foxhunt maybe ?
To: Repeater-Builder@yahoogroups.com
From: mwbese...@cox.net
Date: Sat, 24 Apr 2010 13:09:08 -0400
Subject: RE: [Repeater-Builder] Pager Interference Revisited
That’s one I hadn’t thought of, Chuck. Definitely
be a bugger to find!
Mike
WM4B
From:
Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On
Behalf Of Chuck Kelsey
Sent: Saturday, April 24, 2010 12:57 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Pager Interference Revisited
Since it sounds like the "problem" is
there continuously (with the correct
WX conditions) it pretty much rules out another TX that is less than
continuously "on."
My very first thought was a TV antenna preamp. I've seen those generate a
lot of crap before. The paging may be mixing at the preamp.
Just a thought.
Chuck
WB2EDV
----- Original Message -----
From: "Mike Besemer (WM4B)" <mwbese...@cox.net>
To: <Repeater-Builder@yahoogroups.com>
Sent: Saturday, April 24, 2010 12:08 PM
Subject: [Repeater-Builder] Pager Interference Revisited
> This is a continuation of the repeater interference issue we started to
> have
> last October. Maybe with a few new pieces of data, it'll spur some new
> thoughts.
>
> Background:
>
> Last October, our repeater (146.850 MHz) started experiencing pager
> interference. The interference can be clearly heard on the input from
> various diverse locations around town. Most of the time, the interference
> seems to drift across the receiver passband (you can hear it coming and
> going as it drifts through), although this year it seems pretty much stuck
> in the repeater input (don't hear the drifting anymore).
>
> Last year, the interference was also heard on a couple of other area
> repeaters, 145.43 in Macon (15 or so air miles away) and 145.11 in Cochran
> (20 air miles away), so you can see that whatever this is covering a
> pretty
> large portion of the spectrum. I've also been told that it's been heard
> on
> public-service frequencies as well, although I don't know what those
> frequencies are (exactly) and have never witnessed it myself. Yesterday,
> the interference moved from the input of 146.85 to the input of 145.11 in
> a
> very rapid manner. a period of 5 minutes or so, and then reversed itself a
> couple of hours later.
>
> We know that the paging interference is coming from 462.775 MHz. The
> paging
> company owner is a ham and has been very helpful. The interference can
> come
> from any one of three different sites, one locally, one in Macon and one
> in
> Roberta (about 25 air miles away), all on the same frequency. He has set
> up
> a phone number that I can call and leave a voice page on the local system,
> which help us with the tracking immensely. I believe he's going to do the
> same for the other two systems.
>
> I've sat very near his system locally and heard NOTHING on the repeater
> input while the interference event is occurring. I've also checked all
> the
> likely mixing products as well as frequencies in his multiplier chain and
> heard nothing.
>
> We feel certain that it's got to be a mixing issue, (it's not likely he
> has
> three transmitters with the same garbage on the output) but given the way
> it
> behaves it's hard to locate the source. The large, rapid frequency
> excursions are a bit baffling. If you just consider 462.775 and 146.25,
> it
> puts you very near the audio carrier of CATV Channel 39, but seeing it
> move
> to the input of 145.11 and 145.43 puts the possible mix frequency
> somewhere
> between Channel 39 and Channel 40.
>
> The issue disappeared over the winter months. If it's a hot, sunny day
> you
> can be sure the problem will be present. A hot, cloudy day is also a
> fairly
> good bet. Also, a cooler, sunny day will bring it out. Cool and cloudy
> or
> cold and sunny do not allow the problem to manifest. The issue has been
> present during and after several days of rain, so that seems to eliminate
> the 'rusty bolt' syndrome. I tend to believe it's an amplifier mounted on
> a
> pole or tower someplace that's going spurious with heat, but that is just
> a
> theory. Beam headings tend to point to the paging transmitters rather
> than
> the possible mixing source, which is baffling me as well.
>
> I feel like I must be missing something obvious here, but all the back and
> forth ideas we've all been working on never seem to answer all of the
> questions.
>
> What do you guys think?
>
> 73,
>
> Mike
> WM4B
>
>
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