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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: EDWARDS, EDDIE J" <eedwards@oppd.com (EDWARDS, EDDIE J)
Date: Tue, 1 May 2001 09:01:58 -0500
> -----Original Message-----
> From: John Pelham 
> 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.
And you might be able to hear it at your station if your antenna where a
different polarization or running 90 degrees from where it lays now or in
some other configuration.  You hafta take into consideration that the noise
is being propagated and emitted by a "transmission line".  All transmission
lines have a "Standing Wave".  That's what causes what Pete-ZR called
"peaks" all along a transmission line.  There are also nulls to go with them
peaks.  AND the really strange thing is the peaks in the vertical polarity
are nulls in the horizontal and vice versa! Page 104 of Nelson's book shows
this real well except no description about the polarity effects.  Of course
make sure the rig's noise blankers & DSP are turned off as mentioned in
another post.

BTW: GREAT JOB on the 5BDXCC!!!  I'm a DXer as well, but a little ways from
5 band yet.  Only 64 to go on 75/80 mtrs!  But I have 4 band DXCC using just
verticals only!

> 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.
Welcome to deregulation and one of it's many negative effects (if you can
call it that--it's actually just re-regulation).  I work for a power company
here in Nebraska (the only state that's fully Public Power, and we have not
deregulated yet either).  The place to start may be to call their
telecommunications department (if they have one, and most do because they
cover large areas and need microwave & 2-way systems).  Why call them?  They
know about the FCC!  They know about FCC rules, and they know if their
company is found in violation of any FCC rules it could mean that the FCC
will take a real close look at all of their FCC licensed equipment and
systems.  Nobody, no matter how diligent, wants the FCC to get out the
microscope and examine things.  They're bound to find problems!  This means
WORK and HEADACHES for the telecomm department.  They will want to avoid
that at all costs.

Usually it's the telecomm dept that is called in to resolve RI issues.  We
have one tech devoted to RI all the time, and he keeps the store room
stocked and in order on the side.  We've sent him to specific power line
noise training.  I occassionally get the chance to help out in the field.

It is not your responsibility to find the problem pole for them.  The FCC
has been clear on this issue.  HOWEVER, it may help to speed things up and
get a faster resolution if you do find it for them.  Your pwr co. obviously
sent out the wrong guy, troubleshooters are electrical system
troubleshooters, not RFI techs.  They find electrical distribution problems
causing outages or other related problems, not noise.  Our troubleshooters
wouldn't know a CBer from a Ham or even RF noise from normal static.

> My problem is, assuming it's power line noise, is how do I find the
> offending pole(s)?
Track it on VHF in the 130-150 Mhz range if possible.  200 MHz is even
better since the yagi would be smaller with more gain.  You must use a high
gain yagi to find the nulls and peaks.  The null is more useful in finding
the specific pole.  The power company should then be able to use a sniffer
or ultrasonic detector to verify that the pole is a problem and exactly
which hardware is the source.  As with everything, using the right tools or
equipment makes this an easy and fast job.  If the company doesn't have that
stuff, it is their own fault.

> 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).    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.
Use of a yagi is the only way to do this correctly

>   I went up to the base of many of the power poles -- I heard the
> noise some of the time, sometimes not.
Peaks & nulls from standing waves.  These noises may not have anything to do
with your noise at your station.

> 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.
Use a yagi with as high of gain as you can carry around.  We use 200 Mhz
since it's easy to carry 8 elements around and still have feeling in your
are after an hour of searching. ;^)

My guess is you have loose hardware on a nearby pole that is emitting noise
due to ESD (electrostatic discharge).  It can even be some metal structure
near power lines that does this, and in this case it's not the power
company's responsibility to resolve the problem.  The E-fields near the
lines can be very high causing arcing in anything that wiggles or is bent to
close to something else (like squirrel guards sometimes do).  The noise
you're hearing is probably NOT being conducted down the transmission so the
search must be done at high VHF using a yagi going pole to pole; either that
or an ultrasonic detector would be even better.

Good luck John, and let us know how it goes.

de ed -K0iL
-.-. --.-  -.-. --.-  -.. .  -.- ----- .. .-..  .-.-.  -.-
Ed Edwards, Communications Engineer
2-Way & Paging Systems
Omaha Public Power District   
Omaha, NE  
Phone: (402) 552-5425
--... ...--  . ...  --. .-..  - ---  ..-  --- --  ...-.- . .

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