>         When operated in a series resonant mode, the crystal
> is operating at the frequency where its internal inductive
> and capacitive reactances cancel.
>         When operating in parallel resonant mode, the crystal
> is operating at a frequency above the series resonant
> frequency so it looks like an inductor. This inductor,
> combined with external capacitor(s), form a parallel resonant
> circuit. Thus, the parallel resonant frequency is determined
> by the crystal AND the external capacitors, while the series
> resonant mode is a function of the crystal itself. The
> "parallel resonant frequency" varies with "load capacity"
> since a different inductive reactance is required to resonate
> with the varying capacity. Choosing the offset from the
> series resonant frequency yields the desired inductance.

So would this mean you could operate a series crystal w/o any load
capacitors?  I know some will oscillate but it's not neccessarily
stable/reliable.

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