Presented here, are some pictures and information on an
Ultrasonic Power Line Arc Detector that I constructed, based upon an article
by James Hanson, W1TRC, in the April 2006 QST Magazine.
When used with the 135 MHz Portable beam antenna (Also designed by
W1TRC, More info HERE)
you will have a very effective system for tracking down RFI problems.
Once I have localized the problem pole, using the 135 MHz beam, I use
the Ultrasonic Arc detector to identify the exact location of the noise
source. Standing on the ground under the pole, you can easily
determine which component on the pole is causing the problem. Loose
hardware, bad cutouts, insulators, and lightning arrestors can be heard with
the detector.
From actual experience; if you hear any noise at all, no matter how
weak, there is a problem. Sometimes you have to listen very
carefully. Try adjusting the frequency control to make any noise you
might hear, more audible. When is pole is “Clean”, you should not
hear anything but the background “hiss” generated by the detector. Most
power companies have a smaller version of an ultrasonic detector, that can
be attached to a “Hot Stick”. This unit can be moved very close to
each component on the pole to confirm the identity the “culprit”.
W1TRC’s article does a wonderful job of explaining construction and
operation of the Ultrasonic Power Line Arc Detector, so it is not my
intention to go into this. If you carefully read and follow his
instructions, you will be very pleased with the results. It has recently
come to my attention that a PC Board was designed by Tom Hammond, N0SS and
is available from FAR
CIRCUITS for $5.00. Tom
read my article and kindly provided me one of the boards, which works very
well. (Much better than my original breadboard J)
Tom also provided me with a copy of the schematic, construction notes
from Jim Hansen, W1TRC, a detailed parts list, and a cover label, which can
be found at http://www.farcircuits.net/w1rtc_notes1.pdf
When you are out in the field using the detector, just rub your thumb
and finger together in front of the dish, to verify the unit is working.
I live in a very dry climate, and have very dry skin. The detector can
easily detect my fingers being rubbed together from 10 feet away!
Remember this unit is detecting noises generated at 40 KHz.
I want to really thank Tom, N0SS, and James Hansen for such a useful
project.
Good Luck, and happy hunting!
73’s Frank, K7SFN
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