[time-nuts] 10811

Richard (Rick) Karlquist richard at karlquist.com
Tue Nov 18 12:10:49 EST 2014

On 11/17/2014 5:54 PM, Bert Kehren via time-nuts wrote:
> I ground one side of the tuning diode and use the 2 to 12 V as the external
>   OCXO for my FRK's along with increasing the time constant. I have not
> verified it but I think removing the zener Voltage should also improve  ADEV.
> Bert Kehren

The choice for the Zener diode came from my old boss at HP,
who was very knowledgeable about using discrete zener diodes
as low noise references.  According to him, this particular
part number has very respectable noise.  This is just something
you have to know experientially, there is no theory of zener
noise AFAIK.  You might try measuring the noise of the 6.2V
reference voltage directly at baseband, and then multiplying
by the 1 Hz/volt sensitivity.  Let us know your results.

Rick Karlquist N6RK
(Now retired from HP/Agilent/Keysight)

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