[Lowfer] PC noise reduction experiments here

[Andy - KU4XR]

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"
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