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Linking
6.85 and 5.11 Repeaters (cont..)
Here’s
the latest:
The
link will be located at the 6.85 site. It will
consist of a 2-meter radio tied to our CAT-1000
repeater controller. The controller has the
ability to tie the audio from the 6.85 receiver to
the link radio transmitter, which is tuned to the
input frequency of the 5.11 repeater.
Likewise, receive audio from the link radio will be
tied (via the CAT-1000) to the 6.85 transmitter.
Users will have the ability to raise and drop the
link at-will. Ultimately, the raising the link
will change the courtesy tone on both repeaters
letting users know that the link is active.
The link will be set to time-out after a certain
period of inactivity.
The
link radio is a late-70’s vintage FT-227R
Memorizer. Out of the box, this radio is not
usable as a link radio, so some fairly major surgery
is required. The radio is designed to default
to 147.00 MHz after a power-cycle, which is not good
for a link radio. So, the radio was modified
to power up on 145.11 with a -600 KHz offset.
Also, the radio had no COS
(carrier-operated-squelch) output, which is required
for operation with the CAT-1000. Fortunately,
it was a simple matter to tap into the ‘Busy’
light to drive a single-transistor switch to provide
the COS signal. Another requirement for the
controller is a fixed audio level from the receiver,
which was also not available. Discriminator
audio was tapped and made available for the
controller via a 100K trimmer, providing 0 – 400
mV of audio output. The final mod involved
reworking the radio’s 1750 Hz tone-burst encoder
for use as part of the CWID circuit. With all
this accomplished, the link radio is ready.
CWID
will be provided by a N0XAS ID-O-Matic. I had
one of these on-hand and it seems to fit the need
well. Doing some research on-line, I
discovered that there is a new version of the ID-O-Matic
available which is even better suited for use as a
link-radio ID’er. I’ve already ordered and
received the upgraded version, but unfortunately it
arrived without the PIC microcircuit that is the
heart of the whole thing. I’ve already
notified N0XAS about the problem and I’m sure the
problem will be corrected quickly. In the
meantime, I need to complete the interface between
the link radio and the ID-O-Matic.
Once
the link radio and ID-O-Matic are interfaced, the
only remaining work will be getting the antenna
cable into the shack, adding a few more wires to an
already overcrowded DB-25 connector on the CAT-1000,
and finishing up the programming.
I
have no real time-frame in mind for getting this all
done. I’m entering one of my busiest times
of year at work right now and family commitments
(AKA: Soccer) are taking up most of my free time.
Nonetheless, I’ll plug away at it as time permits
and I’m sure it won’t take too long to finish it
all up.
73,
Mike
WM4B
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5.11
Repeater Story... Will-NM4W
Just to
give you some history on how it came to be, back on
May I called Mayor Towns to ask him about using a
city tower to activate the old 2 meters
repeater that used to be here in Cochran. He was
very much supportive of the idea.
The Mayor referred
me to Mike Smith EMC for Bleckley Co. Mike was very
interested as well, and told me that there was a
possibility to use the old site where the previous
repeater used to be housed.
I immediately contacted Pete Seabolt with SERA and
asked him about the 145.110 pair. He indicated that
the previous holder of that frequency had not
submitted any paper work for the past 10 years, and
that he would be glad to re-coordinate the frequency
for me. I did call the previous holder for that pair
and he was ok with the idea. In matter of days I had
the frequency coordinated by SERA under my name and
call sign.
I presented the idea of re-activating the repeater
to the Central Georgia Amateur Radio Club in the May
meeting. WM4B - Mike
was very interested in help putting it together and
working with Dan - KF8DB.
In the June meeting Mike presented the motion to
CGARC to sponsor the repeater in Cochran and
informed the group that he had the old Mark IV that
was hit by lighting. In no time, Mike and Dan worked
on the old Mark IV and had it up and working.
The club also had an old duplexer to be used. Mike
ordered the new crystals for the 145.110 pair and
CGARC paid and provided the old equipment to put
together this repeater in Cochran.
Mike Smith spoke with sheriff Lancaster about giving
us the antenna and the hard line with the tower on
the cat walk that they had used for their
repeater.
Sheriff Lancaster thought having the repeater up and
running again would be a good asset to Bleckley Co
and the surrounding counties.
On July 22, 2008 the Cochran Amateur Radio 2 meters
repeater was on the air. Mike and Dan have put an
incredible effort and a supportive team to make it
happen with the sponsorship of the Central Georgia
Amateur Radio Club. Dan, KF8DB
donated the Heavy Duty batteries for back-up power
to the repeater and the emergency power is available
now.
This is the only repeater in Bleckley Co with this
backup system among the other City and County
repeaters.
Will-NM4W
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Breaking
News Saturday
8/23/2008 9:00 pm
Phone patch is
alive.
Will-NM4W |
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