Part Number: RBS-RF100

Short Description: PLL FM Transmitter Circuit Module 7W 87.5-108 Mhz for Amateur and Professional Fm Broadcasting Station Adjustable Frequency 7 Watt VHF Radio Band RF Amplifier with 2x16 LCD Module


This PLL transmitter circuit module is specially designed for broadcasting in the FM band. The product consists of PLL control and RF amplifier circuit board units. The broadcast signal connected to the audio input can be modulated at the desired frequency between 87.5-108 Mhz thanks to the precision PLL control. In addition, the output power of the transmitter can be adjusted between 0 - 7 Watt.

A compact structure is made by connecting the power transistors to the heatsink under the circuit. In this way, the circuit is ready for use directly, without requiring any mechanical installation. No need for extra cooling.

Broadcast frequency can be adjusted via the ADJUST knob by following the LCD screen on the control circuit. Frequency adjustment and also the current status of frequency locking (UNLOCK, LOCK, LOCKING) can be followed with a 2x16 LCD screen. On the control card, there are UNLOCK and LOCK signal leds related to locking. Locking can also be monitored with these leds.

The lamp at the RF output of the transmitter is for both output testing and dummy load. You can test the circuit with this lamp. Before using the circuit, please remove this lamp and never operate the transmitter circuit without a load.

Harmonic components in the RF output are considerably reduced thanks to the LP filter. Impedance output is adjusted for 50 Ohm load/antenna. Function tests, broadcast test and output power test of all PLL FM transmitter modules are performed before shipping. During these tests, trimmer capacitors and trimpot resistors are adjusted. You are free to change these settings according to your usage needs. Please follow the instructions for this.


Our HQ Stereo Encoder and Clipper/Compressor/Limiter circuit modules can be used to take the broadcast quality one step further and reach the professional broadcasting level. In addition, our RDS Encoder module can be used to send dynamic information and station messages. These circuit modules are compatible with this PLL FM transmitter.


Applications

- FM broadcast,
- Audio and signal transmission systems,
- Data transfer systems,
- Preamplifier for FM Power amplifiers,
- Possibility of use as a signal generator for 87.5 – 108 MHz,


Highlights

- Phase locked precision frequency control,
- Wide Band: 87.5 – 108 MHz broadcast frequency range,
- 0.05 Mhz (50 kHz) frequency adjustment step,
- Adjustable output power up to 7 Watts,
- Very stable output power,
- Low Pass Filter (9 pole LPF) at the output,
- Low level harmonic components and spurs,
- Suitable for use before Power Amp,
- Polarity protection,
- Low noise and distortion,
- Adjustable audio input gain,
- Adjustable circuit supply voltage,
- Fine output impedance adjustment according to broadcast frequency,
- Fine frequency tuning adjustment,
- Two pre-emphasis settings (with Jumper), 50us (EU) or 75us (USA)
- Ability to transmit MPX and RDS signal,
- Audio input filter (with Jumper),
- Possibility of boxing with the ground ring around the circuit and creating a Faraday shield,
- Separate ground ring for modulation unit,
- Internal heatsink,
- Input for RDS encoder,
- RCA input for audio signal, compatible for stereo encoder (MPX),
- Connectorless RF output for the most comfortable use,
- Compact structure for boxing and ease of use,
- User-friendly with LCD screen and indicator LEDs,
- Control with a single button,
- RF Output on/off setting,
- Storing the last set frequency.


Technicial Specifications

- Supply Voltage: Min 15Vdc, Max17Vdc (Supply voltage affects output power),
- Current: 140mA when output is off, Max: 900mA when output is turn on (variable in frequency band),
- Frequency Control: Phase Locked Loop Synth,
- Frequency Band: VHF, FM 87.5 – 108 MHz,
- Frequency Adjustment Step: 0.05 Mhz (50 kHz),
- RF output power: Max 7 Watt (adjustable with trimpot),
- Output impedance: 50ohm,
- PLL frequency locking stability: <± 50Hz Max (< 0.6 ppm),
- Fine Tune Adjustment: ± 200Hz Max (crystal controlled, on board),
- Harmonic Rejection: Better than -46dB down on carrier,
- Spurious: Better than -68dB down on carrier,
- Dimensions: PLL Circuit 140 x 84 x 45 mm, LCD Circuit: 115 x 50 x 38 mm.


Setting and Functions

For the PLL transmitter circuit:
- Trimpot for increase audio input gain (named trimpot R4),
- Trimpot for increase the RF output power (named R25 trimpot),
- Trimpot for fine adjustment of supply voltage (named trimpot R2),
- Fine frequency adjustment for PLL (C19 trimmer),
- Preamplifier impedance adjustment (C31 and C32 trimmer),
- Output impedance adjustment (C35 and C36 trimmer),
- 50us (EU) or 75us (USA) pre-emphasis settings (jumper position on JP1: 1-2 is 50us, 2-3 is 75us),
- Audio filter (can be turned On or Off by changing the jumper position on JP2).

For the control circuit:
- LCD contrast (trimpot named Contrast),
- Up and down encoder with button for frequency adjustment (Adjust knob).


ADJUST knob is the encoder with push button. You can increase or decrease desired broadcast frequency via turning knob and set frequency with pushing the knob. When the circuit is powered for the first time, the RF output is off, after adjusting the broadcast frequency and set it, the PLL locks to the frequency within 2-3 seconds and the RF output is turned on. To turn off the RF output, it is enough to press the knob again. When the RF broadcast output is on, the frequency adjustment function is disabled to prevent the frequency from changing with any wrong touch. You can set the broadcast frequency again by turning off the RF output.


Fine frequency tuning for PLL does not affect normal operation. Adjustment is not necessary, the PLL frequency is very precise. More precise adjustment can be made with the help of frequency counter.

LCD Screen Functions and Indicators:

1. Interface
- During the broadcast frequency setting, the frequency is followed.

2. Interface
- This screen appears after the frequency is set,
- The current broadcast frequency set is displayed,
- PLL locking status is displayed (Unlock, Locking …, Locked),
- The green led lights up if the PLL is not locked,
- The red led lights up if the PLL is locked.

If you have any problems during installation and use, please contact us. Do not hesitate to contact us. We will be happy to solve your problems.