At 09:15 AM 3/24/00 +1100, you wrote:
>Hi Alan,
>Do you mean you can retune the Xtal to one of its component harmonics? Can
>one ever make an oscillator that oscillates at a non harmonic component?
>                                                John
>

There is a whole section on this stuff in Mchp's application
note AN588. Too much drive may excite the xtal to one of its
harmonic overtones.

- Dan