[Lowfer] 600MRG> PC noise reduction experiments here

[dave.riley3]

A small AM hand held radio makes a great noise sniffer...

If you want more definition, make a small e-probe and couple it to the 
radio. then search around...

TNX from Dave @ /17


----- Original Message ----- 
From: "Andy - KU4XR" <ku4xr at Yahoo.com>
To: "600 meter group" <SHMRG at piobaire.mines.uidaho.edu>; "Part-15 Yahoo" 
<part15 at yahoogroups.com>; <lowfer at mailman.qth.net>
Sent: Tuesday, January 26, 2010 12:11 PM
Subject: 600MRG> PC noise reduction experiments here


> Well OK !! I get it now !! the aluminum foil on the power cord
> wasn't a worthwhile effort, But don't let the aliens know that.
> Here are some things I tried, and what happened. I took the side
> panel off the PC, ( radio on, tuned to the noise ) and right away
> the noise started to lower in frequency on 600 meters, dropping
> from around 505 KHz down to around 488 KHz. --- 17 KHz of shift!!
> just by removing the panel. I won't even pretend to know why that
> happened. ( I know; somebody wants to make a smart crack about
> just use it with the panel off ). I have read that the ribbon
> cable to the HDD can radiate some nasty noise at times, so I
> twisted it into a round cable, and snapped 2 ferrite cores on it
> at the MOBO end, then passed it 2 times thru one of the square
> snap on cores from radio shack. I also put a fairly large snap
> on around the power supply wires right at the MOBO. Turned the PC
> back on, and the noise was still below 600 meters. I put the side
> panel back on, and slowly the noise started to rise in frequency,
> and finally stopped at around 498 KHz +/-. On USB the noise is
> gone at 501.5 KHz. So at least the noise as of last night had
> shifted out of the main portion of 600 meters, and I had the
> lowest noise level I've ever had. Just to try it; I wrapped the
> mouse cord thru a snap on about 4 turns, Nothing !! did the same
> with the keyboard, Nothing !! I took my 4 foot coax jumper to the
> radio and wrapped it 3 times thru a square snap on, did it twice
> for a total of 6 turns. There was improvement but very little at
> 600 meters as would be expected. The best improvement was on the
> higher HF bands. It helped to clean up 160, 80 meters is a total
> wipeout with hash noise, 40 is clean as a whistle, and on 30 mtr,
> only about 6dB of noise ( one S-unit ) with the PC on, whereas
> before, 30 mtrs was unusable. AND !! I discovered that the PC has
> a shielded power cord on it already.
> My PC at the rig is not the only noise source for me, but it is
> the closest, and most difficult.
>
> It was nice to tune across 600 meters and not have to listen to
> all the buzz, and hash.
>
> 73 everyone ::::
>
> Andy - KU4XR - EM75xr - Friendsville, TN.
> LOWfer Beacon " XR " @ 185.29866 KHz ( QRSS-60 )
> Coordinates:  N:  35* 43' 54" - W:  84* 3' 16"
> http://www.myspace.com/beaconxr
> http://webpages.charter.net/ku4xr/
>
>
>
>
>
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