[RFI] Noise gone but don't know why

[WA2BPE]

Maybe you got "lucky"  - for the moment.  Sometimes they will clear themselves
but it usually doesn't last unless a hot tap welded itself shut. Problems are
almost always hardware related and with 7-15KV feeders and it is common to
dissappear when it rains only to come back with a vengence as things dry off.
It doesn't have to be the actual wires either, loose hardware - any hardware in
the electrical field, guy wires, etc. can be just as bad.  Cracked insulators
might not clear up when it rains - have seen both ways.  Corona problems
(usually a hiss/frying), on the other hand, are associated with much higher
voltage lines and typically gets worse in wet weather.

It is very curious that both(?) types of noise quit at the same time, and it's
hot and sunny?? - high humidity usually doesn't help that much.  Something
doesn't add up here - unless thermal expansion has temporarily closed a
microgap.  Watch carefully the next time a (real, not whimpy) cold front moves
thru.

Sorry, but I would hazard a guess that there is a 90% probability that it'll be
back!  Do your homework and keep a diary of time (sun/daylight sensitivity is
common), wx, frequencies bothered, pole numbers, etc. and pass the info to a
troubleshooter/engineer.  Unfortunately, most linemen (unless they have special
training or a *lot* of experience) are not usually familiar with RFI even if
they are good at what they do.  Engineers - some are, some aren't familiar -
helps a lot if you can get them interested and actually have them listen to the
problem.

If you don't have them, pick up both the ARRL RFI book and the book by Loftness
- one really needs both.

Good luck & keep us informed.

Tom - WA2BPE


"Rob Atkinson, K5UJ" wrote:

> An update on the power line noise situation:
>
> Several months ago I described noise at my qth which was both corona noise
> and lower voltage pulsing (arc noise) which was coming in at about S6 to S7.
>   I managed to do some DF work and think I've got it down to a set of poles
> near my house.  A few weeks ago I stopped by the City Electrical Dept. on my
> way out of town to simply try to find out the name of someone to talk to--I
> wanted to begin with a casual discussion if possible, of things like what
> kind of df equipment they have, let them know about my problem and that I'd
> be in touch with them upon my return and have a contact to call.   A
> secretary took down some information and I left on my vacation trip with the
> name and number of the senior engineer.  When I returned about a week ago
> and got on the air last weekend the noise was totally gone.  It's been great
> and I've been really enjoying the HF bands since then.
>
> Here's the problem (actually more of a puzzlement):  I called the Elect.
> Dept. and talked to the senior engineer to find out what they had done.
> Apparently they hadn't done anything--the problem seems to have taken care
> of itself.  The only thing I know is that during the past 3 or 4 weeks it
> has been blazing hot and no rain here but I don't see how that kind of wx
> could help the situation.  Anyone have any ideas?  I'm glad to be enjoying
> the great condx but I'm a bit irked because I imagine that as soon as the wx
> gets too cold and crummy to work on the lines the noise will return.  I'd
> almost rather have a constant problem that can be attacked rather than an
> intermittent one that will vanish the moment the crew is out about to climb
> a pole.
>
> Rob Atkinson
> K5UJ
> St. Charles IL
> k5uj@hotmail.com
>
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