Jim,
Below is a quote from Terman on this subject.
"Zirconium is also a useful metal in this regard. Zirconium at 1400
deg C will absorb copius quantities of such gasses as oxygen,
nitrogen, carbon monoxide, and carbon dioxide. The optimum temperature
for taking up hydrogen is 350 deg C, and at higher temperatures
hydrogen begins to be given off by the metal. As a result of these
properties it is possible to maintain an extremely high vacuum,
provided that there is zirconium in the tube at these two
temperatures. This can be accomplished either by employing two
zirconium filaments with different filament currents, or by using a
single piece of zirconium in which different parts of the metal are
raised to different temperatures, so that the temperature range
extends from 300 to 1400 deg C".
Terman references this;
Zirconium and its compounds with a high melting point. Phillips Tech
Journal, Worlds fair issue, 1939, by J. D. Fast.
According to the temp. chart by Tempil, 1400 deg C is yellow in color.
300 deg c is no color. I don't know of any 3-500z that would run this
color without melting the glass. Tempil manufacturers temperature
detection and measurement devices and the tempil stick paints. A copy
of the chart can be had here;
Thanks,
Will
--- In ham_amplifiers@..., "pentalab" <jim.thomson@...>
wrote:
--- In ham_amplifiers@..., "craxd" <craxd1@> wrote:
Jim,
Did you ever get to speak to anyone at Eimac about where the
getters
were at in a 3-500Z? That's a question I'd say a few of us would
like
to find out about as I think there is some erroneous info floating
around on the net about it. One said it was the anode itself, but
it
doesn't get hot enough in my opinion to do it, and would actually
have
relaeased hydrogen gas if, a certain gettering material were
applied
to it. Any thoughts on this?
73,
Will
### No I have not. 1 e-mail to eimac ought end the
discussion . Rauch claims amperex etc... all use zirconium
coated anodes... and gettwring is done when tubes shoe
colour... aprx 800 deg C. I'm inclined to agree. A 3-500Z
has no internal getter........ so it's either the tube has
zirconium on the anode..... or it has NO getter at all !
Jim VE7RF
