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A radar display on which slant range is shown as the distance along a horizontal trace .
(1) Dissipation of radio or sound waves as they interact with matter. (2) The absorbing of light waves without reflection or refraction .
An instrument used to measure audio frequencies .
An electrode charged several thousand volts positive and used to accelerate
electrons toward the front of a cathode-ray tube .
A servosystem that controls the acceleration (rate of change in velocity) of a load .
A device that measures the acceleration to which it is subjected and develops a
signal proportional to it .
An impurity which, when added to a semiconductor, accepts one electron from
a neighboring atom and creates a hole in the lattice structure of the crystal. Also called TRIVALENT
A very small tube with closely spaced electrodes and no base. The tube is connected to its circuits by short wire pins that are sealed in a glass or ceramic envelope. The acorn tube is used in low-power uhf circuits .
The science of sound .
Operational phase of a fire-control or track radar during which the radar system searches a small volume of space in a prearranged pattern .
A satellite that amplifies the received signal and retransmits it back to earth .
The part of a switch that is acted upon to cause the switch to change contact connections; for example, toggle, pushbutton, and rocker .
An abbreviation for the amphibious flagship data system .
Panel that monitors the dry-air input at each user equipment .
A transformer composed of two or more coils that are wound around a
nonmetallic core .
A junction formed by recrystallization of a molten region of P-type material on
an N-type substrate, or vice versa .
The emitter-to-collector current gain in a common-base circuit .
An electrical current that constantly changes amplitude and changes
polarity at regular intervals .
The vertical distance of an aircraft or object above a given reference, such as ground or sea level .
(1) The movement of aluminum wire from a point where pressure is applied. (2)
The "retreat" of heated aluminum wire as it cools .
The surrounding temperature such as the temperature of air surrounding a
conductor in a compartment or within a piece of equipment .
Echoes that exceed the prt of a radar and appear at incorrect ranges .
An instrument for measuring the amount of electron flow (in amperes)   .
The basic unit of electrical current .
The magnetomotive force developed by 1 ampere of current flowing through a coil of one turn .
AMPERITE (BALLAST) TUBE
A current-controlling resistance device designed to maintain
substantially constant current over a specified range of variation in applied voltage or resistance of a
series circuit .
A special dc generator in which a small dc voltage applied to field windings controls a large output voltage from the generator. In effect, an amplidyne is a rotary amplifier that often times produces gain of approximately 10,000 .
The voltage gain of an amplifier with no load on the output  .
AMPLIFIER—The device that provides amplification (the increase in current, voltage, or power of a signal) without appreciably altering the original signal  .
AMPLITRON—See CROSS-FIELD AMPLIFIER .
AMPLITUDE—The size of a signal as measured from a reference line to a maximum value above or below the line. Generally used to describe voltage, current, or power  .
AMPLITUDE DISTORTION—Distortion that is present in an amplifier when the amplitude of the output signal fails to follow exactly any increase or decrease in the amplitude of the input signal  .
AMPLITUDE MODULATION—Any method of varying the amplitude of an electromagnetic carrier frequency in accordance with the intelligence to be transmitted .
AMPLITUDE STABILITY—Amplitude stability refers to the ability of the oscillator to maintain a constant amplitude in the output waveform .
AND CIRCUIT—See AND GATE .
AND GATE—(1) An electronic gate whose output is energized only when every input is in its prescribed state. An AND gate performs the function of the logical "AND"; also called an AND circuit. (2) A binary circuit, with two or more inputs and a single output, in which the output is a logic 1 only when all inputs are a logic 1 and the output is a logic 0 when any one of the inputs is a logic 0 .
Modulation in which the angle of a sine-wave carrier is varied by a modulating
ANGLE OF INCIDENCE
The angle between the incident wave and the normal .
ANGLE OF INCLINATION
The angular difference between the equatorial plane of the earth and the
plane of orbit of the satellite .
ANGLE OF REFLECTION
The angle between the reflected wave and the normal .
ANGLE OF REFRACTION
The angle between the normal and the path of a wave through the second
The unit used to define the wavelength of light waves .
The property of a radiator that allows it to emit strong radiation in one direction .
(1) A positive electrode of an electrochemical device (such as a primary or secondary electric cell) toward which the negative ions are drawn  [6) . (2) The semiconductor-diode terminal that is positive with respect to the other terminal when the diode is biased in the forward direction .
A conductor or set of conductors used to radiate RF energy into space or to collect RF energy from space or to do both .
ANTENNA BEAM WIDTH
Width of a radar beam measured between half-power points .
A device used for impedance matching between an antenna and a transmitter or receiver .
Routes RF energy from the transmitter, radiates the energy into space, receives
echoes, and routes the echoes to the receiver .
An electronic circuit used to minimize the effects of enemy countermeasures, thereby permitting radar echoes to be visible on the indicator .
A silicon-based, high-temperature lubricant applied to threaded components
to aid in their removal after they have been subjected to rapid heating and cooling .
APERTURE—See SLOT .
ALLOWANCE PARTS LIST (APL)—Repair parts required for units having the equipment/ component listed .
The point in the orbit of a satellite the greatest distance from the earth .
The effect of the earth's rotation on a gyro that causes the spinning axis to appear to make one complete rotation in one day. Also called APPARENT PRECESSION or APPARENT ROTATION .
That power apparently available for use in an ac circuit containing a reactive
element. It is the product of effective voltage times effective current expressed in volt-amperes. It must be multiplied by the power factor to obtain true power available .
APPARENT PRECESSION—See APPARENT DRIFT .
APPARENT ROTATION—See APPARENT DRIFT .
The part of a circuit breaker that confines and divides the arc which occurs when the contact of the circuit breaker opens .
(1) In a relay, the movable portion of the relay . (2) The windings in which the output voltage is generated in a generator or in which input current creates a magnetic field that interacts with the main field in a motor .
Copper losses, eddy current losses, and hysteresis losses that act to decrease the efficiency of armatures .
The effect in a dc generator of current in the armature creating a magnetic
field that distorts the main field and causes a shift in the neutral plane .
ARRAY OF ARRAYS
ARRAY OF ARRAYS—Same as COMBINATION ARRAY .
ARTIFICIAL TRANSMISSION LINE
An LC network that is designed to simulate characteristics of a
transmission line .
A noncombustible, nonconductive, fiber-like mineral used as an insulating material .
Fibrosis of the lungs caused by inhalation of asbestos fibers .
A number of parts or subassemblies, or any combination thereof, joined together to perform a specific function .
A multivibrator that has no stable state. Also called free-running
because it alternates between two different output voltage levels during the time it is on. The frequency is determined by the RC time constant of the coupling circuit .
An abbreviation for the antisubmarine warfare tactical data system .
A multivibrator that generates rectangular waves .
The teletypewriter operation where the transmitter and receiver do not operate continuously .
One where the satellite does not rotate or move at the same speed as the
An abbreviation for the airborne tactical data system .
A tube that isolates the transmitter from the antenna and receiver. Used in conjunction with a tr tube .
The ability of a filter circuit to reduce the amplitude of unwanted frequencies to a level below that of the desired output frequency .
The force that tends to make two objects approach each other. Attraction exists between two unlike magnetic poles (north and south) or between two unlike static charges .
An amplifier designed to amplify frequencies between 15 hertz (15 Hz) and 20
kilohertz (20 kHz) .
A system that uses amplitude modulation to change dc mark and
space impulses into audio impulses .
AUTOMATIC GAIN CONTROL
A circuit used to vary radar receiver gain for best reception of signals that have widely varying amplitudes .
Tracking done by equipment that compares the direction of the antenna axis
and the direction of the received signal and uses the difference (error) signal to reposition the antenna .
AUTOMATIC VOLUME/GAIN CONTROL
A circuit used to limit variations in the output signal strength of a receiver .
A reverse breakdown effect in diodes that occurs at reverse voltages beyond 5
volts. The released electrons are accelerated by the electric field, which results in a release of more electrons in a chain or "avalanche" effect .
(1) The peak power value averaged over the pulse-repetition time . (2) Output power of a transmitter as measured from the start of one pulse to the start of the next pulse .
The average of all the instantaneous values of one-half cycle of alternating
The standards adopted in the United States for the measurement of wire sizes .
A straight line, either real or imaginary, passing through a body around which the body revolves
Angular measurement in the horizontal plane in a clockwise direction .
The larger resistance value observed when you are checking the resistance of a
A waveguide arrangement that resembles a T and uses crystals for coupling the
output to a balanced transformer .
BALANCED PHASE DETECTOR
A circuit that controls the oscillator frequency (afc) .
A tuned circuit that does not pass a specified band of frequencies  .
A filter that allows a narrow band of frequencies to pass through the circuit.
Rejects or attenuates frequencies that are either higher or lower than the desired band of frequencies 
The difference between the highest usable frequency of a device (upper frequency limit) and the lowest usable frequency of the device (lower frequency limit) - measured at the half-power
points    .
A type of bolometer characterized by an increase in resistance as the dissipated power rises .
The element in a transistor that controls the flow of current carriers . (1) A reference value. (2) A number that is multiplied by itself as many times as indicated by an exponent. (3) Same as radix. (4) The region between the emitter and collector of a transistor that receives minority carriers injected from the emitter. It is the element that corresponds to the control grid
of an electron tube .
Similar to a control-grid modulator. The gain of a transistor is varied by changing the bias on its base .
A device for converting chemical energy into electrical energy .
The amount of energy available from a battery. Battery capacity is expressed in
A measurement of speed based on the number of code elements or units per second .
Part of an antenna array .
See LOBE .
Semiconductor chip with electrodes (leads) extended beyond the wafer .
An electron tube in which the grids are aligned with the control grid. Special
beam-forming plates are used to concentrate the electron stream into a beam. Because of this action, the beam-power tube has high power-handling capabilities .
An angular measurement of the direction of an object from a reference direction, such as true north .
Ability of a radar to distinguish between targets that are close together in
Difference and sum frequencies, which result from the combination of two
separate frequencies .
The difference between the oscillator frequency and the unknown audio frequency
An additional oscillator used in a receiver when it is receiving a
cw signal. It provides an audible tone .
The unit that expresses the logarithmic ratio between the input and output of any given component, circuit, or system .
The ratio of a change in collector current to a corresponding change in base current when the collector voltage is constant in a common-emitter circuit .
A horizontal, long-wire antenna designed for reception and transmission of
low-frequency, vertically polarized ground waves .
Difference of potential applied to a vacuum tube or transistor to establish a reference operating level .
Current that flows through the base-emitter junction of a transistor and is adjusted to set the operating point of the transistor .
An array that radiates in opposite directions along the line of maximum
(1) A number system that uses a base, or radix, of 2. Two digits (1 and 0) are used in the binary system. (2) Pertaining to a characteristic that involves the selection, choice, or condition in which there are only two possibilities. (3) A bistable multivibrator (flip-flop) is one example of a binary device .
A method of representing two possible conditions (on or off, high or low, one or zero, the presence of a signal or absence of a signal). Electronic circuits designed to work in such a way that only two conditions are possible .
(1) A character that represents one of the two digits in the number system that has a radix of two. (2) Either of the digits 0 or 1 that may be used to represent the binary conditions of on or off .
See BINARY NUMBER SYSTEM .
BINARY NUMBER SYSTEM
A number system using two digits, symbols, or characters (usually 1 and 0) .
The radix point that separates powers of two and fractional powers of two in a binary number .
The state in which conditions are expressed by a series of binary digits (0's and 1's) .
A device that is capable of assuming either one of two stable states .
A multivibrator that has two stable states. It remains in one of the
states until a trigger is applied. It then flips to the other stable state and remains there until another trigger is applied. Also referred to as a FLIP-FLOP  .
The reference color of equipment that passes unclassified information. It normally refers to patch panels .
The current through a bleeder resistor. In a voltage divider, bleeder current is
usually determined by the 10 percent rule of thumb .
A resistor used to draw a fixed current .
See PIP .
A diagram in which the major components of an equipment or a system are
represented by squares, rectangles, or other geometric figures, and the normal order of progression of a signal or current flow is represented by lines .
A method of keying in which the bias is varied to turn plate current on and
A condition in an amplifier, caused by overdriving one or more stages, in which the amplifier is insensitive to small signals immediately after reception of a large signal .
A loading device that undergoes changes in resistance as changes in dissipated power occur .
Fine wires connecting the bonding pads of the chip to the external leads of the
(1) Pertaining to the process used in the algebra formulated by George Boole. (2) Pertaining to the operations of formal logic .
A system of logic dealing with on-off circuit elements associated by such
operators as the AND, OR, NAND, NOR, and NOT functions .
