MUTUAL INDUCTANCEA 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 [2].
NANDA logic function of A and B that is true if either A or B is false [13].
NAND CIRCUITA 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 [13].
NATURAL FREQUENCYSee RESONANT FREQUENCY [9].
NATURAL HORIZONThe line-of-sight horizon [10].
NAUTICAL MILEThe length of a minute of arc of a great circle of the earth (6,076 ft) [18].
NAUTICAL RADAR MILESee RADAR MILE [18].
NEAR SYNCHRONOUS ORBITAn orbit in which the satellite rotates close to but not exactly at the same speed as the earth [17].
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NEGATIONThe process of inverting the value of a function or variable [13].
NEGATIVE ALTERNATIONThat part of a sine wave that is below the reference level [2] [10] [12].
NEGATIVE CLAMPERA circuit that clamps the upper extremity of the output waveshape to a dc potential of 0 volts [9].
NEGATIVE ELECTRODEA terminal or electrode having more electrons than normal. Electrons flow out of the negative terminal of a voltage source [1].
NEGATIVE FEEDBACKFeedback in which the feedback signal is out of phase with the input signal. Also called DEGENERATIVE FEEDBACK [8].
NEGATIVE LOGICThe 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 [13].
NEGATIVE-RESISTANCE ELEMENTA 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 [11].
NEGATIVE TEMPERATURE COEFFICIENTA characteristic of a semiconductor material, such as silver sulfide, in which resistance to electrical current flow decreases as temperature increases [1] [4] [7].
NETWORKA combination of electrical components. In a parallel circuit it is composed of two or more branches [1].
NEUTRAL(1) In a normal condition, hence neither positive nor negative. A neutral object has a normal number of electrons (the same number as protons) [1]. (2) The teletypewriter operation where current flow represents a mark and no flow represents a space [17].
NEUTRALIZATIONThe process of counteracting or "neutralizing" the effects of interelectrode capacitance [8].
NEWTON'S SECOND LAW OF MOTIONIf 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 [15].
NODEThe fixed minimum points of voltage or current on a standing wave or antenna [10].
NOISE(1) In reference to sound, an unwanted disturbance caused by spurious waves that originate from man-made or natural sources [10]. (2) In radar, erratic or random deflection or intensity of the indicator sweep that tends to mask small echo signals [18].
NOISE FIGUREThe ratio of output noise to input noise in a receiver [18].
NOISE LIMITERCircuit that clips the peaks of the noise spikes in a receiver [17].
NOISE SILENCERSee NOISE LIMITER [17].
NOISE SUPPRESSORSee NOISE LIMITER [17].
NO-LOAD CONDITIONThe condition that exists when an electrical source or secondary of a transformer is operated without an electrical load [2].
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NONDEGENERATIVE PARAMETRIC AMPLIFIERA parametric amplifier that uses a pump signal frequency that is higher than twice the frequency of the input signal [11].
NONDIRECTIONALSee OMNIDIRECTIONAL [10].
NONLINEAR DEVICEA device in which the output does not rise and fall in direct proportion to the input [6] [7] [12].
NONLINEAR IMPEDANCEAn impedance in which the resulting current through the device is not proportional to the applied voltage [12].
NONLUMINOUS BODIESObjects that either reflect or diffuse light that falls upon them [10].
NONRESONANT LINEA transmission fine that has no standing waves of current or voltage [10].
NONTRIP-FREE CIRCUIT BREAKERA circuit breaker that can be held in the ON position during an overcurrent condition [3].
NORA logic function of A and B that is true if both A and B are false [13].
NOR GATEAn 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 [13].
NORMALThe imaginary line perpendicular to the point at which the incident wave strikes the reflecting surface. Also called the perpendicular [10].
NOT CIRCUITA binary circuit with a single output that is always the opposite of the input. Also called an INVERTER CIRCUIT [13].
NPNAn NPN transistor is formed by introducing a thin region of P-type material between two regions of N-type material [7].
NULLOn a polar-coordinate graph, the area that represents minimum or 0 radiation [10].
NUMBER(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 [13].
