Anyway few options but nothing worked so I responded:
Thanks all for comments on and off list...
I tried a few options but it is just not (easily) possible to capture TX SSB audio from the rig directly so the idea is that I will use a small external box that M5CHH built with me a while back for RSGB IOTA contest which is a voice keyer, you plug a mic into it (RJ45), and a cheap Technika USB key sized MP3 player to it (could be any ipod input really). It has the option of feeding the MP3 player output or the mic input into the rig, nothing prevents you from splitting the audio that is used, feed one side back to a CAT5/RJ45 terminated cable that will feed mic input to the rig as per usual. The other side amplify (random op amp I used a NE5534 which was OK at 5V) and feed to a 3.5mm socket that can be plugged into a PC and recorded. At the same time I'll feed the RX audio into the box, from a Y audio splitter and this to the same 3.5mm socket. I will switch between them, probably just by relay and use the PTT line so you record RX or TX not both at same time (but I could add that option).
I thought I could also feed Rx to one mono out and TX to another, then record in stereo you get TX audio in one ear and the RX audio in the other...
I built it ugly style on the bench and it works so I'll bodge the current keyer with the extra bits.
The box power comes from 5V from the pin 3 MIC power line. I could add a 12V feed so use the rig PSU add an LM7805 and couple caps to obtain a 5V regulated feed too. The MP3 player needs 1.2V and I used a bare LM317 connect in to 12V or 5V, adj and out and you get 1.2V out.
I'll write up with images and circuits on this blog soon.
An Audio TX monitor option for the FT897 or FT817 would be a nice add on.