See BOOLEAN ALGEBRA .
The two conditions that the E-field and H-field within a waveguide must
meet before energy will travel down the waveguide. The E-field must be perpendicular to the walls and the H-field must be in closed loops, parallel to the walls, and perpendicular to the E-field .
An individual current path in a parallel circuit  .
In a switch, the number of breaks refers to the number of points at which the switch opens the circuit; for example, single break and double break .
The phenomenon occurring in a reverse-biased semiconductor diode. The start of the phenomenon is observed as a transition from a high dynamic resistance to one of substantially lower dynamic resistance. This is done to boost the reverse current .
The name given to the potentiometer used to vary the potential applied to the
control grid of a CRT .
An array in which the direction of maximum radiation is perpendicular to the
plane containing the elements  .
Sliding contacts, usually carbon, that make electrical connection to the rotating part of a motor or generator .
A voltage amplifier used between the oscillator and power amplifier .
An amplifier that isolates one circuit from another. It decreases the loading effect on an oscillator by reducing the interaction between the load and the oscillator  .
BUILT-IN TEST EQUIPMENT (BITE)
A permanently mounted device that is used expressly for testing an equipment or system .
The input resonant cavity in a conventional klystron oscillator .
In a velocity-modulated tube, the grid that concentrates the electrons in the electron beam into bunches .
A tool used to clean and polish contacts on a relay .
A heavy copper strap or bar used to connect several circuits together when a large current-carrying capacity is required .
A capacitor used to transfer unwanted signals out of a circuit; for example,
coupling an unwanted signal to ground. Also called a DECOUPLING CAPACITOR .
Either a stranded conductor (single-conductor cable) or a combination of conductors insulated from one another (multiple conductor cable). Small sizes are commonly referred to as stranded wire or as cords .
A group of wires or ribbons of wiring used to interconnect electronic systems and subsystems .
The property of an electrical circuit that opposes changes in voltage .
The opposition, expressed in ohms, offered to the flow of an alternating
current by capacitance. The symbol for capacitive reactance is X C  .
An electrical device capable of storing electrical energy in an electrostatic field .
This filter is used on extremely high-voltage, low-current power supplies and
also where the ripple frequency is not critical .
A type of single-phase, ac induction motor in which a starting winding
and a capacitor are placed in series to start the motor. The values of XC and R are such that the main-winding and starting-winding currents are nearly 90 degrees apart and the starting torque is produced as in a two-phase motor .
A microphone in which sound waves vary the resistance of a pile of carbon
granules. May be single-button or double-button .
Procedure designed to restore breathing after cardiac arrest. Includes clearing air passages to lungs and heart massage .
The frequency of an unmodulated transmitter output  .
A shipboard radar system used to guide aircraft to safe landings in poor visibility conditions .
(1) One or more digits, produced in connection with an arithmetic operation, that is/are forwarded to another digit place for processing there. (2) The number represented by the digit or digits in (1) above .
In a velocity-modulated tube, a grid on which the spaced electron groups induce a signal. The output of the tube is taken from the catcher grid .
(1) In an electron tube the electrode that is the source of current flow . (2) The general name for any negative electrode . (3) The negative terminal of a forward-biased semiconductor diode, which is the source of the electrons .
The method of biasing a vacuum tube in which the biasing resistor is placed in the common-cathode return circuit, thereby making the cathode more positive with respect to ground .
A system in which the cathode circuit is interrupted so that neither grid current nor plate current can flow .
Voltage on the cathode is varied to produce the modulation envelope .
A process of producing thin film components .
CATHODE-RAY TUBE (CRT)
An electron tube that has an electron gun, a deflection system, and a
screen. This tube is used to display visual electronic signals .
A space totally enclosed by a metallic conductor and supplied with energy in
such a way that it becomes a source of electromagnetic oscillations. The size and shape of the enclosure determine the resonant frequency .
An instrument used to measure microwave frequencies .
A single unit that transforms chemical energy into electrical energy. Batteries are made up of cells .
Connecting the center of an antenna to a transmission line which is then
connected to the final (output) stage of the transmitter .
A unit of volume of large rectangular or square conductors. The cross-sectional
area equals 1 square centimeter with a length of 1 centimeter .
A carrier frequency assignment, usually with a fixed bandwidth .
A letter, digit, or other symbol that is used as part of the organization, control, or representation of information .
The ratio of voltage to current at any given point on a transmission line represented by a value of impedance .
Represents electrical energy. A material having an excess of electrons is said to have a negative charge. A material having a shortage of electrons is said to have a positive charge .
The period of time that a capacitor in an electrical circuit is storing a charge .
An inductor used to impede the flow of pulsating dc or ac by means of self-inductance  .
A joint between two sections of waveguide that provides a good electrical connection without power losses or reflections .
The complete path of an electric current .
An area equal to that of a circle with a diameter of 0.001 inch. It is used for measuring the cross-sectional area of wires .
A unit of volume of a conductor having a cross-sectional area of 1 circular mil
and a length of 1 foot .
A circuit in which either the upper or lower extremity of a waveform is fixed at a desired value .
CLASS A AMPLIFIER OPERATION
The type of operation in which the amplifier is biased so that variations in input signal polarities occur within the limits of cutoff and saturation .
CLASS AB AMPLIFIER OPERATION
The type of operation in which the amplifier is biased so that collector current is cut off for a portion of the alternation of the input signal .
CLASS B AMPLIFIER OPERATION
The type of operation in which the amplifier is biased so that collector current is cut off for one-half of the input signal .
CLASS C AMPLIFIER OPERATION
The type of operation in which the amplifier is biased so that collector current is cut off for more than one-half of the input signal  .
Confusing, unwanted echoes that interfere with the observation of desired signals on a radar indicator .
Cable in which the center conductor is separated from an outer conductor by a
dielectric material; used in RF transmission .
A type of transmission line that contains two concentric conductors .
In teletypewriter operation, code is a combination of mark and space conditions representing symbols, figures, or letters .
COEFFICIENT OF COUPLING
An expression of the extent to which two inductors are coupled by
magnetic lines of force. This is expressed as a decimal or percentage of maximum possible coupling and represented by the letter K .
A definite phase relationship between two energy waves, such as transmitted frequency and reference frequency .
Radiation on one frequency .
In cw radar an oscillator that supplies phase references to provide coherent
video from target returns .
An inductive device made by looping turns of wire around a core .
A gas-filled electron tube that conducts without the use of filaments. Cold-
cathode tubes are used as voltage regulators .
The element in a transistor that collects the current carriers .
The transistor equivalent of a plate modulator. Modulating voltage is applied to a collector circuit .
An array with all the elements in a straight line. Maximum radiation is
perpendicular to the axis of the elements .
An array system that uses the characteristics of more than one array .
A series-parallel circuit .
A technique in which a combination of peaking coils in series and parallel
(shunt) with the output signal path is used to improve high-frequency response .
A transistor circuit in which the base electrode is the common element to both input and output circuits .
A transistor circuit configuration in which the collector is the element
common to both the input and the output circuits .
A circuit configuration in which the emitter is the element common to both the
input and the output circuits .
COMMON IDENTITIES LAW
In Boolean algebra this law states that anytime the expression A(A + B)= AB or A + AB = A + B appears, it can immediately be simplified to AB without going through the process of using the distributive law, complementary law, or the law of union to simplify .
An amplifying detector in which detection occurs in the emitter-base
junction and amplification occurs at the output of the collector junction .
Often used in receivers to supply detected and amplified output. The emitter-base junction acts as the detector .
The act of a commutator in converting generator output from an ac voltage to a dc voltage .
In Boolean algebra this law states that changing the order of the terms in an
equation will not affect the value of the equation. Example: A + B = B + A; A • B = B • A .
A mechanical device that reverses armature connections in motors and generators at the proper instant so that current continues to flow in only one direction. In effect, the commutator changes ac to dc .
An equipment that compares incoming signals and selects the strongest to be fed to a teletypewriter through a patch panel. This is used in diversity operation .
Windings embedded in slots in pole pieces, connected in series with the
armature, whose magnetic field opposes the armature field and cancels armature reaction .
The process of overcoming the problems associated with high frequencies in an
A number or state that is the opposite of a specified number or state. The negative of a number is often represented by its complement .
A number that when added to another number gives a sum equal to the base
of the number system of operation. For example, in the decimal number system, the complement of 1 is 9 .
COMPLEMENTARY (SECONDARY) COLORS OF LIGHT
The colors of light produced when two of the primaries are mixed in verlapping beams of light. The complementary colors of light are magenta, yellow, and cyan .
In Boolean algebra this law states that the logical addition of a quantity and
its complement will result in 1 and the logical multiplication of a quantity and its complement will result in a product of 0 .
(1) A waveform other than a sine wave . (2) A wave that is produced by
combining two or more pure tones at the same time  .
COMPOUND-WOUND MOTORS AND GENERATORS
Machines that have a series field in addition to a shunt field. Such machines have characteristics of both series- and shunt-wound machines .
Longitudinal waves that have been compressed (made more dense) as they
move away from the source .
A data processor that can perform substantial computation, including numerous arithmetic or logic operations, without intervention by a human operator during the run .
Pertaining to the occurrence of two or more events or activities within the same specified interval of time .
The ability of a material to conduct or carry an electric current. It is the reciprocal of the resistance of the material and is expressed in mhos or siemens   .
A partially filled energy band in which electrons can move freely .
The ease with which a substance transmits electricity .
(1) A material with a large number of free electrons. (2) A material that easily permits electric current to flow .
A tubular raceway, usually metal or plastic, for holding wires or cables .
Scanning in which the movement of the beam describes a cone, the axis of
which coincides with that of the reflector .
Another term for DRIVEN ARRAY .
In radar, an object that reflects RF energy; target .
An uninterrupted, complete path for current flow  .
The on-off keying of a carrier .
CONTROL DIFFERENTIAL TRANSMITTER (CDX)
A type of synchro that transmits angular information equal to the algebraic sum or difference of the electrical input supplied to its stator, the mechanical input supplied to its stator, and the mechanical input supplied to its rotor. The output is an electrical voltage taken from the rotor windings .
The electrode of a vacuum tube, other than a diode, upon which a signal voltage is impressed to regulate the plate current .
CONTROL SYNCHRO SYSTEMS
Synchro systems that contain control synchros and are used to control large amounts of power with a high degree of accuracy. The electrical outputs of these systems control servosystems, which in turn generate the required power to move heavy loads .
A group of components systematically organized to perform a specific control
purpose. These systems are categorized as either closed- or open-loop systems. The main difference between the two is that the closed-loop system contains some form of feedback .
CONTROL TRANSFORMER (CT)
A type of synchro that compares two signals: the electrical signal
applied to its stator and the mechanical signal applied to its rotor. The output is an electrical voltage, which is taken from the rotor winding and is used to control a power-amplifying device. The phase and amplitude of the output voltage depends on the angular position of the rotor with respect to the
magnetic field of the stator .
CONTROL TRANSMITTER (CX)
A type of synchro that converts a mechanical input, which is the
angular position of its rotor, into an electrical output signal. The output is taken from the stator windings and is used to drive either a CDX or CT .
Uses a variation of grid bias to vary the instantaneous plate voltage
and current. The modulating signal is applied to the control grid .
In communications, equipment that changes the audio output of a receiver to dc pulses. These pulses are fed to a tty to indicate marks and spaces .
A mechanical magnetron tuning device that changes the frequency by
changing the capacitance of the anode cavities .
COPPER LOSS (I2R LOSS)
The power lost because of the resistance of the conductors. In transformers
the power lost because of current flow (I) through the resistance (R) of the windings   .
A method of increasing the number of discrete components in a given space.
Resembles wood stacked for a fireplace .
Any material that affords a path for magnetic flux lines in a coil .
A half-wave antenna with a reflector consisting of two flat metal surfaces meeting at an angle behind the radiator  .
The discharge of electricity from a conductor with a high potential .
Includes location and repair of equipment failures .
The term given to the positions of the rotors of a synchro transmitter and a
synchro receiver when both rotors are on 0 degree or displaced from 0 degree by the same angle .
A measure of the quantity of electricity. One coulomb is equal to 6.28 x 1018 electrons .
Also called the LAW OF ELECTRIC CHARGES or the LAW OF ELECTROSTATIC ATTRACTION. Coulomb's Law states that charged bodies attract or repel each
other with a force that is directly proportional to the product of their individual charges and inversely proportional to the square of the distance between them .
A circuit that counts input pulses .
