[Elecraft] OT: Street lights - for US hams only

[Matthew Cook]

Be thankful that you're not seeing your sodium lamps replaced with LED
solutions, the number of streetlights in the average suburb are quite
simply staggering.

Don't think for a second that these LED lamps were designed for low noise
or that compliance with EMC standards will prevent unwanted interactions.

A single LED luminaire is permitted to conduct and or radiate RF across HF
up to and including 50dBuV, which equates to S9+15dB  (S9 ~ 34dBuV into
50ohms).

I'm now resigned to moving my HF station out and into a remote location
that doesn't have these nasties with a bulls roar of my receiver..

Sad but true.

73

Matthew
VK5ZM

On 18 September 2017 at 14:46, Al Lorona <alorona at sbcglobal.net> wrote:

> Yellow sodium vapor street lights can be a significant source of nighttime
> RFI on the lower bands. They are ignited at dusk by an RF arc that
> typically lasts between 5 and 10 seconds, the lamp lights, and the arc is
> extinguished. This arc noise sounds like a constant, dense static and is
> easily seen as a higher noise floor of up to 10 dB on the screen of a P3
> panadapter or equivalent, depending on how far the street light is from
> your antenna.
>
> The problem occurs when the lamp reaches end-of-life. After turning on for
> the first time in the evening it will go off again after a period of
> seconds or minutes and must be ignited again.  Therefore, every so often
> the noise floor suddenly rises, stays there for some time, and then returns
> to normal after the lamp re-lights. This cycle can repeat several dozen or
> hundred times per evening until it turns off for good at sunrise. 160, 80
> and 60 meters are the bands most affected by these lights.
>
> I have been able to lower my ambient noise floor by several dB by going
> out on 'street light patrol' at night, armed with a flashlight, MP3
> recorder and roll of bright orange tape. I drive around out to about a mile
> from my house looking for street lights that are cycling on and off. An
> efficient way to do this is to look for street lights that are off and
> watch them for a few minutes to see if they come on again, while listening
> on the car's AM radio for the characteristic interference. When I find an
> offending light, I use the flashlight and record the location, pole number,
> and any other important information on the audio recorder. Then I mark the
> pole with the bright orange marker tape and continue to search for other
> lights. On a good night, I can find 5 or more lights within a radius that I
> know can cause RFI at home. I have found that lights a half mile away will
> raise the noise floor only a couple of dB, while those within a block or
> two can add 10 dB to the noise flo
>  or.
>
> My local electric utility has a web site to report street light outages. I
> simply log in and transfer the information from the MP3 recordings to the
> form on the web site and submit the report. I'm extremely fortunate that my
> utility, Southern California Edison, faithfully replaces lamps within a
> business week of my report. They like several reports at once which makes
> it worth their while to spend a day replacing lights in one area, and they
> also appreciate the orange markers which helps them sight the poles easily.
>
> A few poles in my city are owned by the city, not the electric utility. In
> that case, I have made friends with the city worker in charge of taking
> outage reports and so I have someone to e-mail my reports to.
> Interestingly, the city can take several weeks to replace a bad lamp.
> [Government always seems to be less efficient than business.]
>
>
> I encourage you to be vigilant for sodium vapor street lights that could
> be a large source of HF nighttime interference for you.
>
>
> Al  W6LX
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