Mike,

I'm coming to this late, but I have comments and questions.

What type of hardware are the paging transmitters?  What are the
repeaters in question, and what type of duplexers, feedline, and
antennas are used?

On 4/24/2010 3:42 PM, Mike Besemer (WM4B) wrote:
>  
>
> Not sure what you mean by 'come and go'.  It's there when the pager
> transmitter is up, gone when it's not. 
>
In another message you implied it sweeps across multiple repeater inputs. 
>
> It also comes and goes with heat and sun... we may have days with no
> interference if it's cool and cloudy or just plain cold.  Rain makes
> no difference.
>
We saw the same thing with Radio Shack and Winegard active TV antennas
on RVs.  The problem was a high band pager and our UHF radio inputs.
>
> Nothing remarkable about the audio... sounds like clean, clear paging
> tones.  Never heard anything else.
>
This implies a first order contribution to a mix or spur.  If the second
or third harmonic of the pager was involved, the deviation would be a
suitable multiple and should sound distorted.  Might be good to ask him
what transmit dev. he runs, or measure it.
>
> There is an abundance of TV stations, DTV, translators, AM, FM... you
> name it.
>
Yeah but this sounds like something flying.  If mixes sweep across your
input one contributor is almost always an amplifier that is oscillating.
The two frequencies you mention would require a channel 37 station and
those don't exist in the US.
>
> The paging signals are both, depending on which site it's coming from.
>
Eh?  what do you mean here?
>
> I can get my hands on pretty much anything I need.  Spectrum analyzer
> is no problem.  I have a good 'connection'.  Did some hunting with a
> spectrum analyzer last year to no avail, but now that I have the
> ability to call the system and have it send out a page we have a
> little better advantage.
>
Is the paging system key down, or is it transmit on demand?

Can you hear the interference far from your site (several miles?)  The
ability to DF it sort of implies this. 
>
> I'd call the area 'populated', but not 'urban'.  Mostly housing around
> the site, but plenty of industry (and towers) visible from the top of
> the water tank.  (We are, by the way, the only user on the tank.)
>
What kind of sites are the paging transmitters on?  Rental tower,  water
tank, building?

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