[Amps] 4CX1000A

[Ron Youvan]

   Val LZ1VB wrote:

> Thank you very much for the explanation. I completely agree.
> The question is how a tube, showing maximum reverse screen current leading
> to an excessive screen dissipation could be used in an amateur amplifier.
> Yes, the screen is in a danger only when the amplifier is moderate driven,
> but the PA is supposed to work at any drive level from 0 to max.

   I'm not mike, but I think the reverse screen current is not strictly normal, in a perfectly built 
tube you should see none.
These tube are built with the screen grid components hiding in the electron shadow of the control 
grid elements.  When the alignment isn't perfect the electron beam strafes the side of the G2 
elements which produces emission via secondary emission.
I suspect most new good tubes of this kind show negotiable emission.  Those that do emit 
significantly may find their way onto the hands of HAMS more easily.
-- 
    Ron  KA4INM - Did you know ...
                  ... that no-one ever reads these things?