[Amps] General question on filament life

[Larry]

> I'm curious as to how you determined that these tubes (4-400A's) 
> developed a filament to cathode short, ESPECIALLY SINCE THEY DO NOT HAVE 
> A CATHODE!
> 
> 73, Dave, K1FK
> Fort Kent, ME
> 
> 

Yeah Dave, good catch! Please excuse my typo. My brain said grid,
my fingers typed cathode. It seems like I spend twice as much
time correcting as I do typing these days. Chalk it up to old age.

73, Larry