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@contesting.com> on behalf of Richard
Karlquist <richard@karlquist.com>
Sent: Thursday, December 29, 2022 10:15 PM
To: rfi@contesting.com <rfi@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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