[time-nuts] Homebrew H Maser

Corby Dawson cdelect at juno.com
Sun Aug 29 20:27:13 UTC 2010

After keeping an old EFOS 2 H maser running the last couple or three
years here are a few bits of advice.

-The triple magnetic shields are VERY important. The first time I removed
the top
 shield to access the RF section the Maser stopped oscillating! Replacing
the shield
restored oscillations!
-The cavity does not have to be machined to "super precise levels", in
this Maser once the coarse setting (mechanical at factory) is made, the
medium tuning is done by adjusting the cavity temperature. The fine is
done with the cavity varactor. This cavity is aluminum.
-from a cold start it takes about 1 week for the ovens to come up to
operating temp.!
-this maser has two vacuum sections, an outer that enclosed the cavity
and thermally insulates it. This allows the cavity temperature to be
regulated to within .001 degree C. The inner chamber keeps the cavity
evacuated so all you have in it is the H atoms.
-Making a homebrew collimator (at the discharge bulb output) might be
hard, google it and you will see it's  tricky.
-As stated the electronics are pretty easy these days. Main points are a
low Insertion loss, high isolation circulator on the cavity output, a low
noise figure RF amp and a low noise downconvertor.

I have, somewhere, a scan of the two manuals. There is lots of theory and
full schematics. Might be a good read if you are serious in trying to
homebrew one.
I'll dig them up and see if anyone could host them on a website. (Files
are quite large!)

Corby Dawson
1 Tip for Losing Weight
Cut down 2 lbs per week by using this 1 weird old tip

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