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SERVOSYSTEM—An automatic feedback control system that compares a required condition (desired
value, position, and so forth) with an actual condition and uses the difference to drive a control device
to achieve the required condition [15].
SET—A unit or units and the assemblies, subassemblies, and parts connected or associated together to
perform a specific function [17].
SEXADECIMAL—Same as HEXADECIMAL [13].
SHADOW—A dead spot (minimum radiation) caused by the physical obstruction of transmitted waves by a
feed horn [18].
SHAPING CIRCUIT—A circuit that alters the shapes of input waveforms [9].
SHARP-CUTOFF TUBE—The opposite of a remote-cutoff tube. An electron tube that has evenly spaced
grid wires. The amplification of the sharp-cutoff tube is limited by the bias voltage and tube
characteristics [6].
SHELF LIFE—The period of time that a cell or battery may be stored and still be useful [1].
SHIELDED PAIR—A line consisting of parallel conductors separated from each other and surrounded by a
solid dielectric [10].
SHIELDING—(1) A metallic covering used to prevent magnetic or electromagnetic fields from affecting
an object [1]. (2) Technique designed to minimize internal and external interference [14].
SHORT CIRCUIT—An unintentional current path between two components in a circuit or between a
component and ground; usually caused by a circuit malfunction [1] [3] [16].
SHORT-CIRCUITED LINE—A transmission line that has a terminating impedance equal to 0 [10].
SHUNT—A resistive device placed in parallel with another component. Appreciable current may flow
through it and an appreciable voltage may exist across it [12].
SHUNT-DIODE DETECTOR—A diode detector in which the diode is in parallel with the input voltage
and the load impedance. Also known as a current detector because it operates with smaller input levels
[12].
SHUNT-FED OSCILLATOR—An oscillator that receives its dc power for the transistor or tube through a
path both separate from and parallel to the tank circuit [9].
SHUNT PEAKING—A technique used to improve high-frequency response in which a peaking coil is
placed in parallel (shunt) with the output signal path [8].
SHUNT RESISTOR—A resistor in parallel. In an ammeter, shunt resistors are used to provide multiple
ranges [3].
SHUNT VOLTAGE REGULATOR—A regulator whose regulating device is in parallel with the load
resistance [7].
SHUNT-WOUND MOTORS AND GENERATORS—Machines in which the armature and field
windings are connected in parallel (shunt) with each other [5].
SIEMENS—The new and preferred term for MHO [1].
