The T3-Micro is a Tracker3 in a USB dongle form factor, presently in beta testing.
Pinout (3.5mm TRRS connector, starting with tip):
|Tip||Audio out (to mic)|
|R1||PTT (open collector)|
|R2||Audio in (from speaker)|
The T3-Micro has no jumpers. Handheld PTT mode, required for most handhelds except those by Kenwood and most Chinese imports, is set using the command HTPTT ON, or the "HT PTT" checkbox in otwincfg.exe located in the Radio Interface panel. When setting the option in otwincfg, you must first write the new configuration before the change will take effect.
Firmware build 56471 or later must be loaded for the HTPTT command to function.