[time-nuts] homebrew H maser

Bob Camp lists at rtty.us
Wed Sep 1 17:18:02 UTC 2010


My guess is that you put the adjuster entirely inside the vacuum enclosure.
Pump the gizmo down, stabilize it, measure where it's at. Do some math, pop
it open move the adjuster x.xx turns. Step and repeat. Possibly have a fine
and a coarse mechanical adjust screw. 

It's a one time only sort of thing. You can afford to do it the hard way. 

Another option would be to allow the screws to come through the envelope and
leak a little bit during the adjust process. Once you were done with
adjustment, seal them up with a low out gassing epoxy. My guess is that
would be a problem thermally. If you need 0.001C gradients, you can't have
more than one thermal path to the cavity.

That's all getting complicated, and we're only talking about the easy to
understand and address stuff...

My understanding is that the guys at Kvarz spent years poking at their
design in the secret back room before it worked as well as it does today.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Attila Kinali
Sent: Tuesday, August 31, 2010 12:13 PM
To: jfor at quik.com; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] homebrew H maser

On Sun, 29 Aug 2010 10:03:02 -0700 (PDT)
"J. Forster" <jfor at quik.com> wrote:

> [snip]
> >> complicating aspect is the self-tuning stuff for which several
> >> strategies may be chosen.
> >
> > I'd start here at getting a cavity that is resonant at the frequency
> > at all. Getting sub-milimeter precision in tooling is quite easy
> > (given you have the tools and knowledge, or can pay someone to do it for
> > you),
> > but if the cavity has to be resonant within a couple of Hz of the
> > 1.4xxxGHz, then you have to get a precission in the range of 10^-9
> > which basically impossible mechanically. So the cavity would need to
> > a mechanical tuning system too, but one that doesn't lower the cavity's
> > Q or add any additional resonant modes.
> A tuning plunger driven with a Burleigh Inchworm, either through a bellows
> or with a vacuum Inchworm.

Yes, but that's only half of the story. How do you make it vacuum tight?
And how do you design the end in the cavity so that you do not create
unwanted resonant modi?

				Attila Kinali
If you want to walk fast, walk alone.
If you want to walk far, walk together.
		-- African proverb

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