I’m regularly getting questions about Digirig cables/configuration for the transceivers that already have soundcard/CAT onboard and do not require any additional hardware for digital modes. The frequently mentioned models are:
ICOM IC-705
ICOM IC-7100
ICOM IC-7300
ICOM IC-7600
Yaesu FT-991A
Yaesu FTDX10
Xiegu X6100
Please suggest the additions to the list and I’ll maintain it.
I own a Yaesu FT991 and whilst a lot can be done through the USB connection for audio and CAT control (PSK, FT8/4, SSTV and all those kinds of modes work fine), there is one area where you need an external soundcard modem, VARA FM Wideband. VARA on HF is fine.
This link will explain more Configuring the FT 991A for 9600 bps FM packet · rfrht/FT-991A Wiki · GitHub and much better than me trying to re-explain it all.
I believe this is a similar issue on the ICOM VHF/UHF radios, but I have no details on that, just hearsay.