If your local utility is cooperative, they may share with you maps of
their distribution lines.
73,
Scott K9MA
On 3/10/2021 11:18 AM, Don Kirk wrote:
Hi Eddie,
Thanks for sharing your very similar story, and very interesting based on
the configuration of lines I was dealing with. As a matter of fact I was
using Google Earth this morning to look at the lines I was dealing with
yesterday and wish I knew more about power distribution to better
understand all the hardware. Nevertheless I too was dealing with parallel
running lines in the area where I found the suspect pole. One set of
lines which appear to be 3 phase run the full length of the road on the
North side of the street, and the suspect pole I located was also on the
North side of the street but it was fed by parallel running lines on the
South side of the street and I don't believe the South side of the street
lines are 3 phase. The suspect pole then fed some additional poles running
up a very long driveway to a house set way back off the road. The lines
that my antennas always pointed perpendicular to were the 3 phase lines on
the North side of the street which were not physically connected to the
lines with the suspect pole as far as I can tell, and if my theory is
correct that would say the RFI I was getting induced into the 3 phase lines
by the lines running on the South side of the street that were connected to
my suspect pole.
We shall see, but boy my story sounds very familiar with yours as far as
parallel running lines with a cross over to my suspect pole right under
what I'm calling the 3 phase lines that run the full length of the street
East/West.
Thanks,
Don (wd8dsb)
On Wed, Mar 10, 2021 at 10:49 AM EDWARDS, EDDIE J <eedwards@oppd.com> wrote:
Don,
Great story! Thanks for sharing.
We had a very similar experience near my QTH several years ago affecting
my home location and also another ham on about a mile north of me. Only
difference was it was strong on low bands, and it was strongest on 80
meters at S9+, and probably on 160meters too but neither of us had antennas
for 160 meter back then. The other ham is a mile north of me and we are
both in nearly a north-south line perpendicular to a 161 KV transmission
line.
Also, I should mention that I work in the utility department that is
responsible for tracking power-line noise although it's our technicians
that do these RFI cases regularly. I only get involve in problem case, or
in this case when I am affected at my home shack.
It appeared to be coming from the direction of the161KV line that runs
East-West; however, when the tech was using our new HF loops we had the
same perpendicular indications no matter which direction we traveled. It
was staying strong for 1 to 2 miles in each direction before beginning to
fade. Our mistake was to stay too focused on using HF freqs for tracking
that day, but we were also initially confused by the southwest direction we
got at the ham's QTH 1.5 miles north of the 161KV line. We only switched
to VHF/UHF in the area to the southwest finding nothing there.
We unknowingly drove past the actual source directly south of both ham's
QTHes a few times not realizing this before ending our search at the end of
the work day (techs are union, no OT on RFI cases).
The actual source turned out to be a distribution pole on a 13.8KV line
that ran parallel with the 161KV line for a short distance as it crossed
over the main street perpendicular to both lines to reach a couple houses
on that street. The RFI source was apparently causing induction into the
161KV line from the shorter 13.8KV line.
We never had to track the source down to fix it. On my way home from the
office that same day, as I drove toward the 161KV line while listening to a
blank spot on my AM radio, it appeared the noise was already gone! As I
approached the 161KV line I see a couple of our utility trucks working to
install a new pole replacing one of the old poles on the line that ran
parallel under the 161KV line. Since the noise never returned, I assume
the old pole that was replaced was our source pole.
Some days you just get lucky!
73, de ed -K0iL
-----Original Message-----
From: RFI <rfi-bounces+eedwards=oppd.com@contesting.com> On Behalf Of Don
Kirk
Sent: Tuesday, March 9, 2021 6:27 PM
To: RFI <rfi@contesting.com>
Subject: [RFI] Difficult power line RFI find.
Just thought I should share something that was a first for me when
tracking down power line RFI and man it was frustrating, and I have tracked
down a lot of powerline RFI.
I noticed some weak RFI at Dans (KB9AX) on 160 meters earlier this year
but did not have time to track it down. Dan also complained about the RFI
and he mentioned this week that it was not strong but had become very
consistent. It definitely looked and sounded like powerline noise (120 Hz
spikes observed on audio scope and SDR receiver, etc.) ---snip---
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Scott K9MA
k9ma@sdellington.us
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