Will Matney wrote:
>>>Getters like zirconium
>>liberate
>>>hydrogen gas when heated above 300 deg C, and start working around 700-800
>>>deg C to absorb O2, CO2, CO, etc. The optimum temperature is said to be
>>1400
>>>deg C. Tantalum though does not have the problem of emitting hydrogen gas
>>>and its optimum temperature is around 1000 deg C if I recall.
>>>
>>Overnight I remembered some older correspondence about this. Because
>>getter materials mop up different gases at different
>>temperatures, some transmitting tubes have multiple getters at different
>>locations, possibly using different materials as well. For example, the
>>3-500Z has getters located at the base of the grid and the base of the
>>filament, as well as the big one sprayed on the anode (information from
>>an Eimac tube designer).
>
>
>Ian, correct, that's the only way it could have ever worked. Zirconium
>on the anode only would have left a tube full of hydrogen gas.
>Something else had to be heated up to collect it. In some ways,
>hydrogen is worse that the other gasses because of the speed in the
>ions it creates.
>
What is your reference for the behavior of various getter materials as a
function of temperature, Will?
"Full of hydrogen gas" would be an exaggeration, but I see the point
you're making.
--
73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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