[Amps] warm up time for TX tubes

[John Flood]

New to this reflector.  

 

Hope someone can help me understand tube warm up requirements.

 

Specifically, What are the necessary conditions for voltages at plate ,
screen and control grid during Warm up for indirectly heated tetrode tubes.


 

I have seen directions that say no plate voltage during warm up, but some
amps (MLA2500) apply plate voltage and limit cathode current to a few mA by
self-bias during warm up.

 

What I have in mind for my amp with gu74b  (4cx800) is to apply fil voltage
for 3 minutes while screen is at 0v, plate is full on and 
G1 is biased to cutoff (approx. -75v).  

 

Is my approach workable?

 

And

 

What are the necessary conditions condition for the tub during warm up?..

 

Thanks in advance for your help

 

John  K4dlx