[time-nuts] WWVB SDR discussion

[John Magliacane]

 On Tuesday, August 11, 2020, 07:14:12 PM EDT, Bob kb8tq <kb8tq at n1k.org> wrote:

> The problem with the crystal is that it has a temperature coefficient. As a
> narrow band filter, it will have a *lot* of delay. Crystal resonance moves
> (with temperature) and the delay changes.

I agree. The crystal needs to be ovenized. ;-)

That very concern led me in my design to derive nearly all my receiver selectivity at baseband (DC) using op-amps, forgo any crystal filters, and keep the Q of the loop antenna low.


73.000 de John, KD2BD