They should never leak He. Were the lines between the compressor and the head very long?
-John =============== > 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 >> >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.