Hi Don,
Aside from the safety issue, any time you find metal on metal contact
near a power line, without secure bonding, you have a potential noise
source. One example I found was a lateral guy touching a neutral wire,
right below a single phase HV line. The electric and magnetic fields
from the HV lines can produce currents in nearby conductors, and arcing
where there is poor contact.
73,
Scott K9MA
On 3/16/2021 10:51 AM, Don Kirk wrote:
Hi Scott and gang,
Thought I would provide a status report on this case, and also provide
a warning to others regarding something I did which I certainly don't
condone (I'm certainly not proud of what I did and I can't stress
safety enough). I hate to even admit what I did in public, but
thought I should mention it as it's a good example of needing to be
extra cautious around power poles even if you think you are safe.
We were hoping the power pole (wooden pole) I found generating RFI
last week belonged to Johnson County REMC but I could not tell since
the pole tag number was covered up by a solar light that was likely
installed by a homeowner. Johnson County REMC responded to our report
and said the pole actually belonged to AES, so we discussed the
situation with our inside contact person at AES and let them know we
were going to get some additional data before filing a formal
complaint but we did send them a link to a youtube video I created
along with some pictures of the suspect pole. Here is a link to my
video documenting the suspect pole: https://youtu.be/uo5atDTo19w
<https://youtu.be/uo5atDTo19w>
I went back to the pole on Sunday to get more data and someone had
relocated the solar light so it was no longer covering the poles tag
number but one of two guy wires we previously reported were wrapped
around the pole was now partially covering part of the pole number. I
used a wooden stick to push the guy wire slightly to the side (like a
1/4") to make sure I could read the pole number and the RFI suddenly
stopped on 135 MHz which I had been monitoring by chance and the RFI
started right back up as soon as I stopped pushing on the guy wire.
I then did a closer inspection of the two guy wires that were wrapped
around the pole and one of them (not the one I was pushing on) did
have a connection to the neutral line high up on the pole and neither
of the guys were connected to ground as both of their bottom ends were
just wrapped around the pole about a foot up from earth (probably due
to a car accident or farm implement incident, etc), and both of these
guys were in contact with each other due to their wrapping around the
pole on top of each other near the bottom of the pole. It appears
that my pushing on the one guy wire caused slight tension on a
teardrop type clip that was on the top end of the guy wire I was
pushing and this teardrop clip (almost like a D ring) rests
(straddles) on a through bolt assembly high on the pole which acts as
the anchor point for the guy. Note: At least the neutral line on this
pole is located below the hot (live) line so little chance for the guy
lines to come in contact with the hot (live) line even though they're
not properly secured.
I then did similar tests on 24.98 MHz, 1.8 MHz, and 1710 KHz, and the
RFI stopped each time slight pressure was applied to the guy line that
was covering the pole tag number. I actually set up HF gear a good
distance from the pole, had my Iphone camera recording the HF gear
while I ran back to the pole to push slightly on the guy wire with my
wooden stick.
I then contacted our inside person at AES and told them (admitted)
what I had done and that I was now concerned this pole was not just an
RFI issue but also a potential electrical safety issue since the guy
wires were not connected to earth at the bottom of the pole while one
of them is also connected to the neutral line up on the pole and the
guys are also not properly secured even though they are are wrapped
around the pole (better to remove them versus have them like they
currently are). Our AES contact person then said they had actually
already responded to the area on Friday after our initial informal
report to them and had identified a couple poles generating RFI in the
area which included the one I had identified, and they had already
issued a rush work order to fix the poles.
Note: one of the two guy wires might have actually been a steel strand
for supporting telephone wire in the past, I really have no idea.
I did take what I thought was reasonable precaution using my wooden
stick, but you can never be safe enough in my opinion and no reason to
take the risk.
Bottom line (no pun intended) is that you should not touch anything on
a power pole even if you think you are totally safe with what you are
doing. This is just my opinion, but I think it's sound advice which I
know has been mentioned previously (I know hitting a pole with a
hammer has been mentioned as a no no in the past, etc). It took me a
day to work up the courage to post this story, and please don't
chastise me.
73,
Don (wd8dsb)
On Wed, Mar 10, 2021 at 3:53 PM K9MA <k9ma@sdellington.us
<mailto:k9ma@sdellington.us>> wrote:
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 <mailto: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
<mailto:oppd.com@contesting.com>> On Behalf Of Don
>> Kirk
>> Sent: Tuesday, March 9, 2021 6:27 PM
>> To: RFI <rfi@contesting.com <mailto: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 <mailto:k9ma@sdellington.us>
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