A
suppressor grid is a grid used in a thermionic valve (also called
vacuum tubeIn electronics, a vacuum tube, electron tube , thermionic valve, or valve 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...
) to suppress
secondary emissionSecondary emission in physics is a phenomenon where primary incident particles of sufficient energy, when hitting a surface or passing through some material, induce the emission of secondary particles. The primary particles are often charged particles like electrons or ions. If the secondary...
. A suppressor grid is also called the antidynatron grid, as it helps to reduce the
dynatronFor the brand, see Dynatron Radio LtdThe dedicated dynatron vacuum tube was invented by Albert Hull in 1918. It has three electrodes: a thermionic cathode, a perforated anode, and a supplementary anode or plate, and its characteristic curves have a region exhibiting negative resistance, which is...
effect.
In its simplest form, a suppressor grid, typically of coarse structure, is interposed between the
screen grid and the
anodeAn anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID . Electrons flow in the opposite direction to the electric current...
(
plateSee anode.A plate is a type of electrode that formed part of a vacuum tube. The plate is impressed with a positive charge so that it may capture and flow electrons within a circuit....
) of a
tetrodeA tetrode is an electronic device having four active electrodes. The term most commonly applies to a two-grid vacuum tube. It has the three electrodes of a triode and an additional screen grid which significantly changes its behaviour.-Control grid:...
, turning it into a
pentodeA pentode is an electronic device having five active electrodes. The term most commonly applies to a three-grid vacuum tube, which was invented by the Dutchman Bernhard D.H. Tellegen in 1926...
.
The suppressor grid is usually connected to the cathode and more often than not, this connection is made within the glass envelope.
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A
suppressor grid is a grid used in a thermionic valve (also called
vacuum tubeIn electronics, a vacuum tube, electron tube , thermionic valve, or valve 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...
) to suppress
secondary emissionSecondary emission in physics is a phenomenon where primary incident particles of sufficient energy, when hitting a surface or passing through some material, induce the emission of secondary particles. The primary particles are often charged particles like electrons or ions. If the secondary...
. A suppressor grid is also called the antidynatron grid, as it helps to reduce the
dynatronFor the brand, see Dynatron Radio LtdThe dedicated dynatron vacuum tube was invented by Albert Hull in 1918. It has three electrodes: a thermionic cathode, a perforated anode, and a supplementary anode or plate, and its characteristic curves have a region exhibiting negative resistance, which is...
effect.
Placement
In its simplest form, a suppressor grid, typically of coarse structure, is interposed between the
screen grid and the
anodeAn anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID . Electrons flow in the opposite direction to the electric current...
(
plateSee anode.A plate is a type of electrode that formed part of a vacuum tube. The plate is impressed with a positive charge so that it may capture and flow electrons within a circuit....
) of a
tetrodeA tetrode is an electronic device having four active electrodes. The term most commonly applies to a two-grid vacuum tube. It has the three electrodes of a triode and an additional screen grid which significantly changes its behaviour.-Control grid:...
, turning it into a
pentodeA pentode is an electronic device having five active electrodes. The term most commonly applies to a three-grid vacuum tube, which was invented by the Dutchman Bernhard D.H. Tellegen in 1926...
.
Electrical connection of grid
The suppressor grid is usually connected to the cathode and more often than not, this connection is made within the glass envelope. Because the grid is negatively charged relative to both the anode and the screen grid, it repels any secondary electrons back to the anode preventing them from contributing to the screen grid current, and to any
negative resistanceNegative resistance is a property of some electric circuits where an increase in the current entering a port, results in a decreased voltage across the same port. This is in contrast to a simple ohmic resistor, which exhibits an increase in voltage under the same conditions. Negative resistors...
characteristic.