[time-nuts] FTS4060 C Field Time Constant

Brooke Clarke brooke at pacific.net
Thu Feb 17 16:18:48 EST 2005


In still in the process of setting the C field on my FTS-4060 and have an interesting observation.  After a cockpit error where I made a change in the wrong direction the time interval plot was going up steeply.  In line with my latest theory of how to make the adjustment (which is to do a binary search rather than try and compute the required adjustment) I then set in a new value.  I thought I saw a time constant of about 3 hours (i.e. it took about 3 hours to get to 63% of what I thought was the final value).  

The next day (24 hours later) for about 8 hours the time interval was constant to within 10 nano seconds, phenomenally stable operation.

Now 3 days after that I can see that the time interval has a down slope.    So the very stable operation 24 hours after the C field change was during the time when the frequency was changing and was at the level part of the curve. 

This indicates that for a C field change on the FTS4060 you need to wait at least 2 or 3 days before making any measurements!  

This also may explain why trying to compute the amount of a change does not seem to work.  This would be the case if the effect of the prior change had not yet settled in.

Have Fun,

Brooke Clarke, N6GCE
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml

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