DRAWS PTT not working on Yaesu FT3D


I am trying to get my DRAWS board working with a Yaesu FT3D HT. I can see received APRS packets coming in, but I can't get the PTT to work. I have continuity between the PTT output on pin3 and the PTT/CLONE ring R1 on the TR1R2S plug. I think this pin is mislabled - this radio actually uses a combined MIC/PTT signal. Grounding the MIC ring R2 puts the radio into transmit. I used the ptt_ctrl script on both ports with the same result.

I also have a Mobilinkd TNC3 which I have used with this radio. I had to select 'Multiplexed' PTT to get it to work. Does anyone know of a way to get PTT to work with this radio?

Phil Lewis W4EVV