Tubes Asylum

RE: I thought that the KT77 is a beam tetrode...

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Vinyl Valet

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In Reply to: RE: I thought that the KT77 is a beam tetrode... posted by Tre' on March 14, 2023 at 19:21:03

But doesn't the pentode have an additional beam forming plate, so the the two aren't exactly the same; tetrode with four elements (cathode, control grid, screen grid and anode) and pentode with five elements, the fifth being the suppressor grid? If there are only four elements in a KT77, why would you want to call it a pentode? Do you believe the two function in exactly the same manner?

Open up your mind, in pours the trash. - Meat Puppets, 1987

Follow Ups:

RE: I thought that the KT77 is a beam tetrode... - Tre' 09:54:43 03/15/23 (1)
No, a true pentode (el34) has a cathode, control grid, screen grid, suppressor grid and a plate. No beam forming plate at all. Just a cathode a plate and three grids in between.
some people call a beam power tube a pentode because they consider the beam forming plate to be a fifth element.
A beam power tube does not function exactly like a power pentode but close enough that it can be a direct drop in replacement. 6ca7 for a el34 for instance.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

Edits: 03/15/23
- RE: I thought that the KT77 is a beam tetrode... - Vinyl Valet 10:04:51 03/15/23 (0)
  Yes, you are correct in that regard.
  
  Open up your mind, in pours the trash. - Meat Puppets, 1987

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