Electronics > Projects, Designs, and Technical Stuff

Servicing Stirling Crycocoolers

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LaserSteve:
Oven or "Bottle"  brazing is done in H2 or Forming gas. Your parts come out bright, shiny, oxide free, and annealed in many cases. At least for the processes I've contracted for or witnessed.

There are silver based   brazes we use in the lab with minimal damage to copper. The  trick is proper surface prep , the proper oxidation state of tbe flame, and a flux that you really never want to be around on daily basis. They are not exactly cheap, either. I doubt you'd see them in Europe due to small amounts of Cadmium in them.

On a production basis the braze is in the form of a "preform" or near net shape. For pipes and flares I make my own preforms.


Steve

LaserSteve:
Several hundred Psi of Helium under compression by a free piston at like 30 to 60 Hz generally calls for something other then lead based solders, which are subject to brittle failure. Especially if the mating substrate is Steel.

You might want to find a modern edition of
Handbook of Electronic and Vacuum Tube Techniques by Fred Rosebury. It covers some of the "old" ways. The one free copy I found online was very early and incomplete.

Steve

coppercone2:
yea that sounds vicious on plumbing, not what I had in mind. sounds very tempremental

I was imagining torch brazing

adammunich:
Seems I missed the new reply bell, sorry about that!

I wouldn't consider soldering to the cooler itself, just the plug that keeps in the gas. Vibration seems to be relatively low on this machine, it is not a free piston type (i wish it were though, it would last longer!).

I did get my hands on a different cryocooler though, a DS 1.5 from sunpower. It supposedly works if you give it a 60HZ feed signal in the two internal voice coils, but I tried this and didn't get much cooling, just a warm hot end. I wonder if the displacer is stuck in the cold finger somehow.

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