[RFI] Noise Level During Power Outage

[Hare, Ed, W1RFI]

What was the model number of the offending device/supply?

If a device does meet the FCC emissions limits, it is still likely that it will exhibit moderate interference when used in an amateur's own home.

Ed


________________________________
From: RFI <rfi-bounces+w1rfi=arrl.org at contesting.com> on behalf of David Eckhardt <davearea51a at gmail.com>
Sent: Wednesday, February 1, 2023 7:03 PM
To: K9MA <k9ma at sdellington.us>
Cc: rfi at contesting.com <rfi at contesting.com>
Subject: Re: [RFI] Noise Level During Power Outage

In specifying this home and the lighting, we had some task ceiling lighting
installed.  I specified only "transformers" to power the lights as they
operated on 12 vdc.  You can guess what came next.  Sure I got the modern
incantation of an iron-and-copper "transformer", an "electronic"
transformer, a.k.a., switcher.  Of course, lots of RFI.  After two days of
searching on the www for the ultimate supplier of the lighting, I hit
paydirt.  When I relayed the problem to them, the answer came back, "Oh,
you can't use those with radios.  You need the FCC kind."  OK, I ordered
the FCC approved "transformers" - at 4X the price of the switchers.
Further, they had only some 120 of the FCC units in stock and tens of
thousands of the switchers in stock.  Need I write more.......

Dave - WØLEV

On Wed, Feb 1, 2023 at 11:24 PM K9MA <k9ma at sdellington.us> wrote:

> 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
> >> _______________________________________________
> >> RFI mailing list
> >> RFI at contesting.com
> >> http://lists.contesting.com/mailman/listinfo/rfi
> > _______________________________________________
> > RFI mailing list
> > RFI at contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
>
>
> --
> Scott  K9MA
>
> k9ma at sdellington.us
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>


--
*Dave - WØLEV*
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