[time-nuts] Fwd: Re: homebrew H maser

Brian Kirby kilodelta4foxmike at gmail.com
Thu Sep 2 03:04:07 UTC 2010


Back when I worked with cryo-LNA's, we had helium for the cryo's and 
nitrogen for the waveguide (to pressurize it).  The cryo's were located 
in a tropical environment and we had to add helium every day.

Then you get a new person, who comes back and ask if they were suppose 
to use the pink bottle or green bottle.  Before you could get to the 
cryo's, you would hear the displacers grinding away on the frozen nitrogen.

I took about 3 days to repair, you spent one day letting the unit come 
up to ambient, then you cleaned it with freon and let it dry out, and 
then you spent a day or two vacuuming the unit back down and purging it.

These units were for early day's satellite communications and they were 
cooled down to 18 degree's kelvin.  Use to use a hydrogen temp gauge to 
measure that low.

Brian

On 9/1/2010 7:40 PM, Robert Darlington wrote:
> And cryo means ultra high purity helium.  I learned about that the hard
> way.  They don't like pumping gravel (solidified trace amounts of oxygen,
> argon, etc.)
>
> -Bob
>
>



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