sets and getting real DX, 

as I want to compare notes. 

I like RADIO News much better since the change 

in policy. 

GILBERT HALE, 

Douglas, Arizona. 

PHONOGRAPH SWITCHOVER 


I recently invested in a phonograph pick -up; one 

of those which, by inserting a plug in the detector 

socket of the set, allows you to use the audio 

tnd as an amplifier for the phonograph music. 

SECONDARY 

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500 Radio .\'ewers for November, 1928 

1 Make Sure That My Entire Family Reads 

BODY " - -- There's a Reason 

"INVARIABLY, every time I bring home 

1 the new issue of YOUR BODY, my 

daughter makes a rush to capture it. I don't 

stand a chance of getting it back until she 

has digested its entire contents. Of course 

I have to be reasonable. I realize that, much 

as I want to read it, the contents of YOUR 

BODY is of great value in teaching her the 

real truths of life. I know that each issue 

is practically an endless source of information 

on sex, prevention and care of diseases, 

the senses and the normal functions of nature 

as related to our bodies. All of this 

worth -while knowledge is of great importance 

in forming a basicly firm character in 

adolescent children. That is the reason I 

willingly share my newspaper with my wife 

and wait patiently until Madeline, having 

read every page, grudgingly hands it back. 

However, in the future, I have a little 

scheme that will make it possible for both 

of us to read YOUR BODY at the same 

time. I am going to buy two copies; then 

I won't have to wait." 

This is the story that just one of our readers 

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"YOUR 

BODY. They know that it is a medium devoted 

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In YOUR 

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CONTENTS 

FALL ISSUE 

Decoding the Sex Question 

Evolution of Our Footgear 

Hermaphrodism 

Why the Doctor Examines You from Head 

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Wonders of Biology 

Menopause or Change of Life 

The Art of Living 

Sex Education 

Chemistry of Our Digestion 

Twilight Sleep 

The Art of Healing at the Dawn of History 

Before the Baby Comes 

Whooping Cough 

Psychoanalysis 

Etc., etc. 

50c. per copy 

AT ALL NEWSSTANDS OR WRITE DIRECT 

EXPERIMENTER PUBLISHING COMPANY, INC. : 230 FIFTH AVENUE, NEW YORK, Y. 

Please say Ton sa,;, it in RADIO FEINS

' 



LYNCH 


Amplifier Kit 

My set having only the ordinary two -stage amplifier 

using 201 -A tubes, did not give me enough 

volume. 

After a little figuring and experimenting I came 

across a way in which the detector tube could be 

used along with the audio tubes, making in all a 

three -stage amplifier: and that without having to 

remove the detector tube every time you want to 

rue- your pick -ul.. The result is all the volume 

you need. 

The only apparatus you need for changing over 

your set is a double- circuit jack. (which you probably 

have lying around among some old junk), 

two phone tips, a phone plug and also a few pieces 

of rubber- covered wire for connections, 

Remove the two connections that are soldered 

to the positive filament and plate prongs in the 

socket plug and attach phone tips to each, so that 

the terminals can then he placed in phone plug, 

which in turn can be placed in the jack whenever 

the nick -up is to be used. 

The diagram explains the way in which I connected 

the jack in the circuit. By studying the 

latter closely you will see the way it functions. 

J. Co MILLER, 

310 Riclle Avenue, Verdun, Que., Canada. 

WITH 

this precision -built kit you can assemble 

at minimum trouble and expense an efficient 

amplifier for securing quality reproduction in 

your television reception apparatus. 

The audio amplifier is an extremely important 

part of television receivers. Where the signal to 

be received contains frequencies of from 18 to 

20,000 cycles, the audio amplifier must be able to 

amplify all frequencies within these limits. Such 

an amplifier is available at your dealer in the 

Lynch resistance coupled amplifier kit. 

Your dealer has a Lynch precision - 

built resistor for every resis- 

tance need. Send for free book. 

ARTHUR H. LYNCH, INC. 

General Motors Building 

1775 Broadway, at 57th Street 


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Name 

Address 

Plcasc 

A PROUD CONSTRUCTOR 


I received my copy of the September issue and 

was surprised to see the Strobodyne dressed up in 

a new suit of clothes. I am the proud possessor 

of an original Strobodyne. which I constructed last 

fall, and with it I have received coast -to-coast 

under favorable weather conditions with tremendous 

volume. I deviated a little from the original 

design by incorporating one stage of resistance 

coupling in the first stage audio and push -pull 

in the last. I have tried out many circuits, but 

none SO far has surpassed the Strobodyne in performance. 

I am anxious, therefore, to try out 

the new circuit to see if it is actually better. 

Please send blueprint No. 63, for which accept 

my thanks in advance. 

JOHN C. A. COtSOER, 

1076 So. Lee Street, Des Plaines, Illinois. 

UNSUITED TO OTHER WAVES 


I thank you for your reply to my letter, though 

you misunderstood the query. I have now as fine 

a Strobodyne as anyone could wish, using S -M 

plugin coils rewound to suit. I have no trouble in 

getting J DKA and CKGW on 'twelve inches of 

antenna, right now in this hot weather; but what 

I wish to get information on is this: 

What may I expect from 18 to 200 meters and 

from 550 to 3000 meters with coils to cover these 

bands? I have started a screen -grid Strobodyne. 

Will you please send blueprints Nos. 62 and 63 

and oblige. 

T. RASMUSSEN, 

649 Spaulding Ave., Chicago, Illinois. 

(The American Strobodyne is not designed with 

a view to obtaining such a [ride range, and while 

toils might be obtained to cover the European 

broadcast bands, it is not recommended with so 

delicately -balanced a receiver. .9s for the shortwave 

broadcasts, the simplest remedy is to use a 

one- or two -tube short -Le'av'e tuning unit, such as 

have been described in recent issues of RADIO NEWS, 

and plug into or connect by switch to the receiver's 

audio amplifier. This involves fewer complications 

that the attempt to use the intermediate 

amplifier of the superheterodyne.- EnreoR.) 

REFORMING A TIN HORN 


I believe I can go Mr. Coleman several better 

in regards to treating a "tinny" horn. One of my 

first really good speakers (three years ago) was an 

old- fashioned "flower" horn and tone arm from 

a Victrola. I removed the entire horn and bracket 

from the cabinet and mounted it on the edge of an 

oak block 6 x 6 x 2 inches, which made a very 

good base. I then melted two cakes of paraffin, 

into which I dumped about two tablespoonfuls of 

salt and one -third of a cup of vinegar; and painted 

many coats of this preparation, while very hot, on 

the inside of the horn proper. After allowing it 

to dry for several days, I painted this with bronze 

paints of different colors, to represent a large 

morning glory. Use your own taste for colors and 

design. This horn, after being so treated, is the 

equal, if not superior to, an all -wood horn. This 

mixture is very hard when dry and will stand 

very high temperatures without melting or becoming 

greasy. 

:My latest speaker is a coiled up 12 -foot exponential 

horn with a Baldwin concert unit, which makes 

a very pleasing home speaker if coupled to a good 

A.F. amplifier. I am using a 5 -tube set with one 

screen -grid R.F. stage, regenerative detector 

say you safe it. in RADIO 

NEWS 

Put your set and loudspeaker 

anywhere. Place them as far 

apart as you wish. Then connect 

them with the wonderful 

Belden Extension Floor 

Cord. It lies flat under the 

rug. Out of the way -no 

wiring -no fuss. Get one at, 

your dealer, now! 

Belden 

Mfg. 

Company 

2114-A 

S. Western 

Avenue 

Chicago


502 

ran. smission of Photo's by Radio 

ANSMISSION OF PHOTOGRAPHS 

BY RADIO - Various methods have 

been devised and are now in use for 

the transmission of photographs by 

radio. Among these may be mentioned 

the systems of Belin (q.v.), Baird, and 

Jenkins. The principles underlying 

the Jenkins system are explained 

under the heading of Television. 

Using the system developed by Capt. 

R. H. Ranger, photographs were 

transmitted by radio from Honolulu 

to New York, a distance of 5,136 miles. 

Recently commercial picture transmission 

service has been inaugurated 

between New York and London using 

the Ranger apparatus. Two distinct 

ethods have been applied for analyzing 

the picture in the process of trans- 

thè electron flòw constitutes a discharged 

circuit, so that the grid becomes 

less negative. The first amplifying 

tube is a direct current potential 

amplifier, and is resistance cô :pled. 

The grid and plate connections of the 

amplifier are connected across a condenser 

which becomes discharged with 

the fall in the grid to plate resistance 

of the valve brought about by the grid 

potential fluctuations. A charging circuit' 

is connected to the condenser and 

is controlled by a valve, the grid circuit 

of which operates by variations 

of the potential across the condenser. 

The charging current is fed through 

the plate circuit of this valve, in which 

a relay is connected, which working 

through other mechanical relays in 


(1I2A), one stage of straight transformer A.F. 

(112A), and a last stage of push -pull with two 

171A tubes and 180 volts on plate. 

Will some of the fans send in data on their 

experiences with airplane cloth speakers? I am 

just getting material to build my first. 

