My radio was unusable until I added an isolation transformer between the mike input and audio output (1 each). Just used junk box transformers with no idea of the input/output impedance. The PC Sound card is very high impedance so no need to assume you need to have a 1:1 or 20K to 4 ohm, picked for their size (SMALL ) Signal level was such that I had to add a 100K/1K divider feeding the Sound card. Got rid of all noise except the noise from the oscillators in the PC and monitor. Since you end up adding the CAT-IO interface it is kind of hard to eliminate any ground return (and associated ground-loop) unless you also add an optical isolator.
Rich, KE0X _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
