TM271A with Open Track USB

[N0WRE]

Been looking at using the TM271A for APRS. Pulled the cover and found the pads to wire a cable to the unit but was wondering if anyone had wired one of these for the Open Track USB serial port. If you did what configuration did you use and did you have the APRS data coming in from the data cable or did you have to plug in a speaker plug to get the incoming packets heard? Any help would be appreciated.

Thanks,

Peter

 

[AK9R]

If your plan is to use the TM-271A with an APRS tracker or TNC, you need to connect transmit audio, receive audio, PTT, and ground between the radio and the tracker/TNC.

 

[K4APR]

Yes! I have four TM-271 mobiles. I love that the pads were there for a packet interface. I use cut off six pin mini DIN female cable ends. Under the power cable grommet there is a little square of foam. Remove that and it's the perfect place to feed the cable into the radio. Look up the standard mini DIN packet interface for pinout. Ohm out the pins from the connector to the wires in the cable and solder them right to the board. When you put the radio back together, you'll have a standard packet interface and never have to open the radio again. I'll take a picture of one of my converted radios tonight and post it. I used to have pictures of the conversion process, but I have no idea where those are now.

Oh, don't forget to use a little ziptie on the inside to secure the packet cable to the power wires. This offers strain relief for the packet cable you just added.