RE: [Repeater-Builder] OT: 155.190 intereferes with Ham Radio Frequencies

Wed, 03 May 2006 05:26:21 -0700

I tried to find a licensed user of 155.190 MHz in an area 40 miles north of
your QTH, around Michigan City, but found none.
 
Fulton County Sheriff's Department, Rochester, Indiana
Rochester Police Department, this is the department that can be heard.
 
 
I also couldn't find a coordinated repeater on 147.285 MHz in that area. Please identify by callsign the repeater on 147.285, and where it is located. I simply assumed that "here" refers to your QTH. Are there any other transmitters at that location?
 
K9WZ Repeater in Plymouth, Indiana
He aslo mentioned that he could hear them on 146.535 Mhz, they operate there on simplex.
 
Can you identify what Sheriff Department is using 155.190 MHz,
and where it is located? I ask these questions because I suspect that the
Sheriff's signal may be mixing with a third carrier and that station may be
generating IM, unbeknownst to the Sheriff. This third station may very
likely be at the same site as the Sheriff's repeater, and I can look at such
candidates only if I know where each site is located. It may be very
instructive to set up a spectrum analyzer to see what signals are present
when the interference occurs.

At this point, I do not know where the actual repeater is located in their county.  I'm assuming from what he explains that it is there in Rochester, as that is the main city for the county.
 
Some questions come to mind:

1. Is the signal from the Sheriff repeater being heard by the complainers'
radios directly, or is the Sheriff's signal being repeated over the 147.285
machine?
The only time they hear the repeater, and from what was explained, they can hear them very clearly, is when the city of Rochester talks on the repeater. 
 
2. If the Sheriff's signal is being repeated on the 2m machine, what
happens when the repeater transmitter is shut off? That is, can you still
hear the Sheriff's signal on the 2m repeater's monitor speaker at the site,
with the TX off?
 
At this point I have not contacted Wayne, K9WZ whom is the owner of the 147.295 repeater.  Wanted to do some research before I get in touch with anyone, to make sure we don't make enemies.  I do know they told me they are hearing it on more than one frequency in the two meter band.

3. Is the interference also heard over a commercial-grade radio? This
might eliminate an image reception issue.
 
At this point I have to say no.  I will be taking a number of radios with me when I visit the location this Saturday.

4. What are the details about the 2m repeater? (Make/model of receiver,
transmitter, duplexer, filters, antenna, etc.)
 
This I would have to contact Wayne to get this information.  If you have access to IRLP, I do know he has IRLP and Echolink access, however I do not know either of his nodes.

5. When the interference is heard, is it a mixture of voices or tones, or
is just the Sheriff dispatcher heard clearly?
 
They stated they can hear them clearly, however until I hear it for myself, I can't say what is actually being heard.
 
Thanks!
 
Mathew


73, Eric Lemmon WB6FLY



-----Original Message-----
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of n9lv
Sent: Tuesday, May 02, 2006 8:22 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] OT: 155.190 intereferes with Ham Radio
Frequencies

I've have been asked to assist with an issue in a town about 40
miles from here regarding a commercial system that is causing
interference with Ham Radio.

At best, the information that I have thus far, is that there is a
repeater that is owned by the county sheriff's department, this
repeater itself is on the output of 155.190, and is said to not be
causing interference. The only time that it interferes with the
hams in the area is when the city talks on the repeater for 911
dispatches. At this time I do not know how much power or what type
of radio they are using, antenna height, or brands.

The radios thus far that is receiving the interference, from two
locations, one about a mile away and the other about a block away,
is the IC-2100H mobile radios, and an ADI AT600 handi talkie. There
has been other complaints, I'm supposed to get additional
information this weekend, and possibly make a trip up there to hear
the interference.

Questions I have is, what should I be looking for? What avenues
should be taken? I do know that the Chief has been notified of the
situation, but refuses to see a problem and has done nothing to
rectify the situation.

At this point, I do know they say that on the receive of 147.285
that there is noted a nearly full scale signal, making it impossible
to hear the repeater that is about 25 miles north of there, of which
is on a 400 ft tower, classified as a large scale repeater.

Thanks
Mathew









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