NUMBER REPRESENTATIONThe representation of numbers by agreed sets of symbols according to agreed rules [13].
NUMBER SYSTEMLoosely, a number representation system. Any system for the representation of numbers (see POSITIONAL NOTATION) [13].
NUMERAL(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 [13].
NUTATINGMoving an antenna feed point in a conical pattern so that the polarization of the beam does not change [18].
OCTAL NUMBER SYSTEMA number system based on powers of eight. This system is used extensively in computer work [13].
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OFF-LINE TEST EQUIPMENTEquipment that tests and isolates faults in modules or assemblies removed from systems [14].
OHMThe 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 [1].
OHMIC VALUEResistance in ohms [1].
OHMMETERA meter used to measure resistance [3] [16].
OHM'S LAWThe 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 [1].
OHMS PER SQUAREThe resistance of any square area of thin film resistive material as measured between two parallel sides [14].
OILCAN TUBEA 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 [6].
OMNIDIRECTIONAL ANTENNAAn antenna that radiates and receives equally in all directions (nondirectional) [10] [18].
ON-LINE TEST EQUIPMENTContinuously monitors the performance of electronic systems [14].
OPAQUEThose substances that do not transmit (pass) any light rays; that is, the light rays are either absorbed or reflected [10].
OPEN CIRCUIT(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 [1].
OPEN-ENDED LINEA transmission fine that has a terminating impedance that is infinitely large [10].
OPERATIONAL AMPLIFIER (OP AMP)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 [8].
OPTICAL COUPLERA coupler composed of an LED and a photodiode and contained in a light- conducting medium. Suitable for frequencies in the low-megahertz range [7].
OPTIMUM WORKING FREQUENCYThe most practical operating frequency that can be used with the least amount of problems and is roughly 85 percent of the maximum usable frequency [10].
OPTOELECTRONIC DEVICESDevices that either produce or use light in their operation [7].
ORDER-WIRE CIRCUITA circuit between operators used for operations control and coordination [17].
ORGANIZATIONAL-LEVEL MAINTENANCE (SM & R CODE O)Responsibility of the user organization [14].
OR GATEA gate that performs the logic OR function. It produces an output 1 whenever any or all of its inputs is/are 1 [13].
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ORIGINThe point on a graph where the vertical and horizontal axes cross each other [10].
OSCILLATORAn oscillator is a nonrotating device that produces alternating current. The frequency is determined by the characteristics of the device [9].
OUT-OF-CIRCUIT METERA 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 [3].
OUTPUT ENDThe end of a transmission line that is opposite the source; receiving end [10].
OUTPUT IMPEDANCEThe impedance that is presented to the load by the transmission line and its source [10].
OVERDRIVENWhen the input signal amplitude is increased to the point that the transistor goes into saturation and cutoff [7].
OVERMODULATIONA condition that exists when the peaks of the modulating signal are limited [12].
PACKAGING LEVELSA system developed to assist maintenance personnel in determining the repairability of components, printed circuit boards, modules, and so forth [14].
PAGE PRINTERA high-speed printer that prints teletypewriter characters one at a time in a full-page format [17].
PARABOLIC REFLECTORAn antenna reflector in the shape of a parabola. It converts spherical wavefronts from the radiating element into plane wavefronts [18].
PARALLAX ERRORThe 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 [3].
PARALLEL CIRCUITTwo 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 [1].
PARALLEL-CONNECTED DUPLEXERConfiguration in which the tr spark gap is connected across the two legs of the transmission line one-quarter wavelength from the T-junction [18].
PARALLEL LIMITERA resistor and diode, connected in series with the input signal, in which the output is taken across (parallel to) the diode [9].
PARALLEL-POSITIVE LIMITERA 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 [9].
PARALLEL-RESONANT CIRCUITA 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 [9] [10].
PARALLEL-WIREA type of transmission line consisting of two parallel wires [10].
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PARASITIC ARRAYAn antenna array containing one or more elements not connected to the transmission line [10] [18].
PARASITIC ELEMENTThe passive element of an antenna array that is connected to neither the transmission line nor the driven element [10].
PARTA part is one component or two or more components joined together. It is not normally subject to disassembly without destruction [17].