The voltage generated within a coil by a moving magnetic field cutting across the coil itself. This voltage is in opposition (counter) to the moving field that created it. Counter emf is present in every motor, generator, transformer, or other inductance winding whenever an alternating current flows  .
A network of wire connected to a quarter-wave antenna at one end. The network provides the equivalent of an additional one-fourth wavelength .
The process of transferring energy from one point in a circuit to another point, or from one circuit to another .
A capacitor used to couple signals .
A coupling coil that connects the transmitter to the feeder .
A type of linkage between atoms in which the atoms share valence electrons .
Cardiopulmonary Resuscitation .
The peak of the positive alternation (maximum value above the line) of a wave .
The maximum angle at which radio waves can be transmitted and still be refracted back to earth .
The maximum frequency at which a radio wave can be transmitted vertically
and still be refracted back to earth .
The area of a "slice" of an object. When applied to electrical conductors it
is usually expressed in circular mils .
A high-power electron tube that converts dc to microwave power by a
combination of crossed electric and magnetic fields .
See SPROCKET TUNER .
A natural substance, such as quartz or tourmaline, that is capable of producing a voltage when under physical stress or of producing physical movement when a voltage is applied .
A device for artificially growing cylindrical crystals to be used in the production
of semiconductor substrates .
A microphone that uses the piezoelectric effect of crystalline matter to
generate a voltage from sound waves .
A closed oven maintained at a constant temperature in which a crystal and its holder are enclosed to reduce frequency drift .
The movement of electrons past a reference point. The passage of electrons through a conductor. Measured in amperes .
The safe current-carrying capacity of a wire or cable on a continuous basis .
A circuit that provides a constant current output .
CURRENT STANDING-WAVE RATIO (ISWR)
The ratio of maximum to minimum current along a transmission line .
Same as CENTER-FEED METHOD .
Sharp phase reversals .
The condition in a tube or transistor whereby the reverse bias prevents current flow .
The frequency at which the attenuation of a waveguide increases sharply and
below which a traveling wave in a given mode cannot be maintained. A frequency with a half-wavelength that is greater than the wide dimension of a waveguide .
A circuit that detects the presence of RF oscillations and converts them into a
useful form .
(1) One complete positive and one complete negative alternation of a current or voltage  . (2) A 360-degree rotation of a vector generating a sine wave .
CYLINDRICAL PARABOLIC REFLECTOR
A parabolically shaped reflector that resembles part of a cylinder .
D'ARSONVAL METER MOVEMENT
The permanent-magnet moving-coil movement used in most meters  .
A sinusoidal wave in which the amplitude steadily decreases with time. Often
associated with energy loss .
(1) The process of smoothing out oscillations. (2) In a meter, this process is used to keep the pointer of the meter from overshooting the correct reading . (3) A mechanical or electrical technique used in synchro receivers to prevent the rotor from oscillating or spinning. Damping is also used in
servosystems to minimize overshoot of the load  .
The execution of a systematic sequence of operations performed upon data.
Synonymous with information processing .
The transfer of information from one place to another or from one part of a
system to another .
An abbreviation used to represent power levels above or below a 1-milliwatt reference .
A short circuit having minimum resistance .
Pertaining to the number representation system with a radix of ten .
In decimal notation, one of the characters 0 through 9 .
A fixed radix notation where the radix is ten .
A decimal representation of a number .
The radix point in decimal representation .
A capacitor used to transfer unwanted signals out of a circuit; for example, coupling an unwanted signal to ground. Also called a BYPASS CAPACITOR .
In a cathode-ray tube, coils used to bend an electron beam a desired amount .
Two pairs of parallel electrodes, one pair set forward of the other and at right
angles to each other, parallel to the axis of the electron stream within an electrostatic cathode-ray tube .
The process whereby a part of the output signal of an amplifying device is returned to its input circuit in such a manner that it tends to cancel part of the input .
Feedback in which the feedback signal is out of phase with the input signal; also called NEGATIVE FEEDBACK .
The number of axes about which a gyro is free to precess .
The potential at which ionization of the gas within a gas-filled tube ceases and conduction stops; also referred to as extinction potential .
In a spark gap, the time required for ionized gas to return to its neutral state
after the spark is removed .
A three-phase connection in which windings are connected end-to-end, forming a closed loop that resembles the Greek letter delta. A separate phase wire is then connected to each of the three junctions .
The removal of intelligence from a transmission medium .
A circuit used in servosystems to convert an ac signal to a dc signal. The magnitude of the dc output is determined by the magnitude of the ac input signal, and its polarity is determined by whether the ac input signal is in or out of phase with the ac reference voltage .
A theorem which states that the inversion of a series of AND applications is
equal to the same series of inverted OR applications, or the inversion of a series of OR applications is equal to the same series of inverted AND applications.
(1) The compactness of a substance. (2) Mass per unit volume .
The region in a semiconductor where essentially all free electrons and holes
have been swept out by the electrostatic field which exists there .
DEPOT-LEVEL MAINTENANCE (SM&R CODE D)
Supports SM&R Code I and SM&R Code O activities through extensive shop facilities and equipment and highly skilled personnel .
Operational phase of a fire-control or track radar during which the radar is directed to the general direction of a desired target .
The separation of low-frequency (audio) intelligence from the high-frequency carrier .
A mixer or converter in a superheterodyne receiver .
Uncased chips .
Process of mounting a chip to a package .
An insulator; a term applied to the insulating material between the plates of a capacitor .
The ratio of a given dielectric to the dielectric value of air  .
The space between and around charged bodies in which their influence is felt.
Also called ELECTRIC FIELD OF FORCE or an ELECTROSTATIC FIELD .
The heating of an insulating material by a high-frequency electric field .
DIELECTRIC HYSTERESIS LOSS
Power loss of a capacitor because of the changes in orientation of
electron orbits in the dielectric; the changes in orientation are caused by rapid reversal in polarity of line voltage. The higher the frequency, the greater the loss .
Power loss of a capacitor because of the leakage of current through the
dielectric. Also relates to leakage resistance; the higher the leakage resistance, the lower the dielectric leakage .
The losses resulting from the heating effect on the dielectric material between
conductors  .
The ability of an insulator to withstand a potential difference without
breaking down (usually expressed in terms of voltage) .
See BEAT FREQUENCY .
DIFFERENCE OF POTENTIAL
A voltage between two points .
A circuit that amplifies the difference between two input signals .
The bending of waves (as light or RF) when the waves are met with some form of obstruction .
(1) The scattering of reflected light waves from an object, such as white paper . (2) Controlled application of impurity atoms to a semiconductor substrate .
A symbol that represents one of the nonnegative integers smaller than the radix. For example, in decimal notation a digit is one of the characters from 0 through 9 .
(1) A computer in which discrete representation of data is used. (2) A computer
that operates on discrete data by performing arithmetic and logic processes on these data .
An electron tube containing two electrodes: a cathode and a plate . (2) A two element, solid-state device made of either germanium or silicon; it is primarily used as a switching device  .
A demodulator that uses one or more diodes to provide a rectified output with an average value that is proportional to the original modulation  .
A common type of half-wave antenna made from a straight piece of wire cut in half. Each half operates at a quarter wavelength of the output .
An electric current that flows in one direction only .
Same as SHORT CIRCUIT .
An antenna that radiates most effectively in only one direction .
A device that samples the energy traveling in a waveguide in one direction
The ability of an antenna to radiate or receive more energy in some directions than in others. The degree of sharpness of the antenna beam   .
DIRECTLY HEATED CATHODE
A wire, or filament, designed to emit the electrons that flow from
cathode to plate. The filament is designed so that a current is passed through it; the current heats the filament to the point where electrons are emitted .
The parasitic element of an array that reinforces energy coming from the driver element .
Individual transistors, diodes, resistors, capacitors, and inductors .
A circuit in which amplitude variations are derived in response to phase or frequency variations .
The refraction of light waves that causes the different frequencies to bend at slightly different angles .
The current that appears to flow through a capacitor .
Water that has been purified through a process of evaporation and condensation .
Any unwanted change between an input signal and output signal  .
The constants of inductance, capacitance, and resistance in a transmission line. They are spread along the entire length of the line and cannot be distinguished
In Boolean algebra the law which states that if a group of terms connected by like operators contains the same variable, the variable may be removed from the terms and associated with them by the appropriate sign of operation (for example, A(B + C) = AB + AC) .
A theory of magnetism based upon the electron-spin principle. Spinning electrons have a magnetic field. If more electrons spin in one direction than another, the atom is magnetized .
The easiest mode to produce in a waveguide, and the most efficient mode in terms of energy transfer .
An impurity that can make a semiconductor material an N-type by donating extra "free" electrons to the conduction band .
See PENTAVALENT IMPURITY .
An electron tube that is similar to the acorn tube but larger. The doorknob tube is designed to operate, at high power, in the uhf frequencies .
The process of adding impurities to semiconductor crystals to increase the number of free charges that can be moved by an external, applied voltage. Doping produces N-type or P-type material  .
(1) The apparent change in frequency or pitch when a sound source moves either toward or away from a listener . (2) In radar, the change in frequency of a received signal caused by the relative motion between the radar and the target .
The difference between transmitted and reflected frequencies; caused by the
Doppler effect .
DOUBLE NEGATIVE LAW
In Boolean algebra, the law which states that the complement of a
complement is the equivalent of the original term .
A fine and coarse synchro receiver enclosed in a common housing with a two-
shaft output (one shaft inside the other) .
In a transmitter output tube, the abrupt and random change from one frequency to another .
Another name for the dipole antenna .
This is a type of two-equipment installation where one unit can be substituted for another in the event of failure .
The frequency used to transmit an amplified signal from a satellite or other craft back to earth .
In an electron, a region free of external fields in which relative electron position depends on velocity .
An array in which all of the elements are driven .
The element of an antenna connected directly to the transmission line .
The final stage of amplification .
An efficient, popular type of armature designed so that the entire length of
the winding is cutting the field at all times. Most wound armatures are of this type .
An electrical cell in which the electrolyte is not a liquid. In most dry cells the electrolyte is in the form of a paste .
Provides dehumidified air for electronic equipment that is moisture critical .
DUAL IN-LINE PACKAGE (DIP)
IC package having two parallel rows of preformed leads .
A two-gate MOSFET in which either gate can control the conductor
independently, a fact which makes this MOSFET very versatile .
Easily drawn out (as to form filaments or wires) .
Trapping of an RF wave between two layers of the earth's atmosphere or between an atmospheric layer and the earth .
See DUMMY LOAD .
A dissipative but nonradiating device that has the impedance characteristics of an antenna or transmission line. Also called ARTIFICIAL LOAD   .
A radar device that switches the antenna from the transmitter to the receiver and vice versa .
In a transmitter, ratio of time on to time off  .
A device in which sound waves move a coil of fine wire that is mounted on
the back of a diaphragm and located in the magnetic field of a permanent magnet .
Electric field that exists when a difference in electrical potential causes a stress in the dielectric between two points .
A special form of differential transformer employing an E-shaped core. The
secondaries of the transformer are wound on the outer legs of the E, and the primary is wound on the center leg. An output voltage is developed across the secondary coils when its armature is displaced from its neutral position. This device is used as an error detector in servosystems that have limited load
A waveguide junction in which the junction arm extends from the main
waveguide in the same direction as the E-field in the waveguide .
(1) The reflection of the original sound wave as it bounces off a distant surface . (2) The RF signal reflected back from a radar target .
A resonant cavity device that is used to check the overall performance of a radar system. It receives a portion of the transmitted pulse and retransmits it back to the receiver as a slowly decaying transient .
A condition in which the satellite is not in view or in direct line of sight with the sun. This happens when the earth is between them .
Induced circulating currents in a conducting material that are caused by a varying magnetic field  .
EDDY CURRENT LOSS
Losses caused by random current flowing in the core of a transformer. Power
is lost in the form of heat .
Also called RICHARDSON EFFECT. The phenomenon wherein electrons emitted
from a heated element within a vacuum tube will flow to a second element that is connected to a positive potential .
Same as ROOT-MEAN-SQUARE .
The ratio of output-signal power compared to the total input power, generally expressed as a percentage  .
The ability of a substance to return to its original state .
ELECTRIC (E) FIELD
The field of force that is produced as a result of a voltage charge on a conductor or antenna  .
The flow of electrons .
Symbol Q, q. Electric energy stored on or in an object. The negative charge is
caused by an excess of electrons; the positive charge is caused by a deficiency of electrons .
The action of converting chemical energy into electrical energy .
ELECTRICAL POWER SYSTEM
Provides the necessary input power .
Graphic symbols used to illustrate the various electrical or electronic
components of a circuit .
