[RFI] Computer RFI problem

[Rob Atkinson, K5UJ]

I for one have been educated which is never a waste of time for me.  I have 
had a similar odd problem in the form of qrn from AC power line noise.  It's 
odd because at its worst, I rx it on 20-80, and 15 but 17 meters is 
strangely quiet.  Re the computer noise, if I had to guess I'd say the rf 
from the computer is getting rejected everywhere except as some sort of 
product at some stage in the receiver, mixing and coming out on 14 mhz which 
might explain the one band phenomenon?

Rob Atkinson
K5UJ


----Original Message Follows----
From: "James C. Hall, M.D." <nwtncc@iswt.com>
To: "Ian White, G3SEK" <g3sek@ifwtech.co.uk>, <rfi@contesting.com>
Subject: Re: [RFI] Computer RFI problem
Date: Thu, 8 Aug 2002 12:48:32 -0500

Jim, I hope you haven't been up in the loft re-routing the coax! If not,
 > Rob is the one you have to thank for saving you a lot of wasted time -
 > and once again, my apologies

Ian and Rob:

I have been following this thread with great interest and no - haven't
ventured into the rafters ... yet  ;)  Certainly it makes sense to go after
the offending source as agressively as possible.  I have - with toroids and
chokes on all cables eminating from the computer and, as mentioned before,
replacing the power supply with a much cleaner and filtered one.  This
eliminated my problem with low band interference last year.  The monitor has
also been replaced and is very quiet.  What I don't get is why 1) I didn't
have the problem with the previous R7 and now do with the R7000 and 2) why
only 20 meters.  Turning off the computer (but not the monitor) absolutely
cures the problem - 100%.  What in the computer could be singing at 14 MHz
???  And why all of a sudden now ?  Nothing in the computer is failing as
far as I can see.

Jamie
WB4YDL


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