This is an *UPDATE *to a question I posted on Jan. 28, 2024:
/archives//html/RFI/2024-01/msg00031.html
<http://lists.contesting.com/archives//html/RFI/2024-01/msg00031.html>
*Background*:
When it got cold (5 to 35 degrees F.) this major RFI would sputter and then
become steady at approximately *30 dBm* above normal noise floor on 7 MHz.
Using my 2-element 40-meter beam I determined the general direction of the
source. Then, with a 440 MHz AM receiver with a 7-element yagi, I located
the main source pole. This pole supported 7200 volts lines on the lower
level and 34,500 volts lines above that.
The utility responded. They used the new ("second generation") Radar
Engineers Model 251 ultrasonic dish from up close in a bucket truck).
With the ultrasonic dish, the utility people also located some additional
source components on an adjacent pole on the same line.
A work order was placed.
*Work done this past week:*
After 2+ months wait, the faulty hardware was replaced this past week.
Specifically, they replaced *a cross arm* and *all the insulators *on the
main source pole (34 KV). And they also replaced *all of the insulators*
on the adjacent pole on that same line. Tightened all hardware too.
Since this RFI source would activate with lower temperatures, I won't know
for sure until cold weather returns in late-Fall . . . but the basic noise
floor in that direction is 30+ dBm lower without any of the sputtering,
etc. that was still present in warmer weather.
*THIS DOESN'T ANSWER THE (academic) QUESTION:*
- They don't know which specific component was faulty - because they
just replaced almost everything.
- As a practical matter, I guess that's fine as long as the RFI is gone
(which it seems to be).
*Another RFI source was also eliminated on the same day*:
In another direction, I previously located a pole that generated strong RFI
on the higher bands: 17, 15, 12, 10 & 6 meters. Easy to pinpoint with my
SteppIR 3 el. and up close with 440 rig & 7 el. I had submitted that one
as a separate trouble ticket.
The utility similarly used its ultrasonic dish to "pinpoint" the faulty
hardware on this 7200-volt distribution line. At my request, this old
line, rotting supporting poles, and all the ancient hardware had been
replaced a year ago, i.e. March 2023. They figured an "LBU" (breaker) was
faulty - and needed to be replaced. But, the RFI source turned out to
be a *ground
wire* that was too close to a transformer. The RFI stopped as soon as they
increased the clearance. *Another RFI problem solved. Two in one day!*
*Side Note:*
- Our entire area had a widespread power outage on May 6th (wind storm).
It lasted for 6 to 8 hours.
- During that time, I powered my K3 and antenna switching by battery.
- All RFI was entirely gone until power was restored. Not just
powerline RFI but also everything that comes from all local homes
(appliances, microprocessors, solar panel inverters, etc.).
- I guess that's what it is like living way out in the country!
73,
~ Alan K0AV
Colorado Springs
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