A standard synchro position, with a definite set of stator voltages, that is used as the reference point for alignment of all synchro units .
A synchro zeroing method. This method is used only when the rotors of the
synchros to be zeroed are free to turn and their leads are accessible .
The terminal at which electricity passes from one medium into another, such as in an electrical cell where the current leaves or returns to the electrolyte .
ELECTRODYNAMIC METER MOVEMENT
A meter movement using fixed field coils and a moving coil; usually used in ammeters and wattmeters .
A meter using an electrodynamic movement to measure an electric
The process of changing the chemical composition of a material by passing an electric current through it  .
A solution of a substance that is capable of conducting electricity. An electrolyte may be in the form of either a liquid or a paste .
An electrically excited magnet capable of exerting mechanical force or of
performing mechanical work .
The term describing the relationship between electricity and magnetism. A
quality that combines both magnetic and electric properties .
The combination of an electric (E) field and a magnetic (H) field .
The production of a voltage in a coil because of a change in the number of magnetic lines of force (flux linkages) passing through the coil  .
Man-made or natural interference that degrades the quality of reception of radio waves  .
The radiation of radio waves into space .
The generation of a magnetic field around a current-carrying conductor 
The force (voltage) that produces an electric current in a circuit .
The elementary negative charge that revolves around the nucleus of an atom .
An electrode of a CRT that is equivalent to the cathode and control grid of
conventional tubes. The electron gun produces a highly concentrated stream of electrons .
ELECTRON ORBITAL MOVEMENT
The movement of an electron around the nucleus of an atom .
A group of electrons which have a common energy level that forms part of the
outer structure (shell) of an atom .
The movement of an electron around its axis .
ELECTRONIC COUNTER-COUNTERMEASURES (ECCM) CIRCUITS
See ANTIJAMMING CIRCUITS .
ELECTRONIC FREQUENCY COUNTER
An instrument that counts the number of cycles (pulses) occurring during a precise time interval .
Scanning in which the axis of the beam is moved, relative to the antenna
axis, in a desired pattern .
A circuit that causes a start-and-stop switching action by electronic means
In a reflex klystron, changing the frequency and output power of the tube by
altering the repeller voltage .
A device that provides an alternate dry-air input in the event of failure of the central dry-air system. It may include a compressor .
ELECTRONICS DRY-AIR BRANCH
A common line for providing dry air to various electronic equipment, such as search radar, fire-control radar, and repeaters .
Pertaining to electricity at rest, such as charges on an object (static electricity) .
The method of deflecting an electron beam by passing it between parallel charged plates mounted inside a cathode-ray tube .
The field of influence between two differently charged bodies .
ELECTROSTATIC METER MOVEMENT
A meter movement that uses the electrostatic repulsion of two sets of charged plates (one fixed and the other movable). This meter movement reacts to voltage rather than to current and is used to measure high voltage .
The force exerted on an insulator by the voltage in a conductor .
(1) A substance, in chemistry, that cannot be divided into simpler substances by any means ordinarily available . (2) A part of an antenna that can be either an active radiator or a parasitic radiator .
Ducting used for ventilation purposes .
The angle between the horizontal plane and the line of sight to a target or object  .
Temporary source of limited electrical power used upon the loss of the normal
power source .
EMF (ELECTROMOTIVE FORCE)
The force that causes electricity to flow between two points with
different electrical charges or when there is a difference of potential between the two points. The unit of measurement is volts .
The element in a transistor that emits current carriers (electrons or holes)  .
The transistor equivalent of the cathode modulator. The gain is varied by changing the voltage on the emitter .
A synthetic compound of cellulose acetate (wood pulp and magnesium). Used to insulate wire in meters, relays, and motor windings .
Imbedded in solid material or enclosed in glass or metal .
A method in which one end of an antenna is connected through a capacitor to the final output stage of a transmitter .
An array in which the direction of radiation is parallel to the axis of the array .
The ability or capacity to do work .
The characteristic curve of an electron tube used to graphically depict the relationship between plate voltage (Ep) and plate current (Ip) .
A table showing the precalculated position of a satellite at any given time .
A method of depositing a thin, uniformly doped crystalline region (layer) on a
An orbit that occurs when the plane of a satellite coincides with the plane of the earth at the equator .
A resistance that represents the total ohmic values of a circuit component or group of circuit components. Usually drawn as a single resistor in a simplified circuit .
The positioning of a gyro into a desired position and the maintaining of that
The component in a servosystem that determines when the load has deviated from its ordered position, velocity, and so forth .
The name commonly given to the servomotor in a servosystem. So named because it reduces the error signal by providing feedback to the error detector .
(1) In servosystems, the signal whose amplitude and polarity or phase are used to correct the alignment between the controlling and the controlled elements. (2) The name given to the electrical output of a control transformer .
An alloy that changes directly from a solid to a liquid with no plastic or semiliquid state .
An alloy of 63 percent tin and 37 percent lead. Melts at 361o F .
The supply voltage required to activate a circuit .
The current that flows in the primary winding of a transformer when the
secondary is open-circuited; it produces a magnetic flux field. Also called magnetizing current .
A function whose output is a 1 if one and only one of the input variables is a 1 .
A gate that produces a logic 1 output when the inputs are different, but not
when they are the same .
The numeral written in superscript (102) which indicates the power to which the base is to be raised .
A validated series of variables, constants, and functions that can be connected by operating symbols to describe a desired computation .
EXTERNALLY EXCITED METER
A term used to describe meters that get their power from the circuit to which they are connected .
EXTERNALLY SYNCHRONIZED RADAR
A radar system in which timing pulses are generated by a master oscillator external to the transmitter .
EXTREMELY HIGH FREQUENCY
The band of frequencies from 30 gigahertz to 300 gigahertz .
EXTREMELY LOW FREQUENCY
The band of frequencies up to 300 hertz .
A semiconductor in which impurities have been added to create certain charge carrier concentrations .
The method for transmitting and receiving still images. These images can be maps, photographs, and handwritten or printed text .
Any of the elements, quantities, or symbols that, when multiplied together, form a product .
Variations in signal strength by atmospheric conditions [101 .
The basic unit of capacitance. A capacitor has a capacitance of 1 farad when a voltage potential of 1 volt across it produces a charge of 1 coulomb .
The rotation of the plane of polarization of electromagnetic energy when it
passes a substance influenced by a magnetic field that has a component in the direction of propagation .
Differentiator circuit in the first video amplifier that allows only the leading edges of target returns, no matter how small or large, to be used .
The return of a portion of the output of a circuit to its input  .
A transmission line that carries energy to the antenna .
A horn radiator used to feed a reflector .
A synthetic type of insulation (fluorinated ethylene propylene) .
A powdered and compressed ferric oxide material that has both magnetic properties and light resistance to current flow .
A ferrite device that blocks the flow of energy through a waveguide by rotating the electric field 90 degrees. The rotated energy is then reflected or absorbed .
A highly magnetic material, such as iron, cobalt, nickel, or their alloys .
The cylindrical metallic ends of a cartridge fuse .
Conductors or optical waveguides that readily pass light .
An outer covering used to protect a conductor's insulating material. Commonly made from cotton, linen, silk, rayon, or fiberglass .
(1) The faithful reproduction of a signal. (2) The accuracy with which a system reproduces a signal at its output that faithfully maintains the essential characteristics of the input signal    .
The electromagnet which furnishes the magnetic field that interacts with the armature in motors and generators .
The creation of a steady magnetic field within the field windings by the
application of a dc voltage either from the generator itself or from an external source .
FIELD OF FORCE
A term used to describe the total force exerted by an action-at-a-distance
phenomenon such as gravity upon matter, electric charges acting upon electric charges, and magnetic forces acting upon other magnets or magnetic materials .
A transistor consisting of a source, a gate, and a drain. Current flow is controlled by the transverse electric field under the gate .
The cathode of a thermionic tube, usually a wire or ribbon, which is heated by current passing through it .
Conductive or nonconductive material deposited on a glass or ceramic substrate. Used for passive circuit components, resistors, and capacitors .
A selective network of resistors, capacitors, and inductors that offers comparatively little opposition to certain frequencies, while blocking or attenuating other frequencies  .
FINAL POWER AMPLIFIER
The final stage of amplification in a transmitter .
See MIXER .
A constant value of bias voltage   .
A resistor having a definite resistance value that cannot be adjusted .
FIXED SPARK GAP
A device used to discharge the pulse-forming network. A trigger pulse ionizes the air between two contacts to initiate the discharge .
A transmission line that has no standing waves. This line requires no special timing devices to transfer maximum power .
An IC package .
An earlier name for a diode, or a two-electrode vacuum tube used as a detector .
FLEXIBLE COAXIAL LINE
A line made with an inner conductor that consists of flexible wire insulated from the outer conductor by a solid, continuous insulating material .
A monolithic IC packaging technique that eliminates the need for bonding wires .
A device having two stable states and two input terminals (or types of input signals), each of which corresponds with one of the two states. The circuit remains in either state until caused to change to the other state by application of a voltage pulse. A similar bistable device with an input that allows it
to act as a single-stage binary counter .
(1) In electrical or electromagnetic devices, a general term used to designate collectively all the electric or magnetic lines of force in a region . (2) A solution that removes surface oxides from metals being soldered  .
The number of magnetic lines of force passing through a given area .
The ability of a resonant circuit to operate continuously because of stored energy or energy pulses .
An electrode of a CRT that is used to focus the electrons into a tight beam .
An ordinary half-wave antenna (dipole) that has one or more additional conductors connected across the ends parallel to each other .
The energy band in an atom lying between the conduction band and the valence band. Electrons are never found in the forbidden band but may travel back and forth through it. The forbidden band determines whether a solid material will act as a conductor, a semi-conductor, or an insulator .
The type of AGC that causes an amplifier to be driven towards saturation .
An external voltage that is applied to a PN junction in the conducting direction so that the junction offers only minimum resistance to the flow of current. Conduction is accomplished by majority current carriers (holes in P-type material; electrons in N-type material)   .
The smaller resistance value observed when you are checking the resistance
of a semiconductor .
A circuit that uses a double-tuned RF transformer to convert frequency variations in the received FM signal to amplitude variations. Also known as a phase-shift discriminator .
An antenna array with three parasitic elements and one driven element .
The process of synchronizing a facsimile receiver to a transmitter. This allows proper picture reproduction .
Those electrons that can be moved by an externally applied voltage .
The loss of energy of radio waves caused by the spreading of the wavefront as it travels from the transmitter .
(1) The number of complete cycles per second existing in any form of wave motion, such as the number of cycles per second of an alternating current  . (2) The rate at which the vector that generates a sine wave rotates .
FREQUENCY COMPENSATION NETWORK
Circuit modification used to improve or broaden the linearity of its frequency response .
The frequency at which the filter circuit changes from an action of rejecting the unwanted frequencies to an action of passing the desired frequencies. Conversely, the point at which the filter circuit changes from an action in which it passes the desired frequencies to an action in which it rejects the undesired frequencies .
The amount the frequency varies from the carrier frequency .
Transmitting (and receiving) of radio waves on two different frequencies
A meter used to measure the frequency of an ac signal  .
Angle modulation in which the modulating signal causes thecarrier frequency to vary. The amplitude of the modulating signal determines how far the frequencychanges, and the frequency of the modulating signal determines how fast the frequency changes .
Special RF power amplifiers that multiply the input frequency .
Special RF power amplifiers that multiply the input frequency .The measure of a servo's ability to respond to various input frequencies .
Varying the output frequency to achieve electronic scanning .
In a radar, the entire range of frequencies contained in an RF pulse or signal
Refers to the ability of an oscillator to accurately maintain its operating
A process that uses hetrodyning and frequency selection to produce a signal
(1) A frequency source of high accuracy . (2) A bank of oscillators in which the outputs can be mixed in various combinations to produce a wide range of frequencies .
A circuit that provides the desired response (maximum or minimum impedance) at a specific frequency .
Multiplexing that transmits and receives the full 360 degrees of each sine wave .
A curve showing the output of an amplifier (or any other device) in terms of voltage or current plotted against frequency with a fixed-amplitude input signal .
Frequency modulation somewhat similar to continuous-wave (cw) keying in AM transmitters. The carrier is shifted between two differing frequencies by opening and closing a key .
The ratio of the energy radiated in the principal direction compared to the
energy radiated in the opposite direction .
A circuit that uses both positive and negative alternations in an alternating
current to produce direct current  .
FULL-WAVE VOLTAGE DOUBLER
Consists of two half-wave voltage rectifiers and is used to reduce the output ripple amplitude .
A specific purpose of an entity; its characteristic action .
