W9TC Radio Frequency Interference

On Jan 21, 2017 Jay (W9TC) asked for my assistance in confirming the source of some RFI that's interfering with his reception on all of the lower HF bands. Jay suspects the interference is originating from one of 2 different light poles located behind a commercial building just to his West. He also mentioned that he tried to contact this business, but has not had a response in over 3 days time.

While out driving just after dark on the 21st listening to 1710 AM on my cars radio I drove around the area where W9TC lives, and came upon what must have been the 2 light poles Jay suspects are the problem. One light pole was not working (dark), while the other one was working and I was receiving a tremendous amount of interference on 1710 KHz.

I then went home and loaded my car with some HF as well as VHF direction finding equipment and headed back out to the area of these two suspect poles. Listening on 136 MHz AM using a directional 4 element beam, I was able to confirm that the RFI is originating from the light pole that's not working (identified as "S1"). Below is a plot of the audio received on AM 1710 KHz, and you can see the light pole is generating noise at a frequency of 120 Hz (probably arcing during each half cycle of the 60 Hz power). Using Google Earth, the suspect pole is located 560 feet from W9TC at a heading of 285 degrees.

Audio plot of the noise received on 1710 KHz AM

Map Showing Location Of Suspect Light Pole

(website created and maintained by Don Kirk (wd8dsb), January 22, 2017)