This sounds like a power supply problem. It must work without the USB cable in it.
Here is my K3 CAT Checklist:
CAT Checklist for K3 Twin
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Note first that in a "Twin" configuration, COM2 is used to "tie" the two ends together and carries the CAT data. In order to access CAT, you need to get to COM2 without touching it. The easiest method is to duplicate COM2 over COM1 using a function in the RRC as follows:
- Change both RRC's COM1 to mode-7. Note that the baud rate does not have to be identical with COM2 to fit a lower bandwidth or software requirement.
- If using a "real" serial cable:
- connect a straight through serial cable between the control RRC's COM1 and the PC. If using a USB to serial converter cable, make sure it is using an FTDI chipset.
- note that if you also use the radio RRC's COM1, the pinout is not the standard straight-through serial port. Use the pinout description in the RemoteRig manual, or just try a null-modem cable which usually works (may need a gender changer).
- the serial setting for COM1 "Use USB Com Port as COM1" must be set to NO
- If using USB:
- make sure that first Microbit Setup Manager is installed first on the control PC to get the drivers.
- Then change the serial settings for COM1 to change "Use USB Com Port as COM1" to YES
- connect the USB cable between the RRC and computer and wait for the drivers to finish installing
- go to the Windows Device Manager and look at which virtual serial port was assigned to COM1 and use that for your software, taking the correct baud rate into account.
Note also that you can pull CAT data in parallel off of the radio RRC to use a PC on that end, or to sync with a remote device (amplifier, SteppIR, etc.)
73,
Mitch DJ0QN / K7DX