[time-nuts] FTS4060 C Field Time Constant

John Ackermann N8UR jra at febo.com
Thu Feb 17 17:12:39 EST 2005

Brooke Clarke wrote:
> Hi John:
> The only reason I saw this was because the plot had a steep positive 
> slope, then 24 hours later appeared to be perfect, now a few days after 
> that obviously has a negative slope.  My initial estimate of the time 
> constant, based on the perfect performance, of 1 tau = 3 hours, was way 
> off.  The real tau is more like 1 day.  So I'll wait another day before 
> making the next adjustment.
> Do you have plots that cover longer time periods?

I've done lots of short runs while tweaking this thing... I plan to let 
the current run go until at least early next week, when I want to do 
some equipment reconfiguration that will require shutting the counter 
(but not the Cs) off.

I just acquired three HP 5334A counters (great TICs with 2ns resolution, 
1U rack height, and no fan -- and in the $125 range on eBay) to use for 
long-term monitoring.  I plan to monitor the 5061A continuously vs. GPS, 
and the 5065A Rb vs. the 5061A.  That'll free the 5370B up from one-off 
measurements where I can use the better resolution to get results more 


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