Milt:
I am not a power professional, but have my bruises and scabs from a dozen
years of battling noise locally.
The most common noise source around here is due to the use of spring clips
on lag bolts connecting the metal crossarm braces to the wooden pole. As
those lags loosen, expand and oxidize with pole shrinkage and expansion,
they create a wonderful diode at the center of a dipole that radiates back
into the lines. Unfortunately, in prior years, the installation procedure
taught to the linemen was poorly thought out w.r.t. to these situations, so
that even "by-the-book" installation caused downstream problems.
We also had enormous opposition from local yard supervisors to ameliorating
ham-reported problems. "Snarling arrogance" would be a descriptive term.
Attempts to educate supervisors of the benefits of having an unpaid but
technically aware group of field observers, who could and did prevent
outages, fell upon deaf ears. Recently, however, pressure from Riley
Hollingsworth, in response to Ed Hare, W1RFI at ARRL and our own persistent
complaints, has resulted in a productive dialogue with a VP of the utility,
and we are currently enjoying improved communication and response with the
utility.
The utility recently and at long last replaced locally most of the brown
ceramic insulators (especially the deadend bells) --which were also
notorious sources of arcs at their clevis pins-- with newer-design gray
epoxy insulators, and also replaced a huge number of rotten poles. However,
they still use the metal crossarm braces, although hopefully with improved
lags and clips.
On 160, though, the most common sources are usually not due to powerline
hardware but customer-owned "inadvertent radiators" such as unfiltered (read
"cheap") dimmers, touchlamps, doorbell transformers, fishtank heaters,
defective flourescents, and poor grounds---i.e. the usual suspects. This
time of year, add Christmas lights, which make holiday contesting all that
much more fun. For me, these have proven much more difficult, as they are
not on all the time, not all neighbors are cooperative, etc.
Regarding noise on Topband, I consider it imperative to determine the
probable source of the noise before contacting the utility. That is, be
pretty sure that the noise is due to powerline primaries and not your
neighbor's dining room dimmer before complaining to the power folks. The
best way to differentiate these sources is to determine spectral
characteristics. If the noise decreases in amplitude smoothly and
monotonically with frequency up to the top of HF and into VHF, it is
probably powerline in origin. Conversely, if the noise is spikey with
frequency, and/or dies out at or below 40m, it may be your neighbor's dimmer
or his flickering, burnt-out garage flourescent.
73,
Garry, NI6T
|