The basic frequency or first harmonic frequency .
See ALLOYED-JUNCTION .
(1) The ratio between the amount of energy propagated from an antenna that is directional compared to the energy from the same antenna that would be propagated if the antenna were not directional . (2) Any increase in the strength of a signal .
The number that results when the gain of a circuit is multiplied by the
bandwidth of that circuit. For an operational amplifier, the gain-bandwidth product for one configuration will always equal the gain-bandwidth product for any other configuration of the same amplifier .
A crystalline form of lead sulfide used in early radio receivers .
A meter used to measure small values of current by electromagnetic or
electrodynamic means   .
The emitter-to-base current ratio in a common-collector configuration .
The process used to tune two or more circuits with a single control .
One of the three states of matter; it has no fixed form or volume .
As applied to logic circuitry, one of several different types of electronic devices that will provide a particular output when specified input conditions are satisfied. Also, a circuit in which a signal switches another signal on or off .
Circuit that permits automatic gain control to function only during short time intervals .
An FM demodulator that uses a special gated-beam tube to limit, detect, and amplify the received FM signal. Also known as a quadrature detector .
The process of selecting those portions of a wave that exist during one or more selected time intervals or that have magnitudes between selected limits. Also, the application of a specific waveform to perform electronic switching .
GENERAL PURPOSE ELECTRONIC TEST EQUIPMENT
Test equipment that has the capability, without modification, to generate, modify, or measure a range of electronic functions required to test several equipments or systems of basically different designs  .
A machine that converts mechanical energy to electrical energy by applying the principle of magnetic induction. A machine that produces ac or dc voltage, depending on the original design .
See INPUT END .
A grayish-white metal having semiconductor properties .
An alkali metal introduced into a vacuum tube during manufacture. It is fired after the tube has been evacuated to react chemically with (and eliminate) any remaining gases .
A mechanical frame, with two perpendicular intersecting axes of rotation, used to support and furnish a gyro wheel with the necessary freedom to tilt in any direction .
Discharge of electricity through a gas in an electron tube .
An inefficient type of armature winding in which many of the turns are
shielded from the field by its own iron ring .
A pictorial presentation of the relation between two or more variable quantities, such as between an applied voltage and the current it produces in a circuit .
A constant fixed potential applied between the grid and the cathode of a vacuum tube to establish an operating point .
The current that flows in the grid-to-cathode circuit of a vacuum tube .
A method of changing the center frequency of a resonant cavity by physically
changing the distance between the cavity grids .
A self-bias provided by a high resistance connected across the grid capacitor or
between the grid and cathode 
(1) The point in a circuit used as a common reference point for measuring purposes. (2) To connect some point of an electrical circuit or some item of electrical equipment to earth or to the conducting medium used in lieu thereof .
Unwanted echoes, from surrounding land masses, that appear on a radar indicator .
The portion of a ground-plane antenna that acts as ground .
Copper planes used to minimize interference between circuits and from external sources .
Zero potential with respect to the ground or earth .
The distance on the surface of the earth between a radar and its target. Equal to slant range only if both radar and target are at the same altitude .
GROUND REFLECTION LOSS
The loss of RF energy each time a radio wave is reflected from the earth's surface .
A series of conductors buried below the surface of the earth and arranged in a radial pattern. Used to reduce losses in the ground .
Radio waves which travel near the surface of the earth .
A radar system used to guide aircraft to safe landings in poor visibility conditions .
A type of antenna that uses a ground plane as a simulated ground to produce low-angle radiation 
A collection of units, assemblies, subassemblies, and parts. It is a subdivision of a set or system but is not capable of performing a complete operational function .
The forward progress velocity of a wave front in a waveguide .
A method of mixing P-type and N-type impurities into a single crystal while the
crystal is being grown .
A system which provides information that is used to guide a missile to a target
Abbreviation for gyroscope .
A mechanical device containing a spinning mass mounted so that it can assume any position in space .
Any space or region in which a magnetic force is exerted. The magnetic field may be produced by a current-carrying coil or conductor, by a permanent magnet, or by the earth itself .
A waveguide junction in which the junction arm is parallel to the magnetic lines of force in the main waveguide .
A point on a waveform or radar beam that corresponds to half the power of the
maximum power point   .
HALF-WAVE DIPOLE ANTENNA
An antenna, consisting of two rods (1/4 wavelength each) in a single line, that radiates electromagnetic energy .
A rectifier using only one-half of each cycle to change ac to pulsating dc
HALF-WAVE VOLTAGE DOUBLER
Two half-wave voltage rectifiers connected to double the input voltage .
The operation where one earth terminal yields control to another as a satellite moves out of its area of coverage .
A high-vacuum electron tube modulator that uses a driver for pulse forming .
A frequency that is a whole-number multiple of a smaller base frequency    .
A device (preferably a clip-on type) used to absorb heat and protect heat-sensitive components during soldering .
Same as a FILAMENT .
A radar that provides target altitude, range, and bearing data .
(1) A spirally wound transmission line used in a traveling-wave tube to delay the forward progress of the input traveling wave . (2) A large coil of wire. It acts as a coil and is used with variable inductors for impedance matching of high-power transmitters .
A building at a transmitter site that contains antenna loading, coupling, and tuning circuits .
The electromagnetic unit of inductance or mutual inductance. The inductance of a circuit is 1 henry when a current variation of 1 ampere per second induces 1 volt. In electronics, smaller units are used, such as the millihenry (mH), which is one-thousandth of a henry (H), and the microhenry (μH) which is one-millionth of a henry .
A unit of frequency equal to one cycle per second .
A half-wave antenna that is installed some distance above ground and positioned either vertically or horizontally .
The use of an a.f. voltage to distinguish between available signals. The
incoming cw signal is mixed with locally generated oscillations to give an a.f. output .
(1) The process of mixing two frequencies across a nonlinear impedance . (2) The process of mixing the incoming signal with the local oscillator frequency. This produces the two fundamentals and the sum and difference frequencies .
Same as SEXADECIMAL. A number system with a base of sixteen; also pertains to
conditions, choices, or selections that have sixteen possible values or states .
Pertaining to the number system with a radix of sixteen. It uses the ten
digits of the decimal system and the first six letters of the English alphabet .
The band of frequencies from 3 megahertz to 30 megahertz .
See PEAKING COIL .
A filter that passes a majority of the high frequencies on to the next circuit and
rejects, or attenuates, the lower frequencies. Also called a LOW-FREQUENCY DISCRIMINATOR .
HITS PER SCAN
The number of times an RF beam strikes a target per antenna revolution .
In the valence band, a process of conduction in which electrons move into holes, thereby creating other holes that appear to move toward a negative potential. (The movement of holes is opposite the movement of electrons.) 
On a graph, the straight line axis that is plotted from left to right .
The part of a radiation pattern that is radiated in all directions along the
horizontal plane .
An imaginary plane that is tangent (or parallel) to the earth's surface at a given
location  .
A pair of parallel electrodes that moves the electron beam from side to side in a CRT .
Waves radiated with their E field component parallel to the earth's surface .
A funnel-shaped section of waveguide used as a termination device and as a radiating antenna .
See HORN RADIATOR .
A tapered, tubular or rectangular microwave antenna that is widest at the open end .
The English unit of power equal to work done at the rate of 550 foot-pounds per second; equal to 746 watts of electrical power .
A permanent magnet or electromagnet bent into the shape of a horseshoe or
having a U-shape to bring the two poles near each other .
A carrier, which may be either a hole or an electron, that has relatively high energy with respect to the carriers normally found in majority-carrier devices .
A semiconductor diode in which hot carriers are emitted from a semiconductor
layer into the metal base. Also called HOT-ELECTRON DIODE. An example is the Schottky barrier diode .
HOT-WIRE METER MOVEMENT
A meter movement that uses the expansion of a heated wire to move the pointer of a meter; measures dc or ac .
A circuit where passive components (resistors, capacitors) are deposited onto a
substrate made of glass, ceramic, or other insulating material. Then the active components (diodes, transistors) are attached to the substrate and connected to the passive components on the substrate with a very fine wire .
Two or more integrated circuit types, or one or more integrated circuit types and discrete components on a single substrate .
A waveguide junction that combines two or more basic T-junctions .
See BALANCED MIXER .
A hybrid-waveguide junction that combines a series of E-type T-junctions in a ring configuration. When properly terminated, energy is transferred from any one branch into any two of the remaining three branches  .
An instrument used to measure specific gravity. In batteries hydrometers are used to indicate the state of charge by the specific gravity of the electrolyte .
The time lag of the magnetic flux in a magnetic material behind the magnetizing force producing it. Caused by the molecular friction of the molecules trying to align themselves with the magnetic force applied to the material .
The power loss in an iron-core transformer or other alternating-current device as a result of magnetic hysteresis .
See COPPER LOSSES .
Obsolete synchros with reverse rotation and limited torque capabilities .
In Boolean algebra, combining a quantity with itself either by logical addition or logical multiplication will result in a logical sum or product that is the equivalent of the quantity (for
example, A + A = A; A • A = A) .
In Boolean algebra, the law which states that any expression is equal to itself
In a parametric amplifier, the difference between the input signal and the pump signal frequency. Also called the LOWER-SIDEBAND FREQUENCY .
Usually a narrow-bandwidth IF amplifier that is tuned to one of the output frequencies produced by the mixer .
Any field-effect transistor that has an insulated gate .
An undesired frequency capable of producing the desired frequency through
The total opposition offered to the flow of an alternating current. It may consist of any combination of resistance, inductive reactance, and capacitive reactance. The symbol for impedance is Z  .
The inward bursting of a CRT because of high vacuum. The opposite of explosion .
Applied to the condition that exists when two waves of the same frequency pass through their maximum and minimum values of like polarity at the same instant .
A meter permanently installed in a circuit; used to monitor circuit operation .
(1) The wave that strikes the surface of a medium. (2) The wave that travels from the sending end to the receiving end of a transmission line .
Refers to radiation on a broad band of frequencies .
INDEX OF REFRACTION
The degree of bending of an RF wave when passing from one medium to
Equipment in radar that provides a visual presentation of target position information .
INDIRECTLY HEATED CATHODE
Same as the directly heated cathode with one exception: The hot filament raises the temperature of the sleeve around the filament; the sleeve then becomes the electron emitter .
An electrostatic charge produced on an object by the electric field that surrounds a nearby object .
Current caused by the relative motion between a conductor and a magnetic field .
INDUCED ELECTROMOTIVE FORCE
The electromotive force induced in a conductor because of the relative motion between the conductor and a magnetic field .
See INDUCED ELECTROMOTIVE FORCE .
A MOSFET in which there is no actual channel between the source and the drain. This MOSFET is constructed by making the channel of the same type of material as the substrate .
The property of a circuit that tends to oppose a change in the existing current flow. The symbol for inductance is L  .
An ac bridge circuit used to measure an unknown value of inductance .
The act or process of producing voltage and current by the relative motion of a magnetic field across a conductor .
The electromagnetic field that is produced about an antenna when current and
voltage are present on the same antenna .
The losses that occur when the electromagnetic field around a conductor cuts
through nearby metallic objects and induces a current into that object .
A simple, rugged, ac motor with desirable characteristics. The rotor is energized by transformer action (induction) from the stator. Induction motors are used more than any other type .
Coupling of two coils by means of magnetic lines of force. In transformers,
coupling applied through magnetic lines of force between the primary and secondary windings .
The opposition to the flow of an alternating current caused by the inductance of a circuit, expressed in ohms. Identified by the symbol X L  .
The physical tendency of a body in motion to remain in motion and a body at rest to remain at rest unless acted upon by an outside force (Newton's First Law of Motion) .
(1) Extending indefinitely, endless. (2) Boundless, having no limits. (3) An incalculable number .
The band of frequencies from 300 Hz to 3,000 Hz .
Sounds below 15 Hz .
The current, voltage, power, or driving force applied to a circuit or device .
The end of a two-wire transmission line that is connected to a source .
Impedance presented to the transmitter by the transmission line and its load .
The amplitude at any given point along a sine wave at a specific instant in time .
INSTANTANEOUS AUTOMATIC GAIN CONTROL
A circuit that can vary the gain of the radar receiver with each input pulse to maintain a nearly constant output peak amplitude .
The magnitude at any particular instant when a value is continually varying
with respect to time .
A material used to prevent the leakage of electricity from a conductor and to provide mechanical spacing or support as protection against accidental contact with the conductor  .
The resistance offered by an insulating material to current leakage .
(1) Material of such low conductivity that the flow of current through it can usually be neglected. (2) A device having high electrical resistance; used for supporting or separating conductors so as to prevent undesired flow of current from the conductors to other objects .
