[time-nuts] FTS4060 Saga -WOW!

Brooke Clarke brooke at pacific.net
Mon May 22 22:34:52 EDT 2006


WOW!  I've got s/n 1227 to parts in E-14 and think I'm within one 
C-field tick of getting it as good as the factory step sizes allow.  Now 
at 492 on the thumb wheels and maybe 491 would be better.  Also s/n 1013 
that I thought had a bad C-field adjustment was just way off in it's 
C-field setting.  The optimum setting remains to be seen but when at 909 
it's within parts in E-13 of s/n 1227.  This is being measured by using 
the 1 MHz out of both sources and feeding that into the start and stop 
inputs of an HP 5345 counter. 

The thing that has made all the difference is feeding the cesium output 
to the SR620 10 MHz rear panel Reference input and taking the front 
panel 1 kHz reference output and using that instead of the 1 Mhz from 
the standard for the stop signal.  By dividing down the noise is reduced 
radically.  I'm now seeing 500 second averages that typically differ by 
a couple hundred pico seconds.  When I was using the cesium 1MHz as the 
stop input adjacent 500 second averages might differ by up to 8 nano 

Having Fun,


w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml

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