[Amps] re: baking out tubes

[Steve Thompson]

On Monday 25 October 2004 12:44, Traian wrote:
> Hi Bill,
>
> May a rather expensive power tube to not have an internal gettering sytem?
> The getter is used even for the cheapest small signal and low power glass
> tubes, so why to not be provided for a $500 (or maybe $5000) power
> transmitting tube?!(Unless, it include a vacion device, of course).
>
> Details about vacuum tube conditioning can be found in the Eimac's
> AB21 Application Bulletin and in the newer edition of Care and Feeding...
>
> I have made experiments for some tube conditioning and I have already
> posted some results and personal observations, see:
>
> http://lists.contesting.com/archives/html/Amps/2004-05/msg00030.html
>
> From then now, I have also verified six 8122's and other two GU43B
> tetrodes with the same positive results. The breakdown voltages are
> increasing by "debarnacling" for the NOS tubes but it seems that is not
> for the heavy used ones? (at least not for a used 4S040 and 4CX1000 I
> have tried).
For what it's worth, my theory is that a well used tube with an oxide cathode 
has minute amounts of cathode material spread around the inside, and this 
leads to a leakage level that won't reduce.

Steve