[Motorola] MOCOM on Data

[Leo Whiteway]

Ken Cechura wrote:
> 
> Score one for me, i got the Rx to work.  Score one for the MOCOM 70 (VHF),
> It won't Transmit.  I had a Kantronics KAM rigged in, and it would key the
> MOCOM, but i got no audio.  My KPC9612 won't even key up the radio.  Where
> is the best PTT point, and where is the best place to feed in audio (also,
> do i need to, in some form, transform the audio?)
> 
> I have the former mobile 4 ch MOCOM 70 mounted in the Consolette base
> station, so i have multitudes of wires in it.  any help is much appreciated.
> 
> Thanks
> Ken

Hello Ken; Some time back I connected some TNCs to the MOCOM 70. I found
the mike input jack was expected to be connected to a microphone with an
amplifier in it. This means that the mike hi pin has a few volts on it.
If my memory is ok, The transistor that this voltage came from needed
this voltage terminated with the mike amp. I think the impedance of this
mike amp was in the neighborhood of a just a few hundred ohms. This also
meant the the input must have had quite a high level of audio voltage
from the mike amp. I remember adding a 2n2222 into the mike line and
played with resister values till I got enough audio voltage to the mike
jack to make the deviation at 3.6 khz. I think that was about optimum
for what I think packet works best at.
73 VE7UW in Kelowna, BC, Canada
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