UNIVERSAL TIME CONSTANT CHARTA chart used to find the time constant of a circuit if the
impressed voltage and the values of R and C or R and L are known .
UNTUNED LINEAnother name for the flat or nonresonant line .
UP LINKThe frequency used to transmit a signal from earth to a satellite .
UPPER-FREQUENCY CUTOFFThe highest frequency a circuit can pass .
UPPER SIDEBANDAll of the sum frequencies above the carrier .
VACUUM EVAPORATIONProcess of producing thin film components .
VALENCEThe measure of the extent to which an atom is able to combine directly with other atoms. It
generally depends on the number and arrangement of the electrons in the outermost shell of the atom
VALENCE SHELLThe electrons that form the outermost shell of an atom .
V ANTENNAA bidirectional antenna, shaped like a V, which is widely used for communications .
VARAbbreviation for volt-amperes reactive .
VARACTORA PN junction semiconductor, designed for microwave frequencies, in which the
capacitance varies with the applied voltage   .
VARACTOR FM MODULATORAn FM modulator that uses a voltage-variable capacitor (varactor)
VARIABLEA representative symbol that can assume any of a given set of values .
VARIABLE ATTENUATORAn attenuator for reducing the strength of an ac signal either continuously
or in steps, without causing signal distortion .
VARIABLE-MU-TUBESame as REMOTE-CUTOFF TUBE .
VARIABLE RESISTORA wire-wound or composition resistor, the value of which may be changed over
a designed range .
VARNISHED CAMBRICCotton cloth coated with insulation varnish. An insulation used on high-
voltage conductors .
VECTORA line used to represent both direction and magnitude  .
VEITCH DIAGRAMA diagram consisting of joined squares, which is used to give a graphic
representation of basic logic relations .
VELOCITYThe rate at which a disturbance travels through a medium .
VELOCITY MODULATIONModification of the velocity of an electron beam by the alternate
acceleration and deceleration of electrons .
VELOCITY SERVOSYSTEMA servosystem which controls the speed of the load it is driving .
VERTICAL AXISOn a graph, the straight line axis that is plotted from bottom to top .