Vacuum Tubes, Pentode vs. Beam Tetrode

Discussion in 'General Electronics Chat' started by ThyratronTube125, Mar 13, 2012.

  1. ThyratronTube125

    Thread Starter New Member

    Feb 7, 2012
    I saw on a datasheet for tubes, a PL36 vintage tube that I have, claims to be a 'Pentode' while when I look at the tube itself, it appears that it has a set of beam forming plates rather than a 3rd grid.:confused:

    Also, with the 6L6GC, it commonly states that it is a Beam pentode, while in reality it is a Beam Tetrode.
  2. #12


    Nov 30, 2010
    Quoting from RCA Receiving Tube Manual RC-19:

    "When a beam power tube is designed without an actual suppressor grid, the electrodes are so spaced that secondary emission from the plate is suppressed by space charge efects between the screen grid and the plate."

    Thus the need to suppress secondary emission from the plate is achieved. You didn't actually ask a question, so I'm guessing at what you need. Does this help?
    Last edited: Mar 13, 2012
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