(1) A circuit in which many elements are fabricated and interconnected by a single process (into a single chip), as opposed to a "nonintegrated" circuit in which the transistors, diodes, resistors, and other components are fabricated separately and then assembled . (2) Elements inseparably associated and formed on or within a single substrate .
In communications any signal that conveys information (voice, teletypewriter,
INTENSITY (OF SOUND)—The measurement of the amplitude of sound energy. Generally synonymous with loudness .
The region in an electron tube where the electrons interact with an alternating
electromagnetic field .
The point where two lines drawn on a graph cross each other .
The capacitance between the electrodes of an electron tube  .
Any disturbance that produces an undesirable response or degrades a signal .
A lower frequency to which an RF echo is converted for ease of amplification .
INTERMEDIATE POWER AMPLIFIER
The amplifier between the oscillator and final power amplifier .
Direct support and technical assistance to user organizations. Tenders and shore-based repair facilities .
Small auxiliary poles, placed between main field poles, whose magnetic field opposes the armature field and cancels armature reaction. Interpoles accomplish the same thing as compensating windings .
In Boolean algebra, the law which states that if one input to an AND gate is
already TRUE, then the output will depend upon the state of the other inputs only .
Inverted or reversed in position or relationship .
To change a physical or logical state to its opposite state .
A circuit with one input and one output. Its function is to invert or reverse the input. When the input is high, the output is low, and vice versa. The inverter is sometimes called a NOT circuit, since it produces the reverse of the input .
An electrically charged atom or group of atoms. Negative ions have an excess of electrons; positive ions have a deficiency of electrons .
(1) The process of producing ions. (2) The electrically charged particles produced by high-energy radiation, such as light or ultraviolet rays, or by the collision of particles during thermal agitation  .
The potential required to ionize the gas of a gas-filled tube. Sometimes called
firing potential .
To make an atom or molecule of an element lose an electron, as by X-ray bombardment, and thus be converted into a positive ion. The free electron may attach itself to a neutral atom or molecule to form a negative ion .
The most important region of the atmosphere extending from 31 miles to 250 miles above sea level. Contains four cloud-like layers that affect radio waves .
Disturbances in the earth's magnetic field that make communications practical only at lower frequencies .
A metal plate with an opening through which electromagnetic waves may pass. Used as an impedance-matching device in waveguides .
The prevention of unwanted interaction or leakage between components .
A diagram showing the outline of a ship, aircraft, or equipment and the
location of equipment and cable runs .
The radiation of energy equally in all directions .
(1) The connection between two or more conductors. (2) The contact between two dissimilar metals or materials, as in a thermocouple .
A box with a cover that serves the purpose of joining different runs of wire or cable and provides space for the connection and branching of the enclosed conductors .
A two-terminal device containing a single crystal of semiconducting material that ranges from P-type at one terminal to N-type at the other .
A bipolar transistor constructed from interacting PN junctions. The term is
used to distinguish junction transistors from other types, such as field-effect and point-contact .
See KEEP-ALIVE VOLTAGE .
DC voltage applied to a tr gap electrode to produce a glow discharge that
allows the tube to ionize faster when the transmitter fires .
Interference in the form of "clicks" or "thumps" caused by the sudden application or removal of power .
Filters used in keying systems to prevent key-click interference .
A transmitter in which one stage is used to produce the RF pulse .
(1) A device that changes dc pulses to mark and space modulation for teletypewriter transmissions . (2) A synchronizer .
Relays used in radio transmitters where the ordinary hand key cannot accommodate the plate current without excessive arcing .
A prefix meaning one thousand .
Energy that a body possesses by virtue of its motion .
(1) The algebraic sum of the current flowing toward any point in a circuit and
the current flowing away from it is zero. (2) The algebraic sum of the products of the current and resistance in each of the conductors in any closed path in a network is equal to the algebraic sum of the electromotive forces in the path .
KLYSTRON POWER AMPLIFIER
A multicavity microwave electron tube that uses velocity modulation .
KNEE OF THE CURVE
The point of maximum curvature of a magnetization curve. (Shaped like the
knee of a leg that is bent.) 
A device upon which lacing may be wound to prevent fouling the tape or cord and to aid the lacing process. (Usually made from brass, aluminum, fiber, or plastic) .
The amount one wave is behind another in time; expressed in electrical degrees .
A core built up from thin sheets of metal insulated from each other and used in
Conductors or runs on pcbs .
An armature winding in which opposite ends of each coil are connected to adjoining segments of the commutator so that the windings overlap .
LARGE SCALE INTEGRATION
An integrated circuit containing 1,000 to 2,000 logic gates or up to 64,000 bits of memory .
An acronym for light amplification by stimulated emission of radiation .
LAW OF ABSORPTION
In Boolean algebra, the law which states that the odd term will be absorbed
when a term is combined by logical multiplication with the logical sum of that term and another term, or when a term is combined by logical addition with the logical product of one term and another term
(for example, A(A + B) = A + AB = A) .
LAW OF MAGNETISM
Like poles repel; unlike poles attract .
LC CAPACITOR-INPUT FILTER
This is the most common type of filter. It is used in a power supply where output current is low and load current is relatively constant .
LC CHOKE-INPUT FILTER
This filter is used in power supplies where voltage regulation is important
and where the output current is relatively high and subject to varying load conditions .
The opposite of lag. Also a WIRE or CONNECTION .
The inductance of the lead wires connecting the internal components of an
electron tube .
A continuous jacket of lead molded around a single conductor or multiple conductor cable. Generally used to ensure conductors are protected from water or extensive moisture .
A cell in an ordinary storage battery in which electrodes are grids of lead containing an active material consisting of certain lead oxides that change in composition during charging and discharging. The electrodes or plates are immersed in an electrolyte of diluted sulfuric acid .
The small amount of current that flows through the dielectric between the
conductors of a transmission line .
Magnetic flux lines produced by the primary winding that do not link the turns of the secondary winding .
The electrical resistance that opposes the flow of current through the
dielectric of a capacitor. The higher the leakage resistance, the slower the capacitor discharges or leaks across the dielectric .
LEAST SIGNIFICANT DIGIT
The LSD is the digit whose position within a given number expression has the least weighting power .
LEFT-HAND RULE FOR GENERATORS
A rule or procedure used to determine the direction of current flow in a generator  .
The current induced in a circuit, caused by its motion in a magnetic field or a change in it's magnetic flux, in such a direction as to exert a mechanical force opposing the motion or to oppose the change in flux .
Light waves emitting from a source in straight lines .
A PN-junction diode that emits visible light when it is forward biased. Depending on the material used to make the diode, the light may be red, green, or amber .
An electron tube shaped like a lighthouse that is designed to handle large amounts of power at uhf frequencies .
A device that prevents (limits) a waveform from exceeding a specified value .
An amplifier in which the response is linear for weak signals and logarithmic for
large signals .
LINE OF FORCE
A line in an electric or magnetic field that shows the direction of the force .
LINE OF SIGHT
Straight line from a radar antenna to a target .
Circuit that stores energy and forms pulses in the same circuit element,
usually the pulse-forming network (pfn) .
Having an output that varies in direct proportion to the input .
An impedance in which a change in current through a device changes in direct
proportion to the voltage applied to the device .
One of the three states of matter. It has a definite volume but no definite form (water is a liquid) .
Source of cooling for high-heat producing equipments, such as microwave components, radar repeaters, and transmitters .
A combined, simultaneous display of the amplitude and phase relationships of
two input signals on a CRT .
(1) A device through which an electric current flows and which changes electrical energy into another form. (2) Power consumed by a device or circuit in performing its function  .
See OUTPUT END .
A passive attenuator in which the loss in one direction is much greater than that in the opposite direction. One example is a ferrite isolator for waveguides that allows energy to travel in only one direction .
See LUMPED-IMPEDANCE TUNING .
The effect of a voltmeter upon the circuit being measured that results in an
inaccurate measurement. Loading effect is minimized by using a voltmeter with an internal resistance many times higher than the resistance of the circuit being measured .
An area of greater signal strength in the transmission pattern of an antenna  .
A continuation of current flow within a battery cell when there is no external load. Caused by impurities in the electrode .
Receiver that uses a linear logarithmic amplifier (lin-log) instead of a
normal linear amplifier .
The basic principles and applications of truth tables, interconnections of off-on circuit elements, and other factors involved in mathematical computation in automatic data processing systems and other devices .
The primary control information processor in digital equipment; made up of electronic gates and so named because their operation is described by simple equations of a specialized logic algebra .
In computers and data processing equipment, a diagram representing the logical
elements and their interconnections without necessarily expressing construction or engineering details .
The smallest building blocks that can be represented by operators in an appropriate system of symbolic logic. Typical logic elements are the AND-gate and the flip-flop, which can be represented as operators in a suitable symbolic logic. Also a device that performs the logic function .
Any instruction that executes a logic operation that is defined in symbolic
logic, such as AND, OR, NAND, or NOR .
A nonarithmetical operation in a computer, such as comparing, selecting, making references, matching, sorting, and merging, where the logical YES or NO quantities are involved .
A diode matrix (See MATRIX) or other switching arrangement that is capable of
directing an input signal to one of several outputs .
A symbol used to represent a logic element graphically. Also a symbol used to
represent a logic operator .
An antenna that is a wavelength or more long at its operating frequency .
Those waves in which the disturbance (back and forth motion) takes place in
the direction of propagation. Sometimes called compression waves .
A curved conductor that connects the ends of a coaxial cable or other transmission line and projects into a waveguide or resonant cavity for the purpose of injecting or extracting energy  .
Inefficient coupling of energy from one circuit to another that is desirable in some applications. Also called weak coupling .
The band of frequencies from 30 kHz to 300 kHz .
Modulation produced in an earlier stage than the final .
See PREAMPLIFIER .
A filter that passes a majority of the low frequencies on to the next circuit and
rejects, or attenuates, the higher frequencies. Also called a high-frequency discriminator  .
All difference frequencies below that of the carrier .
The lowest frequency a circuit will pass .
LOWEST USABLE FREQUENCY
The minimum operating frequency that can be used for communications between two points .
See LEAST SIGNIFICANT DIGIT .
The properties of inductance, capacitance, and resistance in a transmission line
LUMPED IMPEDANCE TUNING
The insertion of an inductor or capacitor in series with an antenna to
electrically lengthen or shorten the antenna .
A method of cw keying using punched tape or other mechanical means to key a
See BALANCED MIXER .
A combination of H-type and E-type T-junctions .
Wire coated with an enamel insulation and used in coils, relays, transformers, motor windings, and so forth .
An electromagnetic device that uses one or more saturable reactors to obtain
a large power gain. This device is used in servosystems requiring large amounts of power to move heavy loads  .
(1) The region in which the magnetic forces created by a permanent magnet or by a current-carrying conductor or coil can be detected  . (2) The field that is produced when current flows through a conductor or antenna  .
Generating a voltage in a circuit by the creation of relative motion between a
magnetic field and the circuit. The relative motion can be the result of physical movement or the rise and fall of a magnetic field created by a changing current .
MAGNETIC LINES OF FORCE
Imaginary lines used for convenience to designate the direction in which magnetic forces are acting as a result of magnetomotive force .
A microphone in which the sound waves vibrate a moving armature. The
armature consists of a coil wound on the armature and located between the pole pieces of a permanent magnet. The armature is mechanically linked to the diaphragm .
The section of a magnet where the flux lines are concentrated; also where they
enter and leave the magnet .
MAGNETIC TRIP ELEMENT
A circuit breaker trip element that uses the increasing magnetic attraction of a coil with increased current to open the circuit .
The property possessed by certain materials by which these materials can exert
mechanical force on neighboring masses of magnetic materials and can cause currents to be induced in conducting bodies moving relative to the magnetized bodies .
An electron tube that provides a high power output. Theory of operation
is based on interaction of electrons with the crossed electric and magnetic fields in a resonant cavity .
Work done to correct, reduce, or counteract wear, failure, and damage to equipment .
The lobe in which the greatest amount of radiation occurs .
The mobile charge carriers (hole or electron) which are predominate in a
semiconductor material; for example, electrons in an N-type region .
A quarter-wave antenna that is operated with one end grounded and is positioned perpendicular to the earth .
An interval during which a signal is present. Also the presence of an RF signal in cw keying. The key-closed condition (presence of data) in communications systems .
The state where a circuit is closed and current flows in teletypewriter operation .
A device used to deposit materials on a substrate in the desired pattern .