M. A. PORTER, 

1616 Mohawk St., Chicago, Ill. 

FILAMENT INPUT 

Edtor, RADIO NEws: 

I note some records reported by set builders 

claiming to use new hook -ups with 15inch to 15- 

foot aerials. If they will take the ground wire 

off, they won't get these results; might just as 

well use no aerial at all. If either "A-" or 

"A +" or "B-" or " +" is grounded, on turning 

the filament up a signal will enter the receiver via 

ground through the filament of the R.F. tubes, to 

the plate. I have cut out all grids of R.F. tubes, 

put ground on "A-" and received stations to either 

coast, using only a straight settoground wire. I 

also find this can be done using a power unit; a 

signal comes in via the "A" unit, filament to plate, 

etc. 

If you want a real test on these remarkable receiving 

sets, disconnect both aerial and ground; 

use the old -fashioned "A" and "B" batteries: then 

see how much aerial it requires to get enough 

power for loudspeaker volume. 

O. R. AIKMAN, 

Salem, Illinois. 

(Some of ]1r. aikman's fellow-experimenters who 

haven't been able to get the coast on a 150 -foot 

aerial will probably Leant to know Irmo he does it. 

How many readers have been able to receive on 

tlic power-unit line alone as an aerial.' -EDITOR.) 

A pencil of light traverses the picture which is attached to the glass drums and is analyzed by a 

slow rotating action as well as a backwards and forwards movement of the carrier. 

mission. One arrangement cbhsists of 

roducing an image as a non- conductdeposit 

upon a metal foil which is 

versed by a stylus, while the other 

thod makes use of an opaque image 

osited upon a transparent film 

iich is traversed by a beam of light, 

le light interruptions being recorded 

y a light sensitive cell. The Ranger 

rstem makes use of this latter method. 

he image is p r to.. - rded 

ipon a cel 

ecor 

S.Gernsback's 

Radio 

Encyclopedia 

A facsimile of a portion of a page from S. 

Gernsback's Radio Encyclopedia is reproduced 

herewith. A glance at the thorough manner in 

which each item is treated cannot fail to instill a 

true appreciation of the value of the remarkable 

book. S. Gernsback's Radio Encyclopedia is 

the first ever published. It is not a dictionary. 

It covers every possible phase of radio. Every 

circuit, each piece of apparatus, all the leading 

characters of the industry, broadcasting, receiving, 

television, telephoto, everything connected 

even in the slightest way with the growth 

of radio or its kindred sciences, is most authentically 

explained. There are over 1930 separate 

definitions, 549 illustrations, a complete cross 

index, and many other special features. 

S. Gernsback's Radio Encyclopedia comes in 

two beautiful bindings, large 9 x 12 in. size. 

Cut here COUPON Cut here 

Beautiful Limp Suede Edition (de luxe) $5.00 

Keratol- Leather Stiff Binding $2.00 

Write your name and address in the margin 

below, mark which binding you prefer, and 

the book uiU be sent to you C. O. D. plus 

postage. 

S. GERNSBACK 

230 FIFTH AVE. NEW YORK, N. Y. 

cascades, controls the radio transmitter. 

, Wave trains from the transmitting, 

station after detection and 

amplification, are applied to the pic -tt 

ture recorder. The recording mechanism, 

in order that it may be sensitive 

to exceedingly small currents, comprises, 

a small moving coil, in a magnetic,fleld 

created by three electromagnets. 

The coil of wire, in moving in 

the field, as the received fluctuations 

recording mechanism of the receiver. Thy 

which a moving co 

applied through its windings, 

ates a- stylus while travelling 

ss the surface of the paper. The 

us traverses the -paper in perfect 

chrony with the carriage of the 

nsmitter, the paper being Iifted 

Please say volt saw it in 

A DOUBLE -GROUND SYSTEM IN EUROPE 


I read with interest the article by Dr. W. Griffith, 

as I have been using his hook -up for the last 

fourteen months. I inherited a V- shaped aerial, 

aboui 120 feet long and 40 feet high and, as it 

gave excellent results, I had no reason to inspect 

it any closer. One day I noticed by chance that the 

other end was carefully grounded. First I wondered 

how my set could have worked at all, but soon I 

realized that I was using a big loop. 

My set is a power Supradyne, which is wired 

for operation with loop and aperiodic aerial. It 

reaches easily the noise level. As soon as the 

idea of the loop had struck me, I changed the 

connections over to the loop terminals, tuned it as 

such, and found that the set worked about equally 

well. 

This aerial gives good results with wavelengths 

from 15 to 3,000 meters. At night, a 3 -tube, shortwave 

set fills the house with good music from 

2XAD right across the Atlantic Ocean. 

I wish to call the attention to another very 

important fact. For wavelengths of the American 

broadcast band, the noise level can be lowered 

considerably by connecting the ground wire only 

to one of the terminals marked "loop." It has to 

be tried out, which one of the two gives more volume. 

The volume decreases but, if the set is powerful 

enough to be brought up to the same volume, 

it will be found that the noise level has been 

lowered considerably, and that stations can be 

reached which were well below the noise level 

before. 

If the lead -in wire is eliminated, or if the loop 

is closed, all reception is cut out. This shows that, 

even with the ground -connection alone, the whole 

loop is at work and not only the ground part, as 

might be supposed. 

For long and very short waves, I always have 

to connect both wires. The directional effect must 

be very small, as America is coming in at right 

angles almost. 

OTTO BAUMANN, 

3 Travessa do Ascite de Oliveira. 

Barreiro, Portugal. 

IN' THE WINTER, THEY DON'T FISH 


I can term myself a listener, for about three 

months out of the year- during the dry season; for 

reception is quite impossible, on broadcast waves, 

during the wet season. We on the Canal Zone 

find it pretty nice to "rear back" in our chairs 

and get the baseball scores almost as fast as they 

are made. And it's also nice to be able to drag 

in a concert from England or Holland (short. 

wave, of course), even though there is a little 

squeal or motor noise "back of it." It's better 

than going to a theater and sitting in front of a 

gum- smacking, title -reading, so- called "listener," 

who explains aloud all the scenes of the thriller. 

We're all anxious to hear new ideas to improve 

broadcast reception, but we don't want the blah of 

a few high -hat listeners who haven't even an amateur 

op's license. In spite of the powerful "locals" 

RADIO NEWS


Radio News for V ovetnber, 1928 

TUB 

COAST -ZA 

-0-0-t--10 RADIO 

jJ//Pau mountecl 

- -Ai erj 

t,COAST W (» 

RECEP- !'vm' . 1,, 'A. 

TION 

Superphonic 7 is world beater! An exceptionally high 

grade receiver that is amaringthe Radio World. Latest 

tube tuned radio tre ncy circuit, using 4 radio frequency 

amplifiers, detector an 2 etagesofaudio. Power tube can be 

used in last audio stage, Extremely selective marvelous sensitivity. 

Single drum dial control. Straight line wave length 

condensers permit accurate, equally spaced tuning over entire 

wave band. All sockets spring cushioned to eliminate 

microphonic noises. Bakelite subpanel SWW" deep ) insures 

minimum dielectric losses. Clear and rmfistic reception guaranteed. 

An exceptionally beautiful. walnut finish, metal front 

panel 7" x 18 ". Complete chassis. No extra parts to . All 

parta mounted ready to wire. No special tools needed. All 

hook-up wire and colored battery cable included. Value 

$60.00; our price S16.95. 

TESTED AND APPROVED 

Severe laboratory tests haveprovedthe remarkable efficiency 

of this . Owners everywhere us lettere praising 

its set r receptive quale 

SIMPLE WIRING DIRECTIONS 

Very easy to wire this set with the instruction we furnish. 

Just connect a few wires. All you have to do is to follow 

numbers. Simple as adding 2 and 2. 

Can be wired in a few minutes by anyone. 

No radio knowledge needed. Make money 

by wiring these sets in your spare time and 

selling them to your friends. 

Just write your name and address one poet card and ask us to send 

this wonderful outfit. We ship right away. Uponarr,yal pay only 

$Ì6.9S plus mall delivery harge. (Foreign countries send 

519.50 with order. We pay shipping charges.) 

RADIO EQUIPMENT CO. 

549 S. Welts St., Dept.12 -L. CHICAGO, ILL. 

AXLE 

tja 

Yrzca- 

Junior Rheostat 

Small in size, but a 

master instrument. 

Ask your dealer to 

show you the exceedingly 

fine adjustment 

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smooth action. 

Diameter, 1?fG in. 

Up to 400 ohms $0.75 

1,000 and 2,000 ohms 1.00 

Potentiometers extra .25 

Self -attaching, positive -acting switches 

for Junior Rheostats 

.40 

FILAMENT AND GRID TYPE 

RESISTANCE UNITS 

Here is where you need absolute dependability 

and you get it with Yaxley Resistance Units. 

Runt true to rating. Convenient screw eye 

and soldering lug terminals for easy mounting. 

One to 3,000 ohms, 15c. to 40c. 

YAXLEY MFG. CO. 

Dept. N 

9 So. Clinton St., Chicago, Ill. 

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Tremendous stock and sales volume, 

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CORP RATION 

711 W LAKE STREET. CHICAGO 



Publishing Co., 230 Fifth Ave., N. Y. C. 

