From:Cecil_A_Moore@ccm.hf.INTel.COM (Cecil A Moore) Newsgroups:rec.radio.amateur.misc Subject:Ramsey FX transceiver kits Date:8 Jun 93 22:20:07 GMT Organization:ucsd usenet gateway Lines:29 Message-ID:<930608142007_2@ccm.hf.intel.com> NNTP-Posting-Host:ucsd.edu Originator:daemon@ucsd.edu For all you Ramsey FX transceiver kit owners, here are some needed modifications. 1. How to cure the transmit audio problem. Ramsey engineers forgot to put load resistors on the outputs of the LM324 so above a certain level the transmit audio has cross-over distortion. Install a 10k ohm resistor from U4 pin 1 to ground and another 10k ohm resistor from U4 pin 7 to ground. They forgot to put in a transmit audio gain control for loud mouths, like me. Replace the audio gain resistor, R58, with a 2k ohm pot which allows gain control so loud voices do not saturate the op-amps. 2. How to cure the squelch problem. The squelch circuit does not have enough hysteresis. Turn R24 around so the bottom is where the top used to be. Solder the anode of a 1N34A to the new top of R24 and solder the cathode of the 1N34A to where the bottom of R24 used to be. Solder a 10k ohm resistor from the anode of the 1N34A to +5v (top of R11). This allows pin 10 of U1 to swing 0 to +5v like it was designed to do, instead of swinging 0 to 2.7v with not enough hysteresis. 73...KG7BK Cecil_A_Moore@ccm.hf.intel.com  Amsterdam View Our Stats   CLICK FOR A FREE DOMAIN NAMES HTTP://WWW.YOURNAME.TK FOR YOUR OWN WEBSITE IF YOU CLICK HERE AND YOU CAN VOTE FOR OUR FREE WEBSITES IN THE TOP 100 LIST  WANT A TOP RANKING ? USE THE ULTIMATE SOFTWARE SUITE FOR WEB SITE PROMOTION  FreeWebSubmissions Submit Your Site To The Web's Top 50 Search Engines For Free THE ALEXA BANNER, THIS BANNER GIVES THE DALLY STATISTICS OF THIS FREE WEB SITE The World of Free Packet Radio Software Amsterdam The World Of Free Packet Radio Software Amsterdam The Netherlands |