[time-nuts] Poor man's oven

[Richard (Rick) Karlquist]

On 6/6/2017 4:26 AM, Poul-Henning Kamp wrote:

> But I cant imagine the ovens used are so perfect that they have the
> same regulation performance at all temperatures.
> 
> I can choose the exterior temperature, which I should prefer ?
> 
> Disregard aging of electronics and materials, we all know that
> stuff, what I'm interested in is at which exterior temperature
> OCXO ovens work best ?
> 

My experience has been that, while ovens may not be perfect,
they are inherently linear.  So the exterior temperature is
a don't care.

I extensively characterized the E1938A oven.  By adjusting
the ratio of heat to the top/bottom vs edge, I was able to
get the thermal gain into the millions.  At that point,
finally a modicum of non-linearity showed up and the thermal
gain varied with ambient temperature.  It might be 2 million
at the ambient where I adjusted it, and drop to 1.5 million
when well away from that temperature.  Or it might change
sign at some ambient.  (Yes, you can have negative thermal
gain).  You shouldn't need to worry about this for any ordinary oven.

Rick N6RK