I think part of the misconception that carbon anode tubes are more
gassy
is because when most people look at one they associate the carbon with
something more familiar to them. Namely charcoal. Charcoal does absorb gas
and such and it great for filters however graphite is quite a different
thing. Graphite unlike charcoal pacts very tight with its rather flat
molecules. The nice thing about carbon ( which most power tubes have in
them anyway some where). Is that when they go to bake and pump down the
tube any oxides that form on the graphite turn to gas and are pumped out.
CO and CO2 are both gasses. Any other materials (metals) will be coated
with the oxides that form on them. Most CRT's are coated inside between the
neck and screen with graphite. Commonly called DAG. This is a coating that
is painted on and allowed to dry before pumping down the tube.
73
Bill wa4lav
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