[RFI] Audio Interfacing to Sound Card and RFI

Pete Smith n4zr@contesting.com
Mon, 19 Nov 2001 13:12:21 -0500

At 12:39 PM 11/19/01 -0500, Peter D. Vouvounas wrote:
>Boy this sounds familiar!!!!
>This weekend was the first time that I tracked the same type of issue....
>Yes I've operated before with WriteLog and found some RFI / audio issues but
>it was in the heat of battle. 

I wouldn't think this is Writelog specific.  This weekend I had a lot of
trouble with my SBDVP software based sound-card system.  Traced it to the
"mic in" line on the sound card, and largely cured it with a single Radio
shack snap-on toroid on the mic line with about 6 turns, close to the sound
card.  I'm going to work up a better fix, because there is still a litle
raspiness on the worst band, but it is a LOT better.

Seems to me it makes sense to look at any line that runs into an amplifier
with relatively high gain, and to apply the RFI fix as close to the
amplifier as possible.

73, Pete N4ZR