Bulletin:  MX1001
Vendor:    Motorola
Subject:   Modifying The Maxar For 9600 Baud Packet


Maxar: get RX audio from pin 6 of the detector IC.  Lift the 10uF capacitor
off the wiper of the deviation pot and feed the TX audio into the cap.
That's it.

I have found that you have to be careful to not load down the
discriminator IC in the Maxar/Moxy rigs or you will obtain poor
performance. Both the TAPR and MFJ 9K6 modems loaded down the
discriminator too much, thus causing high BER. What I have done is to
lift R80 and R43, which effectively removes the audio/squelch stages from the
discriminator and allows only the modem to load the discriminator.
Works great! However, you then cannot monitor the rx audio and listen
to the channel. (Who wants to listen to noise anyway?)
The ultimate solution might be to use an outboard
Op-amp gain stage between R43 and your modem to buffer the signal,
and not impose any more load on the discriminator, and allow the
audio stages to still function. I have not tried this however.

I prefer to insert an emmitter follower between the output of the
IC and the modem...  using a general purpose NPN ( 2n2222 or
equiv).. collector to V+, base to pin 6 of the discriminator IC,
and the emmitter to the top end of a 1K resistor with the other
end of the rsistor to Ground...  the modem can attact directory to
the emitter/1k junction or you may provide dc blocking with a 1uf
Capacitor.