[600MRG] Fw: RFI identified

[sbjohnston at aol.com]

Clamp-on ferrite chokes of the right material  on the AC power wiring at the cabinet of the fridge might help reduce the conduction and/or radiation of the noise.  Or one could try one of the shielded line filters like this:


And here's a view of one installed in a chassis for a project I am building here at WWVH...



You might be able to mount it to the metal frame of the fridge for ground-bonding.  It might also be helpful to confirm the fridge itself is well-grounded. 


Steve WD8DAS   

sbjohnston at aol.com   
http://www.wd8das.net/   http://af4k-crystals.com/   
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Mein Ohr ganz nah am Weltempfänger...


 

    On Friday, January 3, 2025 at 06:48:06 AM HST, Paul N1BUG FN55mf <paul at n1bug.com> wrote:   

 Since my return I have been plagued by periodic RFI that reduces S/N on
630m by 10 to 15 dB, maybe more at times. It tends to cycle on for one
to three hours, then be off for a few to several hours. Audibly in AM
mode it is a somewhat rough 120 Hz buzz. Noise blankers don't touch it.
I can identify this RFI from below 10 kHz to above 500 kHz, but there
are several broad peaks and valleys across the range. The worst of them
is very broad centered approximately on 450 kHz but remaining almost
flat up to and across 630m. I have not tried to find the upper frequency
limit since I really don't care about anything above 500 kHz.

Early this morning I found it the culprit. It is my refrigerator!
Perhaps a line filter will help, although my luck is rarely that good.

I'm still chasing one, possibly two serious RFI sources affecting 2200m
but won't go into that here.

73,
Paul N1BUG

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