PASSIVE SATELLITEA satellite that reflects radio signals back to earth [17].
PATCH PANELA panel used to tie a receiver or transmitter to its associated equipment [17].
PEAK AMPLITUDEThe maximum value above or below the reference line [12].
PEAK CURRENTThe maximum current that flows during a complete cycle [6].
PEAK DETECTIONDetection that uses the amplitude of pam or the duration of pdm to charge a holding capacitor and restore the original waveform [12].
PEAKING COILAn inductor used in an amplifier to provide high-frequency compensation, which extends the high-frequency response of the amplifier [8].
PEAK POWERThe maximum value of the transmitted pulse [12].
PEAK-REVERSE VOLTAGEThe peak ac voltage that a rectifier tube will withstand in the reverse direction [6].
PEAK-TO-PEAKThe measure of absolute magnitude of an ac waveform, measured from the greatest positive alternation to the greatest negative alternation [2].
PEAK VALUEThe maximum instantaneous value of a varying current, voltage, or power. It is equal to 1.414 times the effective value of a sine wave [2].
PEAK VOLTAGEThe maximum value present in a varying or alternating voltage. This value may be positive or negative [6].
PENTAVALENT IMPURITYA type of impurity that contains five valence electrons and donates one electron to the doped material. Also called DONOR IMPURITY [7].
PENTODE TUBEA five-electrode electron tube containing a plate, a cathode, a control grid, and two grids [6].
PERCENT OF MODULATIONThe degree of modulation defined in terms of the maximum permissible amount of modulation [12].
PERFORATORA device that stores a teletypewriter message on a paper tape [17].
PERIGEEThe point in the orbit of a satellite closest to the earth [17].
PERIOD TIMEThe time required to complete one cycle of a waveform [2] [10] [12].
PERIODIC WAVEA 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 [9].
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PERMANENT MAGNET SPEAKERA speaker with a permanent magnet mounted on soft iron pole pieces [17].
PERMEABILITYThe measure of the ability of a material to act as a path for magnetic lines of force [1] [8].
PERSISTENCEThe length of time a phosphor dot glows on a CRT before disappearing [6] [18].
PHANTASTRONA variable-length sawtooth generator often used to produce a sweep on an A-scope [18].
PHASEThe 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 [2].
PHASE ANGLEThe number of electrical degrees of lead or lag between the voltage and current waveforms in an ac circuit [2] [12].
PHASE MODULATION (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 [12].
PHASE-SHIFT DISCRIMINATORSee FOSTER-SEELEY DISCRIMINATOR [12].
PHASE SHIFTERA device used to change the phase relationship between two ac signals [11].
PHASE-SHIFT KEYINGSimilar 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 [12].
PHASE SPLITTERA 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) [8].
PHOSPHORThe material used to convert the energy of electrons into visible light [6].
PHOTOCELLA light-controlled variable resistor which has a light-to-dark resistance ratio of 1:1000. Used in various types of control and timing circuits [7].
PHOTODIODEA light-controlled PN junction. Current flow increases when the PN junction is exposed to an external light source [7].
PHOTOELECTRIC VOLTAGEA voltage produced by light [1].
PHOTOETCHINGChemical process of removing unwanted material in producing printed circuit boards [14].
PHOTOTRANSISTORAn optoelectronic device that conducts current when exposed to light. Produces more current and is much more sensitive to light than the photodiode [7].
PHOTOVOLTAIC CELL (SOLAR CELL)A device that acts much like a battery when exposed to light and converts light energy into electrical energy [7].
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PICOA prefix adopted by the National Bureau of Standards meaning 10 -12 [1].
PICTORIAL DIAGRAMA diagram showing actual pictorial sketches of the various parts of an equipment and the electrical connections between the parts [4].
PIEZOELECTRIC EFFECTThe 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 [1].
PIP (BLIP)On a CRT display, a spot of light or a baseline irregularity representing the radar echo [18].
PITCHA term used to describe the frequency of a sound heard by the human ear [10].
PLANAR TUBEAn 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 [6].
