AI-5
SCREEN GRIN—A grid placed between a control grid and the plate and usually maintained at a positive
potential.
SELF-BIAS—The voltage developed by the flow of vacuum-tube current through a resistor in a grid or
cathode lead.
SHARP-CUTOFF TUBE—The opposite of a remote-cutoff tube. An electron tube which has evenly
spaced grid wires. The amplification of the sharp-cutoff tube is limited by the bias voltage and
characteristics.
SPACE CHARGE—An electrical charge distributed throughout a volume or space.
TETRODE TUBE—A four-electrode electron tube containing a plate, a cathode, a control grid, and a
screen grid.
THERMIONIC EMISSION—Emission of electrons from a solid body as a result of elevated
temperature.
THYRATRON TUBE—A gas-filled triode in which a sufficiently large positive pulse applied to the
control grid ionizes the gas and causes the tube to conduct, after which the control grid has no effect
in conduction.
TRANSCONDUCTANCE—A measure of the change in plate current to a change in grid voltage with
the plate voltage held constant. Transconductance (gm) is usually expressed in micromhos or
millimhos. Mathematically,
TRANSIT TIME—The time an electron takes to cross the distance between the cathode and the plate.
TRIODE TUBE—A three-electrode electron tube containing a plate, a cathode, and a control grid.
VARIABLE-mu-TUBE—Same as remote-cut off tube.
VERTICAL DEFLECTION PLATES—A pair of parallel electrodes in a CRT that moves the electron
beam up and down.
VOLTAGE GAIN—Ratio of voltage across a specified load.
