Perhaps ft857 does it like my ft847: When you give PTT over CAT it doesn't modulate from Data-In-Out connector -> no HF power in SSB without modulation. My 847 wants PTT (from RTS or CTS pin) on Data-In-Out connector and of course varac must be configured to make ptt over RTS - still the same com1 is allowed for both, CAT (eg. frequency control) and RTS pin (ptt). I often had my ft847 with "no HF power although sound is produced" (due to missing PTT on the same connector)

Thanks, no problem any longer. I only wanted to confirm that you got the ft847 working with CAT and RTS. And I only wanted to add the HW needs (0.47u, ptt and modulation on Data-In-Out connector) necessary to get the ft847 working with any kind of soundcard.

Great response -already the next working day ! You are right RTS must be Hi for PTT because the usual circuit has a npn transistor that pulls ft847 PTT down -> transmit. BUT: All CAT commands EXCEPT ptt must go over serial com. PTT must not be serial CAT command, it must be RTS for ft847. Why ? Because ft847 modulates only from the same connector as it gets PTT. So PTT must be RTS via transistor to pull "HF data in" down where modulation is on the same "HF data in". With serial CAT PTT command the ft847 makes PTT but without modulation, because ft847 then has it on different inputs: PTT on serial CAT command and modulation on "HF data in". Gives PTT without modulation. And it must be ONE serial com for cat-serial-data and RTS-pin-switching. OmniRig obviously does serial-CAT-command-PTT what causes no-modulation. Thank you for the fast response and sorry that ft847 takes that serious. Michael