[RFI] Powerline noise question

[Hare, Ed, W1RFI]

I once located a power-line noise with only an 80-meter receiver and step attenuator. It was S9+40 dB along about a half mile of power line.  I drove the line, got a rough idea of the worst area.  I then stopped and cranked in maximum attenuation. I heard the characteristic hiss of the receiver front-end noise.  I then reduced attenuation until I could just hear the 120-Hz buzz above the receiver noise.  I then drove the line again and found that it went up to about S3 at the next pole, then tapered off in either direction.  I then set attenuation to zero and found that I could hear it weaker and weaker all the way to the amateur's house.  This requires a "trained" ear that can tell the difference between receiver noise and `120-Hz buzzy power line noise, but it was a valid technique that worked.
________________________________
From: RFI <rfi-bounces+w1rfi=arrl.org at contesting.com> on behalf of Richard Karlquist <richard at karlquist.com>
Sent: Thursday, December 29, 2022 10:15 PM
To: rfi at contesting.com <rfi at contesting.com>
Subject: [RFI] Powerline noise question

I have a powerline noise coming from about 2 miles away, which is
nevertheless quite strong at my QTH.

Here are the symptoms:

1.  A 120 Hz noise burst at regular intervals, about 0.9 seconds apart.

2.  The noise goes away after a rain; then comes back after things dry
out.

3.  Can be heard from 500 kHz up to a few MHz.

4.  The noise is very strong along a road for a few miles.  There is a

power line that follows the road.  I haven't been able to localize it
better than

that so far.  From my QTH, though, it is definitely coming in at a
specific azimuth

which is consistent with the noisy road a few miles away.  (Using a loop
antenna

for DF'ing).

Any help appreciated.

--
Rick Karlquist
N6RK
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