You need a small UHF beam and AM mode receiver. Operating at
(say) 440 Mhz, you can use a beam to idetify actual sources. I
used aircraft band AM to get close to a source, and zeroed in
on it with 1.2 GHz.
The source which was bothering me actually was about 2 miles
from my QTH. HF impulse nosie was due to lower frequencies
being conducted along the AC power and grounded messenger
strands and reradiated elsewhere. Turned out the origin was
at a local airport, and THAT got quick attention.
Cortland
ka5s
------Original Message------
From: "John Pelham" <john@radiophile.com>
To: rfi@contesting.com
Sent: May 1, 2001 11:26:49 AM GMT
Subject: Re: [RFI] A description of my RFI problem - help
solicited
Wow! I'm surprised and gratified at the number of responses
to my RFI
problem. Thanks to everyone. Let me answer some questions
and discuss some
issues raised in the responses:
I have done some reading on RFI. I have the ARRL Handbook,
and the
Interference Handbook by Nelson. There also have been some
QST articles on
the subject, which I've been able to read by searching "RFI"
on the ARRL Web
site. 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!
My antennas below 20M are indeed different from those above,
as K0iL asked.
They're wire antennas of lower gain. But they're by no means
particularly
inefficient (I just need a few more 80M QSLs for 5BDXCC ;-)
and I would
think I'd at least be able to detect the noise on 40, 80 or
160M if it's S9
on 6M.
I've already had an unpleasant experience with my local power
company about
this. A few months ago I called in a complaint, and the power
company sent
out a "troubleshooter." I was fortunate to be home when he
showed up. To
give an idea of how our conversation went, he didn't know what
ham radio
was, really (he said he had a ham friend, but his description
was that of a
CBer). He said that if he couldn't pick the noise up on the
AM radio in his
truck, he could do nothing. When I mentioned, in a mild and
roundabout way,
that it was the power company's responsibility to silence
their noise
sources, he laughed. He suggested that I put "noise filters"
on my ham
radios. He left saying that someone else from the power
company would call
me, but no one did, and I didn't pursue the matter. He did
say that if I
found the offending pole(s) that they would check them.
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
segments. Anyway, given that unreliable indication, I walked
around within
500-1000 feet of my house, and the noise came and went in no
particular
pattern. I went up to the base of many of the power poles --
I heard the
noise some of the time, sometimes not. I drove around within
a two mile
radius with the HT in hand -- here it was harder to tell what
was going on
because the noise was so weak, but I thought that I heard the
noise most
everywhere, again with no particular pattern or apparent
source. The
diffuse, source-less character of the noise, at least with my
limited
investigation so far, is discouraging.
73, John
John Pelham
E-mail john@radiophile.com
Antique radio Web site http://www.radiophile.com
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