Tubes Asylum

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

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Tre'

In Reply to: RE: I thought that the KT77 is a beam tetrode... posted by Vinyl Valet on March 14, 2023 at 09:18:02

"beam power pentode" and "beam tetrode" are interchangeable language.

Also "beam power tube". All three have been used over the years to describe a tetrode with beam forming plates between the screen grid and the plate of the tube.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

Follow Ups:

RE: I thought that the KT77 is a beam tetrode... - Vinyl Valet 21:09:40 03/14/23 (2)
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
- 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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