rfi-digest wrote:
>
> rfi-digest Wednesday, July 8 1998 Volume 01 : Number 080
Yo, Marty! I had the same problem last month and found the offending
light is a CdS photocell, a SCR (or TRIAC) and a small incandescent
lamp. When the light level dropped, the thing switched on and off at a
rapid rate and hashed up everything in the area! It turned out that the
lamp was visually feeding back to the photocell. The waveform was a
really weird sawtooth. I found that the little porthole for the
photocell was removable, so I took it out and cemented a 3/8 inch ID x 1
inch long kraft paper tube in its place to shield the photocell from the
lamp light. Everything got quiet and I can still see to go to the can in
the middle of the night!
I also looked for better designs and found a type that is an
electroluminescent disk, plugs in, runs all the time, draws about 12ma
and shows nothing on my spectrum analyzer. They are supposed to have a
minimum 10 year life and cost ~$4 at Sam's many stores.
73,
Jim Keyes WA1TQG/5
>
> ------------------------------
>
To: <rfi@contesting.com>
> Date: Wed, 08 Jul 1998 21:13:27 -0500
> From: Marty Tippin <martyt@pobox.com>
> Subject: [RFI] Nightlight Causes EMI!
>
> Here's one I haven't read about or heard of before... Thought I'd pass it
> along just in case anyone else runs into the problem... I ran into this
> one while searching for some possible CATV leaks...
>
> A nightlight with an electric eye in our downstairs bathroom was throwing
> out a tremendous hash - took me an hour of tracing with an AM portable
> radio to figure out where it was coming from (I replaced the light switch
> in the bathroom first because I thought it was the source - when I turned
> the lights on, the noise stopped; when the light was off, the noise came
> back. Took me a while to correlate that with the nightlight going on and
> off... So I'm a little slow...)
>
> Anyone know what it is in the nightlight that causes the problem? I'll bet
> on the electric eye being at the heart of the matter. In any case, that
> light will no longer be illuminating the bathroom at night...
>
> Unfortunately, it didn't do much reduce the S5 QRN I have on 20m almost
> continuously. So I'll be heading for the neighbor's houses before too long
> to see what wonderful noise sources I can find there.
>
> - -Marty
>
> ===========================================================================
> Marty Tippin KI0LO | Tippin's Law #9: Stupid people outnumber the rest
> martyt@pobox.com | of us by at least 5 to 1...
> ===========================================================================
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>
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> ------------------------------
>
> End of rfi-digest V1 #80
> ************************
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