I was just going to use the generic Jason serial output, just the 8 bit
words taking on values 0 - 16 at 9600 baud.   The PIC would calculate the
accumulator value for each tone by multiplying the received number by a
constant derived from the stored clock, then adding on the requested cenre
frequency.

Ok, this means less work for me... :-) But if you need modifications to the
format, they can be done.

Question... Is the nominal frequency of a Jason transmission the centre
frequency (Tone 8 ), or Tone 0 ?  My understanding is the former, the centre
tone. But just checking.
[...]

Tone 8 is the centre frequency, and is also the idle tone, transmitted when
the input buffer is empty.

73  Alberto  I2PHD