[RFI] Strong, broadband noise during wet conditions

[Pete Smith N4ZR]

Had the local utility RFI guy over this morning. While they didn't find 
my main noises yet, they did replace a lightning arrestor on a 
transformer feeding a neighbor's house. He said these are virtually the 
only source that makes noise when it is actively raining.

73, Pete N4ZR
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On 3/15/2013 5:00 PM, K1TTT wrote:
> If it was not snowing at the time then it was likely dirty or damaged
> insulators on the primary power line.  The noise could be conducted quite a
> distance on the primary wire so would cover a big area.  Noise like that may
> sometimes only occur when things are damp because the small amount of
> moisture will cause arcing through small cracks or across dirt on the
> insulators, but when it is fully wet by rain it may stop... so try to check
> in the morning if there is dew, or just as rain starts, or when snow or ice
> is melting as you have seen.  Be prepared to check a relatively large area,
> a mile or two would not be surprising.  Since you are looking for arcing the
> higher you can go in frequency the closer you can define the source, vhf or
> uhf AM or SSB receivers are good, especially with hand held yagis...
> ultrasonic dishes are good for locating the source once you have it down to
> a pole or two.  Beware, there may be more than one source, especially if it
> is a contamination problem... if you are downwind of plowed farmland or
> industrial area contamination can be a real problem.
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>
>
> -----Original Message-----
> From: Matt [mailto:wedgef5 at gmail.com]
> Sent: Friday, March 15, 2013 20:22
> To: rfi at contesting.com
> Subject: [RFI] Strong, broadband noise during wet conditions
>
> I'm having a problem with very strong, very broad noise that seems to be
> associated with wet conditions.  We recently had two significant snowfalls,
> and of course everything was very wet as the snow melted.
> The noise I have is just a constant grinding (I can't think of a better term
> to describe it) that is virtually continuous from 40m up through 10m.  It is
> worst on 40-20m.  The snow is all melted now and things have dried out a
> bit, and my noise level is back down to normal.  The connection to the
> moisture is a subjective evaluation, but I've observed the high noise level
> during wet conditions, which then abated upon drying, on at least two
> occasions.
>
> I had a friend come by with a mobile HF installation to see if he could hear
> it in my driveway, and perhaps isolate it to something inside the house.
> Not only could he hear it in the driveway, but he could also hear it 1.5
> miles away as he drove home!
>
> My initial thought is something power line related, but I thought I'd bounce
> it off of the RFI experts on here.  I'm not sure what else could produce
> such strong noise over such a wide area.
>
> Thoughts?
>
> Matt, N0EYE
>
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