[VHFcontesting] Re: RFI/Power line noise problem

[Steve McDonald]

John...one of the best ways to 'track' these noise sources is with an
ordinary AM transistor portable, with a built-in ferrite bar antenna. Tune
it as low as it goes or as high as it goes (in the AM band) to find which
end provides the loudest sample of the QRN source. Start walking and
rotating to see if you can find the rough direction. Remember that the
source of the signal will be in the plane of the ferrite bar when the signal
is nulled, not peaked. You may have to go several houses away or even one
street over, either way, but you will be able to null it eventually. If you
can get a few nulls from different locations, you should be able to get
fairly close to the source.
Does it peak while standing under the power lines? Follow the lines until it
gets weaker or stronger. Often times an offending appliance (the noise
source) will send crud down the main hv line and appear to be coming from
the line itself. Eventually you should be able to trace it's source this
way...it could be several properties away.
Does the noise source ever go off? This can give you a clue, especially if
there is a pattern. Particularly bad are outdoor lights on photo-electric
sensors. They can make a hell of a racket from several properties away.
Do you have a metal tower? It can pick-up and re-radiate power line noise
very efficiently and can sometimes look like it is the noise source itself.
And first (I know you mentioned this)...be sure it is not at your place.
Kill the main breaker if need be to determine this.
As well...do you have any "switching" power supplies close to the rig? They
can cause a lot of weird sounding "hashy" signals from LF to VHF. As well,
these new xenon track lights are awful things. Whoever invented these things
should be forced to listen to the crap they produce for a few weeks. They
have a cheap 12V switching supply that sounds like the best H-P noise source
you could buy.
You may have to walk onto some properties other than your own or the public
streets to do this so be careful and think about how best to approach this.
You know your neighbours better than I!


Steve / VE7SL



From: John Geiger <johngeig at yahoo.com>
To: <dx at mailman.qth.net>; <dx-list at yahoogroups.com>;
<yaesu at mailman.qth.net>; <FT100 at yahoogroups.com>; <FT-100 at yahoogroups.com>
Cc: <vhf at w6yx.stanford.edu>; <vhfcontesting at contesting.com>;
<wsvhf at mailman.qth.net>
Sent: Wednesday, September 18, 2002 6:17 AM
Subject: RFI/Power line noise problem


> Turning to the reflectors for some help in this
> problem.  I seem to have a decent amount of static
> (s5-6) at times on HF (especially 30 meters and below)
> and on 6 meters.  I even bought a FT100D to use on the
> reputation of its noise blanker,and the NB does work
> on it at times.  Other times it even overcomes the NB.
>  I called the local power company who came out to
> check for power line noise-using some equipment that
> received in the VHF range.  They found nothing from
> power lines, but did locate 1 house several blocks
> away that was throwing out some static-it isn't this
> house that is affecting me as we tried some tests
> yesterday turning off their power, etc.
>
> The power companies conclusion is "Sorry, it is not
> our lines, we can do nothing more, good luck."  So
> what do I do now?  This noise is frustrating at best,
> and really interfering with my receiving at worst.  I
> am not ready to conclude that it is not power line
> noise, as it seems to me that most people with line
> noise problems, get them in the lower HF range, not in
> the VHF range like the power companies equipment
> tested.
>
> I have tried to locate the offending source in my own
> house, and nothing here seems to be causing it.  Cant
> seem to null it out using my miniquad-it seems to be
> coming from all directions and it is worse still on my
> G5RV dipole.
>
> I do have some noise on 2 meters, not as bad, that is
> coming from the NE-I can null this with my 13B2.  I
> also can't figure out what this is, or if the two are
> related.
>
> Anyone else been through something like this, and any
> help or ideas?
>
> 73s John NE0P
>
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