Joerg wrote:

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?

Strange. Maybe another resonance mode?

Regards, Joerg


Maybe use them with the 60.000 KHz crystals to build a very narrow
crystal filter?

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida