[time-nuts] 53132A Polish UHS Time Base Option Interesting Ovservation

Bob Camp kb8tq at n1k.org
Tue May 12 17:38:02 EDT 2015


Hi

The answer to any complicated question is always going to be “that depends” …

You can indeed buy acceleration compensated OCXO’s. You can get them that only 
compensate simple (DC) acceleration or that compensate vibration as well. It all depends
on the requirements of your system.

Bob

> On May 12, 2015, at 11:49 AM, D W <watsondaniel3 at gmail.com> wrote:
> 
> 
> And this is where one question leads to another. For an oscillator that is going to be used at very high velocities and accelerations, like in a missile, would it be calibrated somehow under the target G force? Or would you just compensate some other way? Or just not worry about it?
> 
> Dan
> 
>> On May 12, 2015, at 6:51 AM, Bob Camp <kb8tq at n1k.org> wrote:
>> 
>> Hi
>> 
>> All  OCXO’s are sensitive to acceleration. Gravity is one form of acceleration. A
>> sensitivity in the 0.5 to 2 ppb / G is not uncommon. 
>> 
>> Bob
>> 
>>> On May 11, 2015, at 9:24 PM, J. L. Trantham <jltran at att.net> wrote:
>>> 
>>> I recently obtained a 53132A and added the HP Opt 010 High Stability Time
>>> Base option with a 10811 variant OCXO.
>>> 
>>> 
>>> 
>>> I left it on for over a week and it, ultimately, seemed to slow down in its
>>> drift, with the displayed frequency, as it 'read' my GPSDO, slowly
>>> decreasing, suggesting that the Time Base was, slowly, increasing in
>>> frequency.
>>> 
>>> 
>>> 
>>> I then removed the HP option and installed a Polish UHS Time Base option
>>> with a Morion DOCXO.  After about 72 hours, it seemed to stabilize.  I then
>>> 'calibrated' the 53132A by connecting my GPSDO to Channel 1.  The displayed
>>> frequency was +/- 1 to 2 mHz of 10.000 000 000 MHz for the past week or so,
>>> with no drift noticeable.
>>> 
>>> 
>>> 
>>> I had 'calibrated' the 53132A with it sitting at about +30 degrees, propped
>>> up on its 'handle' in a 'vertical' position.  I then had occasion to move
>>> the 'handle' under the unit whereby the unit was 'flat', at which point the
>>> displayed frequency dropped to 9.999 999 997 MHz, +/- 1 to 2 mHz.  The
>>> displayed frequency was the same this evening when I came home.  When I
>>> again 'elevated' the unit by moving the handle to its more 'vertical'
>>> position, the displayed frequency moved to 10.000 000 000 MHz +/- 1 to 2
>>> mHz.
>>> 
>>> 
>>> 
>>> I'm not sure what this means.  
>>> 
>>> 
>>> 
>>> It is a 'repeatable' observation.  It displayed the lower frequency all day
>>> and when I 'elevated' the 53132A this evening, the frequency again went to
>>> 10.000 000 000 Mhz.  Is this a 'gravity' effect?  Is this an issue with the
>>> DOCXO?  Is this an issue with the 53132A?  If I am correct in my
>>> calculations, the displayed frequency is +/- 1 to 2 parts in 10E-10 of 10
>>> MHz, assuming my GPSDO is accurate and stable.  Otherwise, the GPSDO and
>>> 53132A 'drift' is exactly the same.
>>> 
>>> 
>>> 
>>> I would appreciate anyone's thoughts regarding this analysis and observation
>>> and how to go about 'quantifying' it in a more scientific method, assuming
>>> it's worth pursuing.
>>> 
>>> 
>>> 
>>> Thanks in advance.
>>> 
>>> 
>>> 
>>> Joe
>>> 
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