[time-nuts] E1938A PN measurments

[Bill Dailey]

I have a corby ocxo (datum-1111c) that I am coupling with a fury oem board soon (need some connectors). I wish someone with good measurement equipment lived nearby.  I would like to measure this vs my standard fury.  I think the ocxo is mid 10-13 at 1s.  Anybody near Kansas City?

Doc

Sent from my iPad

On Sep 30, 2012, at 7:02 PM, EWKehren at aol.com wrote:

> Doc
> The units I mentioned have been done by Corby, but I let units run two  
> weeks before I do any test. In the future when I do the 40+ two a week running  
> parallel and the best rerun after 4 week soak.
> Bert
> 
> 
> In a message dated 9/30/2012 7:55:43 P.M. Eastern Daylight Time,  
> docdailey at gmail.com writes:
> 
> Bert,
> 
> When you do tests like this, how long do you let the  oscillators "settle" 
> prior to testing?
> 
> Doc
> 
> Sent from my  iPad
> 
> On Sep 30, 2012, at 4:23 PM, EWKehren at aol.com wrote:
> 
>> Rick 
>> I have some 10811's all below 1 E-12 in the 1 to 100 sec. range,  a few 
> as  
>> low as 4 E-13 at 10 seconds. How low have you seen, I  have the 
> opportunity 
>> to  test 40+ units and hope to find a few  even better ones. Any guidance 
> will 
>> be  appreciated.
>> My  best reference is 3 E-13 so any thing as good or better would have to 
> be  
>> tested by some one else after initial test.
>> Bert  Kehren
>> .
>> 
>> 
>> In a message dated 9/30/2012  3:49:33 P.M. Eastern Daylight Time,  
>> richard at karlquist.com  writes:
>> 
>> I only  measured one 10811.  However, John  Vig's tutorial
>> (available at IEEE  UFFC) rather categorically  states that
>> piezoelectric resonators have  flicker noise of  frequency.
>> What I measured was most closely related to  phase  noise,
>> as opposed to Allan Deviation.  Phase noise of  10811's  is
>> more consistent unit to unit than ADEV and certain  more  consistent
>> than aging.  BTW, ADEV at HP was measured  against  a
>> special 10811 that was 500 Hz off frequency.  I  was never
>> able to  find out how they arrived at this "golden"  unit.
>> But it seems clear that it  could not have been the
>> best ever unit for ADEV, thus the real "golden"  units
>> that came  down the pike were simply rated as ADEV too good
>> to   measure.  I tried to get a project started where we
>> would use  a  frequency synthesizer to do the offset.
>> Then we could take the  best units  and compared them against
>> each other.  Then, as  well accumulated test  data, the
>> cream would gradually rise to  the top and we would have
>> some  true golden units.  The  problem was that there ADEV
>> at those levels  wasn't a "money  spec".
>> 
>> Rick
>> 
>> On 9/30/2012 12:16 PM, Ed  Palmer  wrote:
>>> Would this characteristic be similar across  all 10811s or would  there 
> be
>>> as much unit to unit variation  as there is for aging and  Allan 
> Deviation?
>>> 
>>> Ed
>>> 
>>> On 9/30/2012 11:03 AM,  Richard (Rick)  Karlquist wrote:
>>>> I recently modified an old 10811  to  bring out the crystal
>>>> leads on miniature coax (instead  of  having them connect
>>>> to the oscillator circuit).   This allowed  me to measure
>>>> the crystal's inherent  flicker noise of  frequency.
>>>> The measurements indicate  that the 10811 phase noise  out
>>>> to at least 100 Hz is  entirely due to the crystal.
>>>> An interesting aspect of flicker  noise of frequency
>>>> is that Allan  deviation is  independent of tau.  Thus,
>>>> just one number   describes the crystal noise.
>>>> 
>>>> Rick
>>>> 
>>>> On 9/30/2012 4:44 AM, Bob Camp   wrote:
>>>>> Hi
>>>>> 
>>>>> Close  in, it looks  like it's pretty much the crystal and the  loading
>>>>> of the  bridge  oscillator.
>>>>> 
>>>>> Bob
>>>>> 
>>>>> On Sep 29, 2012, at 11:46 PM, Richard  (Rick)  Karlquist
>>>>> <richard at karlquist.com>   wrote:
>>>>> 
>>>>>> The E1938A uses a crystal  that is  basically the same as
>>>>>> the 10811 crystal  except that it is  in a reduced height
>>>>>> package.  However the phase noise  is not as good as  a
>>>>>> 10811 due to broadband noise in the  automatic  frequency
>>>>>> control circuit.  By the time I   discovered this, it
>>>>>> was too late to try to fix   it.
>>>>>> 
>>>>>> Rick Karlquist   N6RK
>>>>>> E1938A designer
>>> 
>>> 
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