[time-nuts] Poor man's oven

Charles Steinmetz csteinmetz at yandex.com
Mon Jun 5 18:38:25 EDT 2017

Chris wrote:

> Today all you need is a reliable way to measure the error
> between the crystals' current temperature and the set  point.

That's all that's ever been needed.  But it is devilishly difficult to 
measure the actual quartz temperature, or even to find a good proxy that 
is easier to measure.

There is a fair body of published research on these topics, including 
Rick's (et al.) work on zero-gradient ovens.

Keep this in mind when someone says they are controlling the "oven 
temperature" to 0.001C (or even 0.1C).  They are measuring *something*, 
and may even be holding whatever it is "constant" within fairly tight 
tolerances.  But they have no idea what the quartz temperature is, and 
no way to know with precision the relationship between the measured 
temperature and the actual quartz temperature.

Some years ago, I consulted for a research group that was using a number 
of non-contact technologies to measure the temperature of oscillating 
quartz crystals.  The results were promising, but there were some issues 
with measuring the temperature (which is, essentially, quantifying tiny 
random molecular motions within the crystal lattice) against the 
background of the hugely greater macro motion of the vibating quartz.  I 
never knew the final conclusions, nor am I aware of any systems designed 
using these principles or methods.  But it is something to think about 
if you *really* want a temperature-stable oscillator.

Best regards,


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