Thanks for mentioning the lightning shunts, Dave.
I didn't see any on the pole Alan identified as
the suspect one, but perhaps that's my eyesight.
There is a capacitor bank on the left-side pole
in Alan's photo, and it appears there may be lightning
shunts on those taps for the capacitors.
We rarely observe the failed/failing lightning
shunt source of arcing here even though we
do get lightning in the summer. Jeff, W4DD
has commented on the prevalence of those
sources in the southeast U.S. (he's in Georgia)
where he does his RFI sleuthing. The behavior
of those shunts is the opposite of what we
see with tie wire arcs - the failing shunts arc
more steadily in humid or actively precipitating
weather. Tie wire arcs go quiet when wet enough.
73,
Mike, K8CN
________________________________
From: David Eckhardt <davearea51a@gmail.com>
Sent: Sunday, January 28, 2024 2:59 PM
To: Michael Carter <Mike.Carter@unh.edu>
Cc: Alan Higbie <alan.higbie@gmail.com>; Rfi List <rfi@contesting.com>
Subject: Re: [RFI] Source power pole located - but wonder which components most
likely temperature sensitive
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Don't neglect the standard lightning shunts on the poles. My last case
involved just those. Once the power provider replaced a single lightning
shunt, the RFI totally vanished. They can and do become damaged by shunting
multiple lower-level discharges, much like MOVs.
Dave - WØLEV
On Sun, Jan 28, 2024 at 7:40 PM Michael Carter via RFI
<rfi@contesting.com<mailto:rfi@contesting.com>> wrote:
Hi Alan,
I was intrigued by the 2-level primary distribution
lines - not something we see here in New England.
I wasn't able to zoom into the photo to see the
detail of the insulator type. Older bell insulators
with tie wires have been a chronic problem in
my neighborhood - the tie wires fracture and
create perfect spark gaps. The local utility has
gone to using 'vise-top' insulators that eliminate
tie wires altogether when they replace the bell
insulators.
The cessation of arc noise at moderate temperatures
is curious. The arc sources in my neighborhood
have been sensitive to humidity and actual precipitation
more than temperature. Have you noticed any reduction
of arc noise intensity when there is active precipitation at temperatures
below 35F?
Your local utility should acquire an ultrasonic dish
locator - it's remarkable the pinpoint accuracy of
this tool down to locating a hidden arc on a bolt/nut
junction.
Is there any change in RFI level after dark while
temperature remains close to the end-of-day temperature?
The presence of the street lamp on the suspect pole
is the reason for the question.
73,
Mike, K8CN
________________________________
From: RFI
<rfi-bounces+mike.carter=unh.edu@contesting.com<mailto:unh.edu@contesting.com>>
on behalf of Alan Higbie <alan.higbie@gmail.com<mailto:alan.higbie@gmail.com>>
Sent: Sunday, January 28, 2024 12:30 PM
To: Rfi List <rfi@contesting.com<mailto:rfi@contesting.com>>
Subject: [RFI] Source power pole located - but wonder which components most
likely temperature sensitive
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I have located the source of the power line RFI.
The local utility RFI engineer (P.E.) has my RFI trouble ticket in the
queue. Hopefully within the next week or so.
But, now I'd like to gather ideas about WHICH COMPONENT(s) are the
likeliest suspects - so I can be as helpful as possible when the
utility guys show up.
Otherwise they'll go up with hot stick and wiggle components - which is how
they have located problem hardware in the past.
Background:
1. This source produces approx. 30 dB increase in noise floor on 40
meters. Similar on other bands.
2. DF'ed: first with 40 meter beam; then with portable flag
unidirectional antenna; then zero'ed in with 440 mHz 7 element yagi.
Repeated process.
3. Important clue: The RFI is steadier (and stronger) with lower
temperatures. Example: absolutely horrible with outside air temp. of 0
degrees F. But, more of spitting intermittent irregular approx. 1-3
impulses per second when temperature gets above 35 deg. F - and settles
down at 40-45 deg. F. All under windless conditions.
4. I don't know enough about what hardware components on pole would be
most likely to be temperature sensitive.
This reflector does not allow attachments.
So, I have temporarily uploaded a PHOTO to my QRZ.com page
https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.qrz.com%2Fdb%2FK0AV&data=05%7C02%7Cmike.carter%40unh.edu%7C44ee17d476c548d0384d08dc2026dd46%7Cd6241893512d46dc8d2bbe47e25f5666%7C0%7C0%7C638420598501112815%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=kCN2N4c78lQnb1b18N9OxFqqRbQ0zmOW6oxF%2F6K07QY%3D&reserved=0<https://www.qrz.com/db/K0AV><https://www.qrz.com/db/K0AV>
*Note:* The RFI is coming from the pole on the *RIGHT - NOT the one on the
left.*
Thanks for ideas.
73, Alan K0AV
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Dave - WØLEV
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