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

[Bob Camp]

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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