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Please 

(b- r- o -a-d, powerful spark and LC.W.). we Zouìtcs 

get a good deal of enjoyment out of the little black 

boxes. 

Broadcast stations in the States are as thick as 

I.izzies. It seems to me that it would be better to 

limit the stations to one to each state; Texas 

might need two. ln that way, I think, we will 

gain a great deal and lose these '-fox-in -a- hencoop" 

programs that have been reported heard in Hague, 

S. D. 

C. MAYNE ROY, 

Hq. Battery, Ft. Sherman, Canal Zone. 

(A simple solution, so far as the Canal Zone is 

concerned, and where all broadcasts are DX. 

Whether it Will meet conditions in the U. S. .4., 

let the Radio Commission bear witness. However, 

the increasing number of short -wave broadcast stations 

is bringing comfort to the dwellers in distant 

outposts, not only of the United States, but of all 

the countries of Europe.) 

-AS THE LADY SAID, WHEN 

SHE KISSED THE COW 


I can't see why people spend so much money to 

buy sets or make them; this also includes speakers. 

I know many who have $30 speakers, and still their 

results are not so good. I think I have the cheapest 

speaker in the world and the most perfect for 

that price. It is a unit with a 10 -cent megaphone 

over it and cost me $2.69. My sets are a five - 

tube T. R. F. set and a six -tube resistance -coupled 

set known the world over for its selectivity. Many 

of my friends who have expensive sets and speakers, 

both built -in and separate, have to admit that 

my sets sound 100% better than theirs. Both give 

me very good results both on low waves and high 

waves, and both cost me less than $25 complete. 

I use 135 volts "B" power on them, with a power 

tube in the last stage, and either a 200 or 201A 

detector. An output transformer helps to clarify. 

SAMUEL DONNER, 

309 Floyd St., Brooklyn, N. Y. 

WHEN A GROUND'S OVERHEAD 


The generally- accepted doctrine that a water 

pipe makes the most perfect ground was abruptly 

shattered, to my mind, when a peculiar constant 

hum that has been present in my set for the past 

five years instantly ceased on my changing to a 

deep earth ground. This hum was of variable 

intensity, apparently coordinated with electrical 

conditions in the air, and attended long- and 

short-wave code as well as broadcast reception. 

My diagnosis is that there was a six -foot range 

boiler in the water -pipe circuit, and this was in 

metallic connection with a steel standpipe 165 feet 

above the set. This in some way brought about a 

conflict or interference between the radio waves. 

In any event, divorcing the combination ended the 

trouble, and my 150 -foot aerial seemed to appreciate 

the relief. 

C. E. BUZZELL, 

Leaf River, Ill. 

(It is possible that a pipe line may contain an 

insulating ring- meter, etc. -between set and 

ground; and an extremely long antenna system 

subject to power-line pick -up resulted. .lfany of 

our readers may be able to take a tip from Mr. 

Bacaell's experience.- EmToa.) 

WHERE THE DX IS 


I received about 175 letters from DX fans (most 

of whom enclosed a stamp) about my recent communication 

to RADIO NEWS, and have answered 

them all. I like to correspond with those who 

are interested in reception of distant stations. These 

schedules may be of interest to listeners: all hours 

given are Eastern Standard Time. 

CYJ, Mexico City, 410 meters, 1,000 watts: 

9 to 10:30 p. m., except Sundays. 

PWX, Havana, Cuba, 400 meters, 500 watts: S 

to 11 p. m., every night. 

6KW, Tuinucu, Cuba, 365 meters, 100 watts: 

11 to 12:30 p. m., Fridays, Saturdays and Sun- 

days. 

This station has very good carrying power, 

and reception from it is very good. 

WKAQ, San Juan, Porto Rico, 322 meters, 

500 watts: 9 to 11 p. ni. Wednesday, 10:30 to 

11:30 p. m. Fridays. 

HHK, Port au Prince, Haiti, 357 meters, 1,000 

watts: 8 to 9 p. m. Friday, 6:45 to 7:15 p. m 

Saturdays. 

KGBU, Ketchikan, Alaska, 400 meters, 500 

watts: 1 to 3 a. m. Tuesdays, Thursdays and 

Sundays. 

O AX, Lima, Perot, 380 meters, 6,000 watts: 

11 to 12 p. tn. Mondays and Wednesdays, 9 to 

11 p. m. Tuesdays and Thursdays. 

SMZK, Falun, Sweden, 357 meters (will probably 

be changed to 333 or 315 meters) 2.000 watts, 

say you saw it in RADIO A E 

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500 

504 


EDITION 

TELE VIdICN 

(i/aya the ¡or Mefxper/men %ng Ian 

"TELEVISION" is a magazine pledged to further the art 

of the infant industry for which it is named, and to supply 

the "fans" with the latest information and developments 

in this fast -growing field. Television, as a 

science, occupies the same position today as radio 

did ten years ago. Like the radio fans of years 

back, enthusiasts of this new field have had to 

' fight for whatever meager knowledge they 

have been able to obtain. This magazine, 

then, comes as manna to the ininformation- 

hungry fan. It is our 

purpose to keep these enthusiasts 

constantly informed, through 

"TELEVISION," of each 

In the Television field there 

are all of the thrills that the 

radio fan knows so well. Get 

on the band wagon with your 

fellow enthusiasts. Be the 

first in your neighborhood to 

own a television set. Obtain a 

copy of "TELEVISION "; 

it will show you how to build 

a real Television receiver. 

new development. 

The 

second issue of "TELE- 

VISION" is now on 

the newsstands. 

You will find be-. 

low a partial 

list of its interesting 

con - 

tents 

Partial List of Contents 

The first Television magazine 

was published by the 

EXPERIMENTER PUB- 

LISHING COMPANY about 

a year ago. Over 50,000 

copies of this magazine, 

"TELEVISION," have since 

been sold. This, alone, is 

sure proof of the popularity 

of this interesting new art. 

New Jenkins Radio Movies 

Practical Demonstrations Scheduled for Station WRNY 

New Belin Photo Transmitter 

Campbell Swinton Television System 

Vacuum Cameras to Speed Up Television Quartz Crystals Synchronize Television Sets 

Infra -Red "Eye" Sees at Night 

Baird Optical Lever Increases Speed 

Valensi Television 

Recording Pictures with Air Jet 

Connection of Photo -Electric Cell 

How to Build a Radio Photo Recorder 

and many other articles of equal interest 

AT ALL 

NEWSSTANDS 

THE25CCOPY 

OR WRITE 

DIRECT 

EXPERIMENTER PUBLISHING Co., INC., 230 Fifth Ave., New York, N. Y. 

EXPERIMENTER PUBLISHING COMPANY, INC. 

230 Fifth Avenue, New York City, N. Y. 

Gentlemen: Please forward to me a copy of TELEVISION. Enclosed find 25 cents. 

Name 

Address City State 


11:30 to 3:30 p. m. daily. There is a chain of 

28 stations on the Swedish national programs. 

"Ravag," Vienna, Austria, 517 meters, 7,000 

watts: 3 to 7 p. m. daily. 

2L0, London, England, 361 meters, 5,000 watts: 

4:15 to 6 p. m. daily except Sundays; then it is 

from 9:30 a. m. to 4:30 p. m. 

5CL, Adelaide, South Australia, 409 meters, 

5,000 watts; 3:45 a. m. to 2:55 p. m. daily. 

5SC, Glasgow, Scotland, 405 meters, 1,500 watts: 

5 a. m. to 5 p. m. daily except Sundays; then 

9:30 a. in. to 4:30 p. m. 

5SW, Chelmsford, England, 24 meters, 15.000 

watts; 7:30 to 8:30 a. m., 3 to 4 and 4:15 to 

7 p. m. daily except Saturdays and Sundays. 

JOCK, Nagoya, Japan, 370 meters, 10,000 watts: 

6:45 p. m. to 8 a. m. daily except Sundays; then 

7:30 p. m. to 2:10 a. m. 

IVA, Auckland, New Zealand, 333 meters, - 

watts: 10 a. m. to noon, except Sundays; then 

9 to 11:30 a. m. 

MTI, Budapest, Hungary, 555 meters, 20,000 

watts, 10 a. m. to 3 p. m. daily. All these stations 

are of very good carrying power and are receivable 

in the United States. 

I am using an NR7 Freed -Eisemann with a 

"master oscillator" of my own design, with 280 

volts of "B" and 80 of "C ": a three -stage Magnavox 

amplifier; a 500 -foot aerial 62 feet high, and 

400 square feet of grounding surface. In conjunction 

with this, I have a three -tube short -wave 

set of my owj, design. I may say in conclusion 

that I have received from thirty-nine countries on 

wavelengths between 5 and 700 meters. I have 

worked about four months on the master oscillator, 

which can be plugged into any set, and I have 

it working now on three different sets. I am 

always willing to help a DX "ham" who runs up 

against something that puzzles him. 

