> I am still looking for the physical dimensions of the 72-key
> Carl Frei tracker scale.  Can anyone help?

Sorry, I forgot to include this in yesterday's reply.  The spacing of
the keys is the usual 3.5 mm (or more precisely, 3.49 mm) with 10.5 mm
from the leading edge to the centre of the first key.  The width of the
music card is 264 mm.

Regards,
John Page