I wrote about the oscillator on the Parallax SX-Key demo board:
> It's a surface mount crystal; it appears to be marked 50.00, although the
> lighting here (and my eyes) are not so good.  I didn't think one could get
> fundamental-mode crystals at that high a frequency.

Steve Baldwin <steveb@KCBBS.GEN.NZ> replied:
> You can get fundamental mode crystals at that frequency but they are far
> from cheap and I know of only two companies that can do them. There are
> ceramic resonators at that frequency and it seems that the Scenix folks
> have concentrated on them, rather than crystals. I expect that is what they
> have used.

Could well be.  I haven't seen surface-mount ceramic resonators before, and
I didn't know they were available at such high frequencies.  I've used the
Panasonic resonators up to 8 MHz.

What kind of accuracy and stability can be expected from a 50.00 MHz
ceramic resonator?

By the way, it appears that I actually got version 0.3 of the SX-Key software,
although the disk is marked "Version 0.2".

Cheers,
Eric