Looking at the schematic, the TX line switches both the drive to the final and the reverse bias to the diode switches in the LPF.? If separate lines from the uC were used for these two functions, then is should be possible to key the drive to the final for CW rather than turning the Si5351 clock outputs on/off.? With a bit of timing between the LPF switching and the keying, fast breakin should be possible.? Would a key shaping circuit (series transistor to drive power to finals) be needed if the drive is keyed (finals are class D, which like class C is biased beyond cutoff with no signal)?
Iambic keyer, morse to text, and sidetone could be added to the QDX firmware for CW, or be done on the PC side.
And another thing, could the same tricks that were used to transmit SSB on the QCX (uSDX) be used on the QDX?? Some hw mods would be needed of course.
