So here is an update.
HW changes:
Used a 74AC14 as the front end, with a 74HC393 after. ?Tried various divides and div 4 works well (and needs least time).
I've move the SW FET input from pin 11 to one of the TX lines (as I don't use them).
cut the trace on the top of the board and hardwired the 393 output to it.
the new wire was easy to do underneath.
SW changes:
put #ifdef around the Tx PIN code.
moved the cap_sw to one of the TX pins
I changed the display type to a #define, the compiler then removes the code for the other displays.
I added some basic code that checks the freq, if there are settings (or +/- a slot) then try them, if they are good use them, otherwise search. ?If we find a good solution save the settings.
Wrote a debug loop that displays the freq.
Put a signal generator on the input and it maxes out at 17.5MHz.
That's as far as I've got today , need to dig out the proper scope (100MHz) instead of the USB one (24MHz sample rate).
RogerW/GW6HRU