I just noticed the availability of these crystals as I was thinking
about using a crystal in the front end to protect the receiver from
adjacent frequency qrm. Not sure if this can be done unless one has a
chip specially designed to take crystals (such as the Temic U4224B).

Regarding the off frequency crystals.... It might be possible that
these are rejects that didn't quite make the 60.000 kilohertx spec?

Thanks,

A


Of the longwave radio frequencies used for time standards, 40kHz (JJY,
Japan), 77.5kHz (DCF, Germany) and 60 kHz (WWVB and MSF) crystals are
off-the-shelf items in the Digikey catalog at less than a dollar each.
I'm guessing their easy availability is because they are commonly used
in real receivers.

I've always noted with some curiosity that 77.503kHz, 60.002kHz, and
60.005kHz are off-the-shelf crystals too... used in a direct conversion
receiver for DCF/WWV to 3Hz, 2Hz, and 5Hz carrier-detect frequencies
maybe?