SERVOSYSTEMAn 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 .
SETA unit or units and the assemblies, subassemblies, and parts connected or associated together to
perform a specific function .
SEXADECIMALSame as HEXADECIMAL .
SHADOWA dead spot (minimum radiation) caused by the physical obstruction of transmitted waves by a
feed horn .
SHAPING CIRCUITA circuit that alters the shapes of input waveforms .
SHARP-CUTOFF TUBEThe 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
SHELF LIFEThe period of time that a cell or battery may be stored and still be useful .
SHIELDED PAIRA line consisting of parallel conductors separated from each other and surrounded by a
solid dielectric .
SHIELDING(1) A metallic covering used to prevent magnetic or electromagnetic fields from affecting
an object . (2) Technique designed to minimize internal and external interference .
SHORT CIRCUITAn unintentional current path between two components in a circuit or between a
component and ground; usually caused by a circuit malfunction   .
SHORT-CIRCUITED LINEA transmission line that has a terminating impedance equal to 0 .
SHUNTA resistive device placed in parallel with another component. Appreciable current may flow
through it and an appreciable voltage may exist across it .
SHUNT-DIODE DETECTORA 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
SHUNT-FED OSCILLATORAn oscillator that receives its dc power for the transistor or tube through a
path both separate from and parallel to the tank circuit .
SHUNT PEAKINGA technique used to improve high-frequency response in which a peaking coil is
placed in parallel (shunt) with the output signal path .
SHUNT RESISTORA resistor in parallel. In an ammeter, shunt resistors are used to provide multiple
SHUNT VOLTAGE REGULATORA regulator whose regulating device is in parallel with the load
SHUNT-WOUND MOTORS AND GENERATORSMachines in which the armature and field
windings are connected in parallel (shunt) with each other .
SIEMENSThe new and preferred term for MHO .