[time-nuts] Better than average Rb oscillator

[Skip Withrow]

Hello Time-Nuts,
I just finished an almost 27 day run of one of my Rb oscillators and,
at least, I was impressed.

This oscillator is a stock standard LPRO-101 with only one slight
modification.  The 5k C-field pot was brought out external to the unit
and replaced with a precision 500 Ohm 10-turn pot with fixed resistors
on either side to make the total 5k.  The frequency change is about
1.62x10E-13 per division on the turns counting dial.

The oscillator IS in a controlled environment (with a little secret
sauce poured on).

The oscillator is running completely open loop.  In fact, there is
purposely nothing hooked to the EFC line.  During the run nothing was
touched in the system.

There are two attachments.  The first is a TimeLab ADEV plot.  The 4
hour plot is the oscillator against a free running 8602 measured with
a DMTD and TICC (this gives the real short-term performance with the
GPS noise removed).  The 26 day plot was done by logging the
oscillator against GPS with a Thunderbolt every 15 seconds.  The phase
data was imported into TimeLab.  Of course, this plot has the GPS
noise in it as well, but gives a good indication of the unit
long-term.

The second attachment is the phase data plot.  Over the almost 27 days
it moved about 130ns.  And the curve looks reasonably parabolic, which
would indicate the aging is pretty constant.  Aging calculates to
about 4.15x10E-15 per day.  Reasonably good by my standards (but I'm
trying to do better)!

When I monitor my HP5065A with a Thunderbolt side by side with this
rubidium I can see the 5065A move with barometric pressure changes and
ambient temperature changes much more than RUFUS.  And the 5065A
flicker floor seems to be worse (but, of course, I haven't measured
the 5065A yet).

Just had to brag a bit on this one.

Regards,
Skip Withrow
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