IF you can understand this...
View attachment 57612
Their wiring is as follows...
Pin 1 AUDIO
Pin 2 Ground
Pin 3 TX - Grounds Pin 4
Pin 4 RX/TX switch (Relay coil power)
So, if you were thinking this thru...
You really only need 3 wires - similar to the Galaxy where Pins 1 and 4 are grounded all the time - in this radio - Pins 2 and 3 are "grounded all the time"
So, you can then use
Pin 1 Audio
Pins 2 and 3 Ground / Shield (Short together all the time on JACK of the radio)
Pin 4 RX (out) TX (in)
Just in Galaxy perspective, you have the same wiring - only the plug mirrors Pin 1 and 4 and 2 and 3... As if you were assembling Mic wiring in a mirror - it's upside down flipped.