Joel Kolstad wrote:
Anyone have an opinion on whether or not crystal cases (e.g., HC49, HC45,
etc.) ought to be grounded or not? I've done some Googling, and I've found
various cases where people recommend it (albeit without much explanation as to
what they think will change when they do it) and no cases where it was
specifically not recommended.

For most solid-state oscillators it makes sense to ground.

For tube oscillators where the two pins to the crystal could be at high
potential, it is probably better to not ground. In some Pierce or
Modified Pierce oscillators you find either plate or screen potential;
nominally this is supposed to be blocked by a ceramic capacitor (e.g.
0.001uF) in most designs but you'd be surprised how often this was left
out!

Tim.