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How's the power amp behave if screen voltage is higher than the plate?

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  • How's the power amp behave if screen voltage is higher than the plate?

    As the title of the thread. All data sheet have the graphs with screen voltage lower than the plate. What happen if the plate voltage is made lower than the screen?

  • #2
    Then the screen becomes the plate and attracts the electrons, it's a quick way to kill the tube, since Pdg2 is usually much lower than Pda.

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    • #3
      Originally posted by Alan0354 View Post
      What happen if the plate voltage is made lower than the screen?
      The universe will invert and we will all cease to have ever been.






      Actually... What jazbo said
      "Take two placebos, works twice as well." Enzo

      "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

      "If you're not interested in opinions and the experience of others, why even start a thread?
      You can't just expect consent." Helmholtz

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      • #4
        But during normal operation, screen is kept at plate idling voltage ( say 440V). When you have large input signal, the plate can swing down to 200V. So the plate is 240V lower than the screen. Yes, the screen will be drag low a little because of the current cause voltage drop across the screen resistor. But it will not be as low as 200V.

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        • #5
          This is normal as evidenced by the screen grid current, i.e., Ig2 shoots way up when the plate voltage swings low BUT you can not operate the tube like that on a continuous basis (with Eg2 permanantly lower than Ea), obviously grounded plate and other special applications are excluded from the above constrain, but for audio applications that would be the case.

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