CHARLES J. AEGSTADT, 

420 Pennsylvania Avenue, Bernlmrts, Pennsylvania. 

FOR EXCHANGE -OR, WHAT HAVE YOU 


I am a set builder in my community and I do a 

lot of experimenting on all kinds of sets, cape. 

cially the smaller sets such as the short -wave, 

reflex and different types of crystal hook -ups with 

amplifiers. I have built an Interflex and I will 

say that it certainly can deliver the goods. I have 

added one stage of tuned radio frequency ahead of 

the detector, which makes the set more sensitive. 

I have also built a neutrodyne which will get almost 

any high -powered station in the U. S. on any good 

winter night. 

I would like to correspond with radio experimen 

ters and set builders in other countries, as well as 

in the United States, to exchange book -ups and 

ideas on set building. 

GEORGE' MAKER, 

2012 Brainard Ave., Cleveland, Ohio. 

i 

40 Non-Technical 

Radio Articles 

every month for the beginner, the layman 

and those who like radio from the nontechnical 

side. 

SCIENCE AND INVENTION, which can 

be bought at any newsstand, contains the 

largest and most interesting section of 

radio articles of any non -radio magazine 

in existence. 

Plenty of "How to Make It" radio articles 

and plenty of simplified hook -ups for 

the layman and experimenter. The radio 

section of SCIENCE AND INVENTION 

is so good that many RADIO NEWS 

readers buy it solely for this feature. 

Radio Articles Appearing in 

November Science and 

Invention Magazine 

HOW TO BUILD THE "S. & 

TELEVISION RECEIVER 

I." 

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CCELL, O 

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Excello Combination Phono- 

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Completely equipped: GE Elec. phonograph 

motor, etc., and switch from phonograph to 

radio. Receiver compartment is a sliding 

drawer 24 in. x 9 in. x 14 in. Cabinet, walnut 

throughout, with fancy butt walnut 

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At your Dealers, or write for complete 

catalog of full line. 

EXCELLO PRODUCTS CORP. 

4832 W. 16th St., Cicero. III. (Suburb of Chicago) 

Your Set Can 

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Short Waves 

Sent anywhere In the U. S. 

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sure to name set and tubes 

used, such as UV109. 

U X199. W D1t, 201A. U X226 

or UY227. Price 515.00 or 

917.50 for A. C. Sets. 

The SUBMARINER 

will convert your regular set into a short-wave receiver by simply 

Inserting a plug In place of one of the tubes. This takes but a few 

seconds. With "Submariner" it will enable you to tune between 

20 and 65 meters. 

This device operates with all sets such as T.R.F., N eutrodyne, 

Super -Heterodyne and others A C or D C operated. No addi- 

tional tubes. batteries, or colts required. It set operates a 

speaker it will do so with "Submariner" attached. Operates 

as a wave changer with Super -Heterodyne and as detector 

unit with others. 

SHORT -WAVE RECEPTION 

Is practical, as short waves penetrate better and there Is lees 

static. The "Submariner" waveband includes practically 

all powerful stations which broadcast programs. You may 

also listen to amateurs from all parts of the world who transmit 

code messages. You will have one of the most efficient shortwave 

receivers when the "Submariner" is attached to your 

set. Get a "Submariner" so you may have command of the 

short-wave activities as well as the broadcast band. 

Never 

before has so much In radio been offered for so little money's 

A new thrill awaits you! If your Dealer does not carry 

ORDER TODAY DIRECT 

This dories has been nationally advertised, and sold In all parts of 

Ills world for the past two years 

J -M -P MANUFACTURING CO., INC. 

3401 Fond du Lac Ave. Milwaukee, Wis., U. S. A. 

\ \NEWSto Set Builders 

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I Want to Know 


in a 199 tube. \\'hen the set is in operation, the 

rheostat should be turned back as far as possible 

without reducing the volume. If an adjustable 

crystal is used, adjust it until a slight hiss is beard 

in the headphones. The tuning is accomplished by 

turning the condensers Cl and C2. 'l'hey should 

now be turned until a station is heard, and the 

crystal should then be readjusted for maximum 

volume. As explained above, the connections to the 

secondary of the transformer should be reversed, 

and the position found to give better results should 

be used. 

If no signals are heard when the set is tried, 

the first place to look for trouble is in the crystal 

detector. The crystal must be adjusted to a sensitive 

point and, if no signals can be heard when 

it has been adjusted a number of times, place a 

new crystal in the receiver. The next point to 

look for trouble is in the batteries and the aerial 

and ground. Test the batteries with a voltmeter 

or take them to a local dealer, who will have the 

facilities for making these tests. Look over the 

aerial to make sure that it is well insulated and, 

if possible, try another set on it to be sure it is 

in good condition. Finally, if no stations can be 

picked up, check the connections and, if no poor 

contacts or mistakes are found, take the set to 

your radio dealer or a friend and have him look 

it over and test the apparatus. 

The two dials should read almost alike, if not 

exactly so. The only other adjustment to be made 

is that of the filament rheostat. Turn the knob on 

this resistor until the signals are as loud as possible, 

but do not make the tube burn too brightly, 

since this will shorten its life considerably. 

GRID LEAKS 

(2312) Mr. J. M. Johnson, Andover, Mass., 

writes: 

(Q.) "What is a 'grid leak,' and why is it 

used in the grid circuit of the detector tube of 

my set? I should think that a resistance in the 

grid circuit of the tube would have a tendency 

to reduce the volume of the music. Will you 

please explain the reason for its use ?" 

(A.) A grid leak is a high resistor, connected 

between the grid terminal of a detector tube (or 

an amplifying tube) and some part of the filament 

circuit of the tube. Grid leaks are usually rated 

according to their resistance in megohms or in 

fractions of that unit; the megohm is equal to 

1,000,000 ohms. One of the chief difficulties with 

grid leaks has been the uncertainty of their resistance. 

'Many kinds of grid leaks have been used; the 

original type consisted of pencil marks on a piece 

of paper between two contacts. Naturally this 

type of grid leak was affected by moisture in the 

air and changes of temperature. A more recent 

type is made of a piece of fibre impregnated or 

coated with some form of carbon, mounted in a 

short length of glass tubing, and fitted with metal 

ends, which make contacts with two spring clips. 

Leaks of this type are quite satisfactory, if they are 

air -tight so that moisture cannot enter. 

The most recent type of grid leak consists of a 

piece of glass tubing, on the inside of which has 

been deposited a layer of resistant metal, which acts 

as the conducting medium. Another variation of 

this metallic type has the coating on a piece of 

insulating compound inside the tube. 'l'he resist 

ance of these grist leaks is much more constant 

than that of other types and, by carefully %catching 

the amount of metal deposited, the resistance values 

can be made much more accurate. 

Grid Leaks and Detectors 

The purpose of the detector's grid leak is to 

assist in the control of the "grid bias" of the 

detector tube, and also to allow dissipation of the 

excess negative charges (electrons) that accumulate 

on the grid of the tube. Although detection can 

be obtained without a grid leak, by correctly bias 

ing the detector tube, this method is not nearly 

as sensitive as the grid -leak method and, for this 

reason, has not gained much favor. (See the answer 

to Q. 2272, "What is Detection ?" on page 

1151 of RADIO NEtt's for April, 1928.) 

The proper value of the grid leak depends both 

on the type of tube employed and on the strength 

of signal being received. It also depends, to sonic 

extent, on the tendency of the receiver to oscillate. 

When very weak signals are being received, a very 

high -resistance leak should be used, in order to 

get the greatest amount of volume. However, when 

loud signals are being received, a rather low resistance 

must be used to maintain good tone quality. 

From this explanation, it can be seen that a 

compromise value must be chosen, to give good 



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quality and sufficient sensitivity. A variable grid 

leak may be used; but most of them are unsuitable 

because of their tendency to make the set 

noisy, and set owners usually try to avoid adding 

another adjustment. If the grid leak has too high 

a resistance, the receiver will howl and block 

without much provocation. The blocking is indicated 

by a series of popping noises either fast or 

slow, depending on the value of the leak and 

the other constants of the circuit. 

If the resistance of the grid leak is too low, 

the distant stations will be weak, or entirely absent. 

It may also be found difficult to make the set 

regenerate and, when the regeneration point is 

reached, the set will suddenly drop into oscillation. 

\\'ith the "bard" tubes (such as the 201A, 199, 

and 112A) a grid leak with a value of between 

2 and 5 megohms will usually be found satisfactory, 

at wavelengths in the broadcast range. The 

gaseous tubes (of the 200A type) will also use a 

value within this range; while the old -style soft 

tube (similar to the L' \'-200) required a value of 

about %- megobm. However, the best value for 

the grid leak in a particular receiver can only be 

found by experiment. 

Grid Leaks in Amplifiers 

Grid leaks, or grid resistors, are used also in 

amplifiers of certain types. In the choke -coil- and 

resistance- coupled amplifiers, in which the stages 

are coupled through transformers, the grid must 

be supplied with the correct bias. In order to 

keep the "signal" (-\.F. or, sometimes, R.F.) in 

the correct channel, - it is necessary to use an 

arrangement which will allow the direct -current 

potential of the "C" battery to be placed on the 

grid, but will not short- circuit the signal current. 

