David Hachadorian said:
Sounds like the typical switching supply
in a streetlight. Did it by any chance
start up at dawn or dusk? Some streetlights
only make RFI in the daytime when off.
. The harmonics are
> every 200kHz (pretty
> precisely). Every
> other harmonic is one to two S units stronger. The
> signal strength
> dimenishes with increasing
> frequency. It extends we'll into the 20M band. I'm
> sure it's present all
> the way to 10M, perhaps
> even 6M - it's just the signal level has fallen off
> enough shorter than 20M,
> that I can't detect
> it quite as well.
> It does start suddenly, like a switch is
> thrown - I've been operating
> a contest, and it will appear suddenly.
> It sounds like a "smart" battery charger, although
> the 200Khz spacing is a little wide. The ones I've
> encountered are spaced about 70 Khz. These devices
> are essentially switching power supplies, and are
> murderously noisy.
> Look for a kid riding around the neighborhood
> on an electric scooter. These scooters are becoming
> extremely popular, and are sold in auto parts
> stores, such as Pep Boys and AutoZone. The chargers
> run at 24 or 48vdc. I put a Radio Shack AC line
> filter on the input of one in my neighborhood and it
> didn't help at all. Fortunately, the scooter was so
> poorly made that it totally failed in a few weeks,
> so my problem has gone away.
> Recently, I have begun to see "smart" 12V chargers
> for cars in the ads.
> Dave Hachadorian, K6LL
> Yuma, AZ
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