[Amps] Pre-heating of tubes

[Tom W8JI]

> Will said:
>>Under 300 deg C which is just under where you can't see 
>>the anode turn red in the dark, is where zirconium will 
>>not do any good at all, neither for hydrogen or O2 and the 
>>others. These heat colors work for any metal, but not for 
>>graphite. You can check them against any heat treatment or 
>>metalurgical chart.<

Peter said:
 > According to my book on heat rreatment (Hardening, 
Tempering and Heat treatment, Tubal Cain, Nexus  Special 
interests, ISBN 0 85242 837 5) in a dim natural light, 700 
deg C is dull red, 740 blood red, 800 cherry red, 825 bright 
cherry red, 850 red, 900 bright red and 1000 deg C is 
yellow. Not to be confused with the pale straw through dark 
blue used when tempering steel. I would be surprised if 300 
deg C can be seen, even in the dark - unless maybe, you are 
a pit viper!


Peter is correct according to data I have in multiple 
reference sources.

~500 C is the very start of any detectable color as seen in 
dark room
~600 C is a very dark blood red
~700C is a dull red
~800 C is cherry red
~900C is bright red
~1000 C is a lemon color, or the very start of yellow

Please note the color of a 3-500Z anode is not close to 
being even along the length of the anode, so the getter is 
not operated uniformly at one temperature.

73 Tom