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Old July 10th 09, 10:24 AM posted to rec.radio.amateur.antenna
Peter Peter is offline
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First recorded activity by RadioBanter: Feb 2008
Posts: 26
Default Tracking down power line noise


"Michael Coslo" wrote in message
...
Rick wrote:
I have been wrestling with power line noise here for almost a year.
Power company hasn't been very successful in locating it so I started a
coordinated search
on my own. Thinking if I can tell them for certain which poles have the
problem they can confirm and maybe fix.

The noise is a deafening 20 over 9 on 80 meters which makes DXing on 80
and 160 impossible.
The noise can be heard at my QTH as high as 10 and 6 meters but it isn't
troublesome on those bands because it can only be heard at about an S7
level when the yagi is pointed at 210 degrees.
I thought maybe my means of analysis might be interesting to discuss and
maybe others would have other suggestions.

There are 7000 volt lines running on a highway past my house. Tracking
the source on 80m seems impossible.
I made a 2 ft square loop antenna, which has some directivity but the
noise level using it seems to not change
much as I travel the highway. On 10 meters, using a 4 ft whip on the
car, the noise is also hard to localize but
seems to increase in the vicinity of 1 mile from home. 6 meters using a
whip is similar. I found that if I'm close
enough that the 6 meter signal is around S7 I can switch to 2 meters and
again peak the noise by driving slowly up and down the road.

So using this technique and driving 2 miles in each direction I have
managed to find 2 spots, one on the highway and one on a cross road, each
about 1.2 miles from the QTH. I then built a 432 MHz 8 element quagi
beam which enabled me to pinpoint the offending pole at these two
locations. (I have put a LOT of effort into this project !)

At this time I am waiting (hoping) for a return call from the power
company to verify my dicovery.

So my question for the group - Can either of these locations 1.2 miles
distant cause such horrendous noise levels on 80 meters? Is it possible
that a weaker noise source much closer to me is the culprit or are all of
the power line malfunctions detectable on 440 MHz?


There was an article in QST (or was it CQ?) about building a ultrasonic
"downconverter" to listen for noise sources. Yup, sound.. Many (most?)
Power pole RFI sources are mechanical in nature, and have an ultrasonic
component.

re the Power company. They might be more cooperative if they knew that you
could involve the F.C.C. Especially if you decided to "help" them by
finding many more sources of noise.


Agree with last posting regarding an ultrasonic receiver, that is most
likely what the power company was using. Other equipment for locating
powerline noise is a VHF AM receiver and foxhunting type yagi, the signal
will be much weaker at VHF which should make the source more obvious when
found.
A common feature of powerline noise is that it is intermittent and may
disappear for days and vary in intensity from one hour or day too the next.
Power line noise is often the result of loose hardware and dirty insulators
with the noise being generated by small spark gaps between fittings.
Therefore a bit of rain the dry gaps become conductive of the leakage
current and the noise disappears. I mention this because if the noise is
continuous and un-varying it may not be generated by the powerline
equipment, but may be generated from another source and simply travelling
and radiating from the powerline. R.F. welding for example.
Power companies or the F.C.C. may have an information brochures for TVI
complaints which may show examples of various source types as they appear on
TV screens, this may assist in identifying the interferance source.
That shows my age, 'brochures' check their website! And this will not work
for digital TV.

If the F.C.C. is anything like Australian authorities TVI will carry more
weight than ham radio, therefore if you also have an accompanying TVI
problem report that for prompt action.

Best of luck

Peter VK6YSF

http://members.optushome.com.au/vk6ysf/vk6ysf/main.htm