Old HF Transceivers like the Kenwood TS-50s I own do not come with a built in interface for packet/digital operation. Hams all around the world have come up with different ways to mitigate that drawback.
Luckily, TS-50S design engineers have thought way ahead of their time and included a hidden port for UART communication with the rig.
I used this UART interface to CAT Control the rig, and Speaker Out & MIC In ports for audio Out/In.
CAT Control via UART – Fully Isolated
Line In – Fully Isolated
Line Out – Fully Isolated
Update
Audio In/Out – Working as expected
Voice/Digital Switching – Working as expected
CAT Control – Working as expected. Had to wrapping the USB Cable around a ferrite core/clamp to filter out RF currents induced.
PTT on RTS – Passed
CW Keying on DTR – Could not find a way to share DTR pin on CAT Control Serial Port (on FLDigi).