[time-nuts] Improving the stability of crystal oscillators

[Enrico Rubiola]

> Is there something magic about quartz that has a turnover in the  
> region that
> just happens to be handy for OCXOs?  Or is it the other way around:  
> people
> chose the cut angle to get a temperature that works well for ovens?

First, better heat-only than heat-cool or cool-only because of
- efficiency
- temperature stability
(see my recent mail "against" the Peltier cell)

Second, think about the inside of an instrument.  Think about a heat- 
only
control.  Account for some 5 degrees minimum difference between the  
quartz
and its environment.  70-80 degrees Celsius is the most comfortable  
temperature.
Physicists designed the resonator for the inversion temperature to be  
75 deg Celsius.
That's it.


> Could I cut a crystal with a temperature at (say) 0C or something  
> handy for
> Peltiers?

Probably yes, if it made sense.



Very best


















Enrico Rubiola
professor of electronics

web:	http://rubiola.org
e-mail:	rubiola at femto-st.fr

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