[time-nuts] Improving ocxo temp control

Club-Internet Clemgill clemgill at club-internet.fr
Mon May 21 12:23:23 EDT 2018


Thanks for your interesting replies.
What I am actually trying to do is the following: 
I bough a small ocxo (size of half a ping-pong ball) that performs well (Abracon / AOCJY3_B 10Mhz)
Reaching about 5*10E-11 kind of MDEV at low point ("kind of"… because a I use an HP52132a as input to Timelab)
But it’s frequency is slowly drifting with time, with a quasi linear slope. 
I wondered if placing it in a third ovenized enclosure could improve things. 
I tried a few experiments but seems that the temp needs to be very accurately controlled. 
Any similar experience ? 
Could you suggest papers describing high performance analog or digital controllers ? 
Thx, 
Gilles.    


> Le 19 mai 2018 à 16:09, Bob kb8tq <kb8tq at n1k.org> a écrit :
> 
> Hi
> 
> One key point about the need for “zero gradient”: 
> 
> Crystals and many other components are quite sensitive to thermal gradients. Very small 
> fractions of a degree (as a gradient ) can have significant impact on the frequency of an 
> oscillator. 
> 
> One of many “interesting things” about fiddling about OCXO’s. 
> 
> The equally frustrating thing about this is that unless you can tease kind paper authors
> into posting things ( thanks Rick !!) the papers are behind pay walls. I pretty much despise
> that practice. Referencing papers that send people off to spend money ….not so much.
> 
> Bob
> 
>> On May 19, 2018, at 12:03 AM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
>> 
>> In my experience, the oven temperature controller is rarely
>> the determining factor for static oven performance.  This article
>> explains what the real determining factors are:
>> 
>> http://www.karlquist.com/oven.pdf
>> 
>> An analog oven temperature controller will be limited in
>> its dynamics by how much capacitance you are able to
>> design with.  Digital controllers get around this as well
>> as having the capability of double integration for much
>> better transient response.
>> 
>> Rick
>> 
>> On 5/18/2018 11:03 AM, Gilles Clement wrote:
>>> Hi,
>>> I am trying to improve performance of an OCXO.
>>> Could you point me at a good design of a high resolution oven temperature controler please ? Preferably analog.
>>> Thx much,
>>> Gilles.
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