PLANE OF POLARIZATIONThe plane (vertical or horizontal), with respect to the earth, in which the E field propagates [10].
PLANE WAVEFRONTSWaves of energy that are flat, parallel planes and are perpendicular to the direction of propagation [18].
PLANNED-POSITION INDICATORA 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 [18].
PLATE(1) One of the electrodes in a storage battery [1]. (2) One of the electrodes in a capacitor [2]. (3) The principal electrode to which the electron stream is attracted in an electron tube [6].
PLATE DISSIPATIONThe amount of power lost as heat in the plate of a vacuum tube [6].
PLATE KEYINGA keying system in which the plate supply is interrupted [12].
PLATE MODULATORAn electron-tube modulator in which the modulating voltage is applied to the plate circuit of the tube [12].
PLATE RESISTANCEThe plate voltage change divided by the resultant plate current change in a vacuum tube, all other conditions being fixed [6].
POINT BENDERA tool used to adjust the contact spacing on a relay [3].
POINT-CONTACT DIODEA diode in which the end of a fine wire is pressed against a semiconductor. Used as a detector or mixer over the microwave region [7].
POINT OF ZERO DISPLACEMENTSee REFERENCE LINE [10].
POINT-TO-POINT WIRINGIndividual wires run from terminal to terminal to complete a circuit [14].
POLARThe teletypewriter operation in which current flow of one polarity represents a mark, and current of the opposite polarity represents a space [17].
POLAR-COORDINATE GRAPHA 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 [10].
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POLARITY(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] [13].
POLARIZATION(1) The effect of hydrogen surrounding the anode of a cell, which increases the internal resistance of the cell [1]. (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 [2].
POLAR ORBITAn orbit that has an angle of inclination of or near 90 degrees [17].
POLE(1) The number of points at which current can enter a switch; for example, single pole, double pole, and three pole [3]. (2) The sections of a field magnet where the flux lines are concentrated; also where they enter and leave the magnet [5].
POLE PIECE(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 [3]. (2) The shaped magnetic material upon which the stator windings of motors and generators are mounted or wound [5].
POLYMER FUME FEVERA flu-like condition caused by a person breathing the vapors of fluorocarbons when they are heated. Sometimes called FOUNDRYMAN'S FEVER [4].
POLYPHASEA 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 [5].
POSITIONAL NOTATIONA 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 [13].
POSITIONAL WEIGHTINGThe value given a digit based on the digit's position within a given number [13].
POSITION SENSORA component in a servosystem that measures position and converts the measurement into a form convenient for transmission as a feedback signal [15].
POSITION SERVOSYSTEMA servosystem whose end function is to control the position of the load it is driving [15].
POSITIVE ALTERNATIONThe part of a sine wave that is above the reference line [2] [10] [12].
POSITIVE CLAMPERA circuit that clamps the lower extremity of the output waveshape to a dc potential of 0 volts [9].
POSITIVE FEEDBACKFeedback in which the feedback signal is in phase with the input signal. Also called REGENERATIVE FEEDBACK [8].
POSITIVE LOGICThe form of logic in which the more positive logic level represents 1 and the more negative level represents 0 [13].
POSITIVE TEMPERATURE COEFFICIENTThe characteristic of a conductor in which the resistance increases as temperature increases [7].
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POTENTIAL ENERGYEnergy caused by the position of one body with respect to another body or to the relative parts of the same body [1].
POTENTIOMETERA 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 [1] [15].
POWERThe rate of doing work or the rate of expending energy. The unit of electrical power is the watt [1].
POWER AMPLIFIERAn amplifier in which the output-signal power is greater than the input-signal power [8].
POWER-AMPLIFIER (CHAIN) TRANSMITTERTransmitter that uses a series of power amplifiers to create a high level of power [18].
POWER FACTORThe 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 [2] [16].
POWER GAINIn an antenna, the ratio of its radiated power to that of a reference [11] [18].
POWER LOSS(1) The electrical power, supplied to a circuit, that does no work and is usually dissipated as heat [2] [4]. (2) The heat loss in a conductor as current flows through it [10].
