Ed, you're going to have fun with that. In the 80s i did an RFI study on
med base fluorescent lights. I phoned all the major manufacturers and
explain to them what I was doing and who I was doing it for. Each
manufacturer sent me one of every bulb they made for the test. They
cooperated like they really cared. Many bulbs were discontinued because of
the results of my testing. I think I remember Lights of America (LOA) model
2030 as being the worst.
Michael Martin
RFI Services
51 W Bay Front Rd
Lothian, MD 20711
240-508-3760
mike@rfiservices.com
www.rfiservices.com
On Thu, Aug 24, 2023, 6:35 AM Hare, Ed, W1RFI via RFI <rfi@contesting.com>
wrote:
> There is nothing incorrect in what Jim Brown said at all, and he is
> certainly NOT telling people not to start near the device. He is
> explaining a nuance that is important to understand to avoid a common
> troubleshooting error.
>
> For the most part, on HF, devices themselves do not radiate much, but the
> wires that they are connected to do. That is what Jim is explaining.
>
> How that radiation decays with distance depends on how the noise is being
> conducted onto the wiring. If the wiring were reasonably well balanced,
> acting like a leaky transmission line, the strength of the noise would
> decay at about 60 dB/distance decade within about 0.16 wavelength from the
> source and/or the source wiring. If the noise is conducted to the wiring
> as a common-mode signal, the decay rate would be lower and, if the wires
> are long in terms of wavelength, a standing wave along them is often
> developed, with peaks and valleys that can very much confound locating the
> actual device source.
>
> To understand what Jim Brown is telling you, think of an LED bulb. It is
> too small to be an effective HF antenna, but those long wires it is
> connected to can be great antennas. If the noise from an LED street light
> conducts around (or through) the step-down transformer it is connected to
> and gets onto those overhead distribution lines, it can radiate for quite a
> distance an in some instances, may be stronger at some point other than
> right at the pole it is attached to, depending on what antenna you are
> using for receive. (A loop receive antenna may show a NULL when the null is
> pointed at the source, and as you drive away, that null will disaappear.)
>
> I have retired from HQ, but still volunteer there (quite a bit of time on
> this SMC HF petition.) One of my late summer projects is going to be to
> set up a moble noise-measurement system, using accurate equipment, and by
> late fall, I expect to be making measurements of noise over large
> geographical areas. Measuring the noise from an LED street-lighthing
> system in an entire community should be quite the challenge.
>
> From what I have seen in some of the temporary setups I have used over the
> years, and from just listening on a receiver, most of the LED street lights
> seem to be RF quiet. From the reports I have seen, some are not.
>
> What I don't have is make and model number of the LED bulbs that are
> causing a problem. I am sure I can persuade the ARRL Lab to buy one and we
> can make measurements of its conducted emissions. That will be a good
> starting point. If FCC follows its own lead on past decisions, it will
> proclaim those overhead lines to be "non-residential" environments, as it
> did for BPL over a decade ago, even for street lights in residential
> neighborhood.
>
> Ed Hare, W1RFI, ARRL Lab Volunteer
>
>
>
>
>
> ________________________________
> From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of AA5CT
> via RFI <rfi@contesting.com>
> Sent: Wednesday, August 23, 2023 9:27 PM
> To: rfi@contesting.com <rfi@contesting.com>; Jim Brown <
> jim@audiosystemsgroup.com>
> Subject: Re: [RFI] LED Street lights
>
> I don't know where you're coming from Jim. How long has it been since
> you've been in the 'field' with a portable SW receiver?
>
>
> Noisy devices, power poles, even lighting poles all have distinctive
> signatures heard when standing near them. The CLOSER you get the STRONGER
> will be whatever noise/signal the device *may* be generating. Surely this
> aspect need not be spelled out?
>
>
> I still stand with the advice as a first tier investigation to GET NEAR
> THE DEVICE and inspect the ham bands for any anomalous noise. This isn't
> rocket science. This e-mail was a response to Eric for advice looking at a
> NEWLY installed LED lighting pole. Eric, if you have a SW/HF radio in the
> car that might be a way to do a first tier/first pass inspection of the new
> lighting pole too.
>
>
> de AA5CT Jim
>
> ---------------------------------
>
>
>
> On Wednesday, August 23, 2023, 7:54:53 PM GMT-5, Jim Brown <
> jim@audiosystemsgroup.com> wrote:
>
> On 8/23/2023 5:17 PM, AA5CT via RFI wrote:
> > Hmmm ... if an exotic receive apparatus is required to 'spot the noise',
> how serious could the noise really be?
>
> Not all noise is broadband. Indeed, most electronic noise is not. And
> the receiver cited makes an excellent spectrum analyzer. Most noise is
> radiated by wiring, not by the fixtures themselves.
>
> NK7Z's webpage provides lots of excellent troubleshooting advice for
> chasing electronic noise.
>
> 73, Jim K9YC
>
>
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