[RFI] Line noise update

N1BUG paul at n1bug.com
Tue Oct 9 08:16:15 EDT 2012

Several months ago I posted about my severe power line noise. I 
honestly wasn't optimistic about a cure and had a very unfavorable 
opinion of the utility involved (partly due to past experience with 
issues like this). I am happy to report as of last week 80% of my 
noise has been eliminated. This is a very abbreviated summary of 
what took place.

The company T&D Construction Planner came out in June to investigate 
my noise complaint. While some of my offending poles were quiet that 
day he found 9 that were not and the following week wrote a work 
order to address issues on those.

Eventually word of slow progress gave way to word the job was 
complete except for one pole where they were waiting on another 
company to set a new pole. But nearly 100% of my noise remained!

The tone of conversations with the utility were going down hill. He 
had been trying to blame it on devices in homes, etc. which I wasn't 
buying into. I know that happens a lot but I had done my homework 
carefully. Reluctantly he agreed to come out and take another look 
in late September. This time I presented a list of my 6 worst and 
confirmed poles. He checked all 6 and agreed all were noisy.

Three working days later the troubleshooter showed up with a line 
crew. They worked on all 6 of those poles and it made a huge 
difference. I haven't seen noise levels this "low" in years.

Here is a summary of what was done last week in case it may be of 

Pole 1 : 3/4 of a mile from me and my worst noise offender. S9+ 
noise on all bands through 6 meters, also conducted noise from here 
radiating from many poles for a half mile in either direction. 
Suspected to be a lightning arrestor, but changing it out did not 
help. It turned out to be the transformer, which they replaced.

Pole 2 : 1/2 mile from my house, intermittent but very strong noise. 
The problem was a burned insulator on the 46 kV transmission line. 
The insulator was replaced.

Pole 3 : 150 yards from me. Two insulators on 46 kV line loose on 
mounting bracket. Replaced.

Pole 4 : 300 yards from me. Sparking/burning hot-line clamp. Replaced.

Pole 5 : 3/4 mile from me and my other really bad offender. 
Lightning arrestor replaced.

Pole 6 : Over 1 mile from me. Tie wires replaced and or re-tied. 
This was an area of recent storm damage where hasty repairs had been 
done on a Sunday to clear the road and restore power to several 
hundred customers.

Before leaving the area that day, he told me to monitor and let him 
know if any problems remained. I assured him I would! I have been 
monitoring for 6 days since this work was done. I have in that time 
identified two remaining noise sources. One is from that spot where 
a new pole has finally been set but shifting everything over still 
needs to be completed. The other is my "mystery" noise signature 
that eluded me all summer. I knew there was one I had not located. I 
could clearly identify the particular signature using very 
directional antennas from home but could not find an exact match for 
it in the field. It was near one of my really bad 24/7 offenders and 
got lost in the din. Now it is the only remaining source in that 
direction, so it should be easy to find. I haven't had time to 
investigate yet but I do have a suspect structure from earlier work 
as a starting point (and of course antenna bearings from home).

My RFI hunting tool kit has grown since my last report. I never 
leave home to hunt power line noise without:

1) Modified MFJ-856
2) Alinco DJ-X11T 50 kHz-1300 MHz all mode receiver with 445 MHz yagi
3) 40 kHz ultrasonic locator (Midnight Science new & improved model RX3)
4) On-demand ability to retransmit audio from my station receiver 
via UHF FM so I can listen to it while out hunting noise (VERY useful!)
5) digital camera, binoculars, notebook, spare batteries, etc.

At some point I will probably add HF DF loops and possibly other 
VHF/UHF directional antennas to the setup. I am now chair of the 
club RFI committee, so no doubt will have use of these tools beyond 
my own situation. Here is a link to a picture of my "RFI Mobile".



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