[time-nuts] FE-5680A Mechanical Question
Charles P. Steinmetz
charles_steinmetz at lavabit.com
Fri Jan 13 20:36:05 UTC 2012
Bert wrote:
>we would be talking +- one step and using different rate but reading the
>frequency over 1000 seconds would be my answer.
Rather than dithering the existing 7e-13 steps, perhaps it would be
simpler to adjust the 5680A step size? Presumably, the C-field is
being controlled by the current or voltage output of a DAC, and the
7e-13 steps represent the LSB of the DAC. From the reports so far on
the list, the DAC output range is much larger than necessary (I think
someone said ~ +/- 2 Hz ??). If you attenuate the DAC output by 10x
in the analog domain, you would have a +/- 0.2 Hz range with 7e-14
steps (or, if you like, attenuate by 7 for 1e-13 steps, or by 14 for
5e-14 steps). You would have to be a little careful about the tempco
of the implementation (particularly, you may need to add some
low-tempco bias to get the range centered on 10.000000000 MHz again),
but I wouldn't think it would be so critical as to be beyond the
ability of the home time nut.
Best regards,
Charles
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