[RFI] Noise Level During Power Outage

[K9MA]

When I bought some LED fixtures for the kitchen a few years ago, I 
connected a power cord to them at home and tested them for RFI before 
installing them. All were OK. One of my neighbors unwittingly helped me 
identify a quiet power supply for LED light strings, by having a very 
noisy one, The vendor replaced it with one from a different 
manufacturer, which was quiet. I bought some of those for my own home.

73,
Scott K9MA



On 2/1/2023 4:07 PM, Pete Smith N4ZR wrote:
> Very interesting and timely (at least for me).  I am at the beginning 
> of an extensive basement redo, which will involve on the order of a 
> dozen round 6-watt equivalent LED lights in the ceiling.  I was 
> concerned about the same sort of problem, so I bought one example and 
> plugged it into an outlet strip on my operating desk.  I could find no 
> RFI anywhere in HF (or rather nothing that turned on and off with the 
> light fixture).
>
> For anyone who wants to know, the light I tested is a Commercial 
> Electric 6" recessed light kit.  It is made in Thailand and sold by 
> Home Depot.  The item number is 1005 591 792.  The light itself feels 
> like there is a transformer behind the LED panel - simply based on 
> weight. I wrote to Commercial Electric to inquire, and the only 
> response I got was, essentially, "Huh?"
>
> Do those of you who understand such things, more than I do, think that 
> I'm probably safe in going ahead with these units, based on my test?
>
> 73, Pete N4ZR
>
> On 2/1/2023 4:22 PM, Gary NA6O via RFI wrote:
>>>> On 2/1/2023 4:52 AM, K9MA wrote:
>>>>> Besides the preponderance of 120 Hz harmonics in the AM audio, the
>>>>> very broadband nature of line noise is usually the main indicator.
>>>> 120 Hz is also a strong component of electronic noise generated by
>>>> power supplies and power control equipment. The audio spectrum is not
>>>> a great clue -- the RF/IF waterfall shows where the bodies are buried.
>>>>
>>>> 73, Jim K9YC
>>>> _______________________________________________
>>>>
>>> That's true, but I have never seen broadband noise with 120 Hz 
>>> harmonics
>>> in the AM audio which was NOT power line noise. And, alas, I've seen a
>>> lot of line noise.
>>>
>>> 73,
>>>
>>> Scott K9MA
>>
>> I have an LED fixture for you that produces 120 Hz buzz over decades 
>> of bandwidth, nearly indistinguishable from an arcing power line: The 
>> Elite RL675. Twenty-one of these, installed next door, resulted in a 
>> 1.5 year shootout including ARRL and the FCC and even after 
>> mitigation left my home station permanently QRT. Yes, it can be that 
>> bad... Full story is on my RFI page. Here are detailed measurements 
>> on said fixture:
>>
>> https://na6o.com/main/RFI_files/Elite%20RL675%20RFI%20Test%20Report.pdf 
>> <https://na6o.com/main/RFI_files/Elite%20RL675%20RFI%20Test%20Report.pdf> 
>>
>>   73,
>> Gary NA6O
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-- 
Scott  K9MA

k9ma at sdellington.us