[Amps] 3-400Z vs. 4-400A

[W0YR@aol.com (W0YR@aol.com)]

If the tube sockets are wired correctly (and I think they are in this case) 
you should just be able to plug in the 4-400-s and GO!  They will take more 
drive than the 3-400's required but will work great.  I had an amp with 2 
4-400s for years and when they got tired I put in 3-400s and no problems.    
These tubes run ok tieing the screen and control grids together and they act 
as a triode.   

This is the short answer.  I am sure you will receive a long treatise on this 
subject.  But go for it!

Mike
W0YR