Topband: [RFI] Computer RFI on 160

[Jim Brown]

On Wed, 29 Oct 2008 15:40:52 -0400, Bill Tippett wrote:

>On-site I tried about 8 turns of the
>power cord through a Mix 31 2.4" toroid, but that didn't dent the
>noise enough.  

I wouldn't expect it to. You need at least 14 turns on a single #
31, and more turns or more toroids in the stack is better. Use my 
measured data for RG8X on these cores as a starting point. In 
essence, you've got to move the low Q resonance of the ferrite 
choke down to 2 MHz. 8 turns on a single #31 puts the resonance in 
the 5-7 MHz range. 

http://audiosystemsgroup.com/RFI-Ham.pdf

It's good to hear that the Corcom filter worked for you. A surplus 
warehouse in the Bay Area has a bunch of filters like you 
describe, and they have an internet presence. I've seen Corcom, 
Delta, and several other brands there at good prices. 

http://www.halted.com/

There's also good data for Corcom and Delta on the internet. 
Google on part numbers to find it. 

73,

Jim K9YC