[time-nuts] Z3805A cooling requirements?

Bob Camp lists at rtty.us
Thu Dec 20 12:36:56 UTC 2012


Did I miss part of the data? 

The plot I got shows about 9 minutes. Temperature step stress takes a *long* time to settle out.


On Dec 19, 2012, at 9:56 PM, SAIDJACK at aol.com wrote:

> 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.
> bye,
> Said
> 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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