Hi Paul,
Hard to say. I am not an Icom person, but I do know that the CI-V converter must be an original
Icom one to work.
Check your settings under COM2, which is used for CAT. On the control RRC, you must have "use
COM2 for USB" set to NO if using a serial to USB converter externally. To use the RRC's internal USB
converter and only a USB cable, then it is set to YES. I also found that cheap USB converters don't
work all the well with the RRC, so you may try using the internal converter instead.
73,
Mitch