[OKDXA] Power Line Noise

[Tim Duffy K3LR]

Hi Kim:

Take your exact email detail to the RFI guru reflector at rfi at contesting.com

There are a TON of noise experts there and they can help you with this.

73!
Tim K3LR - originator and moderator of the RFI Reflector



-----Original Message-----
From: okdxa-bounces at mailman.qth.net [mailto:okdxa-bounces at mailman.qth.net]
On Behalf Of Kimberly Elmore
Sent: Thursday, February 25, 2010 9:21 AM
To: okdxa at mailman.qth.net
Subject: [OKDXA] Power Line Noise

Recently, I've noticed some pretty severe, intermittent power line noise at
my QTH. It had previously been a marvelously quiet place for radio, but over
the past moth or two, that has changed. I had it again this morning and so
decided to do some sleuthing.

I live E of Norman in the center of a section bordered by Robinson on the S
side, 48th St on the W side, Rock Creek Rd on the N side and 60th St on the
E side. Both OG&E and OEC lines run down all roads. The OG&E lines run 35 kV
-- I don't know what the OEC lines run. My neighborhood is served by OG&E
and all wiring is under ground; step down transformers are above ground on
concrete pads.

Here are the details: 

I cannot detect the noise on any band above 40 m, but it's clearly apparent
on 40, 80 and 160 m. My Orion II noise balnkre is ineffective on 40 m
(either the software or hardware noise blanker) but is very effective on 80
and 160 m. Because I cannot hear it above 7 MHz, I'm pretty sure that the
source is not emanating from a neighbor's house or from a nearby step-down
transformer.

Using my K9AY loops, I can detect the noise when the loops favor either NE
or SE, but not when they favor NW or SW. Thus, the source is either to my N
or my E.

Using my 2 el 40 m beam, I found sharp nulls with the beam pointed either N
or S (probably nulls off of the sides), and less noise when the beam is
pointed W than when it is pointed E (~S9+25 dB pointed E, ~S9+15 dB pointed
W). So, F/B ratio favors a source to my E.

I then got in my car, tuned my mobile rig to the aviation band and to a
quiet frequency (Westheimer tower) so that I could use the AM detector at
VHF and started driving E along Robinson to 60th street. I heard nothing of
substance along Robinson. I turned N and drove along 60th and found a strong
noise source. I double checked my traverse and found the same spot three
different times. It was considerably weaker from across the road than it is
next to the pole. There is a private going E from 60th street and away from
the offending pole and driving down it 100 feet diminishes the signal
strength significantly. The ground wire for the pole appears intact at the
base.  I am absolutely positive that I have identified the pole holding the
faulty hardware. I could see nothing obviously loose, but the culprit is
most certainly there.

The noise is intermittent: it starts and stops abruptly as the wind blows,
though I can detect no obvious correlation to wind changes and the starting
and stopping of the noise.

What now? Whom do I contact with my information? And now for the cynical
question: what are my chances that they will care?

Kim Elmore, N5OP


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