[time-nuts] Temperature controlled TCVCXO

[Dave M]

David wrote:
> I was thinking of holding the temperature right at 25C or maybe a
> little higher at an inflection point to minimize the possibility of
> condensation.  The difficulty is that the ambient temperature could
> vary above or below that so the TEC has to both heat and cool but that
> is a solved problem.
>
> On Fri, 13 May 2016 10:05:02 -0400, you wrote:
>
>> A problem I had with TE heater coolers was condensation when the
>> ambient temperature was higher than the TE temperature. I was trying
>> to operate the crystals on the lower temperature inflection point.
>> After a while, corrosion became a major issue.
>>
>> John  WA4WDL


The HP 3450A & B model digital multimeters used a Peltier device to control 
the temperature of the voltage reference zener diode.  You can download the 
manual for the "B" model from Keysight's web site to get an idea of the 
control circuitry 
(http://www.keysight.com/main/techSupport.jspx?searchT=3450B&id=3450B:epsg:pro&pid=3450B:epsg:pro&cc=US&lc=eng). 
There's also a sales bulletin for that model that gives a bit more 
information about the Peltier device and chamber 
(http://www.ko4bb.com/getsimple/index.php?id=manuals). Search for 3450A on 
that site.

The chamber is controlled to 43C by the Peltier device, allowing quite fast 
warmup times for the instrument, and operation above normal environmental 
temperatures.

Cheers,
Dave M