I finally got an ft8 qso with the bench top bitx. The first few times I tried, including in my last ft8 post, I was manually engaging the ptt with a push button. That got old fast, so I found a vox ptt interface that I could replicate with parts I had on hand. The DuinoVOX is a homebrew device that replicated the features of the Signalink interface. I slapped my own version together this weekend with this usb sound card and an arduino pro mini.
It works great. I need to put it in an enclosure and add the potentiometers to get the full functionality.