[R-390] Crystal substitution puzzle

[David Wise]

My R390A's Y411 (16MHz) has died.  Since it was
cheap to try, I bought all the wire-lead 16MHz crystals
that Mouser stocks, five in all, and put them in.
They run, but every last one of them is 1.5-2.5kHz low,
which is 50% out of spec at best.

This is five different parts, from Citizen, Fox, ECS,
Abracon, and Vishay/Dale, so it's not a bad part or
a bad lot.  The original crystal, though too weak to
mix well, is right on.  It's a disappointment, as the
new ones are around $.50 each and I hoped to open
up an alternate supply for about half of our second-oscillator
crystals.  I can live with the error, but still - what's up?

Dave Wise