[Amps] Zirconium

[Tom W8JI]

>Will said:
>Althought Terman shows this same thing on page 315 of the 
>1st edition, 1943, here is a link to a website below about 
>getters;

(1) http://www.thevalvepage.com/valvetek/getter/getter.htm

>It's impossible to run one temperature on zirconium. It's 
>optimum temp according to Terman is 1400 deg C to absorb 
>oxygen, nitrogen, carbon dioxide, and carbon monoxide in 
> >vacuum power tubes.

Will, I wonder if you aren't a little confused on this 
topic. You said above " It's impossible to run one 
temperature on zirconium. It's optimum temp according to 
Terman is 1400 deg C to absorb oxygen, nitrogen, carbon 
dioxide, and carbon monoxide in vacuum power tubes."

You then sited a link.
http://www.thevalvepage.com/valvetek/getter/getter.htm

The very link you sited says this:

"Zirconium
Zirconium has valuable gettering characteristics and has 
come into wide use during the past decade. It forms very 
stable solid solutions (or compounds) with such gases as O, 
N, CO and CO2. Zirconium metal is cheaper than tantalum and 
requires somewhat lower operating temperatures. Zirconium is 
available either in solid metal form (sheets or wires) or it 
may be applied in the form of a powder to base metals 
(molybdenum) as described above. The proper outgassing 
temperature for zirconium lies between 1,000 and 1,700 C, 
which is attained by either direct or indirect heating of 
the zirconium metal or of the base metal to which zir-conium 
metal or zirconium powder has been applied. Wherever it is 
deemed inadvisable to heat the getter material to this 
temperature range, an outgassing temperature of 700 C must 
be considered minimum for activating the surface of the 
zirconium getter. While zirconium is effective as a getter 
from about 400 C on, it is most active at temperatures up to 
1,600 C if used, for example, on molybdenum and carbon 
anodes."

The very text you referenced says "While zirconium is 
effective as a getter from about 400 C on, it is most active 
at temperatures up to 1,600 C if used,"

It appears the text you referenced says "400deg C up is 
effective". Can you explain why that means it is useless 
below 1700 degrees C, when that isn't what they say? Can you 
also explain why Eimac was successful in using that very 
common gettering material, when you say it is impossible to 
use?

Thanks,

73 Tom