[NCARC] 145.115 shutdown

[Steve Henry]

Howdy-

Unfortunately we've run into an interference problem with the 145.115
repeater output signal.  Great Western Railroad contacted us a little while
ago with this information (courtesy of Jim, N7VDR and a relay from K0OJ).
This has been confirmed by several hams who hve listened on Great Western's
repeater frequency of 160.620 and heard the output signal from the 145.115

It's likely we have an intermod problem, but it is also possible that the
recent repeater realignment may need to be examined.  In the meantime as of
9:00 pm this evening 1/4/04 we will shut down the 145.115 repeater.   Our
plan is to solve the interference problem as soon as possible and then get
the repeater back up and operational.

Here's the general outline of the plan we're following, and how you can
help.

1.	George, AB0SF is working with Jim, N7VDR of Great Western Railroad (glad
we have a ham working at Great Western!) to see if there are hours where we
can make the repeater available for general use where Great Western Railway
won't be using their repeater equipment for train communications.  At a
minimum, we will find out times where we can run experiments to track down
the issue we are facing.

2.	At specific times, we will be running a series experiments to isolate
whether this is intermod problem (likely) or a spur problem from the
repeater:

a)	Rule in or out spur problem:   use a spectrum analyser that we can hook
to a directional antenna and determine what the signal looks like coming
from the 145.115.

b)	If it is a spur problem, George AB0SF can realign the repeater.

c)	If it isn't a spur problem, we need to track down where the mixing is
occuring creating the intermod output on 160.620.

d)	Long distance DFing:   Hams with directional antennas and receivers that
are capable of being tuned to 160.620-- we will need your help during test
times to see if we can determine if the intermod mixing is occuring up at
the Horsetooth site (likely) or somewhere else in the area.

e)	Short distance DFing:  Hams with good experience at DFing will need to go
up to the Horsetooth site and we will need to discover if some piece of
loose hardware or something else is generating the output signal.

If you can help, we would sure appreciate it.  Please email Steve Henry at
steveh291 at comcast.net if you can volunteer in any/all of the following ways:

1.	A few volunteers who can do long distance DFing:  requires receiver at
146.620 and a directional rotatable antenna.  We will set up a time where we
will run an experiment and do some triangulation.
2.	Several volunteers who can do short distance DFing: requires skill (or
willingness to learn the skill) as well as antennuators, directional
antennas, etc.  Also-- a willingness to go up to the Horsetooth repeater
site.
3.	A volunteer who has access to a spectrum analyzer and who know how to run
it. Preferably someone with a directional antenna who can run this
experiment very soon.
4.	2 volunteers with 4 wheel drive vehicles, chains, and skill at going up
(and coming down from) the Horsetooth site.  We will choose a time with
reasonable weather and less than 1 foot of snow on the trail.

If you have suggestions to this plan, please email this reflector
'NCARC at mailman.qth.net' so that all can benefit from your suggestions.


'73

Steve Henry  N7GN
President, NCARC

George Salzmann,  AB0SF
Technical Committee chair,  NCARC