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Re: [RFI] Difficult power line RFI find.

To: K9MA <k9ma@sdellington.us>, Don Kirk <wd8dsb@gmail.com>
Subject: Re: [RFI] Difficult power line RFI find.
From: "Hare, Ed, W1RFI" <w1rfi@arrl.org>
Date: Thu, 18 Mar 2021 07:06:38 +0000
List-post: <mailto:rfi@contesting.com>
No chiding, but this does represent a good example of how some RFI problems can 
represent important maintenance issues.

Even the neutral is not safe.  If there is a problem with a transformer ground 
and an imbalance between the loads on each of the phases, that voltage can rise 
above 0V.  With the problems that you described on that pole, a defective 
ground may well be present... or not present, as the case may be. 🙂

Ed


________________________________
From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of K9MA 
<k9ma@sdellington.us>
Sent: Thursday, March 18, 2021 1:07 AM
To: Don Kirk <wd8dsb@gmail.com>
Cc: RFI <rfi@contesting.com>
Subject: Re: [RFI] Difficult power line RFI find.

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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