FC's Micro Power FM Broadcasting Circuits
Power your FM transmitter with solar power by using a
High Quality Stereo Modulator
This FM stereo matrix generator circuit
can be used to produce stereo modulation for a variety of mono
FM Broadcast Antennas
A good antenna and low-loss feedline are essential for making the most out
of your measily microwatts. This J-pole design works very well if you tune it
up properly. An SWR meter is a must for setting up this antenna.
A J-Pole antenna for the Ramsey FM10a in GIF format
A J-Pole antenna for the Ramsey FM10a in PostScript format
Here are some utility circuits for use with the Ramsey FM10a and other
small FM stereo transmitter kits, such as those that are based on the
Rohm BA1404 IC.
The FM10a kits tend to put out a low-quality, broad-band signal.
This is not a big problem with a 5-10 milliwatt signal, but amplifying
the output of such kits beyond 100mw is a bad idea, as the amplified signal
can cause interference with other radio services, drawing unwanted attention
to your hobby station.
If you want to transmit with higher power, find a better quality
transmitter such as the
Free Radio Berkeley Mono PLL kit, and build my circuit
for an FM Stereo generator (above).
Here are some tips on squeezing the most performance out of an FM10a kit:
Five Essential mods for the Ramsey FM10a
Also see my
circuit, can help to reduce frequency drift in transmitters like the FM10a.
Better yet, just get a PLL-based transmitter that does not have the
frequency drift problem.
Audio Mixer for the Ramsey FM10a in GIF format
Description of the FM10a Audio Mixer
to FC's Electronic Circuits page.