In a transmitter, the oscillator that establishes the carrier frequency of the
MASTER OSCILLATOR POWER AMPLIFIER
A transmitter in which the oscillator is isolated from the antenna by a power amplifier .
In computers, a logic network in the form of an array of input leads and output leads with logic elements connected at some of their intersections .
Any physical entity that possesses mass .
MAXIMUM USABLE FREQUENCY
Maximum frequency that can be used for communications between two locations for a given time of day and a given angle of incidence .
(METROLOGY AUTOMATED SYSTEM FOR UNIFORM RECALL AND REPORTING)—The Navy data processing system designed to provide a standardized system for the recall, scheduling, and documenting of test equipment into calibration facilities .
The reflector, its feed source, or the entire antenna is moved in a desired
The speed in revolutions per minute of armatures in electric motors and engine-driven generators; blade speed in turbines .
Using electric or electro-mechanical switches to represent logic circuits (AND, OR, NOT, NOR, NAND) .
The vehicle through which a wave travels from one point to the next. Air, water, and wood are examples .
MEDIUM ALTITUDE ORBIT
An orbit from 2,000 to 12,000 miles above the earth. The rotation rate of
the earth and satellite are quite different, and the satellite moves quickly across the sky .
The band of frequencies from 300 kHz to 3 MHz .
A prefix meaning one million; also MEG .
Common name for a megohmmeter  .
A meter that measures very large values of resistance; usually used to check for
insulation breakdown in wires .
A protective covering for wires or cables. Made as a woven wire braid, metal
tape, or interlocking metal cover. Made from steel, copper, bronze, or aluminum .
A shorted quarter-wave section of transmission line .
Also known as a DRY-DISC RECTIFIER. A metal-to-semiconductor, large-
area, contact device in which a semiconductor is sandwiched between two metal plates. This asymmetrical construction permits current to flow more readily in one direction than the other .
A device used to measure a specific quantity, such as current, voltage, or frequency .
The part of the meter that moves to indicate some value  .
A resistor placed in parallel with the meter terminals; used to provide increased range capability .
Unit of conductance; the reciprocal of the ohm .
A prefix meaning one-millionth .
A small circuit having high equivalent-circuit-element density, which is considered as a single part composed of interconnected elements on or within a single substrate to perform an electronic-circuit function .
An assembly of microcircuits or a combination of microcircuits and
discrete components that perform one or more distinct functions .
The solid-state concept of electronics in which compact semiconductor
materials are designed to function as an entire circuit or subassembly rather than as circuit components  .
An energy converter that changes sound energy into electrical energy .
The portion of the electromagnetic spectrum from 1,000 MHz to 100,000 MHz
The diameter of a conductor equal to 1/1000 (.001) inch .
A unit of measurement for conductors (diameter of 1 mil, 1 foot in length.) .
Technical requirements and standards adopted by the Department of Defense that must be met by vendors selling materials to DOD .
Standards of performance for components or equipment that must be met to be acceptable for military systems .
A prefix meaning one-thousandth .
Modules, packages, pcbs, and so forth, composed exclusively of discrete
MINIMUM DISCERNIBLE SIGNAL
The weakest input signal that produces a usable signal at the output of a receiver. The weaker the input signal, the more sensitive the receiver .
The lobe in which the radiation intensity is less than that of a major lobe .
Either electrons or holes, whichever is the less dominant carrier in a
semiconductor device. In P-type semiconductors, electrons are the minority carriers; in N-type semiconductors, the holes are the minority carriers .
A very small current that passes through the base-to-collector junction when
this junction is reverse biased .
In radar, a circuit that combines the received RF signal with a local-oscillator signal to effectively convert the received signal to a lower IF frequency signal .
In a magnetron, the inadvertent shifting from one mode to another during a pulse .
Operation in which the magnetron fires randomly, rather than firing on each
successive pulse as desired .
MODIFIED TRANSISTOR OUTLINE
An IC package resembling a transistor .
A technique where printed circuit boards are stacked and connected together
to form a module .
Circuit assemblies or subassemblies packaged to be easily removed for
maintenance or repair .
A complex wave consisting of a carrier and a modulating wave that is
transmitted through space .
An information wave representing intelligence .
The process of impressing intelligence upon a transmission medium, such as radio waves .
(M)—An indication of relative magnitudes of the RF carrier and the
modulating signal .
The ratio of frequency deviation to the frequency of the modulating signal .
(1) A device that produces modulation; that is, a device that varies the amplitude, frequency, or phase of an ac signal  . (2) A circuit used in servosystems to convert a dc signal to an ac signal. The output ac signal is a sine wave at the frequency of the ac reference voltage. The amplitude of the output is directly related to the amplitude of the dc input. The circuit's function is opposite to that of a DEMODULATOR . (3) In radar, it produces a high-voltage pulse that turns the transmitter on and off .
MODULATOR SWITCHING DEVICE
Controls the on (discharge) and off (charge) time of the modulator .
A circuit or portion of a circuit packaged as a removable unit. A separable unit in a packaging scheme displaying regularity of dimensions .
Abnormal variation of moisture content at different altitudes because of high
moisture located just above large bodies of water .
A circuit where all elements (resistors, transistors, and so forth) associated
with the circuit are fabricated inseparably within a continuous piece of material (called the substrate), usually silicon .
ICs that are formed completely within a semiconductor substrate. Silicon chips .
MONOPULSE (SIMULTANEOUS) LOBING
A radar receiving method using two or more (usually four) partially overlapping lobes. Sum and difference locate the target with aspect to the axis of the
A radar that gets the range, bearing, and elevation position data of a target from a single pulse .
See MONOPULSE RADAR .
A multivibrator that has one steady state. A signal (trigger) must be applied to cause change of states .
METAL-OXIDE SEMICONDUCTOR FIELD-EFFECT TRANSISTO. A semiconductor device that contains diffused source and drain regions on either side of a P- or
N-channel area. Also contains a gate insulated from the channel area by silicon-oxide. Operates in either the depletion or the enhancement mode .
MOST SIGNIFICANT DIGIT
The MSD is the digit whose position within a given number expression has the greatest weighting power .
A machine that converts electrical energy to mechanical energy. It is activated by ac or dc voltage, depending on the design .
Any device driven by a motor. Typical loads are drills, saws, water pumps, rotating antennas, generators, and so forth. The speed and power capabilities of a motor must be matched to the speed and power capabilities of the motor load .
The force created by generator armature current that tends to oppose the normal rotation of the armature .
Large resistive devices placed in series with dc motor armatures to prevent the
armature from drawing excessive current until armature speed develops counter emf. The resistance is gradually removed from the circuit either automatically or manually as motor speed increases .
MOVING TARGET INDICATOR
A device that limits the display of radar information to moving targets .
MOVING-IRON METER MOVEMENT
Same as MOVING-VANE METER MOVEMENT .
MOVING-VANE METER MOVEMENT
A meter movement that uses the magnetic repulsion of the like poles created in two iron vanes by current through a coil of wire; most commonly used movement for ac meters .
See MOST SIGNIFICANT DIGIT .
An abbreviation for the marine tactical data system .
Symbol for amplification factor  .
More than one conductor, as in a cable .
Couplers that patch receivers or transmitters to antennas. They also filter out
harmonics and spurious responses and impedance-match the equipment .
An electron tube normally classified according to its number of electrodes
(the multielectrode tube contains more than three electrodes) .
An array that consists of one or more arrays and is classified as to directivity .
MULTIELEMENT PARASITIC ARRAY
An array that contains two or more parasitic elements and a driven element .
A servosystem that contains more than one servo loop; each loop is designed to perform its own function .
A single meter combining the functions of an ammeter, a voltmeter, and an ohmmeter .
The multiple paths a radio wave may follow between transmitter and receiver .
See POLYPHASE .
A method for simultaneous transmission of two or more signals over a common
carrier wave .
The number of times an input frequency is multiplied .
MULTISPEED SYNCHRO SYSTEMS
Systems that transmit data at different transmission speeds; for example, dual-speed and tri-speed synchro systems .
An electron tube containing two or more units within the same envelope. The
multiunit tube is capable of operating as a single-unit tube, or each unit can operate as a separate tube .
A form of relaxation oscillator which comprises two stages that are coupled so that the input of one is derived from the output of the other  .
An astable multivibrator used to provide frequency modulation. The modulating af voltage is inserted in series with the base return of the multivibrator transistors to produce the frequency modulation .
The total flux in the core of a transformer that is common to both the primary and secondary windings. The flux links both windings .
A circuit property existing when the relative position of two inductors causes
the magnetic lines of force from one to link with the turns of the other. The symbol for mutual inductance is M .
A logic function of A and B that is true if either A or B is false .
A combination of a NOT function and an AND function in a binary circuit that has two or more inputs and one output. The output is logic 0 only if ALL inputs are logic 1; it is logic 1 if ANY input is logic 0 .
See RESONANT FREQUENCY .
The line-of-sight horizon .
The length of a minute of arc of a great circle of the earth (6,076 ft) .
NAUTICAL RADAR MILE
See RADAR MILE .
NEAR SYNCHRONOUS ORBIT
An orbit in which the satellite rotates close to but not exactly at the same speed as the earth .
The process of inverting the value of a function or variable .
That part of a sine wave that is below the reference level   .
A circuit that clamps the upper extremity of the output waveshape to a dc
potential of 0 volts .
A terminal or electrode having more electrons than normal. Electrons flow
out of the negative terminal of a voltage source .
Feedback in which the feedback signal is out of phase with the input signal.
Also called DEGENERATIVE FEEDBACK .
The form of logic in which the more positive voltage level represents a logic 0,
FALSE, or LOW and the more negative voltage represents a logic 1, TRUE, or HIGH .
NEGATIVE TEMPERATURE COEFFICIENT
A characteristic of a semiconductor material, such as silver sulfide, in which resistance to electrical current flow decreases as temperature increases  
A component having an operating region in which an increase in the applied voltage increases the resistance and produces a proportional decrease in current. Examples include tunnel diodes and silicon unijunction transistors .
A combination of electrical components. In a parallel circuit it is composed of two or more branches .
(1) In a normal condition, hence neither positive nor negative. A neutral object has a normal number of electrons (the same number as protons) . (2) The teletypewriter operation where current flow represents a mark and no flow represents a space .
The process of counteracting or "neutralizing" the effects of interelectrode
NEWTON'S SECOND LAW OF MOTION
If an unbalanced outside force acts on a body, the resulting acceleration is directly proportional to the magnitude of the force, is in the direction of the force, and is inversely proportional to the mass of the body .
The condition that exists when an electrical source or secondary of a
transformer is operated without an electrical load .
The fixed minimum points of voltage or current on a standing wave or antenna .
(1) In reference to sound, an unwanted disturbance caused by spurious waves that originate from man-made or natural sources . (2) In radar, erratic or random deflection or intensity of the indicator sweep that tends to mask small echo signals .
The ratio of output noise to input noise in a receiver .
Circuit that clips the peaks of the noise spikes in a receiver .
See NOISE LIMITER .
See NOISE LIMITER .
NONDEGENERATIVE PARAMETRIC AMPLIFIER
A parametric amplifier that uses a pump signal frequency that is higher than twice the frequency of the input signal .
See OMNIDIRECTIONAL .
A device in which the output does not rise and fall in direct proportion to the
input   .
An impedance in which the resulting current through the device is not
proportional to the applied voltage .
Objects that either reflect or diffuse light that falls upon them .
A transmission fine that has no standing waves of current or voltage .
NONTRIP-FREE CIRCUIT BREAKER
A circuit breaker that can be held in the ON position during an overcurrent condition .
A logic function of A and B that is true if both A and B are false .
An OR gate that is followed by an inverter to form a binary circuit in which the output is a logic 0 if ANY of the inputs is a logic 1 and the output is a logic 1 only if ALL the inputs are a logic 0 .
The imaginary line perpendicular to the point at which the incident wave strikes the reflecting surface. Also called the perpendicular .
A binary circuit with a single output that is always the opposite of the input. Also called an INVERTER CIRCUIT .
An NPN transistor is formed by introducing a thin region of P-type material between two regions of N-type material .
On a polar-coordinate graph, the area that represents minimum or 0 radiation .
(1) A mathematical entity that may indicate quantity or amount of units. (2) Loosely, a numeral. An abstract mathematical symbol for expressing a quantity. In this sense, the manner of representing the number is immaterial. Take 26, for example; this is its decimal form - but it could be expressed as a binary (base 2), octal (base 8), or hexadecimal (base 16) number .
The representation of numbers by agreed sets of symbols according to
agreed rules .
Loosely, a number representation system. Any system for the representation of
numbers (see POSITIONAL NOTATION) .