This may be accomplished by the use of either a 

choke coil or a resistor of the correct value. Since 

the latter is much simpler and cheaper, it is used 

more frequently. 

The bias applied to the grid is determined by 

the value of the leak and method in which the 

resistor is connected to the filament circuit. If it 

is connected to a "C" battery, the biasing voltage 

depends on the potential of this battery, of course, 

as well as on the resistance of the grid leak. When 

the grid return is connected to the negative terminal 

of the filament circuit, the bias is derived 

from the "A" battery, and it is necessary to use 

the correct resistance in the grid leak in order to 

have the tube correctly biased. The latter method 

is often employed in the first stages of an amplifier 

where the grid voltage does not have to be very 

high. 

I Our 

OM November er Issue: 

The World at Bay, by B. and G. 

Wallis. Part I. Application of 

the fourth dimension, in this 

story, enables the travelers to 

make a journey to the moon and 

back and around the earth in 

an astoundingly short space of time. Our 

new authors have given us a carefully 

studied treatment of the subject of interplanetary 

travel, cleverly interwoven with 

romance and human psychology. 

The Ananias Gland, by W. Alexander, 

What determines the extent of our truth - 

fullness.'. It might very well be glandular 

action of some kind. Mr. Alexander 

cleverly works up an idea of extreme interest. 

The Psychophonic Nurse, by D. H. Keller, 

M.D. Instead of contenting himself with 

the conception of new mechanical laborsaving 

devices -generally involved in the 

human scheme of life -Dr. Keller always 

goes further. He gives us, in a perfectly 

natural manner, the ultimate psychological 

effect of his mechanical innovations, 

on the human being. Though he never destroys-or 

even temporarily puts out of commission 

-his newly developed apparatus, 

we are glad, when we finish the story, 

that we are still a little ahead of the invention. 

The Eye of the Vulture, by Walter Kately. 

The human eye is limited in its vision 

of the colors of the spectrum, just as the 

ear is limited in its range of sound appreciation, 

and it must differ drastically 

from that of animals, birds, insects, etc. 

A bird, for instance, may not see all we 

do; on the other hand, many things within 

the bird's visual range may be completely 

out of ours. In this story, a number of 

theories, novel and interesting, but seemingly 

founded on scientific grounds, are 

introduced. 

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vides a resistance of approximately 150.000 ohms 

in the plate circuit of the tube. A high value of 

inductance is used in the grid circuit of the succeeding 

tube, which gives a step -up ratio through 

the use of the grid inductor as an auto -transformer. 

The plate output of the preceding tube is cou pied 

to the primary tap of the auto -transformer -coupled 

grid inductor through a capacity of such size than 

excellent amplification is obtained between 30 to 

5,000 cycles. The iron -core inductor, plate resistor 

and coupling condenser are encased in an iron 

housing of black enameled finish, 4 inches high. 

with a base 3!i x 31 inches. Excellent quality 

and volume, with great amplification, was obtained 

when the unit was tested in a screen -grid, space - 

charge A.F. amplifier. 

A WARDED THE RADIO NEWS LABORA- 

TORIES CERTIFICATE OF MERIT NO. 2435. 

GRAPHITE (IN SUSPENSION) 

".\quadag," submitted by the Acheson t liblac 

Company. Port Huron, Mich., is a concentrated 

colloidal solution of artificial (electric -furnace) 

graphite in water. which has found successful use 

ill the manufacture of resistance elements for gridleaks 

and variable resistors. It has been used also 

as a dry lubricant for condenser bearings and for 

the drawing of tungsten wire. It has been used 

ill tube manufacture as a "Getter." as an opaque 

coating in the manufacture of photoelectric cells, 

and has been found, as well, useful in establishing 

positive electrical contacts, and as a conductive 

coating for electroplating. It has many other applications, 

and is suitable for uses of the manufacturer, 

either the above- named, or wherever conductive 

material of this type is needed. 

AWARDED THE RADIO NEWS LABORA- 


R.F. CHOKE 

The R.F. choke coil shown, submitted by the 

Hammarlulul Manufacturing Co.. 424 W. 33rd 

Street, New York, N. Y., is of the helical -winding 

type. It was found to have an inductance within 

10% of its rated value, 85 millihenries, when meas. 

tired at 1,000 cycles. The D.C. resistance, as 

measured, is 2,000 ohms. The distributed capacity 

was found to be extremely small, in comparison 

with the inductance. The coil is contained in a 

molded black bakelite housing, 1y, inches high, and 

requires a base space 1% x 2 inches. 



SHORT -WAVE TUNING CONDENSER 

The short -wave condenser (Type ML -7) shown, 

submitted by the same manufacturer, is a 7 -plate 

condenser of the midline- frequency low -loss type. 

It has a sturdy cast -aluminum frame supporting 

the stator, and drilled for base -board or sub -panel 

mounting; two flat -head screws are provided on 

the front of the frame for panel mounting also. 

The stator plates are soldered to plate- spacing 

mounting brackets which, in turn, are fastened to 

the Bakelite insulating strip. 

The stator plates are provided with a spacing 

bar and the entire stator assembly is supported 

from the bottom of the frame. The rotor is of the 

"floating type"; which allows the removal of the 

shaft, and the operation of the condenser in a 

gang. The bearings are of the cotte type, and the 

rotor - is provided with maximum and minimum 

THE MIRACLE OF 

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Mail coupon today for our big, Money-Saving 

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Dept. =IS w 1120S. Clinton St., Chicago, III. 

MAIL THIS COUPON TODAY! 

Diamond Radio Company, Dspt.2114 

820 S. Clinton St., Chicago, III. 

Please Send me your Free Catalog of Diamond 

radios and details of your 30 Day FREE Trial offer 

Name 

Address 

, City State 

Newest 

- 

Radio Hook 

- 

- Ups 

Free 

Send now for the newest radio hook -up book. 

Shows how easy it is to bs lid remarkable new A.C. 

and D.C. receivers of longest range, greatest volume, 

purest, clearest tone, and super -selective. 

Also shows how to make short -wave receivers and 

adapters, how to use new screen grid tube In A.C. 

and D.C. circuits, how to build power amplifiers and 

A -B-C eliminators. Latest information on all new 

radio wrinkles. Send for free copy now. 


4038L3 N. Rockwell St., Chicago. U. S. A. 

Name 

St. and No 


Please sap you saur it in RADIO NEU'S 

IN VENTORSwho 

derive largest 

profits know and 

heed certain simple 

but vital facts before 

applying for Patenta. Our book Patent -Sense gives those 

facts: sent tree. Write LACEY & LACEY, 631 F St. 

Washington, D.C. Established 1663 

1


508 

Radio Nevi's for November, 1928 

New! 

Super MasTennA 

Brings Good News to 

the Radio World! 

A Vertical Aerial 

that is practical, efficient, and 

reliable 

Gets stations, increases the selectivity 

and signal strength. 

Approved by 

Prominent Radio Engineers 

Sold by large Jobbers and Dealers 

Write for FREE BOOKLET 

Gustin-Bacon 

Manufacturing Company 

Dept. 1128 -N Kansas City, Mo. 

MR RADIO MANUFACTURER 

EVERYTOWN, U. S. 

FOR THE RADIO TRADE 

We maintain a complete, up -to-date mailing 

list of U. S. radio dealers' names 

which is continually revised and enlarged. 

These names are on stencils 

and ready for you to use with your next 

dealer mailing. Write us for further 

information. 

EXPERIMENTER PL'Bf.ISHING COMPANY 

230 FIFTH AVENUE, NEW YORK, N. Y. 

Quality Apparatus 

Our latest bulletin No. 929 describing our complete 

line of quality apparatus is yours for the 

asking. Write for it today. 

GENERAL RADIO CO. 

80 State St., Cambridge, Maas. 

stops and a pig -tail connection; its plates also are 

held rigid in position by a spacing bar. A friction 

brake is provided which operates on th'e removable 

shaft. The condenser has a maximum capacity of 

140 mmf. (.00014-mf.) and a minimum capacity of 

15 mmf., and is of excellent electrical and mechanical 

design. 



MICA BALANCING CONDENSER 

The small seini -variable condenser ( "Type 

EC -70) shown, submitted by the liammarlund 

Manufacturing Co., 424 W. 33rd St., New York, 

N. Y., is of the mica -dielectric type and designed 

for neutralizing or balancing radio- frequency circuits; 

it consists of two plates riveted to a rectangular 

piece of bakelite, 1 Vt inches long, 11/16- 

inch wide, and 3/32 inch thick. The stationary 

plate is a flat piece of brass, provided with a 

tongue pierced by a 1 -inch hole for fastening to 

a terminal of a socket or tuning condenser, etc. 

The movable plate is of spring copper and separated 

from the stationary plate by a rectangular 

piece of mica which is riveted to the latter; the 

capacity is adjusted by a brass screw which turns 

into a tap in the center of the insulating support. 

The maximum value was found to be 15 mmf. and 

the minimum 6 mmf. 



