In message <24c547b54ea34a69bacc4f823bb40...@pc52>, "Tom Van Baak" writes:
>I found the original copies of both EFOS manuals, along with
>a few photos. See:
>
> http://www.leapsecond.com/museum/efos/
Interesting.
Page 4/3 in the service manual states:
For the Hydrogen Maser, this unperturbed frequency
is
f(H) = 1 420 405 751.768 +/- 0.002 Hz
In practice, this frequency is perturbed by
interaction of the hydrogen atoms with the walls
of the interaction volume container, doppler
effects, interactions between the atoms themsel-
ves, etc. The resulting frequency for the EFOS
Maser is taken to be
F(o) = 1 420 405 751.689 Hz
I have no idea where the EFOS was produced, but somebody should try
to calculate the relativistic correction for their height above the
geoid, and see how much of the systematic 0.079Hz frequency difference
that explains...
If I were to build a maser myself, I would probably not attempt
to copy the EFOS, as the large mechanical dimensions add significant
cost in materials and machining.
I would be much more tempted by a sapphire loaded cavity design like
this one:
http://www.nict.go.jp/publication/shuppan/kihou-journal/journal-vol50no1.2/0304.pdf)
As that brings the mechanics inside the work envelope of main-stream
CNC machines with the required tolerances.
Poul-Henning
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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