VACUUM EVAPORATION - Process of producing thin film components .
VALENCE - The 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 SHELL - The electrons that form the outermost shell of an atom .
V ANTENNA - A bidirectional antenna, shaped like a V, which is widely used for
communications .
VAR - Abbreviation for volt-amperes reactive .
VARACTOR - A PN junction semiconductor, designed for microwave frequencies, in which
the capacitance varies with the applied voltage .
VARACTOR FM MODULATOR - An fm modulator that uses a voltage-variable capacitor
(varactor) .
VARIABLE - A representative symbol that can assume any of a given set of values .
VARIABLE ATTENUATOR - An attenuator for reducing the strength of an ac signal either
continuously or in steps, without causing signal distortion .
VARIABLE-MU-TUBE - Same as REMOTE-CUTOFF TUBE .
VARIABLE RESISTOR - A wire-wound or composition resistor, the value of which may be
changed over a designed range .
VARNISHED CAMBRIC - Cotton cloth coated with insulation varnish. An insulation used on
high-voltage conductors .
VECTOR - A line used to represent both direction and magnitude .
VEITCH DIAGRAM - A diagram consisting of joined squares, which is used to give a
graphic representation of basic logic relations .
VELOCITY - The rate at which a disturbance travels through a medium .
VELOCITY MODULATION - Modification of the velocity of an electron beam by the alternate
acceleration and deceleration of electrons .
VELOCITY SERVOSYSTEM - A servosystem which controls the speed of the load it is driving
.
VERTICAL AXIS - On a graph, the straight line axis that is plotted from bottom to top .
VERTICAL DEFLECTION PLATES - A pair of parallel electrodes in a CRT that moves the
electron beam up and down .
VERTICAL PATTERN - The part of a radiation pattern that is radiated in the vertical
plane .
VERTICAL PLANE - An imaginary plane that is perpendicular to the horizontal plane .
VERTICALLY POLARIZED - Waves that are radiated with the E field component perpendicular
to the earth's surface .
VERY HIGH FREQUENCY - The band of frequencies from 30 megahertz to 300 megahertz .
VERY LARGE SCALE INTEGRATION (vlsi) - An integrated circuit containing over 2,000 logic
gates or 64,000 bits of memory .
VERY LOW FREQUENCY - The band of frequencies from 3 kilohertz to 30 kilohertz .
VIDEO AMPLIFIER - An amplifier designed to amplify the entire band of frequencies from
10 hertz (10 Hz) to 6 megahertz (6 MHz). Also called a WIDE-BAND AMPLIFIER .
VIDEO ENHANCEMENT FEATURES - See ANTIJAMMING CIRCUITS .
VINCULA - Plural of vinculum (see below) .
VINCULUM - A straight horizontal line placed over one or more members of a compound
logic expression to negate or complement. Also, used to join two or more members together
.
VIRTUAL GROUND - A point in a circuit that is at ground potential (0 V) but is not
connected to ground .
VOID - An area where material is missing on the surface of a tape or on a head's track.
VOLT - The unit of electromotive force or electrical pressure. One volt is the pressure
required to send 1 ampere of current through a resistance of 1 ohm .
VOLTAGE - (1) The term used to signify electrical pressure. Voltage is a force that
causes current to flow through an electrical conductor. (2) The voltage of a circuit is
the greatest effective difference of potential between any two conductors of the circuit .
VOLTAGE AMPLIFIER - An amplifier in which the output-signal voltage is greater than the
input-signal voltage .
VOLTAGE-DIODE DETECTOR - A series-diode detector in which the diode is in series with
the input voltage and the load impedance .
VOLTAGE DIVIDER - A series network in which desired portions of the source voltage may
be tapped off for use in the circuit .
VOLTAGE DROP - The difference in voltage between two points. It is the result of the
loss of electrical pressure as a current flows through a resistance .
VOLTAGE-FEED METHOD - Same as END-FEED METHOD .
VOLTAGE GAIN - The ratio of output voltage to input voltage in an amplifier .
VOLTAGE MULTIPLIERS - Methods of increasing voltages; used primarily where low current
is required .
VOLTAGE REGULATION - A measure of the ability of a generator or power supply to
maintain a constant output voltage from no-load to full-load operation. Expressed as a
percentage of full-load voltage; the better the regulation, the lower the percent .
VOLTAGE STANDING WAVE RATIO (VSWR) - In a waveguide, the ratio of the electric field
(voltage) at a maximum point to that of an adjacent minimum point .
VOLTMETER - A meter used to measure voltage .
VOLUME UNIT (VU) - Unit of measurement of a complex audio signal such as voice or
music. A 0 level is referenced to 1 milliwatt of power into a 600-ohm load.