FILAMENT TRANSFORMER 

The "Dependable" A.C. filament transformer 

shown, submitted by the Leslie F. Muter Co., 76th 

and Greenwood Ave., Chicago, Illinois, operates 

from a 110 -volt, 60 -cycle circuit. The transformer 

is of the step -down type and supplies filament current 

for the operation of 226 -, 227 -, and 112- or 

171 -type vacuum tubes. It has three secondary 

windings for 2, 3, and 5 volts, which are to be 

used in connection with suitable filament -regulating 

e(eeeee)3 

resistors. The 3- and 5 -volt windings are provided 

with a center tap, while the "nodal" point of the 

2 -volt winding is obtained by an external center - 

tapped resistor. A 6 -foot cord, fitted with a standard 

plug, is attached to the primary winding and 

allows direct connection to the house -lighting circuit. 

The iron housing is 4 inches high, with a 

base 31 x 31 inches over all. The transformer 

is of efficient design and its operation was found 

to be satisfactory. 



SOCKET ANTENNA PLUG 

The "socket antenna plug" shown, submitted by 

the Clarostat Mfg. Co., Inc., 285 North Sixth St., 

Brooklyn, N. Y., converts the house -lighting circuit 

into an aerial for the radio receiver; it consists 

of a nickel -plated metal cylinder, 1 inch long and 

11/4 inches in diameter, one end of which is fitted 

with two prongs for plugging into a standard 

receptacle, which in turn is screwed into the light 

socket. The other end of the device is provided 

with two discs of hakelite which are clamped to 

the cylinder by a single rivet in their center; to 

which is soldered a rubber- covered cord approximately 

12 feet in length, provided for connection 

to the receiver's aerial binding post. The measured 

capacity of the device was found to be .0011- 

mí.; the condenser is connected to only one prong, 

SAVE YOUR MONEY ! 

BE YOUR OWN SERVICE MAN 

THE RADIO 

TROUBLE FINDER 

THE RADIO 

TROUBLE 

FINDER 

Even the highest - 

priced radio set 

occasionally de- 

velops a fault and 

that at a time 

when you least 

expect it -maybe 

right in the middle 

of an interesting 

program. But, 

a handy copy of 

The Radio Trouble Finder is the simple 

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remedying it in the easiest manner 

possible. There is no mishap that could 

befall a radio, but what is fully covered 

in this valuable book. 

The Radio Trouble Finder is edited 

by men fully versed in the subject 

covered -men with years of actual experience 

behind them -and who have 

grown to prominence since the infancy 

of radio. 

Don't wait till your set goes bad -get 

your copy of this remarkable guide to 

radio trouble now. Fill in the coupon 

and we will send you by return mail a 

copy of The Radio Trouble Finder, 

a money -saving investment. You can 

be your own service man. 

The 

25C Copy 

BUILD YOUR OWN 

RADIO SET 

150 RADIO 

HOOK -UPS 

This is the latest 

issue of this remarkable 

book. 

Absolutely new 

and up - to - date. 

All the best circuits 

of the day. 

Full instructions 

on how to build. 

Make your own 

set from the diagrams 

shown in 

150 Radio Hook - 

Ups. Write today -pick the set 

you want to build and make it. Then 

you are sure to be satisfied with the 

results you get. 

150 Radio-Hook-Ups was prepared by 

the staff of Radio News. An accurate 

guide to better set construction for the 

radio "fans." 

The 

25C Copy 

MAIL THIS COUPON NOW 

CONSRAD CO., INC. 

230 FIFTH AVENUE NEW YORK, N. Y. 

CONSRAD COMPANY, INC. 

230 Fifth Avenue, New York, N. Y. - 

Gentlemen: 

Kindly send me a copy of 150 RADIO HOOK- 

UPS ..THE RADIO TROUBLE FINDER... 

(check which or both). 

Enclosed and 

cents in lull payment. 

Name 

Address 


City 

State



509 

thus being placed in series with the receiver's aerial 

coupler. To obtain operation in some cases, it 

may be necessary to reverse the position of the 

plug in the socket. The operation of the device is 

found to be satisfactory. 



Price $15.00 

If you insist on 

the best, they must 

hand you Televocals. 

All stand- 

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them at your 

dealers. 

Televocal Corporation 

Televocal Building 

Dept. A -4 

588 12th Street 

West New York, N. J. 

e ear cae 

Quality Tubes 

Everything in 

Radio at Wholesale 

We supply every radio need from 

our mammoth stock of kits. 

parts and sets of latest design. 

Lowest wholesale prices. Expert 

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Write for big, illustrated Catalog 

"B -1. 


Be an Expert RADIO OPERATOR 

Fascinating work. Wonderful opportunities. 

Good pay. Mordent Code Sender teaches you 'TITIp 

at home in halt the usual time. Reproduces acrrml 

sending of expert operators. Sends you messages, 

radiograms, etc.- regular code traffic 

anywhere, any time, any speed. U. S. 

Navy and leading schools endorse Tele- 

ó 

plea as 

á led a,w t extra rra 

e instruction 

cost. Write for Booklet Nit. 

TELEPLEX COMPANY 

76 Cortlandt St.. New York, N. Y. 

Radio has been changing so fast 

lately that its hard to keep up 

with it. Barawik's Big Radio Guide 

will keep you posted on the newest 

wrinkles. Thousands of Illustrations 

of sets, parts, new Ideas. Big chance to 

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rl 

SELF -ADJUSTING A.C. RHEOSTATS 

The ".mperite" (Type 226 shown), submitted 

by the Radial) Company, 50 -52 Franklin St., New 

York City, has been designed for use as a ballast 

in series with the Marnent of a 226 -type tube, 

when operated from a step- down- transformer secondary 

supplying approximately 2 volts. Its resistance 

varies with the current flowing through 

the circuit; at 1 ampere its resistance is 0.5 -ohm 

and, at 1.5 amperes, 1.83 ohms. When this 

.\mperite is used in series with a 226 -type tube 

(whose normal operating requirements are 1.05 

amperes at 1.5 volts) it requires a transformer' 

secondary voltage of 2 and a current value of I 

ampere. 


TORIES CERTIFIC. \TE OF MERIT NO. 2442. 

The same manufacturer submitted also for test 

the Type 227 :\mperite, which is designed for use 

in series with the Marnent of a 227 -type tube, 

when it is operated from a transformer -secondary 

supplying 3 volts. The ballast resistance at 1.5 

amperes is 0.2 -ohm and, at 2 amperes, 0.43 -ohm. 

When it is used in series with the 227 -type tube, 

a transformer -secondary output of 1 at 3 volts is 

required for normal operation. 

AWARDED TIIE RADIO NEWS LABORA- 


FILTER CONDENSER 

The filter condenser (Type R171 shown) submitted 

by the Acme Wire Co., New Haven, Conn., 

has been designed for use in "B" power units of 

the "Thordarson R171 Compact" type, using a 

gas -filled rectifier. It has a continuous D.C. voltage 

rating of 400. Condenser sections of 8, 2, 

2, 1 and 1 mf. Capacity, respectively, are provided; 

the 8- and the 2 -mf. terminals are placed upon the 

top, and the two terminals for the 1 -mf. sections 

at either side. The common terminal (negative) 

of the latter is at the right. The five sections are 

placed in a metallic container, together with an 

insulating compound, and hermetically sealed; the 

metal can is 2 inches thick, 4i4 inches wide, and 

5 r inches high. The respective sections, when 

measured, had capacities within 10 per cent of 

their rated value. When the filter was used in 

connection with the R171 compact, a humless "B" 

power supply was obtained. 



IMPROVING THE OLD SET 


The article in the July issue "Improving reception 

on a slim pocketbook" is along the right 

lines. Help the B.C.L. with the old sets to 

get better reception, and don't forget the beginner 

with a few hints now and then. I shunted the 

grid resistor on the middle dial of my Atwater 

Kent 20, increasing the volume materially on stations 

coming in below 50 on the dials; and as my 

model is a late one with provisions for a 171 

tube and "C" battery I did not have to follow 

the instructions in the balance of the article. 

Also, I wish to commend your items against 

the pure and simple fakes offered by some dealers 

to the radio public. This is a real service to the 

buying public and should be continued in an effort 

to remedy the condition. 

E. B. CLARK, 

724 East 41st St., Baltimore, Md. 

BARAWIIC CO., CH CAGO i=S.A. 

Please say you saw it in RADIO 

AMAZ ING 

REGULATION 

OF A. C. VOLTAGES 

with the new WEBSTER 

AUTO -POTENTIALATOR 

VDU can now obtain an A. C. voltage 

1 regulator that delivers an absolutely even 

flow of A. C. current to your A. C. receiver or 

"A" and "B" eliminator. The Webster Auto- 

Potentialator is a new automatic device that 

has amazed every user with its perfect regulation. 

It not only delivers the proper voltage 

on the normally high or low line, but also 

effectively 

controls the sudden fluctuations 

common to all A. C. lines. 

Contains No Tubes or Liquids 

The Webster Auto -Potentialator contains no 

tubes or liquids. It is entirely automatic in 

operation. Its use will protect your A. C. 

tubes from burnout, and greatly lengthen 

their lives. 

When you hook a Webster Auto-Potentialator 

onto your receiver you do away with 

all voltage -fluctuations and can sit back and 

enjoy the most marvelous reception you ever 

listened to. 

