When viewing the 3.5mm connector from the "top" (the end opposite the cable entry), the pinout assignments are as follows: : RX (Data from Computer to Radio) Ring 1 : TX (Data from Radio to Computer) Sleeve : GND (Ground) Key Connection Details
[1] GND [2] TX [3] RX [6] +5V Locking tab up. Pin 1 left. qyt kt8900 programming cable pinout top