I assume that you are using the K3 Twin mode, since you didn't make that clear.
If so, here is how you get CAT working:
- Go to the serial settings on the radio RRC and change COM1 to "Mode-7, CAT to COM2". Make the rate the same as COM2.
- Go to the serial settings on the control RRC and do exactly the same
- While on that page, change "Use USB COM port to USB" to YES if you want to use the virtual serial port, otherwise connect
a serial cable to COM1 on the control RRC (but watch out - the pinout is backwards from normal!)
73,
Mitch DJ0QN / K7DX