In a message dated 11/04/05 13:52:21 GMT Daylight Time, [EMAIL PROTECTED] writes:
There must be some sort of ground loop associated with the "new" (less old) computer. The old computer was a Toshiba laptop (circa 1994) running Windows 95. The "new" one is a desktop (circa 1997) running Windows 98. ------------------------------------------ The addition of an extra RF filtering cap and an approx 1mH choke in the K2 mic lead may help in removing that as an RF path into the radio. Notes for implementing this are on the Elecraft web site. Additionally it may be worth a try adding a 600 ohm 1: 1 transformer in the audio path to the sound card. I found my Spectrogram test results had a spike at 100Hz intervals (probably 120Hz in the USA) from our 50Hz AC power superimposed on the trace. Presume this was due to the SM power supply in the computer being held above ground at RF with the power input filter network. An isolation transformer offered a total cure. Yours is a different type of problem, but the isolation of the two devices may help. Found a later lap top computer also with a SM PSU gave similar spike problems. Don, W3FPR offered advice at the time to recover this type of transformer from redundant PC modem cards. Bob, G3VVT _______________________________________________ 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
