[aprssig] Kantronix 3 plus to Motorola CDM 1550

Jim (List) jim.list at stuckinthemud.org
Sun Feb 11 02:17:54 EST 2018

I’ve regularly used KPC-3+’s on Motorola kit (mainly GM350) and treated it just like any other standard audio device.


Fed the TX audio into the external mic input (pin 2) and taken RX audio from pin 11.


You need to do a CALIBRATE on the TNC and increase the TX drive as the Moto stuff needs about 80mV (TNC default is designed for a 1mV mic input), but once this is done it’s always been a solid solution.




Jim, G1HUL


From: aprssig [mailto:aprssig-bounces at tapr.org] On Behalf Of C B
Sent: 10 February 2018 22:42
To: aprssig at tapr.org
Subject: [aprssig] Kantronix 3 plus to Motorola CDM 1550




look for the best way to interface the Kantronix 3 plus to Motorola CDM 1550.


it would seem that for RX audio it would be  best is to use the flat output on the 20 pin connector and remover the EQ jumper in the Kantronix 3 plus. Is this correct?


For the TX audio i am unsure if the EQ jumper then makes the output of the Kantronix 3 plus flat or not. Thus should i use the flat input on the 20 pin connector pin 5 or the mike input 20 pin connector pin 5?


Any other advice on settings greatly appreciated.


Thank you in advance for any help.



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