[time-nuts] FTS4060/S24 Location of E26 Test Point & ConfirmOperation?
Tom Van Baak
tvb at leapsecond.com
Fri Jan 7 11:56:18 EST 2005
> Tom Van Baak wrote:
> > It's only a 3 digit
> > thumbwheel with LSD resolution of 2e-14 so the
> > maximum range is 2e-11.
>
> Hi Tom --
>
> That's quite a bit finer resolution than the 5061A C field setting -- I
> think the spec says something like 7x10e-13 settability. My 5061A from
> Corby (which should arrive today, yay!!!) has an FTS tube in it. Do you
> know if the FTS tube has a smaller change per unit of control voltage
> than the HP tube, so that an FTS tube in an HP chassis has finer
> settability than with the HP tube? Or does the FTS chassis just have
> finer control over the C field voltage applied to the tube?
>
> (I'm speculating because it appears the HP option 4 tube also results in
> finer control without any changes in the chassis circuitry.)
>
> John
John,
I think the C-field range is more a function of the fixed
resistors plus knobpot (HP 5061) or digipot (FTS 4060)
voltage divider than anything else. I know early 5061A
had a C-field sensitivity on the order of 1e-12 per minor
division and later 5061A it was 5e-14 per minor division.
This would be a quick experiment for you could do on
your new 5061A. Run a one hour 5061-GPS phase plot
with the C-field at either extreme and tell us about the
triangle that you get.
/tvb
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