[Alex Pogossov]

"Phil Allison" wrote in message
...

"Alex Pogossov"
"Phil Allison"
"Alex Pogossov"

If I understand correctly, the main feature of a beam tetrode is the
same pitch and alignment of the control grid and screen grid.


** That is a design feature of the POWER PENTODE too
- you retarded imbecile.

The above statement is either bull**** or incorrect.


** Fraid it is an ABSOLUTE FACT - you retarded jerk.


In EL84, pitch of the screen grid is about 3 times larger than that of
the control grid.

** No way.

You must be looking at the *SUPPRESSOR* grid - internally connected to
the cathode.


Alex:
I am looking at the screen grid. The suppressor grid has yet larger pitch
(1.5 ... 2 of the screen grid).

In a power pentode, the screen has to sit in the "shadow" of the control
grid or else screen current goes through the roof.

As it happens, the screen current of the EL84 is particularly low.

Alex:
It is low only because the screen grid is not that dense. If you look into a
hi-gm power video power pentode with gm = 20...30mA/V, it would have a frame
grid -- so fine, it is almost invisible. But the screen grid is quite widely
wound. Some of such pentodes would have only suppressor plates, not the
suppressor grid. It is because the distance between the screen and the plate
is long -- almost enough to suppress secondary emission by space charge
alone -- without or almost without suppressor electrodes.


Plus the EL34 and EL84 are very constructed very much alike.