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[RFI] A description of my RFI problem - help solicited

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Subject: [RFI] A description of my RFI problem - help solicited
From: Pete Smith <n4zr@contesting.com> (Pete Smith)
Date: Tue, 01 May 2001 07:55:16 -0400
At 07:26 AM 5/1/01 -0400, John Pelham wrote:
...  I've always thought that my symptoms are clearly power line noise,
>but what throws me off track is that the descriptions of power line noise
>state that the intensity should increase as the frequency goes down.  Mine
>sure doesn't, and I hope that K3RFI and N4ZR are right that it means the
>source is very close.  That'd be convenient!

In the case of the noise I mentioned yesterday, it was inaudible on 40m and
below, barely audible on 20, definitely there on 15, and quite annoying on
10 anytime I pointed my antennas toward Japan.  I suspect it is probably
there on 40 and 80 also, but not loud enough to rise above the ambient noise.

>My problem is, assuming it's power line noise, is how do I find the
>offending pole(s)?  I can't pick the noise up on my car radio either (AM is
>super quiet while the racket is in progress in 6M).  I bought a Yaesu VX-5R
>HT, which can receive AM on 6M (hey, I needed an excuse to buy this neat
>toy).  But I can barely hear the noise on its rubber duck antenna while it's
>S9 on my main station (admittedly much much better antennas!)  The noise is
>so weak on the HT that it only occasionally displays one or two S-meter

Can you borrow a small 6-meter yagi to use with the HT?  Alternatively, do
you have or can you borrow a handi that has VHF AM reception?  Then you
could cobble together a little yagi for any given frequency, or a Moxon
rectangle as suggested in the recent QST article on building an RFI sniffer.  

>From my experience, trying to get to an individual pole below VHF and
without a directive antenna can be quite frustrating.  While tracking my
10m noise using a 10m SW receiver, I found regular peaks in the noise every
1/2 wavelength along the powerlines running in both directions away from
the source.  It was quite hard to tell whether each succeeding peak was
louder or weaker.

The response you've had from the power company is absolutely typical.  Mine
even admits it has some RFI capability elsewhere in its system, but has
been unwilling to call in the experts.  an experienced lineman can be a
help, but usually you're on your own.  If you can get within a relatively
small radius, but can't single out a particular pole, you might try "in the
vicinity of pole no. xxxx."  I also guess I'd start putting it in writing,
so they can see you're building a file. 

73, Pete N4ZR
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