[time-nuts] Z3805A cooling requirements?

SAIDJACK at aol.com SAIDJACK at aol.com
Thu Dec 20 02:56:59 UTC 2012

Not sure about that, if you look at the frequency plot after ~20 minutes in 
 moving air the frequency was still extremely close to 10.000000MHz.. to 
within  <1E-011 of 10MHz. This is a free-running 10811.
Compare that to the plot of the OCXO I had sent out some hours ago when it  
was running stable inside the foil - there was almost no average frequency  
change between the two tests.
If the heaters had an issue keeping average crystal temperature stable,  
then the frequency would have changed from the first plot to the last plot  I 
would think. In my opinion the airflow is just adding a huge bunch of heater 
 control loop noise to the output stability, or there are components on the 
PCB  which are very sensitive to the airlfow. Consider that this unit and 
it's PCB  was designed to live inside the 53132A (very close to the fan) that 
I am now  using as an air source. One thing this tells me: the fan in the 
counter could be  disabled and it would improve the units stability, if one 
keeps an eye on  internal counter temperature.
In a message dated 12/19/2012 18:42:08 Pacific Standard Time,  
actast at hotmail.com writes:

I think  the data shows that the heaters were losing ground, which would 
explain the  steadily falling temp of the SC cut quartz. 

Thomas  Knox

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