[Amps] How do I determine Class

[Jim Isbell]

  This is EXACTLY the answer I needed.  The amp uses a pair of 4-125As 
and the screens are at "350V - 400V"   Plates at "2000V - 3000V" (but no 
terminating resistor) so I guess that makes it a class AB1 linear.  The 
screen grids have several bypass caps to ground but no resistor.  The 
signal is fed to the control grids through the MB-40-L and the plate 
circuit is prety normal..

Just what I needed for my vintage shack linear.

R. Measures wrote:

> Jim -- If the tetrodes are being operated at roughly half of their max 
> screen-V rating, they are likely being run in a non-linear mode.  If 
> they are being operated at their max. screen-V rating, and there is a 
> grid-terminating R, they are probably operating in Class AB1 linear 
> service.
>