Thanks, Irad for the advice. It was set to USB, exactly as all screen shots for FT991A in the manual show 😫. A word of explanation there might be helpful. Hope this will bring the issue to resolution. 73 Marek sp5isz

Albert, Great to see that somebody replied. This problem puzzles me as well. To add some more info: when I send beacons, they seem to go OK (PSK Reporter shows this). The problem shows when I try to reply to somebody's CQ. The radio goes to USB, the PTT switches it to TX, but the output signal is none, because entry from mirophone is expected. I do not understand which file you refer to as the "COM". The CAT commands file is V13, the VarAC is V8.4.4, the Windows version is 10. I am suspicious of one entry in VarAC INI file (see attached picture). It states that the USB mode should be USB, rather than e.g. DATA_U. I will be happy to replace this in the INI file, but I do not know how the DATA_U mode is called in the program vocabulary. 73, Marek sp5isz