[600MRG] RFI identified

[Brian Pease]

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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>>
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>
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