(1) A discrete representation of a number. For example, twelve, 12, XII, 11002 are four different numerals that represent the same number. (2) A numeric word that represents a number .
Moving an antenna feed point in a conical pattern so that the polarization of the beam does not change .
OCTAL NUMBER SYSTEM
A number system based on powers of eight. This system is used extensively in computer work .
OFF-LINE TEST EQUIPMENT
Equipment that tests and isolates faults in modules or assemblies removed from systems .
The unit of electrical resistance. That value of electrical resistance through which a constant potential difference of 1 volt across the resistance will maintain a current flow of 1 ampere through the resistance .
The current in an electrical circuit is directly proportional to the electromotive force in the circuit. The most common form of the law is E = IR, where E is the electromotive force or voltage across the circuit, I is the current flowing in the circuit, and R is the resistance of the circuit .
Resistance in ohms .
A meter used to measure resistance  .
OHMS PER SQUARE
The resistance of any square area of thin film resistive material as measured
between two parallel sides .
A type of planar tube, similar to the lighthouse tube, which has cooling fins. The oilcan tube is designed to handle large amounts of power at uhf frequencies .
An antenna that radiates and receives equally in all directions (nondirectional)  .
ON-LINE TEST EQUIPMENT
Continuously monitors the performance of electronic systems .
Those substances that do not transmit (pass) any light rays; that is, the light rays are either absorbed or reflected .
(1) The condition of an electrical circuit caused by the breaking of continuity of one or more conductors of the circuit; usually an undesired condition. (2) A circuit that does not provide a complete path for the flow of current .
A transmission fine that has a terminating impedance that is infinitely large .
An amplifier designed to perform computing or transfer operations and that has the following characteristics: (1) very high gain, (2) very high input impedance,
and (3) very low output impedance .
A coupler composed of an LED and a photodiode and contained in a light-
conducting medium. Suitable for frequencies in the low-megahertz range .
OPTIMUM WORKING FREQUENCY
The most practical operating frequency that can be used with the least amount of problems and is roughly 85 percent of the maximum usable frequency .
Devices that either produce or use light in their operation .
A gate that performs the logic OR function. It produces an output 1 whenever any or all of its inputs is/are 1 .
A circuit between operators used for operations control and coordination .
Responsibility of the user organization .
The point on a graph where the vertical and horizontal axes cross each other .
An oscillator is a nonrotating device that produces alternating current. The frequency is determined by the characteristics of the device .
A meter that is not permanently installed in a circuit. Usually portable and
self-contained, these meters are used to check the operation of a circuit or to isolate troubles within a circuit .
The end of a transmission line that is opposite the source; receiving end .
The impedance that is presented to the load by the transmission line and its
When the input signal amplitude is increased to the point that the transistor goes into saturation and cutoff .
A condition that exists when the peaks of the modulating signal are limited .
A system developed to assist maintenance personnel in determining the
repairability of components, printed circuit boards, modules, and so forth .
A high-speed printer that prints teletypewriter characters one at a time in a full-page format .
An antenna reflector in the shape of a parabola. It converts spherical
wavefronts from the radiating element into plane wavefronts .
The error in meter readings that results when you look at a meter from some
position other than directly in line with the pointer and meter face. A mirror mounted on the meter face aids in eliminating parallax error .
Two or more electrical devices connected to the same pair of terminals so
separate currents flow through each; electrons have more than one path to travel from the negative to the positive terminal .
A resistor and diode, connected in series with the input signal, in which the
output is taken across (parallel to) the diode .
Configuration in which the tr spark gap is connected across the two legs of the transmission line one-quarter wavelength from the T-junction .
A resistor and diode, connected in series with the input signal, in which the output is taken across the diode and the negative alternation is eliminated 
A resistor and diode connected in series with the input signal, in which the output is taken across the diode and the positive alternation is eliminated .
A resonant circuit in which the source voltage is connected across
a parallel circuit (formed by a capacitor and an inductor) to furnish a high impedance to the frequency at which the circuit is resonant. Often referred to as a tank circuit  .
A type of transmission line consisting of two parallel wires .
An antenna array containing one or more elements not connected to the
transmission line  .
The passive element of an antenna array that is connected to neither the
transmission line nor the driven element .
A part is one component or two or more components joined together. It is not normally subject to disassembly without destruction .
A satellite that reflects radio signals back to earth .
A panel used to tie a receiver or transmitter to its associated equipment .
The maximum value above or below the reference line .
The maximum current that flows during a complete cycle .
Detection that uses the amplitude of pam or the duration of pdm to charge a holding capacitor and restore the original waveform 
The maximum value of the transmitted pulse .
The maximum instantaneous value of a varying current, voltage, or power. It is equal to 1.414 times the effective value of a sine wave .
The maximum value present in a varying or alternating voltage. This value may be positive or negative .
The peak ac voltage that a rectifier tube will withstand in the reverse
The measure of absolute magnitude of an ac waveform, measured from the greatest positive alternation to the greatest negative alternation .
An inductor used in an amplifier to provide high-frequency compensation, which extends the high-frequency response of the amplifier .
A type of impurity that contains five valence electrons and donates one
electron to the doped material. Also called DONOR IMPURITY .
A five-electrode electron tube containing a plate, a cathode, a control grid, and two grids .
PERCENT OF MODULATION
The degree of modulation defined in terms of the maximum permissible
amount of modulation .
A device that stores a teletypewriter message on a paper tape .
The point in the orbit of a satellite closest to the earth .
The time required to complete one cycle of a waveform   .
A waveform that undergoes a pattern of changes, returns to its original pattern, and then repeats the same pattern of changes. Examples are square waves, rectangular waves, and sawtooth waves .
PERMANENT MAGNET SPEAKER
A speaker with a permanent magnet mounted on soft iron pole pieces .
The measure of the ability of a material to act as a path for magnetic lines of force  .
The length of time a phosphor dot glows on a CRT before disappearing  .
A variable-length sawtooth generator often used to produce a sweep on an A-scope .
The angular relationship between two alternating currents or voltages when the voltage or current is plotted as a function of time. When the two are in phase, the angle is zero; both reach their peak simultaneously. When out of phase, one will lead or lag the other; that is, at the instant when one is at its peak, the other will not be at peak value and (depending on the phase angle) may differ in polarity as well as magnitude .
The number of electrical degrees of lead or lag between the voltage and current waveforms in an ac circuit  .
(pm)—Angle modulation in which the phase of the carrier is controlled by the
modulating waveform. The amplitude of the modulating wave determines the amount of phase shift, and the frequency of the modulation determines how often the phase shifts .
A device used to change the phase relationship between two ac signals .
A device that provides two output signals from a single input signal. The two output signals differ from each other in phase (usually by 180 degrees) .
See FOSTER-SEELEY DISCRIMINATOR .
Similar to ON-OFF cw keying in AM systems and frequency-shift keying in
FM systems. Each time a mark is received, the phase is reversed. No phase reversal takes place when a space is received .
The material used to convert the energy of electrons into visible light .
A light-controlled variable resistor which has a light-to-dark resistance ratio of 1:1000. Used in various types of control and timing circuits .
A light-controlled PN junction. Current flow increases when the PN junction is exposed to an external light source .
A voltage produced by light .
Chemical process of removing unwanted material in producing printed circuit boards .
An optoelectronic device that conducts current when exposed to light. Produces more current and is much more sensitive to light than the photodiode .
(SOLAR CELL)—A device that acts much like a battery when exposed to
light and converts light energy into electrical energy .
A prefix adopted by the National Bureau of Standards meaning 10 -12 .
A diagram showing actual pictorial sketches of the various parts of an
equipment and the electrical connections between the parts .
The effect of producing a voltage by placing a stress, either by compression, expansion, or twisting, on a crystal and, conversely, producing a stress in a crystal by applying a voltage to it .
PIP (BLIP)—On a CRT display, a spot of light or a baseline irregularity representing the radar echo .
A term used to describe the frequency of a sound heard by the human ear .
An electron tube, constructed with parallel electrodes and a ceramic envelope, that is used at uhf frequencies. It is commonly referred to as a lighthouse tube .
PLANE OF POLARIZATION
The plane (vertical or horizontal), with respect to the earth, in which the
E field propagates .
Waves of energy that are flat, parallel planes and are perpendicular to the
direction of propagation .
A radar display in which range is indicated by the distance of a bright spot or pip from the center of the screen and the bearing is indicated by the radial angle of the spot .
(1) One of the electrodes in a storage battery . (2) One of the electrodes in a capacitor . (3) The principal electrode to which the electron stream is attracted in an electron tube .
The amount of power lost as heat in the plate of a vacuum tube .
A keying system in which the plate supply is interrupted .
An electron-tube modulator in which the modulating voltage is applied to the
plate circuit of the tube .
The plate voltage change divided by the resultant plate current change in a
vacuum tube, all other conditions being fixed .
A tool used to adjust the contact spacing on a relay .
POINT OF ZERO DISPLACEMENT
See REFERENCE LINE .
A diode in which the end of a fine wire is pressed against a semiconductor.
Used as a detector or mixer over the microwave region .
Individual wires run from terminal to terminal to complete a circuit .
The teletypewriter operation in which current flow of one polarity represents a mark, and current of the opposite polarity represents a space .
An orbit that has an angle of inclination of or near 90 degrees .
A graph with a pair of axes. One consists of a series of circles with a
common center, and the other consists of a rotating radius extending from the center of the concentric circles .
(1) The condition in an electrical circuit by which the direction of the flow of current can be determined. Usually applied to batteries and other direct voltage sources. (2) Two opposite charges, one positive and one negative. (3) A quality of having two opposite magnetic poles, one north and the other south  .
(1) The effect of hydrogen surrounding the anode of a cell, which increases the
internal resistance of the cell . (2) The magnetic orientation of molecules in a magnetizable material in a magnetic field, whereby tiny internal magnets tend to line up in the field .
(1) The number of points at which current can enter a switch; for example, single pole, double pole, and three pole . (2) The sections of a field magnet where the flux lines are concentrated; also where they enter and leave the magnet .
(1) A piece of ferromagnetic material used to control the distribution of magnetic lines of force; that is, it concentrates the lines of force in a particular place or evenly distributes the lines of force over a wide area . (2) The shaped magnetic material upon which the stator windings of motors and generators are mounted or wound .
POLYMER FUME FEVER
A flu-like condition caused by a person breathing the vapors of fluorocarbons when they are heated. Sometimes called FOUNDRYMAN'S FEVER .
A term that describes systems or units of a system that are activated by or which generate separate out-of-phase voltages. Typical polyphase systems are 2-phase and 3-phase; their voltages are 90- and 120-degrees out of phase, respectively. This term means the same as MULTIPHASE .
A component in a servosystem that measures position and converts the
measurement into a form convenient for transmission as a feedback signal .
A servosystem whose end function is to control the position of the load it
is driving .
A numbering system in which a number is represented by means of a stated
set of symbols or digits, such that the value contributed by each symbol or digit depends upon its position as well as upon its value .
The value given a digit based on the digit's position within a given number
The part of a sine wave that is above the reference line   .
A circuit that clamps the lower extremity of the output waveshape to a dc
potential of 0 volts .
Feedback in which the feedback signal is in phase with the input signal. Also
called REGENERATIVE FEEDBACK .
The form of logic in which the more positive logic level represents 1 and the more negative level represents 0 .
POSITIVE TEMPERATURE COEFFICIENT
The characteristic of a conductor in which the resistance increases as temperature increases .
Energy caused by the position of one body with respect to another body or to
the relative parts of the same body .
A variable resistor, used as a position sensor in servosystems, having a terminal
connected to each end of a resistive element and a third terminal connected to a wiper contact. The output is a voltage that is variable depending upon the position of the wiper contact. The potentiometer is commonly referred to as a variable voltage divider. It, in effect, converts mechanical information into
an electrical signal  .
The rate of doing work or the rate of expending energy. The unit of electrical power is the watt .
An amplifier in which the output-signal power is greater than the input-signal
The ratio of the actual power of an alternating or pulsating current, as measured by a wattmeter, to the apparent power, as indicated by ammeter and voltmeter readings. The power factor of an inductor, capacitor, or insulator is an expression of their losses  .
In an antenna, the ratio of its radiated power to that of a reference  .
(1) The electrical power, supplied to a circuit, that does no work and is usually dissipated as heat  . (2) The heat loss in a conductor as current flows through it .
A special purpose tube used to provide high-current gain or power mplification.
Each grid wire is directly in line with the one before and after it, a fact which allows more electrons to reach the plate .
See POWER GAIN .