[time-nuts] E1938A PN measurments

[Richard (Rick) Karlquist]

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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