Hello Tim,

Oh, I'm all for cannibalizing the commercial clocks, what with their
pretuned ferrite loops, 60kHz receiver and demodulator, as a
cost-and-time-effective method. But if someone did want to roll their
own...

In that case I'd probably try to do it with a PLL stabilized
Q-multiplier instead of a crystal filter. Should work just fine at
60kHz. Or a conversion scheme that puts the IF in the low kHz range
where it can be done with active or switched capacitor filters. Still
have to stabilize the oscillator though. Just as a proof of concept...

I have custom ordered tuning-fork style crystals down to 12kHz, and
they were way more than the mass-produced $1 jobbies! I think $30-$50
each in onesies. $1 is really cheap in comparison.

True, $1 is cheap. Custom crystals are less and less popular. Some of
the companies I used way back when are no longer there or aren't doing
it anymore unless you buy thousands.

Regards, Joerg

http://www.analogconsultants.com