[RFI] computer RFI

WA2BPE wa2bpe@exotrope.net
Fri, 01 Mar 2002 17:38:57 -0500

Good luck on a real can of worms with the many places EMI can leak out of
computers.  You, however, are starting right.  PC Power & Cooling offer good
cases/supplies.  Also, if any supply doesn't have one, modifying with a
"Corcom"-type line filter will be essential.  Be sure to clean all edges of
paint, etc; if it isn't RF tight, it will leak (I both get a kick and shiver
at the cases with plastic "windows" now available).  You will also need
ferrites on almost everything attached and may still not eliminate all
noise.  Monitors are especially nasty; some are great; others yuch!  BTW, my
concern for 'puter noise is on 6m - yes, it can be bad even up there!!
Check various publications (ARRL, RSGB) and this forum's archives.

73,  Tom - WA2BPE

Berry Griffin wrote:

> Have any of you had any problems with computer "birdies" showing up on
> your HF rigs?
> I just built a fairly fast system but it can not be on when I am on 75
> meters.  There is a 20 over noise level.
> I have already tried all the usual tests, i.e.: I got the computer up
> and running and then unplugged EVERYTHING that was attached to it except
> the Ac cord.
> That made no difference what so ever.  I have and old and slow 200MMX
> sitting less than 2 feet from the radio and other than hearing the fan
> running I can't tell it is on, but this new system, egad!
> I assume it is the switching power supply or RF leaking from the case.
> Are there any ATX power supplies that are know to be birdie free, or at
> least, very quiet?
> How about cases? There must be some  laboratory or medical cases that
> are built to keep the rf in.
> Any suggestions? I do miss having my  hf rig  and  my computer on
> at the same time.
> 73 all!
> W6EZ
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