For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics. http://www.hamtronics.com/r303.htm When hooked up to the discriminator on the hamtronics board, I could not get the RTCM to calibrate squelch. It usually told me the audio was too low weather the RX level was bumped up or down. I then hooked it up to a motorola SM50 and it calibrated shortly after adjusting RX levels. So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output. Here is the SM50 discriminator out: amsatnet.info/SM50.png Here is the hamtronics discriminator out: amsatnet.info/HAMTRONICS.png Here is an audio sample comparing them (you can probably guess which radio is first): amsatnet.info/Sm50_hamtron_DISC.wav Does anybody else have experience with hamtronics receivers? Thanks, Skyler KD0WHB