On Mon, 12 Jun 2006 08:23:33 +0100, John Wilkinson
wrote:

I have a few crystals that I bought, that are say they are 44.545MHz, but
are really 44.548MHz. I tried pulling the frquency somewhat, but to no
great avail.

Overtone crystals do not oscillate at the _accurate_ integer multiple
of the fundamental frequency due to end effects.

Have you tried to run the crystal in the fundamental mode ? If the
produced frequency is close enough to 14.84833.. MHz, just put a
separate tripler after the oscillator.

I have read that overtone crystals are hard to pull.

The pulling range is proportional to 1/N² and since the needed pulling
range would be 67 ppm and assuming 3rd overtone crystals, the
comparable pulling range for fundamental mode crystals would be 600
ppm, which indeed is quite a lot.

Paul OH3LWR