[RFI] PLN case SOLVED
JimMiller at STL-OnLine.Net
Sun Jan 17 19:51:28 EST 2016
Excellent, Just wondering what was involved in the delay. The rest of the story?
Did they ignore you? Did you have to locate it for them? How far into the three year process was this? Did they delay in the response after you told them the problem location? Were they cooperative in the entire process? Did you have to get people outside of the power company involved to receive cooperation?
Seems there is a lot of variation in cooperation from power companies.
73, Jim KG0KP
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Chris L. Parker
Sent: Sunday, January 17, 2016 6:17 PM
To: RFI List
Subject: [RFI] PLN case SOLVED
Thought it may be helpful to share a powerline noise (PLN) case that’s been dogging me for 3 years. It manifested itself as a very low level (almost at the noise floor) non-stop 120 Hz rasp that made weak signal listening on my Yaesu fatiguing and aggravating. The noise blanker had no effect.
Using a 440MHz beam and homemade ultrasonic pinpointer I finally identified the source as a guy wire rubbing against a secondary (120VAC) ground cable. I will try my best to describe the situation. 2 blocks from my home is a 16kV pole. At the top, the 16kV passes through two cutout fuses and into a pole pig transformer. Since the 16kV wires are from one side only, the tension on the pole is balanced with a diagonal guy wire anchored into concrete at ground level. About midway up the guy wire is a “Johnny Ball” insulator (porcelain strain relief). About halfway up the pole extending horizontally are the 120VAC secondary wires and ground from the pole pig. (2 insulated black wires loosely wrapped around a bare supporting cable which also serves as ground.) The local utility had the foresight to position a 3 ft. long plastic insulating tube around the 120 VAC secondary wires and bare support cable to keep the guy wire (above the Johnny Ball insulator) from rubbing against them. (The guy wire and secondary wires are in the same “plane” so to speak.) Over time, this insulating tube slid away, and residual 16kV, tracking through the old wooden pole, and down the guy wire (above the Johnny Ball) was shorting out against the 120VAC bare support cable. The RFI was particularly bad when the wind blew, as the guy wire would slide back and forth against the bare support cable. To make matters worse, the top half of the guy wire (above the Johnny Ball) made a great antenna. The fix was easy. A utility worker just slid the plastic insulating tube back into position, and secured it with a couple of large plastic tie wraps (instead of the previous electrical tape). The difference in listening to the radio is like night and day. I can hear stations almost at the noise floor I haven’t heard in 3 years. I hope this case description helps someone. Keep persevering!
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