It assures uniform reception, 

wonderful tone clarity. and tremendous 

volume, without any of the variations so 

common in unregulated A. C. sets. 

Order TODAY direct from 

this advertisement 

If your dealer is out of stock and you are in 

a hurry, you can order your Webster Auto- 

Potentialator direct from this ad. Just nu 

out - the coupon below, inclose $15.00. and 

mail to us, and we will ship your Auto- 

Potentialator the same day we receive your 

order. Order TODAY -end your voltage 

fluctuation troubles NOW. 

The WEBSTER CO. 

858 Blackhawk Street 

CHICAGO 

THE WEBSTER COMPANY 

858 Blackhawk Street, Chicago, Ill. 

Send me a Webster Auto-Potentlalator as advertised 

in "Radio News." I enclose 515.00. 

Name 

Address 

City 

State 

New Karas Short -Wave Kit 

Reaches Around the World ! 

New radio thrills await you. Listen to Australia. 

Europe, Asia. Tune in on the world's airplane 

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can do it easily with the remarkable Karas Short - 

Wave Receiver. You can't know the fascinations 

of radio until you experience this new sensation. 

Karas engineers have developed short wave to new 

with of perfection. build. Easy 

art 

tto rio. tune se 

famous Karas condensers, built like a One watch. 

Raras coils and audios -the world's standard. 

Send now for full information and construction 

blueprint -Free. 


4038L4 N. Rockwell St., Chicago, U. S. A. 

Name 

St. and No 



to RADIO NEWS -32.50 a year. Experi- 

menter Publishing Co., 230 Fifth Ave., N. Y. C. 

NEWS

Write Adams Fisher 3f fg. Co., 278 Enright, St. Louie, info. 

. 

t 

r 

s p c C 

o d 

l P a e n M 


OPPORTUNITY AD-LETS 

Follow these advertisements every month. Reliable advertisers from all over the country offer their most attractive specials in 

these columns. 

Classified advertising rate twenty -two cents word for each insertion. Ten per cent discount for 6 issues, 20 per cent discount 

for 12 issues. Names and addresses must be included at the above rate. Cash should accompany all classified advertisements unless 

placed by an accredited advertising agency. No advertisements for less than 10 words accepted. 

Objectionable or misleading advertisements not accepted. Ad vertisements for the January issue must reach us not later than 

November 1st. 

{ CIRCULATION LARGER THAN THAT OF ANY OTHER RADIO PUBLICATION 

EXPERIMENTER PUBLISHING CO., INC., 230 Fifth Avenue, New York, N. Y. 

- - 

A gents Wanted 

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Printing Outfits and 

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Print Your Own Cards. Stationery, Circulars, Adver- 

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Write Adam Fisher Mfg. Co.. 278 Enright, St. Louis Mo 

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monds. crowns, bridges, dental gold. silver, platinum, gold 

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points, old false teeth. Packages re- 

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turned 

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Electric Fun ! Seventy stunts, 110 volts. $L Cooperce, Patent Sense -Valuable book free. See L :use >'s ad, page 

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Established 1869. 

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Write today for our large illustrated 

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information 

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]tangor, Maine. 

Allied /Radio 

CORP RATION 


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Please sat' you sawn it in RADIO NEWS 

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S. A.


Radio IVews for November, 1928 

511 

Again Tyrman Conquers! 

The pioneers of the Shielded Grid Circuit now introduce 

advanced features in a new series of A -C and D -C 

operated Custom Built Shielded Grid Receivers 

(Tyrina n Imperial 8C) 

Custom -Bilt Shielded Grid 

For Complete A -C Socket Operation 

Using A -C Shielded Grid Tubes 

Short 

Wave 

Coils 

UX250 

Amplitying 

Tube 

Phonograph 

Switch 

Designed for those who want to build only the 

finest in A -C Socket Operated Receivers. Note the 

compact factory-like appearance of the chassis. 

Tyrman ingenuity in design places the Power 

Supply with other apparatus on a cadmium plated 

subpanel platform only 13 / in. x 20 34.in. Shielded 

parts beautifully finished in black crystal. Power 

Supply designed solely for the "80" and factory 

assembled. No adjustments. 

The actual performance of the "80" is defined by a clear 10 

K. C. separation over entire broadcast wave band. Tonal 

quality of tremendous volume without distortion. DX reception 

like local without oscillation. Duo Amplification System, 

a new Tyrman development in the final combination with other features 

creates unequaled Sensitivity. Selectivity. Stability and Power. 

Panel only 8 in. x 21 in. of Genuine Butt- Walnut on metal (Pat'd). New 

Tyrman Worm Drive Illuminated Drum. Only three controls with 110 A -C 

and Phonograph Switch on front panel. Simple and quick to assemble. 

Receiver Parts. factory .packed $134.80. "80" Power Supply $65.00. 

Complete Parts for Imperial "80". short wave plug -in .11. 

coils and Power Supply, ready to assemble. 

only 

099 5. 

(Trinan"6fY 

Custom-Bilt Shielded Grid 

For Battery or Eliminator Operation 

For appearance, tone quality, distance, selectivity, sensitivity, 

stability and power, the Tyrman "60" is comparable only to 

other Tyrman Shielded Grid Receivers. An improved design for 

battery or eliminator operation. Especially designed for Shielded Grid Tubes. 

Every part made of finest materials, carefully tested and matched. The Tyrman 

"60" creates a new standard of comparison for performance and value in six 

tube receivers.Panel only 7 i n. x 18 in. equipped with Tyrman st C 

Single Vernier Drum Dial. Complete parts, factory packed. /- 50 

ready to assemble, only 

Tyrman Electric Corporation 

Dept. 218, 314 WEST SUPERIOR STREET 

VVV 

CHICAGO, ILLINOIS 


\t 

AFEW short months ago, Tyrman engineers deveIoped 

and conquered the Shielded Grid Principle 

in radio circuits. Its introduction was heralded by 

Set Builders, Engineers and Editors as the greatest 

advance in radio since broadcasting. Today there is 

not a receiver using Shielded Grid Tubes which does 

not bear the ear marks of Tyrman influence. 

Now after months of systematic experimenting, backed by 

unsurpassed working knowledge in Shielded Grid circuits, 

Tyrman Engineers again conquer principles that reach new 

peaks in Performance, Tonal Qualities, Beauty and Value in 

Custom Built Receivers. 

Send for free descriptive literature. When you examine the diagrams 

and layouts you will quickly see why, in the Tyrman Series, 

you can be assured of hairline selectivity, full, rich tonal quality, 

unequaled power and distance under most trying conditions. 

'4141.111.1111.191111111,1111111, 111.1 

crjrm(/ \ \72" 

Custom-Bill Shielded Grid 

For Battery or A -C Socket Operation 

The Tyrman "72" can be assembled for battery, eliminator or Complete 

A -C Socket operation. Even if assembled as a battery set it is a 

simple matter to convert to complete socket operation. When assembled 

for A -C Socket Operation uses A -C Power Supply especially designed 

for the "72" mounted on subpanel platform. The Tyrman Duo System of 

Amplification,and Tyrman Audio Coupler System assure rich tonal qualities. 

Sensitivity. Stability, Selectivity, Power and Distance comparable only to the Imperial 

"80 ". Front Panel only 8 in x 21 in. of beautiful burl -walnut finish on metal. Tyrman 

Illuminated Worm Drive Double Drum. 110 A -C Switch and Phonograph pick -up 

Jack on panel. Easily and quickly assembled. Complete parts for either battery or A -C 

operation. factory packed, ready to assemble 

The "72" Power Supply for A -C Socket operation. factory assembled, $9 ^CO 

$55.00. Complete set plug -in coils $10. 

Send for FREE literature describing this remarkable 

New Series of Receivers 

r 

Tyrman Electric Corporation (' Without obligation send me free 

Dept. 218, 314 W. Superior St. literature describing Tyrman 

Chicago, Illinois. 

Custom Built Receivers. 

I am particularly interested in 

"80" A -C Operation 

"72" A -C or Battery operation "60" 

Battery Operation. 

NAME 

ADDRES 

Dtv JOBBElt- -


Radio 

512 

- 

News for November, 1928 

,t1 

,ji_.._ , ` 

> > ---- - 

l, 

: 

{, 

r l 

t. 

Ì 

1 

m+h 

Lowest Wholesale Prices 

Set Builders 

Set Builders and experimenters will welcome 

an association here where tremendous 

stocks of practically all of the 

nationally advertised lines are carried 

-coupled with an organization trained 

to serve. Immediate shipments are assured. 

Silver- Marshall- Hammarlund- 

Roberts -Aero -Tyrman and practically 

all of the latest kits and parts are 

available. Your orders, large or small, 

will be handled with a promptness and 

dispatch that should prove a revelation 

to you in Radio Service. 

Dealers 

Dealers who line up with Allied Service 

will never disappoint their trade on 

deliveries. Our immense stocks in 

Sets, Parts, Kits and Accessories enable 

you to render real service to 

your trade. Immediate shipments insure 

rapid turnover -eliminating the 

necessity of carrying large stocks on 

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connection for the live dealer. 

