Date: Thu, 16 Sep 93 04:30:06 PDT
From: Advanced Amateur Radio Networking Group <tcp-group@ucsd.edu>
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Reply-To: TCP-Group@UCSD.Edu
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Subject: TCP-Group Digest V93 #239
To: tcp-group-digest
TCP-Group Digest Thu, 16 Sep 93 Volume 93 : Issue 239
Today's Topics:
Master II on 9600
monax25
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Date: Wed, 15 Sep 1993 20:09:26 -0500 (CDT)
From: Mr. Sampson <ssampson@sabea-oc.af.mil>
Subject: Master II on 9600
To: TCP-Group@UCSD.Edu
Adaptation of GE Master II for 9600 baud operation
25 February 1992
The GE Master II series of radios may be adapted to 9600
baud packet operation by utilizing the temperature compensation
diode in the TX icom as an FM modulator.
There are 3 types of icoms available for the Master II (EC,
2C, and 5C). The EC depends on a 5C plugged in one of the other
channel positions for its compensation. This is accomplished by
the temp compensation network in the 5C supplying a DC voltage
to pin 2 of the icom. Pin 2 of all the icom plugs in the Master
II are tied together so one 5C can provide temp compensation
voltage for up to 15 other EC icoms in a multichannel radio. The
2C icom provides its own temperature compensation and has no
connection to pin 2. Since the unit I was adapting was going to
be used in a controlled environment I utilized the EC icoms. I
removed a .01mfd bypass that is on pin 2 inside the tx icom
(this may not be necessary). I also isolated the pin 2
connection between the TX and RX icoms so as not to load the tx
signal with the rx icom. Also connected 22k resistors from pin
1 (10v reg) to pin 2 and from pin 2 and pin 4 (ground) to supply
5v operating bias to the varicap in the icom. This was done on
both tx and rx boards. If you use a 5C icom this is not
necessary since the internal compensation network supplies this
voltage. The 2C and 5C icoms are identical but the 2C has an
open circuit going to pin 2. It may be modified to a 5C if
needed. TX signal is now applied to pin 2 of the tx icom bank.
The rx signal is supplied by j606 of the rx if/audio
board. The UHF radio I was using was for 450 to 470 mhz. I was
able to tune it to 440.975 mhz with no problem. I tried 430.55
but experianced problems getting the rx multiplier stages to
work. Did not try TX on that frequency. Component changes may
be necessary to go below 440 mhz as per GE manual.
73 Hank WA5JRH@WB5FWE.OK
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Date: Wed, 15 Sep 1993 11:50:03 -0400 (EDT)
From: price@cs.pitt.edu (Harold Price)
Subject: monax25
To: makinc@hhcs.gov.au
I just uploaded a copy of monax25.zip to incoming at ucsd.edu. It is old, but
not corrupt.
Harold Price, NK6K
nk6k@amsat.org
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End of TCP-Group Digest V93 #239
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