In 1926, the tetrode valve was introduced, and enabled further improvements in performance.
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This two-grid tube is called a tetrode, meaning four active electrodes, and was common by 1926.
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The vacuum tube is then known as a triode, tetrode, pentode, etc., depending on the number of grids.
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However, the tetrode had one new problem.
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The beam power tube is usually a tetrode with the addition of beam-forming electrodes, which take the place of the suppressor grid.
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Triode, tetrode and pentode variations of the thyratron have been manufactured in the past, though most are of the triode design.
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To combat the stability problems and limited voltage gain due to the Miller effect, the physicist Walter H. Schottky invented the tetrode tube in 1919.
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The highest-power tube currently available is the Eimac 4CM2500KG, a forced water-cooled power tetrode capable of dissipating 2.5 megawatts.
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Higher-frequency operation could be obtained by welding a second wire on the opposite side of the base, making a tetrode transistor, and using special biasing on this second base connection.
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More examples
A thermionic tube having four electrodes
A tetrode is a type of electrode used in neuroscience for electrophysiological recordings. They are generally used to record the extracellular field potentials from nervous tissue, e.g. the brain. Tetrodes are constructed by bundling together four very small electrodes; each wire is generally less than 30u00A0u03BCm in diameter...
Tetrode can refer to:
Tetrode, also given as van Tetrode and spelled variously as Tetterode, Tetteroo, Tettero, Thetrode and Tetroe, was a Dutch medieval noble family which later became a prominent patrician family in Holland. ...
(Tetrodes) In electronics, a vacuum tube, electron tube (in North America), or thermionic valve (elsewhere, especially in Britain) is a device used to amplify, switch, otherwise modify, or create an electrical signal by controlling the movement of electrons in a low-pressure space. ...
(Tetrodes) pentodes, hexodes, heptodes and octodes were also made, each extra electrode adding another concentric control grid, in the path (usually with half of them just used for faraday screening between the others). In the USA, they were all called tubes. ...
A multi-grid radio valve (or tube) with four electrodes (an anode, cathode, a control grid, and an additional grid-type electrode), commonly used in high-end audio amplifiers etc.
A four-element electron tube, containing a control grid, screen grid, cathode, and plate as active elements, in addition to the filament.