FC's Micro Power FM Broadcasting Circuits
Power your FM transmitter with solar power by using a
CirKits kit.
FM Bugs
High Quality Stereo Modulator
Here are several high fidelity
FM stereo matrix generator
circuits, they can be used to produce stereo modulation for mono
FM transmitters such as the Free Radio Berkeley transmitters
and similar units.
FM Broadcast Antennas
A good antenna and feedline is essential for making the most out of
your measily microwatts, this 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 PostScript format
(28kb)
A J-Pole antenna for the Ramsey FM10a in GIF format
(11kb)
FM10 Stuff
Here are some utility circuits for use with the Ramsey FM10a, and other
small FM stereo transmitter kits. This information may be helpful for setting
up a micro powered FM radio station.
The FM10a and similar kits tend to put out a low quality, broad band output
signal. This is not a big problem with a 5-10 milliwatt signal, but amplifying
the output of such kits beyond 50mw 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 work with a higher power transmitter, 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
constant temperature
circuit, it is highly useful for stabilizing
VFO circuits like that in the FM10.
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
(16kb)
Description of the FM10a Audio Mixer
Useful Links
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