Bob,
See http://audiosystemsgroup.com/HamInterfacing.pdf Do these steps in order,
and stop when it's fixed. :)
1) Bond every chassis to every other chassis, INCLUDING THE COMPUTER, with
short beefy copper braid (like what you can strip from good RG8). On some
computers, you'll need to go to the retaining screw of a DB9 or DB15
connector to find the chassis.
2) Add a ferrite choke to the interface cable tuned to the transmit
frequency. See http://audiosystemsgroup.com/RFI-Ham.pdf for detailed winding
info.
3) If you have a real serial port, you can build a simple Kenwood interface
into a connector. It's nothing more than a zener and a resistor or two. Poke
around on the internet to find details. Works great with N1MM, Writelog, and
Ham Radio Deluxe. I've used it with legal power, both in Chicago with
antennas only 20 ft from the radio, and here in CA with antennas more spread
out.
4) Study my serial cable built with CAT5. That solved some really severe RFI
between my computer and my K2/100 back in Chicago.
73,
Jim Brown K9YC
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