This lead is the audio data cable for some of the Kenwood Mobile transceivers. It is also available as part of the PG-5H kit where it is supplied along with a PG-5G lead.
Following the pictorial guide (right), solder wires between the relevant pins on each plug, not forgetting to slide the Mini DIN plug and the 3.5mm plug casings onto the cable before you start.
The diagram is colour coded and some method of telling the 3.5mm plugs apart is advised:
The Red connection is the Recieved Audio Signal.
The Green connection is the Transmit Audio Signal.
The Black connection is common ground.
After checking the soldering is good and there are no shorts or stray whiskers, replace the covers on the plugs and you're ready to go. If the plug covers are the same colour you may want to label the leads accordingly.