Allied Radio Corporation is composed of a large corps of trained men who 

have had years and years of experience in radio. They know how to get 

results. Their great fund of experience is now available for your benefit. 

They know the newest improvements, the up- to-theminute demands of 

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50,000 Feet of Radio 

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Here are found the latest improved 

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New A.C. Sets and Kits 

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Send for Large, Free, New, Illustrated Catalog "B -1" 

latest and newest in Radio is here 

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Lowest Wholesale Prices 

Tremendous sales volume coupled 

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Immediate .Shipments 

The Allied organization is trained 

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AIIiedFRadi.o 

COR PORTI ON 

Wholesale Radio Distributors 

711 West Lake Street Dept. B -1 Chicago, Illinois 

Please sap 

r 

Cl! 

saw it is RADIO YEWS


last. ave caught *with i 

PROMPT DELIVERIES' NOW ASSURED ON 

and 

&I44E L D G R 

cS. o, 

ATTENTION! 

SET BUILDERS 

Our unique business 

building plan will triple 

yourCustom Set business 

this season. Ask your jr 

ber or check coupor below 

for full particulars. 

Shield 

Grid Am 

puff iier 

gives tremendous 

gain 

unquestionably is t ;. 

otrpowful r 

hate 

e yet produce,. receiver 

eord;al ;invitation 

off set newalaboratont .'. 

our large 

and hear our Whurator, 

hod l und to observe p 

and thr precision and rare 

taken in matehino and test - 

ing all parts of Chia remark. 

obis -et.' 

F.'. H. Scutt 

Challenges the whole radio 

world to any test of 

Distance-Volume-Select" 

The Scott Shield Grid Nine and Power Amplifier 

is a standing challenge to the entire 

world of radio to match its superb performance. 

In range it is practically unlimited 

-due to the tremendous amplification 

of the Shield Grid long range amplifier 

employed. In volume, selectivity, and tonal 

purity, it is absolutely unrivaled. It is the 

successor to a line of famous World's Record 

Receivers -and is to our knowledge the 

most powerful set available today. 

Shield Grid Tubes 

In Improved New Circuit 

Perhaps the greatest single factor in increasing the 

efficiency of this new Scott receiver is the use of 

the new Shield Grid Tubes, in a new, improved 

circuit. This gives many times the amplification 

obtainable from an ordinary circuit using 201A 

tubes, making this receiver more powerful than 

any other existing receiver known to us. 

Perfect Matching of Parts 

Gives Enormous Gain 

To further increase efficiency in the new Scott 

receiver. not only are the tubes shielded, but the 

transformers as well. The extreme care taken in 

matching and testing the transformers is another 

reason for the amazing volume obtained from far 

distant stations. All parts throughout are especially 

designed and painstakingly matched with precision 

equipment. The special Selectone Two -Gang condenser, 

for instance, matches the inductances of 

the antenna and R. F. coils so perfectly that they 

line up throughout the scale and afford astonishing 

SCOTT TRANSFORMER C 

selectivity with maximum amplification from the 

lowest to the highest wave lengths. 

One Spot Reception 

The Scott Shield Grid Nine is a one spot Su 

Stations come in at one point only on the 

both of which track practically together, 

tuning extremely easy. The Scott Power 

used with receiver, makes it possible 

immense volume without the alighes 

This volume is so completely unde 

the turning of one knob covers 

From merest whisper to full aù.' 

always with life -like clarity an 

Low Oper 

The Scott Shield Gri 

operated with dry ba 

tubes incorporated in t 

mils. and will give ample 

home. Where A. C. current is a 

new Scott Power Pack and Amp 

ninth tube for the second stage of au 

This is the latest 250 power tube, affor 

mous volume with matchless tone quay 

economically Th eight 

w 29 

age 

ial 

e 

EASY TO BUILD- 

Results Guaranteed 

Although the Scott Shield Grid Nine is orle of the 

most highly perfected sets ever designed, it is an 

amazingly simple one to build. Anyone can assemble 

it in four hours. Both panel and sub -panel are 

drilled to receive each part, and the shielded grid 

amplifier unit comes to you fully wired and tested 

-ready to be connected into the circuit as simply 

as hooking -up a transformer. No adjustments are 

required of the builder and you can't go wrong on 

the assembly. We positively guarantee that you 

O., 4454 Ravenswood Ave., Chicago,l11. 

SCOTT POWER 

PACK and AMPLIFIER 

This fulluehielded unit is eopeciallp designed tosorplo Beur. 

rent for 

et econe:tagie lof 

!Vane, und ing a 

has m.ee tube. 

wt ge a sameresu s we O. stn rom our a,oratory 

models. 

For the small cost of the Scott Shield Grid Nine 

you can get all that could be desired of radio -the 

very newest, finest developments of the day. Why 

not enjoy World's Record performance when you 

can have it at less cost than inferior reception? 

Why not have a receiver that provides actual 10 

kilocycle selectivity? Why not listen in on a radio 

that gives you the whole world. Build the Scott 

Shield Grid Nine and have it. Enjoy the ultimrv, 

in radio-NOWI Act Today! 

FREE 

Circuit Diagram 

and Particulars 

Write at once for full 

particulars. Let us 

send you FREE the Scott Circuit Diagram. 

Examine it yourself. See with your own eyes why 

it affords unequaled performance -limitless range - 

tremendous power - matchless tone. Proof will be 

sent you FREE. Also copies of 6,000 and 9.000 mile 

reception verifications and other astonishing records. 

Clip coupon and mail today. Do this NOW I 

CLIP THIS NOW AND MAILS 

SCOTT TRANSFORMER CO. 

I 4454 Ravenswood Ave., Chicago, Ill. 

I Please send me FREE circuit diagram, records,and 

full particulars of the new Scott Shield Grid Nine. 

I 

Check here for proposition 

to professional set builders. 

I Name 

Street 

ITown 

State


Compare With Costliest Sets! 

'LI \JUDI AMY VI II IRAC'D 3'D'DA1 YJ EXPENSEEUNL SS DELIGHTED 

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Wide Selection of 

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AC or Battery Sets 

30 DAYS HOME TRIAL 

A popular walnut Hi- 

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A new -type arm -chair 

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SUPER SHIELDED 

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CATHEDRAL TONED, SUPER SELECTIVE, POWERFUL DISTANCE GETTERS 

Celebrating its 9th successful year, hum -free operation, tremendous 

America's big, old, reliable Radio "kick" on distant stations and 

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its latest, Super -powered, 1 -dial features, including phonograph 

Miracos -the 

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ease of tuning, 

beauty, and 

economy -a 

Miraco will 

make you the 

tubes or the new 

envy of many 

BIG DISCOUNTS 

Exclusive Territory 

to User -Agents on 

BATTERY OR AC 

ELECTRIC OUTFITS 

8 -tube models U whose radios 

All Electric 

wholly self -contained, 

hum - 

free, AC -8 and 

AC -9, using AC 

for batteries or Eliminators -you cost 2 to 3 times as much! 

are guaranteed values and savings Many thousands of Miracosunsurpassed 

in the fine set field. bought after 30 day home corn - 

Compare a Miraco with highest- parisons -are cutting through 

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Surprise and entertain with the tone and power of costly 

your friends -get their opinions. sets, their delighted users report. 

Unless 100% delighted, don't buy Miracos are laboratory -built with 

it! Return everything -the corn- finest parts, and embody 9 years' 

AC-8-$71.50 

Unbeatable value In a 3- 

y r guarar teed Super, 

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ptete outfit -at our expense. Your actual experience in constructing 

decision is final- absolutely! fine sets. Approved by Radio's 

Only exceptionally 

Also 

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radios, highest authorities. 

More 

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you splendidly packed The newest and latest in 

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signed 

dayswith 

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Amazing Special Factory Offer! then decide. 

vanced used 

Liberal 3 -year guarantee on electric sets! Same vide 

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Don't Confuse with Cheap Radios and insure satisfaction by dealing direct 

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With its rich, clear Cathedral tone, sets -9th successful year. 

IMPORTANT 

- t 

NOTICE! 

"-30 Day Free Trial" offers usually are money -back guarantees frequently only on the 

Plea, understand that unless 

"set." 

yr, are 

thoroughly pleased we pay return charges and refund 

the FULL purchase price on both the "set" and ALL equipment -tubes, cabinet. speaker, 

antenna (also on batteries or eliminators mill, ultra -8 sets). Could any ger be fairer? 

MIDWEST RADIO CORP'N,404 -AN Miraco Bldg., Cincinnati, Ohio 

BEAUTIFULLY ILLUSTRATED CATALOG, AMAZING SPECIAL FACTORY OFFER, TESTIMONY OF 

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ofMIDWEST RADIO CORPORATION THIS COUPON 

Pioneer Builders of Sets -9th Successful Year IS NOT 

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Check here if Interested In an EXCLUSIVE TERRITORY PROPOSITION 

u NAME ADDRESS 

est mtality,amazinglylow 

priced! 

8-tube Battery 

Super Shielded 

Cassis $49,88 

Tubes, batteries or eliminators 

and cabinets are 

extra. 30 days home trial 

on EVERYTHING'

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