> In the section on Zirconium, the second paragraph points
> out that it
> does sorb hydrogen quite well at temperatures of 300-500C,
> but releases
> it again at 850-1000C. Kohl points out that properly
> treated zirconium
> surfaces can also trap hydrogen down to room temperature,
> though
> obviously less effectively than at the optimum
> temperature.
The 3-500 Zirconium getter works because the anode operates
at widely varying temperatures, with the lower edges much
hotter than upper areas.
You'll never degass a 3-500Z unless the anode shows color.
As a matter of fact the entire family of tubes including
4-125's and 4-400's has the same problem. If the anode
doesn't show some color, the tube will fail prematurely.
According to one of Eimac's engineers who was visiting in
Cleveland while they were developing the 3CX1200, RCA had
that problem in the driver of a large AM transmitter. RCA
had to change to the next tube size down to stop premature
failures. They had to get some color on the anodes.
We had some pretty lengthy conversations about getters and
so on back in the early 80's.
73 Tom
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