[NCARC] The 145.115 saga continues

[Steve Henry]

Here's the latest update on the 145.115 interference story.  The bottom line
is we need someone who can go up with me (or on their own) to solve a stuck
paging transmitter problem to help diagnose the issue as soon as feasible.
Here's the event by event description of the last few days --- an
interesting story is unfolding.


1.	George (AB0SF) pulled together an isolator and low-pass filter and
installed it on Sunday afternoon on the output of the 145.115.  This is
really nice to have so that we have a good clean output signal.  Thanks
again to George for making yet another trip up the mountain in snow.

2.	Testing Sunday evening done by Willis (WA5VRL) indicated very little
difference in signal strength on 160.263 MHz ("GWR" frequency).  George is
one of the lucky hams who can reliably pick up the interference on 160.260
or 160.265 right at his home.

3.	A post from Chris Kelly, K0PF almost prophetically predicted that we may
not see any improvement with an isolator in the event that the mixing was
occurring at.... another transmitter.

4.	From a study of the 3rd-order intermod components, either 129.967 MHz or
152.689 were likely frequencies to create the interference at 160.263 MHz.

5.	A check of the frequencies granted at the Horsetooth site showed,
amazingly enough, Rule Radio having a license for 152.69 MHz.   They have
their transmitter in Dick Redfern's building and antenna mounted low on
Dick's tower, but not very different in height to our new antenna position.
In fact, according to George our antenna aperatures are almost at the same
level.  Thus, instead of maybe 100 feet of vertical separation, we now have
maybe 150-200 feet of horizontal separation between the antennas.

6.	The carrier from Rule Radio is on all the time.  While this is a pager
site, it is unusual for the carrier to be on all of the time.

7.	From a search of the FCC database done both by George, AB0SF and Willis,
WA5VRL-- (attached) I determined the phone number.

8.	George (AB0SF) reported that their pager doesn't have an isolator or
filter on the output transmitter.  It also has a transmitter known to have
some issues.

8.	I contacted Bob Rule and left a message.  Within a few hours I was having
a friendly conversation with Bob.  He is a "one man" operation and has a
number of paging sites in Wyoming.  He also used to own a number of FM radio
stations although he has sold those off.  He still does a "gig" every
morning on one of the stations (he has quite a nice voice --- obviously
radio announcer quality).

9.	Bob indicated that his pager is having a problem with the carrier always
being stuck on.

10.	The pager should only be used maybe once every six months to page a
couple of executives of an oil refinery in Cheyenne who live in Fort
Collins.  This is about how often a fire or explosion happens at their
refinery and ...after hours... (evenings/Weekends) the executives get paged
to drive up and help with the situation.

11.	The stuck carrier means that all of the paging traffic from Cheyenne
(very heavy traffic) gets broadcast in Fort Collins.  Normally this wouldn't
happen as that all transmitters hooked up to be pagers that aren't where the
page should occur get shut down so that pages only get made where they need
to get made.

12.	Bob is seeking our help with solving the stuck carrier problem and...if
experiments show that the mixing is occuring in his equipment....with help
installing the right filtering on his equipment--- basically he will
reimburse us for time and expenses.  He is going in for some surgery and is
welcoming our assistance.

13.	Bob explained to me about how paging works and about where to pull the
plug on his equipment to run the test as well as how to diagnose if the
paging interface is defective.

14.	If we can solve the stuck carrier-- it seems that it will be unlikely if
we need to do much more to solve the interference issue.  The pagers signals
will go off maybe for 20 seconds twice per year once the paging transmitter
doesn't broadcast incorrectly the Cheyenne paging signals.

Now, next steps:

Can anyone make a trip up to the repeater site this week before the fest?  I
can go with at certain times or can certainly be on the other end of a phone
and/or radio to help coordinate a test as well as help to diagnose the stuck
pager.  You need to have some experience/skill at driving on snowy mountain
dirt roads with some occasional ice.  4 wheel drive with optional chains is
a necessity.   It may be in good shape up there due to the warm weather over
the last few days....but not for certain.


Sincerely and '73

Steve Henry, N7GN
NCARC president