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Pinpointing Powerline Radiation

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Subject: Pinpointing Powerline Radiation
From: (ken smith)
Date: Tue, 28 Jan 1997 19:27:36 -0500
>At 12:00 PM 1/23/97 -0800, ve7av wrote:
>>- At this point you should involve your power company.......
>>At work I like using a spectrum analyzer in the vehicle. I usually look at 1
>>to 200 MHz and can frequently drive up to the pole. An IFR 1200 and external
>>attenuator box works great too!  Then I use an HP Ultra Sonic Detector which
>>frequently points to the problem area on the power pole. (The detector is a
>>small parabolic dish with ultra sonic microphone - very directional). Then I
>>give the powerpole markings and any additional details to the power company.
>>   Frank -
>I find that there are two noise sources that can occurr. The ultra sonic
will pick up the type that occur when there is a physical arc or vibration ,
but misses a lot of the high frequency sources. Also if you use a spectrum
analyser be aware of the antenna being used as I find that there are some
false noise peaks that can occur due to the resonant frequencies of the
antenna. Also just because you find a noise peak at a pole doesn't always
mean that the source is there. I have found on a couple of occurences that
the actual noise source was located at a D.S. lightning arrestor more than
10 km away from the area where the noise was a problem, and I figures that
the noise was transmitted down the line( like a spark gap feeding a twin
lead) and the conditions were right at the offending pole to radiate the noise.
>Also I would hope that any recent lines that have gone up are using clamp
top insulators, as the older tye wire types are very prone to loosening and
causing noise. A good starting point if you narrow the problem to a
pole.Cross arm hardware is also a frequent source.

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