In article , "George Csahanin"
wrote:

I once had them track down noise when I lived in North Texas, and the source
was insulators with loose hardware about 2 miles away, destroying 40 and 80
for me. Yup, it is all hooked to a huge antenna...

-GeorgeC

W2DB


Hello, and years ago I needed to do some electrically-small antenna tests
at one of our NRL field sites. These tests involved the entire 2-30 MHz
band so it was always a challenge to find a quiet spot (We were using
rack-mounted R-390 receivers in the testbed). In addition to the usual
atmospheric noise and radio station interference there was always what
appeared to be some local electrical noise that came and went and was
worse on some days than others. A.C power to the site was brought in via
utility poles to pad-mounted step-down transformers.

One of my cowarkers suggested a technique for locating interference that
he claimed to have success with in the past: A hand-held sledge hammer is
used to whack the utility pole while listening for an associated change in
noise on a cheap MW band transistor radio tuned off-station. My cowarker
claimed that if a cracked insulator(s) was the perpetrator this technique
would confirm it.

We tried this technique at the site but with no success. We also drove
down the site access road about 1/4 mile with a car AM radio tuned
off-station and also got the interference in the vicinity of the utility
poles. As a result we never did locate the source. My conclusion was
that while the interference was being coupled to the antenna-under-test it
may have been generated at a considerable distance from the test site and
conducted via the overhead power lines. Sincerely, and 73s from N4GGO,

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

Hello, and years ago I needed to do some electrically-small antenna
tests at one of our NRL field sites. These tests involved the entire
2-30 MHz band so it was always a challenge to find a quiet spot (We
were using rack-mounted R-390 receivers in the testbed). In addition
to the usual atmospheric noise and radio station interference there
was always what appeared to be some local electrical noise that came
and went and was worse on some days than others. A.C power to the
site was brought in via utility poles to pad-mounted step-down
transformers.

One of my cowarkers suggested a technique for locating interference
that he claimed to have success with in the past: A hand-held sledge
hammer is used to whack the utility pole while listening for an
associated change in noise on a cheap MW band transistor radio tuned
off-station. My cowarker claimed that if a cracked insulator(s) was
the perpetrator this technique would confirm it.

We tried this technique at the site but with no success. We also drove
down the site access road about 1/4 mile with a car AM radio tuned
off-station and also got the interference in the vicinity of the
utility poles. As a result we never did locate the source. My
conclusion was that while the interference was being coupled to the
antenna-under-test it may have been generated at a considerable
distance from the test site and conducted via the overhead power
lines. Sincerely, and 73s from N4GGO,


Just in the past few months or more there was a nice article and
product written in either CQ or QST magazine. I have just gone through
the Index for every issue for the past 4 or 5 months of both magazines
and can not find that article.... very frustrating.

The article outlined a product ( kit?) for an untrasound receiver and
illustrated how the author configured it in order to find power line
interference from just the sources you are looking for. It is a much
more elegant solution than trying to use radio and usually pinpoints the
problem right down to the proper cross-arm on a pole.

Wish I could provide more info but I've spent the last half hour
looking for this and am apparently over-looking it. ... sigh

good luck


Ed K7AAT




..

While not the article I was just referring to in my just previously
posted comment, there is a good how-to build project in the April 2006 QST
on this.

Ed K7AAT




..