[time-nuts] 10811

Brooke Clarke brooke at pacific.net
Tue Nov 18 17:31:40 EST 2014

Hi Rick:

When working on Tunnel Diode amplifiers we used (AFAICR) 5.1 V Zener diodes to stabilize the lower voltage that drive 
the diode.
5.1V was supposed to have excellent temperature characteristics in terms of repeatability (don't remember if low noise 
was part of the selection criteria).
The boards with the terminals have the Zener and a custom compensation network using both Veco (spelling?) (-TC) and 
Balco (+TC) and fixed resistors so that the gain stays constant over mil temperature ranges.

Mail_Attachment --
Have Fun,

Brooke Clarke
Richard (Rick) Karlquist wrote:
> 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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