Total posts : 45366
I havent had problems detecting harmonics using a quality TV band variable tune radio using TV channels 7-13. The transmitters that I use “for Lab use”, put out a fair ammout of power at the operating frequency. The second harmonic travles about a fourth block, still to much for me but pretty good as far as im concerned.”
has me wondering a bit. The second harmonic from the FM band (88 to 108 MHz) could be between 176 and 216 MHz which is withing the channel 7 to 13 band of 175 to 216 MHz so you are probably hearing the second harmonic. If this is heard from about 1/4 block distance (blocks = ????feet) I wonder how far your third harmonic (264 to 324 MHz) is going. Usually in unfiltered transmitter circuits the odd harmonics are stronger than the even harmonics since they result from clipping in the amplifiers or symmetric non-linearities.
If I heard my second harmonic as far away as you report I would immediately take the transmitter off the air. How far is your first harmonic going? (the first harmonic is the fundamental, that is, it is your transmit frequency).
You are correct in your observation that computers generate hash and perhaps vermonter will try what you suggest.