This new FM transmitter has been developped to work in a stand alone mode or with a power amplifier unit.

In fact, 30W output power is enough to cover a small town about 15000 people.

The FM synthesizer, the 30w mosfet amplifier and finally the stereo coder included in this design have been already described on this website.

You will find below some pictures of this new homemade transmitter.

 

Exciter Specifications

Frequency Range : 87.5 MHz–108 MHz
RF Power Output : 0.5-30 Watts adjustable(VSWR 1.8:1 or better)
RF Output Impedance : 50 Ohms
Frequency Stability Meets ETSI specifications from 0-50 degrees C
Audio Input Impedance 10kΩ
Audio Input Level adjustable from –10 dBm to +10 dBm for 75 kHz deviation at 400 Hz
Audio Response Conforms to 50 μsec pre-emphasis : ±0.5 dB (30 Hz–15 kHz)
Distortion (THD + Noise) : Less than 0.2% (30Hz-15kHz)
Stereo Separation : Better than –45dB (30Hz-15kHz)
Stereo Pilot 19 kHz ±2 Hz, 10% modulation
Subcarrier Suppression 50dB below ±75 kHz deviation
FM S/N Ratio (FM noise) : Better than –65dB
RF Spurious/Harmonic Products Better than –60dB
Operating Environment Temperature (0°C to 50°C)

The Power Supply: