[RFI] Line noise vs Frequency

[Michael Carter]

Pete,

I find similar patterns of power line arc
noise, but I have only a single 135 foot
doublet, center fed with window line,
as my antenna.  That antenna exhibits
multiple azimuthal lobes on the higher
HF bands, which partially accounts for
the oddly varying RFI levels I observe
across the bands.

The fact that your RFI levels increase with
frequency indicates two possible factors:

-- the arc source is relatively close to
your QTH.

-- the arc source feeds a length of
primary HV conductor that produces
a strong antenna pattern lobe oriented
toward your QTH at 28 MHz.

Here I'm assuming that your antenna(s)
have similar gain on each of the bands
you cited.

If you have a VHF receiver or scanner
with AM detection capability, try a
driving survey to the west of your QTH.
At 135 MHz you may find strong RFI
within 100 meters or so of the pole
on which the arc source is located.
I've used this method for preliminary
location finding of multiple arc sources
in my neighborhood to good effect.
The local electric utility's RFI guru
confirmed my findings - more than
20 arc sources within a 500 meter radius
of my house!

Mike, K8CN
Durham NH

________________________________
From: RFI <rfi-bounces+mike.carter=unh.edu at contesting.com> on behalf of Pete Smith N4ZR <pete.n4zr at gmail.com>
Sent: Sunday, August 8, 2021 8:24 AM
To: RFI List <rfi at contesting.com>
Subject: [RFI] Line noise vs Frequency

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A (probably) dumb question:  I have a severe line noise to my west.  For
some reason it is manageable on 20, much worse on 15 and crippling on
10.  These subjective descriptions are confirmed on my S-meter. Why
would this be happening, and does it offer any helpful clues to finding
the source?

--
73, Pete N4ZR
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