I read that powerline interference will often times diminish when it rains.
This is presumably due to loose hardware becoming temporarily tightened when
moisture causes the utility pole to swell. Well, in my case the noise
substantially worsens and becomes more broadband during periods of rain. Can
anyone explain a possible reason for this? The RFI guy from the local
utility company seems confident that work scheduled for next week in my
neighborhood will correct the problem. I certainly hope this is the case.
Maybe then I can finally hear some dx. Wish me luck.


Brian

Brian wrote:

I read that powerline interference will often times diminish when it rains.
This is presumably due to loose hardware becoming temporarily tightened when
moisture causes the utility pole to swell. Well, in my case the noise
substantially worsens and becomes more broadband during periods of rain. Can
anyone explain a possible reason for this? The RFI guy from the local
utility company seems confident that work scheduled for next week in my
neighborhood will correct the problem. I certainly hope this is the case.
Maybe then I can finally hear some dx. Wish me luck.

Good luck. The local utility here (city owned) is pretty good at figuring out
interference problems. Due to my complaints years ago they went out and
purchased the RF sniffing equipment needed to track down the offending
hardware.

Have had very good luck with them since.

Steve
Holland, MI
Drake R7, R8 and R8B

http://www.iserv.net/~n8kdv/dxpage.htm

Rain usually washes off the dust that collects on insulators and causes arcing
during foggy or humid weather. But if a carbon path has developed on an
insulator, rain will worsen the problem.

Bill, K5BY

Brian thought it a good use of my time to say:
I read that powerline interference will often times diminish when it rains.
This is presumably due to loose hardware becoming temporarily tightened when
moisture causes the utility pole to swell Well, in my case the noise
substantially worsens and becomes more broadband during periods of rain. Can
anyone explain a possible reason for this? The RFI guy from the local
utility company seems confident that work scheduled for next week in my
neighborhood will correct the problem. I certainly hope this is the case.
Maybe then I can finally hear some dx. Wish me luck.

Well, rain is an attenuator. Perhaps the signal you are looking for is
being attenuated by the rain, and, that attenuation plus the noise generated
by the power lines=lower SNR.

I see it all the time(not in SW bands, I am in Satellite
Communications[8GHz], but the theory has to be the same) Rain attenuates
desired signal, lowering C/Kt

(WShoots1) wrote in
:

Rain usually washes off the dust that collects on insulators and causes
arcing during foggy or humid weather. But if a carbon path has developed
on an insulator, rain will worsen the problem.

Bill, K5BY


Everyone assumes the insulators prevent line voltage from escaping and
going to ground. Actually on an AC power line due to the construction of
the insualtors, something very different happens. Typical construction has
the power wires passing over the insulating material, which is mounted on
a metal pin or post. The wire is held in place with a pigtail that passes
through the insulator and is wrapped on the power line conductor similar
to the construction of a 450 ohm ladder line. This gives you a poer wire
that is mouted on a non conductive material with a conductor on the
opposite side of it. That gives you a capacitor and the power line has AC
on it. So the power line voltage is coupled to the top of the pole. Under
normal conditions the very hig resistance of the wood in the pole prevents
significant current flow. However this changes if the top of the pole is
rotten and more current begins to flow. A wet and rainy day will make
conditions worse and increase leakage current flow. Tha's why you have to
be very careful working in the communications space (telephone//cable tv)
further down the pole. As the pole deteriorates, this condition get worse
and worse and the current increases to the point where the pole top heats
up and starts to burn. Thats why pole fires usually occur on wet days and
usually near the top of the pole.

--
Panzer

Sysiphus wrote in :

Well, rain is an attenuator. Perhaps the signal you are looking for is
being attenuated by the rain, and, that attenuation plus the noise
generated by the power lines=lower SNR.

I see it all the time(not in SW bands, I am in Satellite
Communications[8GHz], but the theory has to be the same) Rain attenuates
desired signal, lowering C/Kt



True, but the effect of rain on LF and HF signals are negligible. This has to
do with the significantly longer wave lengths of the LF/HF signals especaily
when compared to that of microwave. As the wave length of the signal
approaches the size of the rain drops, attenuation increases.

Take a look here :

http://www.telesat.ca/satellites/tra...ttenuation.htm


--
Panzer

Sysiphus wrote:




Well, rain is an attenuator. Perhaps the signal you are looking for is
being attenuated by the rain, and, that attenuation plus the noise generated
by the power lines=lower SNR.

I see it all the time(not in SW bands, I am in Satellite
Communications[8GHz], but the theory has to be the same) Rain attenuates
desired signal, lowering C/Kt

At 8GH OK, but not at the frequencies generated by powerline arcing in
the HF spectrum.