AI-4
PEAK VOLTAGE—The maximum value present in a varying or alternating voltage. This may be
positive or negative.
PENTODE TUBE—A five-electrode electron tube containing a plate, a cathode, a control grid, and two
grids.
PERSISTENCE—The duration of time a display remains on the face of a CRT.
PHOSPHOR—The material used to convert the energy of electrons into visible light.
PLANAR TUBE—An electron tube, constructed with parallel electrodes and a ceramic envelope, which
is used at uhf frequencies. It is commonly referred to as lighthouse tube.
PLATE DISSIPATION—The amount of power lost as heat in the plate of a vacuum tube.
PLATE RESISTANCE—The plate voltage change divided by the resultant plate current change in a
vacuum tube, all other conditions being fixed.
POWER PENTODE—A special-purpose tube used to provide high-current gain or power amplification.
Each grid wire is directly in line with the one before and after it, a fact that allows more electrons to
reach the plate.
POWER SUPPLY—A unit that supplies electrical power to another unit. It changes ac to dc and
maintains a constant voltage output within limits.
QUIESCENCE—The operating condition of a circuit when no input signal is being applied to the
circuit.
RECTIFIER—A device which, by its construction characteristics, converts alternating current to a
pulsating direct current.
REGULATOR-—The section in a basic power supply that maintains the output of the power supply at a
constant level in spite of large changes in load current or in input line voltage.
REMOTE-CUTOFF TUBE—An electron tube in which the control grid wires are farther apart at the
centers than at the ends. This arrangement allows the tube to amplify large signals without being
driven into cutoff. This tube is also called a VARIABLE-mu tube.
rgk—The symbol used to express the resistance between the grid and the cathode of an electron tube.
rpk—The symbol used to represent the variable resistance between the cathode and the plate of a tube.
RIPPLE FREQUENCY—The frequency of the ripple current. In a full-wave rectifier, it is twice the
input line frequency.
RIPPLE VOLTAGE—The alternating component of unidirectional voltage. (This component is small
compared to the direct component).
SATURATION—The point in a tube where a further increase in plate voltage no longer produces an
increase in plate current. At this point the upper limit of the conduction capabilities of the tube has
been reached.
SECONDARY EMISSION—The liberation of electrons from an element, other than the cathode, as a
result of being struck by other high-velocity electrons.
