[time-nuts] homebrew maser

[Attila Kinali]

On Tue, 31 Aug 2010 17:02:16 -0700
"John Miles" <jmiles at pop.net> wrote:

> >
> > Microwave test gear and plumbing is very significantly harder to get at 24
> > GHz than at 1.4 GHz.
> >
> > At a guess I've seen easily 100 times more stuff available at 1.4 GHz.
> 
> That is so far down the list of "101 Things That Are Hard About Building a
> Hydrogen Maser" I'm not even sure it makes the top 101. :)
> 
> There is a ton of prior art in the Amateur Radio microwave community on 24
> GHz microwave activity and construction.  At 1.420 GHz, not so much.

I agree here with the other John, 1.4GHz is a lot easier to handle
than 24GHz. While the physics of a H maser are not trivial, handling
frequencies over 5GHz gets difficult. Going over 20GHz, finding electronics
that work reliably there, having a low noise floor etc is something
that even companies specialized in that stuff have difficulties with.
Ie it would lead to the situation where it becomes near impossible
to test whether the electronics is working correctly or whether the
physics package has some problems. Considering this, i'd rather stick
with electronics that can be done with off the shelf components and that
is easy to test and verify.

If the size of the cavity is a problem with the H maser, it would be quite
easy to load the cavity with some high \epsilon material and thus shrinking
it (as it is done with all modern H masers i've read about)

IMHO, the "right" way to build a maser would be first to build the cavity
and the electronics. Verify that the cavity is resonant at the right
frequency, can be tuned in a wide enough range and can be stabilized well
enough that changes in cavity resonance will only have a minor effect on
the maser itself.

Then build and verify the vacuum system.

Then build the beam source, collimator and state selector and verify that
they are working as they are supposed to do.

And last, put everything together, and hope that it magically works ;-)

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