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Re: [RFI] FW: Topband: Exciting noise sources

To: "rfi@contesting.com List" <rfi@contesting.com>
Subject: Re: [RFI] FW: Topband: Exciting noise sources
From: dalej <dj2001x@comcast.net>
Date: Sun, 27 Mar 2011 15:30:37 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Hello Larry,

Can I assume that MFJ noise meter is ok device?  I've been thinking about 
buying one.  Good idea or not?

Regarding noise on poles.  I had a terrible intermittent noise here on 2 
meters.  It turned out to be a pole almost in front of the house.  The pole top 
had rotted out and there were splinters of pole sticking up and the bolts 
holding the insulator assembly loosened up as a result.  So any wind or shaking 
of the wires or pole caused the sparking noise.  The power company, (Xcel 
Energy) lineman cut off the top foot or so of the pole, drilled new holes for 
the bolts and replaced the insulator and hardware.  The noise was gone.  I see 
another pole about a block away with the same problem.  I look closer with 
binoculars.. If I had a noise meter I could do a better job of pin pointing 
noise, which helps when I call in a report.  

Dale, k9vuj

On 27, Mar 2011, at 11:37, Tim Duffy K3LR wrote:

> Yesterday K0HGW and myself spent the day with a line crew from the Otero
> County Electric Cooperative trying to find two noise sources which have
> plagued them for several months and occasioned numerous complaints.  In the
> first case we were able to locate a power pole with our direction finding
> equipment that seemed to be the location of the noise and they began to work
> on the hardware from their bucket truck.  We use an MFJ noise meter coupled
> to an external speaker to let them listen as they tighten hardware, drive in
> staples and adjust wires. There were definite changes in the noise as they
> worked but the situation didn't really improve.  They even took the wire
> (14KV) off the top insulator and cleaned the insulator and replacede thhe
> twist wire holding it but, while there was some improvement,  that didn't
> solve the problem. By shaking the hot wire they could get the noise to
> change, though.  In the meantime we identified another nearby pole
> that showed noise so they moved to it with the bucket truck and repeated
> the entire sequence of tightening hardware,etc.  Once again there was.some
> improvement but, after servicing the pole the original problem was still
> there.  We began checking every pole in the area and found significant noise
> on each pole that could be affected by jarring the pole and poking on
> hardware with a fiberglass rod.  As we moved down the line the overall noise
> level varied and could be changed slightly by manipulating hardware. 
> Finally, at one pole about a half mile from the first one they worked on,
> they pulled on a neutral wire with their pole and the noise completely went
> away.  The wire had been just barely touching the head of an eyebolt holding
> a transformer.  Not only did the noise at that pole disappear but all the
> other noise sources in the area disappeared.       When we went to the other
> noise source (about 5 miles away) the same proceedure was
> followed and we located the primary noise source in the same way.  It was
> also a neutral wire touching a bolt.  When it was moved noise sources that
> we had picked up at other poles up to a half mile away also disappeared. 
> This was not the first time we have found that loose hardware and staples
> can be excited by a distant noise source into emitting noise on their own
> but, once the primary noise source is eliminated, they no longer create
> problems.  Although we know that this problem recurrs we have not found a
> realiable way of detecting the primary source other than pole by pole
> testing and hardware tightening.  The reason is that the primary source is
> no stronger on our detection equipment than any other source, and is often
> less intense that the sorces excited by its radiation down the line.  We
> have developed a good enough relationship with the local power conpany that
> they frequently call on us to help them find noise sources that they
> receive complaints about.
> Larry N7DF
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