[time-nuts] Maser manual

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Sep 1 19:39:01 UTC 2010

In message <24C547B54EA34A69BACC4F823BB4036F at 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/


Page 4/3 in the service manual states:

	For the Hydrogen Maser, this unperturbed frequency
		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:


As that brings the mechanics inside the work envelope of main-stream
CNC machines with the required tolerances.


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at 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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