[RFI] PLN case SOLVED

[Chris L. Parker]

Hello Jim et al.,

I will try to briefly answer your questions and then elaborate.  The 3 year delay was due to my inability to positively locate the source.  (I’m just not that good.) No, the utility did not ignore me.  I did have to locate it myself (I always do).  I located it this year on January 5th, the utility RFI Inspector confirmed and wrote it up on the 6th, and it was fixed on the 8th.  (He’s known me for 5 years and we have a very good working relationship due to (I think) my high hit to miss ratio.  I find the source, he confirms it and writes up a real problem, and then he looks good to his upper management.)  The utility was very cooperative, and I did not have to involve outside people.

Having said all that let me expand for the rest of the story.  First, the layout of my neighborhood here is problematic.  I have 1960ish build 16kV lines/poles directly across the street from my home.  They run north/south and east/west for blocks.  Near the coast, with the saline marine air, this hardware is at the end of its design life.  These poles have the troublesome old porcelain Bell insulators, some of which have been replaced by the newer polymer types.  The rasp was very low level, almost at the noise floor.  But due to the abundance of 16kV poles, it was the proverbial needle in the haystack.  80 meters was the worst, 40 meters was bad, 20 meters was annoying, and the noise many times even made it up to 17 meters.  Surprisingly, heavy rain did not reduce the noise.  For the first 3 years, it proved impossible (at least for me) to get a reliable fix on it.  The noise was so low level it was inaudible on my Sony 7600 portable with tuned 2 ft loop.  I could not get a reliable fix with a VHF aviation band portable RX with 3-element tape measure beam.  I found my Arrow 5-element 440 MHz beam and Yaesu portable lacked adequate sensitivity (the noise power at those frequencies is much lower, and to answer your question David I would say 200 ft would be a rough guess for maximum range on 440 MHz, line of sight of course)  I had previously tracked down and rectified numerous 16kV PLN issues in my neighborhood.  Almost all were bad Bell insulators, a few post insulators were bad, I found one sparking cutout, one bad tie wire, and another was a broken tie wire cable clamp.  I was fairly experienced in locating PLN issues.  But the nature and sound of the rasp was different.  Its constancy, low level, and character did not fit the typical pattern of previous PLN signatures.  So, I focused my attention on my adjoining neighbors and the neighborhood, looking for the usual suspects like LED lights, a noisy WiFi hotspot (by Ruckus) power supply, cable modems, FiOS gear, invisible dog fences, dirty Raptor guards, a plasma TV on standby, a bad streetlight ballast, neon signs, etc.  I suspect my big break came from corrosion.  I speculate the guy wire to ground wire contact became corroded enough to cause the noise to act up with the wind.  This created a specific noise.  (It didn’t do that previously.)  That noise started in December 2015.  With a unique signature (rather than just a rasp) it was a fairly quick process to use the Sony with the loop and then the VHF aviation portable to localize it to a general area.  While investigating one 16kV pole, the 440 MHz beam led me across the street from where I was to another 16kV pole.  Standing about 20 feet from the base of that pole, I aimed the ultrasonic pinpointer almost straight up at the Bells but got nothing.  Then came the revelation.  As I lowered the pinpointer from an overhead aim to the ground it groaned.  Raising it back up just above the horizontal it groaned again.  I was astonished, as it was pointing at the guy wire of the pole.  Then I noticed the guy wire was touching the bare secondary support cable.  And I saw the misplaced insulator tube.  I was not sure this was the source of the rasp, but when confirmed with the 440 MHz beam, it was certainly the source of the noise when the wind blew.  After it was fixed, I realized it was also causing the rasp for the last few years.  In the end, I realize I got real lucky. Hope this helps.

73, Chris