[time-nuts] E1938A PN measurments

[Tom Knox]

Rick it is really fantastic to see Time Nuts occasionally discuse different aspects of products they actually designed. This form is really a treasure.
In the future it would be interesting to here how you would approach the next quartz industry standard. The next generation Blue-Top or BVA.
Thanks;
Thomas Knox



> Date: Sun, 30 Sep 2012 10:03:03 -0700
> From: richard at karlquist.com
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] E1938A PN measurments
> 
> 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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