[600MRG] RFI identified

[Paul N1BUG FN55mf]

There is only one light dimmer. It was one of the first things to go on
my suspect list, but turning off the circuit breaker to the circuit it
is on makes no difference. The dimmer isn't needed and will be removed
soon as a precaution but it appears it isn't the enemy I am looking for.

Paul, N1BUG



On 1/3/2025 2:12 PM, Brian Pease wrote:
> If there is a light dimmer in the house it is a prime suspect and the
> only cure may be to get rid of it.
>
> A great RFI tool is a battery operated AM radio tuned to the low end.
>
>
> On 1/3/2025 1:40 PM, Paul N1BUG FN55mf wrote:
>> Renee, same thing here. Old 1980s fridge never a problem. New 2024
>> fridge big problem.
>>
>> My house is full of assorted LED bulbs, most of which appear to be no
>> problem in that I cannot detect whether they are on or off on either
>> 630m or 2200m. I do have one strange thing happening however. I've got a
>> nasty RFI source on 2200m that is either in my ham shack or not on my
>> premises. I'm not yet certain which, since my receiver is SDR I can't
>> power down a lot of stuff here in the shack to check. The thing is, with
>> my kitchen LED lights ON, that RFI drops 10 dB or more. With the lights
>> OFF, out of the sockets, or the circuit breaker off, the RFI is 10+ dB
>> stronger than when those lights are on. I don't know what is going on
>> there. It's like those bulbs actually absorb RF! Also that source is
>> reduced 2 to 3 dB with my microwave oven plugged IN vs. unplugged. Weird?
>>
>> Paul, N1BUG
>>
>>
>>
>> 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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