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A screen-grid tube in which secondary emission of electrons from the anode causes the anode current to decrease as anode voltage increases, resulting in a negative resistance characteristic. Also known as negatron.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


A type of vaccum tube currently used in high-end audio amplifiers. A tetrode is like a triode with the addition of a "screen grid" between the control grid and the plate (anode). The screen grid is an electrostatic shield typically biased with a fixed voltage that isolates the control grid and protects it from voltage potential changes on the plate.

Dynatrons are special types of tetrodes that utilize a screen grid voltage higher than the plate voltage. This causes the plate current to decrease as plate voltage increases. This characteristic, known as negative resistance, is useful in oscillator circuits. See triode and diode.

The Tetrode Uses Two Grids
In a tetrode, the feedback and oscillation are controlled by the addition of a screen grid between the control grid and plate.
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References in periodicals archive ?
Marek added: "You will be able to order from the 1974 Dynatron catalogue - yes the 1974 catalogue!
The Dynatron Effect|runs from Thursday, November 12, until Sunday, November 15.
He added: "Back in the day, I could only dream of owning a Dynatron, Hacker or Decca hi-fi system.
"The price of a Dynatron topend stereo system was around PS250.00.