[R-390] Gettering old tubes

[MillerKE6F at aol.com]

RE: Getters et al
 
    The Toooob audio folks put a lot of value on the  "Condition" of the 
getter flash on the old premium audio tubes like the 6550  etc.  I know that 
the getter is flashed at some point in the assembly  process by induction 
heating (assuming it's already been rough pumped by  mechanical means) and that 
flash consumes most of the trace gasses inside the  envelope.  My question 
is how much "Gettering" action takes place after the  initial flash?  
 
    I realize that hard glass transmiting tubes use  alloyed (coated?) 
getter material on their anode structures that provide  ongoing gettering 
provided the anode is heated to a very high temperature (red  plates orange plates 
white plates..... take you pick)
 
    73
 
   Bob, KE6F