[Knightsqrss] Paulo's mixer idea

[Murray Greenman]

Well done, Paolo! I have been thinking around the edges of this clever
idea for a week or so. My solution was slightly different -

I planned the NE612 mixer and crystal filters as Paulo has done, but my
signal source plan was to use a 10MHz reference (OCXO or TCXO) and a DDS
'VFO' operating in a micro at 140.1kHz.

The micro can also use the 10MHz reference, although if you have MEPT_JT
in mind, it's best to use a separate 9MHz or 12MHz crystal in order for
the baud rate and spacing to be correct.

If anybody wants to give it a try, I have code for most of the popular
QRSS modes (including sequential MT-Hell and CASTLE) in my LF Exciter
design, and of course 140kHz is well within its range. The processor is
an AT90S2313 or ATTINY2313, and easily patched to another AVR. I don't
have MEPT_JT code yet, but have started the design. 

Congrats also to Johan for getting a MEPT_JT micro going!

73,
Murray ZL1BPU