Fw: [Kenwood] Good rigs for power line noise

2003年3月25日 19:29:03 -0800

> Knowing the general direction the noise is
> in, start walking in that direction pointing the beam at every house and
> power pole along the way, at S6 the source is less than 1/4 mile away
> probably less than 1000 ft.

Not in my case. The power company here finally resolved a case of RFI I
suffered with for 2 years, primarily on 160m. They brought in a specialist,
also a ham, from a neighboring co-op and they isolated it to a particular
style of lightning arrestor ( I think they called it a Cooper?). It wasn't
defective but just was typical of that style of arrestor. My noise was well
over S9 and the arrestor was just over a mile away.
73 Jamie WW3S
Noise signals can travel easily for miles along power lines. Many utilities
do not have people trained in locating radio noise problems. Many more may
have someone who has the responsibility, but very little experience or
training, and many other things he is responsible for. Some utilities have
only an AM radio in a vehicle to try to track noise down with. It can vary
with intensity enough to make that almost useless. By useing an AM receiver
(for instance the high end of the AM aircraft band on a scanner) you might
be able to track it down to a pole.....if it is a hardware or insulator
problem. Many utility folks use trackers capable of 400 Mhz or higher, with
beam antennas insulated for high voltage to pin down the exact location...if
the problem is in fact coming from their lines.
Cooper Power makes a great many products for the electrical industry. Most
work very well and have a long life span. One type of their lightning
arrester worked very well in a vertical position. The same arrester mounted
horizontally tended to let moisture leak in over time, and became a very
effecient noise generator. I've changed a number of them in my 30 years in
the industry.
Power lines can and do occasionally create interference. This can be a
temporary condition, or a dielectric breakdown that gets worse over time, or
something as simple as loose hardware which builds a charge from nearby high
voltage until it finally discharges.
A great deal of the interference I've worked on originates in the home
appliances or very occasionally the wiring. A neighbor's wiring or
appliances, on the same transformer or secondary district, is also a very
likely source. This is not the power company's problem and they are not
responsible for finding or fixing it. The power lines in this case are only
an incidental radiator (or re-radiator) of the interfering signal.
Generally the percentage of problems traced back to the utility equipment is
less than about 20%. About 50% of those are intermittant, and a real bear
to attempt to locate. Much of the location work is part art, part
experience, part science, and some luck thrown in.
My experience......for what its worth.
Dan N7BHB
- - -