[time-nuts] Difference between Datum 4065, A, B & C Cesium T&F standard?

Brooke Clarke brooke at pacific.net
Mon Mar 17 16:45:36 EDT 2008


Hi:

In order to avoid the disaster that happened on my last Cesium frequency 
standard order, see: http://www.prc68.com/I/Pack.shtml#NoP
I shipped the eBay seller a Fast Pack Box which slowed things down a little.

The Datum/FTS 4065B arrived no problem and was locked in about 10 minutes, 
although there are alarms associated with the dead backup battery.  I'm trying 
to recover some the Cyclon cells now.

This is a very nice Time AND Frequency standard.  Unlike the FTS 4060 where you 
manually set the C-Field this one monitors and adjusts based on the following 
items as reported in the Status 5 menu:
Ramsey Error		-10 	S.B. <= 160 mv
Rabi-Ramsey Error	0	S.B. <= 40 mv
Zeeman Error		-15	S.B. <= 160 mv
Rabi-Zeeman Error	-4	S.B. <= 160 mv
Ramsey Confidence	+3	S.B. <= 160 mv

As you can see it's working very well.  The front panel display is a dot matrix 
VFD and is used in two ways.  For the menus it's an 8 line display, but for the 
Time of Year (DOY:HH:MM:SS) is a single line display with very tall characters, 
see: http://www.prc68.com/I/FTS4060.shtml

The seal on the physics package is dated 7/9/99 or 1/9/99.

Sure would like to know more about the subject line, i.e. how do the A, B and C 
versions compare?

The Frequency Offset has been programmed to -001120 (parts in E-15) by a 
previous user.  As far as I can tell you just turn on this box and after it's 
warmed up 30 min. the frequency is correct (better than 8.5E-12 @ 1 sec) 
without any adjustments.  But it can be set much more precisely.  The part in 
E-14 freq offset may reflect setting it to be 100 times better than the min spec.

A two way RS-232 interface allows not only reading a bunch of operational 
parameters but also setting a number of things.  This could be GPS disciplined 
using RS-232 to tweak the frequency.  Maybe that's how the Frequency Offset 
came to be non zero.

I don't have a feel for how well the automatic adjustments actually work, maybe 
  Tom can comment?

Have Fun,

Brooke Clarke
http://www.prc68.com/P/Prod.html  Products I make and sell
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http://www.PRC68.com
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Brooke Clarke wrote:
> Hi:
> 
> Can someone tell me the difference between the various versions of the 4065 
> Cesium T&F standard?



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