I used to handle occasional "we can't find it" problems for a few
large utility companies, and designed some noise locating
equipment for them.
> the "experts" who came out to my QTH to investigate my
> noise problem had one of these plastic dishes sticking out
> the window of his company van.
> He told me that he could not pick up anything; he couldn't
> hear any noise at all.
That does not surprise me! There is nothing that says electrical
noise sources must emit acoustical noise.
> Anyway, here is my test that I made...I walked out of my
> rear garage door and was picking up the noise just as plain
> as day. I then headed to the utility pole on my property
> where a "slack span" (I guess they call it) crosses the road
> to a pole on the other side of the road.
Slack span (as I have heard the term used) is a span between two
poles that is hanging slack with little tension. This often allows
metal-to-metal joints between insulator mounting hardware (held
with loose pins) to corrode and build up a layer of insulating oxide.
That oxide layer arcs from capacitance and leakage resistance of
the insulator charging and discharging the metal ends with each
cycle.
When the line gets wet, the arcing normally stops. You can also
"bump" the pole with a big sledge hammer and usually cause the
noise to "break up".
Slack spans should use post-type rigidly mounted insulators, or be
pulled tight to tension the insulators.
> I told the ComEd "expert" about my findings and he told
> me that the guy wire which didn't have an insulator in it
> belonged to the cable company and that "they weren't
> allowed to touch it." He then suggested that I contact the
> cable company and have them come out to the area and do
> a "sweep" of the area to see if there was any signal leakage!
CATV lines can not cause these problems without totally tearing
up the CATV signals.
The reason you are getting so many conflicting locations is you are
using a low frequency receiver. You have to use a radio at least at
upper HF, near 30Mhz or higher, to reduce standing wave effects
caused by the long wavelength of the received frequency.
Stay away from guy lines and other conductors while looking for
the noise peaks. You will get direct coupling, and have no idea
whether you are getting close to the source or not. Noise can
follow lines for miles!
73, Tom W8JI
W8JI@contesting.com
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