Some LEDS are good. The small simple non-dimmable ~60W equivalent bulbs are the best because they do not have a switching power supply. The circuit is basically a bridge rectifier with a capacitor in series with the AC power to act as a current source. Absolutely zero EMI. Pretty good for ~$1.00 each  at Ace Hardware.

I have some inexpensive Braun 5000 lumen shop lights from Harbor Freight in my lab that are quiet, which surprised me because other HF items such as battery chargers have been terrible.


On 1/3/2025 12:49 PM, Renee K6FSB wrote:
I had same/similar issue extended up into HF and found a simple 20Amp Line filter did the trick for me. I had found it in a surplus store ( like in 2000) and had it for a rainy day....when I replaced the fridge the issue started...old 1970 fridge = no issues , new 2005 fridge  needed filter.
same thing for some of the led replacement florescent bulbs, they may need rfi proof...some companies cheap out..there is a place on their board but no parts....
Renée, K6FSB


On 1/3/25 9:13 AM, Brian Pease wrote:
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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