One type of surge suppressor/lighting arrestor is literally a utility-grade
MOV-type device. Internally they can be comprised of a stack of these MOV
devices, and as temperature changes they can be expected to contract and
expand, so I conclude from research done on this tech +10 years back now.
de AA5CT Jim
On Sunday, January 28, 2024, 2:01:19 PM GMT-6, David Eckhardt
<davearea51a@gmail.com> wrote:
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>
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> on behalf of
> Alan Higbie <alan.higbie@gmail.com>
> Sent: Sunday, January 28, 2024 12:30 PM
> To: Rfi List <rfi@contesting.com>
> Subject: [RFI] Source power pole located - but wonder which components
> most likely temperature sensitive
>
> [You don't often get email from alan.higbie@gmail.com. Learn why this is
> important at https://aka.ms/LearnAboutSenderIdentification ]
>
> CAUTION: This email originated from outside of the University System. Do
> not click links or open attachments unless you recognize the sender and
> know the content is safe.
>
>
> 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>
>
> *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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