[600MRG] RFI identified

Brian Pease bpease52 at gmail.com
Fri Jan 3 12:13:19 EST 2025


Experimenting is in order. One thing you could try, *with care*, is to 
plug in the fridge with a cheater adapter that isolates the frame from 
ground to see if that helps. As a next step, ground the frame to 
something other than the power line 3rd wire. Another thing would be an 
old school 60Hz isolation transformer, although I have found there tends 
to be too much capacitance between windings. A transformer with a 
groundable shield between windings might work. You could try a UPS if 
you had one large enough, but of course they can be their own source of 
RFI.  Then it is on to the line filter option.


On 1/3/2025 11:47 AM, Paul N1BUG FN55mf 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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