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Re: [RFI] Motherboard RFI

To: rfi@contesting.com
Subject: Re: [RFI] Motherboard RFI
From: Peter Laws <plaws@plaws.net>
Date: Mon, 4 Jan 2010 21:58:10 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On Sat, Jan 2, 2010 at 11:40, Peter Laws <plaws@plaws.net> wrote:

> Pulled the cables off one by one.  Got to the motherboard's COM1 and
> all noise vanished ... well, at least where I was listening on 17 m
> (around 18130.0).  OK, a couple snap-on chokes got rid of some but not

Made a little progress this evening.  Took the PC apart and took the
MoBo out.  Found where Thor had been and caused an SMD cap to leave
this plane of existence.  Again, Thor's visit was in 2007 and I have
no idea if the RFI was there before the visit or not.  And the only
thing affected was the built-in network interface.  No cracking or
other obvious mechanical issues on the board.  Plenty of dust.  :-/

All metal stand-offs were present with screws.  I did add more studs
to empty holes in the case for support ... though I didn't check to
see if those interfered with anything under the board.  Oops.  I'm
typing on it now, so nothing shorted.  :-)

Interestingly, after it was all re-assembled ... and worked! ... the
noise on 17 moved up about 12-14 kHz.  This is a good thing given that
more DX stations seem to call on 18130 than on 18143+/-.  :-)

Another time, possibly tomorrow, I'll do the poking the board with a
non-conductive stick thing and see if the noise still changes.

BTW, the snap-on chokes were really cool.  The noise was actually
there until the two halves clicked together.  Just like theory says.
:-)  Someone said toroids are better.  No doubt, but they don't fit
over DB9s very well.


Peter Laws | N5UWY | plaws plaws net | Travel by Train!
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