[RFI] Power Line Noise

RFI Services' Mike Martin mike at rfiservices.com
Thu Feb 25 15:55:59 PST 2010

Your comment below suggests the source of you RFI isn't the source you

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.

If the noise on the pole has different characteristics than the source at
your QTH you will be wasting effort and the opportunity with OEC. It's very
important to be sure that you are sending them to the right noise. 
Since OG&E is your power provider it would be a good idea to start with
them. They have several competent RFI investigators and should do great with
determining the source. If you can get a wav file of the noise send it to
I have Bcc'd OGE.
Best wishes,
Mike Martin
RFI Services
6469 Old Solomons Island Rd
Tracys Landing, Md 20779

-----Original Message-----
From: rfi-bounces at contesting.com [mailto:rfi-bounces at contesting.com] On
Behalf Of Kimberly Elmore
Sent: Thursday, February 25, 2010 4:01 PM
To: rfi at contesting.com
Subject: [RFI] Power Line Noise

K3LR suggested that I submit this here because there are a lot of you that
know a lot more about this than I do. So, here goes:

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

I live E of Norman, OK, 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. On Robinson (the S
side) the OG&E lines are on the S isde and the OEC lines are on the
N side. 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 blankers are ineffective on 40 m
(both the software and hardware noise blankers) but are 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

Using my K9AY loops, I can detect the noise when the loops favor either NE
or SE, but not whenthey 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
Nor 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 a quiet frequency in the
aviation band (118.0 MHz) 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 drive going E from 60th street,
away from the offending pole. 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?

Kim Elmore, N5OP

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