I’ve already shown the round loop FM microphone that I posted here – it used 12AWG solid bare copper house wire. I wanted to make a transmitter using loop out of thinner wire, which is more common. But thinner wire moves around too easily causing the frequency to change. So I twisted together three strands of 24 AWG solid copper insulated wire, I think that they’re from Cat 5 datacomm cable. They’re tightly twisted. Then to hold it still I taped the wires to the end of a 1.5 inch or 38mm square plastic tube a few inches long.
The frequency is at the bottom of the FM broadcast band, around 90 MHz, but can be adjusted a few MHz with the ceramic trimmer capacitor labeled 2 in the photo. I put the 10 pF silver mica in parallel with the trimmer, but it would have been better to use a 6.8 pF (labeled 4) which would have allowed the trimmer to tune higher in the FM band.
