[NCARC] FW: 146.625 Back on the air

[Steve Henry]

Hi folks-

I'd like to take this opportunity to publically thank Chris Kelly, K0PF, and
Virgil Leenarts, W0INK,   as well as Ted Black and Rick Huebner (W0RCY) for
a very successful repair the 146.625.  Chris notes below the items that he
and Virgil took care of after the larger team visited the repeater site and
diagnosed the issues.  The repeater is back up and alive.  I'd encourage
lots of people to try it out-- you will be impressed I think with the new
capabilities.  It has less noise and seems to have an increased range (at
least with some minimal testing).

I've personally learned the benefits of using 100% (double shielded) coax
from this repair, as well as the benefits of using a network analyzer to
tune cavities.  We have some real expert in our community, too!

'73

Steve Henry, N7GN
NCARC President

-----Original Message-----
From: Chris Kelly [mailto:wd5ibs at verinet.com]
Sent: Saturday, June 25, 2005 10:41 PM
To: steveh291 at comcast.net
Subject: 146.625 Back on the air


Howdy:
Well, we got it going about 7:30 PM.
Here is a list of what we did for future reference:

1. Replaced one coax jumper (from transmitter to duplexer).
It had a bad connector(loose connection to coax/shield).
It was also simple RG-8 and should have had 100% shield
or double-shielded coax. Replaced with 100% shield coax
(aluminum mylar plus braid). This was probably the major
problem.

2. Tuned the duplexer cavities to optimize operation.
They weren't far off, but we probably gained about 5-10 dB
of isolation. The net result is about 2 dB insertion loss
on both legs (Tx and Rx) and 85+ dB of rejection in each leg.
One side runs about 90 dB, the other about 85.

3. The Transmit frequency was off, 10 kHz high. I think
there was a bad connection in the channel element/crystal
holder (whatever GE called them in those days. I think this
because when I opened up the unit and tried to get a
frequency counter on it, it shifted back to 146.625.

So, I touched up the solder joints on the channel element,
and put some "pro-gold" connector treatment on the pins of the
channel element where it plugs into the main board.
It seemed stable on 146.625, but without a conclusive problem
found I cannot say if this is fixed or not. (Problems that
go away by themselves often come back by themselves.) If the
repeater audio sounds bad some time in the future,
check to see if it's Tx is off frequency.

4. I placed pro-gold (it's an anti-oxidant) on the RF connectors
of the repeater and the duplexer.

5. I put "power-pole" connectors on the power cable
and on the battery side of the power cable, using the
ARES standard configuration for red/black orientation.

6. I set the squelch so that a noisy signal from Fort Collins
could break the squelch, but tight enough to get pretty
snappy squelch closure at the end of transmissions. I think it
is at "notch 5" on the knob.

We also noted these in the repeater logsheets in the repeater.
Thanks again for having this repeater in such a good spot for
coverage up into the Scout camp area!

73,
Chris Kelly, K0PF