[time-nuts] Re: Custom Quartz crystals

[Richard (Rick) Karlquist]

On 8/14/2022 10:08 AM, Corby Dawson via time-nuts wrote:

> "Y1 is a
> fifth-overtone, AT-cut crystal ground
> for operation in the series-resonant
> mode with a load capacitance of 30 pF"
> 
> I thought that a series resonant crystal did not have a load
> capacitance??
> 


Any crystal can operate with any load capacitance, or in series
mode with "infinite" load capacitance.  This is a function of
the oscillator circuit, not the crystal.

OTOH, the frequency calibration is specified for some load
capacitance.  If you want to operate on that frequency, you
have to use the load capacitance specified for the
frequency calibration.

If you have an existing oscillator that you want a crystal
for, then the crystal has to be specified for the load
capacitance of that oscillator.

Having said that, overtone crystals are usually specified
at series resonance, especially at 5th and higher overtones.

The original text that you quoted is simply nonsense,
as you suspected, so something got messed up along the way.

Rick N6RK