Dave, As a big home brewer, I tend to pick things apart... Besides the lack of agc, the receiver really works well for such a low parts count.
I received my modulator chip today, thanks, and installed it. I got about 30% modulation with the led flashing, using an old electret condenser microphone. I changed some values around, and tried a small pot to set the modulation levels, but am still working on it. With the feedback loop open, its possible to get over 100% modulation, a good sign! The microphone sounds semi nasty, but very punchy, which is what you want with low power. Thanks for the fun kit! Brett N2DTS ----- Original Message ----- From: <k1...@earthlink.net> To: <brett.gazdzin...@verizon.net> Cc: <amradio@mailman.qth.net> Sent: Saturday, April 10, 2010 8:07 AM Subject: RE: [AMRadio] retro 75 > > Brett- > > Glad you found a solution. So far, I haven't heard from anyone else > experiencing this issue. > > I set the audio volume on the Retro-75 up for 'room-filling' levels. The > ALC control engages only at high signal levels and keeps the LM386 audio > final from clipping. With the 3" speaker I'm using, I can fill the entire > house with audio before this happens. It's admittedly not much of an AGC > function per se. > > It wouldn't be too difficult to improve on the receive AGC action, but it > would take more complexity. In particular, an additional audio amp stage > would provide the levels needed for a lower AGC threshold. The AF gain > control would also need to be relocated outside the control loop. > Otherwise, the gain control does nothing once the threshold has been > reached. I solved this on the old WM-75 with a 100-ohm pot/rheostat right > at the audio output. > > 73- Dave Benson, K1SWL > ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
