[TowerTalk] Weird RFI at remote location

[John Langdon]

Do you know if the "main power line" is 7200V or 14400V?  The older lines are 7200 and more prone to transformer issues.  At my site, when they upgraded the lines to 14400 the line noise got much better.  Now I can hear the low band PWM controller noise from the microbrewery to my SW! 😊

73 John N5CQ


-----Original Message-----
From: TowerTalk <towertalk-bounces at contesting.com> On Behalf Of Ignacy Misztal
Sent: Friday, January 1, 2021 7:54 PM
To: tower and HF Antenna Construction Topics. <towertalk at contesting.com>
Subject: [TowerTalk] Weird RFI at remote location

Happy New Year!

I bought 26 ac of land with an old house for a remote station. The power company buried the last 300 ft of power line. Now, the location has 100ft tower with 40-10 beam, 4 sq on 80, with the tower is loaded for 160m. Also
7 beverages and a Spiderbeam. It was fun to have no man--made noise.

A few months ago the first power line noise started only when wet. MFJ 3-el VHF sniffer was going off scale. No arc noise as measured by the ultrasonic dish. It turned out to be a new transformer. Then another transformer by the neighbor 600 ft away started making the identical noise. The power company has replaced both transformers.

Now I have another powerline-like noise, strongest at 15m at S5 but heard on all bands 24h/day. NB blanks sometimes completely sometimes less complete.
On a panadapter, the noise appears to have min and max every 300 KHz. On one beam the max is at 21.2 and on another one is at 21.0.

The main power line is on a road 1500 ft away. The MFJ sniffer could not find anything really loud. I even tried 2m AM radio with 10 el beam, which indicated relatively small noise from an inaccessible pole. On 15m using a magnetic loop, I find strong noise by every pole. Strongest from a distribution pole where wires go to several other poles. It is about 270 degrees from my QTH.

The power company is lost with the new noise. They have no experience in RFI since there are no serious  active hams around.  They say that the noise may be coming from an electric fence.

Any idea on where the noise could originated from? In the past, all my power line RFI occurred when dry and hot.

Another question is how to deal with the power company that wants to help but can't and becomes frustrated? Should I try to hire someone from a nearby EMC that knows how to fix RFI?

Ignacy NO9E
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