The Navy Postgrad School has some real experts, PHD's with climbing harnesses,
and gaffs, spectrum analzyers etc who wrote a multi edition Book on
Power line noise Amelioration. They dispense a lot of practical and
theoretical info on finding and ameliorating line noise sources.
They hae DECADES of experience in ameliorating line noise, to the benefit of
Naval HF receiving sites, which are a disappearing species now.
The ARRL has a downloadable file of one of the NPS' Manuals on the
I seem to remember if you had to name two big offenders as line noise sources,
it was linked together chains of bell insulators (now often updated with
epoxilators ) and Lightning arrestors.
Another lesson that I learned from their book and discussions, is an RFI
source often sets up standing waves of RF on the distribution lines, that
results in rise and fall of RFI noise you hear on an AM radio, as you search.
A peak in the noise level that you hear may mislead your attention to a
particular pole or object, when the actual source may be a number wavelengths
At N6IJ, I did what Peter did, looked at a suspect pole at night, and was
astounded at the amount of arcing and sparking I could see whenever the wind
caused vibration on the pole. I did what the NPS experts say NEVER to do (for
safety reasons) and took a single jack sledge and smacked the pole, and
it really lit up with arcs and sparks. It made me very wary of ever casually
touching ANYTHING associated with poles, guys, grounds, conduits, etc...
All the Best, 73, Merry Christmas,
Pat Barthelow email@example.com
Jamesburg Earth Station Moon Bounce Team
> From: firstname.lastname@example.org
> To: email@example.com
> Date: Fri, 14 Dec 2007 01:10:46 +1100
> CC: firstname.lastname@example.org
> Subject: Re: [TowerTalk] Line Noise
> It would have been interesting to look at the pole at night to see if there
> was any visible arcing between the bracket and the wood.
> That is one of the first things we do in VK land, since like you, our RFI
> lineman only works during the day 9-5. We often have to tell him exactly
> which pole is at fault by observing arcs at night.
> Peter VK3QI
> ----- Original Message -----
> From: "Dennis OConnor"
> Sent: Friday, December 14, 2007 12:33 AM
> Subject: [TowerTalk] Line Noise
>> As I have commented on several of these forums, I have developed a severe
>> line noise problem that especially plagues my 160 operations.. During the
>> ARRL 160 it wiped us out on the NE Beverage being 30 over almost
>> continuously... I had a call in to the power company now for some
>> weeks... Monday I got a call from their noise complaint guy and we made an
>> appointment for 1PM Wednesday...
>> Tuesday nite I got home and checked the noise during a wet snow fall...
>> It was dead silent - just like it is after a good rain...
>> I thought that was just my luck with Consumers coming out the next day...
>> But Wednesday AM at a crisp 25 degrees the 'insulator' had dried and was
>> back to it's usual roaring-snapping self...
>> Anyway, during the phone call with their trouble shooter I was
>> disheartened as the guy asked which radio station was getting the
>> interference... So I gently explained about ham radio..
>> He then asked if that was channel 19 > shoes>...
>> Finally he asked what frequency... I said 1.8 megacycles was the worst...
>> A long silence and he asks, politely, what is a megacycle... ahhh
>> Anyway, he gets there promptly (actually 15 minutes early) on
>> Wednesday... We talk it over and he listens as I switch the Beverages to
>> show the noise direction is Northeast.. I ask (with anticipation) what
>> kind of noise finding equipment the power company has... He looks at me,
>> shuffles his feet, and says, "I use the AM radio in my truck as I'm
>> driving around."
>> Now it's my turn to shuffle my feet... I tell him I can get him within a
>> 1000 feet of the noise source on the road, but that the high tension lines
>> are way back off the road on private property(s) and he can't get his
>> truck in there...
>> I bring out the MFJ noise receiver (highly recommended by me) and show
>> him how to use it and off we go... He likes the MFJ... Finally parked at
>> the point of maximum noise on the road a half mile from my place we get
>> out... There are no trepassing signs visible... I mention to him that as
>> the power company, doesn't he have the legal authority to inspect his
>> power lines... His instant answer is, "Absolutely.", and off he goes... He
>> is a real go getter... If I were hiring I would recruit him...
>> He hikes through the snow, crawls over a fence and goes back in the
>> woods... I see him sniffing around the pole holding up the 4800 volt line
>> A few minutes later he is trotting back towards the road underneath a drop
>> coming out and crossing the road to my side and going towards a neighbors
>> spread... He says the signal strength drops as he gets closer to the HV
>> pole but seems to rise as he comes back towards the road... We go down the
>> road and back up into the neighbors drive... He gets out and starts
>> walking through the woods...
>> "Here it is.", he calls.. I decide they can only shoot me, and I go
>> through the woods to meet him... Right there, he says pointing... I look
>> up the pole at the transformer and the fuse, etc. and see nothing amiss...
>> He says, look at the stand off bracket for the fuse, there is a crack in
>> the fuse holder and the wood on the pole is starting to char... Notice
>> how dark the wood is right at the base of the bracket... I peer at the
>> pole... I don't see the crack, but I do see the ring of darker wood around
>> the base of the bracket...
>> He says the fuse holder is shorted to the metal bracket and there is high
>> voltage on the metal bracket and the current is charring the wood... He
>> also points out that the back guy for the pole is touching the neutral
>> line running to the buildings.. I notice that he does not touch the back
>> guy, but simply leans close and listens to it (it has a fiberglass
>> He says he will enter a work order to have them replace all the hardware
>> on the pole except for the transformer... I ask him about the back guy
>> touching the neutral... He comments they will have the township pull the
>> electrical inspection and see who signed it off...
>> So that is it this morning... I still have noise, but hopefully not for
>> denny / k8do
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