POWER PENTODEA special purpose tube used to provide high-current gain or power amplification. Each grid wire is directly in line with the one before and after it, a fact which allows more electrons to reach the plate [6].
POWER RATIOSee POWER GAIN [11].
POWER STANDING-WAVE RATIO (PSWR)The ratio of the square of the maximum and minimum voltages of a transmission line [10].
POWER SUPPLYA unit that supplies electrical power to another unit. It changes ac to dc and maintains a constant voltage output within limits [6] [7].
PREAMPLIFIER (PREAMP)An amplifier that raises the output of a low-level source for further processing without appreciable degradation of the signal-to-noise ratio [18].
PRECESSIONThe rotation of the spin axis of a gyro in response to an applied force. The direction of precession is always perpendicular to the direction of applied force [15].
PRECESSION VECTORIn a gyro, a vector representing the angular change of the spin axis when torque is applied. The precession vector represents the axis about which precession occurs [15].
PRESTANDARD NAVY SYNCHROSSynchros that are designed to meet Navy, rather than servicewide, specifications [15].
PREVENTIVE MAINTENANCEVisual, mechanical, electrical, and electronic checks that are made to determine whether or not equipment is functioning properly [16].
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PRIMARIES (OF LIGHT)The three primary colors of light from which all other colors can be derived. The colors are red, green, and blue [10].
PRIMARY CELLAn electrochemical cell in which the chemical action eats away one of the electrodes, usually the negative electrode [1].
PRIMARY LOOPIn a cooling system, the primary source of cooling for the distilled water [18].
PRIMARY WINDINGThe winding of a transformer connected to the electrical source [2].
PRIME MOVERThe source of the turning force applied to the rotor of a generator. This may be an electric motor, a gasoline engine, a steam turbine, and so forth [5].
PRINTED CIRCUIT BOARDA flat, insulating surface upon which printed wiring and miniaturized components are connected in a predetermined design and attached to a common base [7] [14].
PRISMA triangular-shaped glass that refracts and disperses light waves into component wavelengths [10].
PROBE COUPLERA resonant conductor placed in a waveguide or cavity to insert or extract energy [18].
PROGRAMMED TRACKINGThe method that uses known satellite orbital parameters to generate antenna pointing angles [17].
PROPAGATIONWaves traveling through a medium [10].
PULSESignal characterized by a steep rise from and decay toward an initial level [9] [12].
PULSE-AMPLITUDE MODULATION (PAM)Pulse modulation in which the amplitude of the pulses is varied by the modulating signal [12].
PULSE-CODE MODULATION (PCM)A modulation system in which the standard values of a quantized wave are indicated by a series of coded pulses [12].
PULSE DURATION (PD)The period of time during which a pulse is present [12].
PULSE-DURATION MODULATION (PDM)Pulse modulation in which the time duration of the pulses is changed by the modulating signal [12].
PULSE-FORMING NETWORK (PFN)An lc network that alternately stores and releases energy in an approximately rectangular wave [12] [18].
PULSE-FREQUENCY MODULATION (PFM)Pulse modulation in which the modulating voltage varies the repetition rate of a pulse train [12].
PULSE MODULATIONA form of modulation in which one of the characteristics of a pulse train is varied [12].
PULSE OSCILLATORA sine-wave oscillator that is turned on and off at specific times. Also known as a ringing oscillator [9].
PULSE-POSITION MODULATION (PPM)Pulse modulation in which the position of the pulses is varied by the modulating voltage [12].
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PULSE-REPETITION FREQUENCY (PRF)The rate, in pulses per second, at which the pulses occur [9] [12] [18].
PULSE-REPETITION RATE (PRR)Same as PULSE-REPETITION FREQUENCY (PRF) [9] [12] [18].
PULSE-REPETITION TIME (PRT)Interval between the start of one pulse and the start of the next pulse; reciprocal of pulse-repetition frequency [18].
PULSE-TIME MODULATION (PTM)Pulse modulation that varies one of the time characteristics of a pulse train (pwm, pdm, ppm, or pfm) [12].
PULSE WIDTHDuration of time between the leading and trailing edges of a pulse [12] [18].
PULSE-WIDTH MODULATION (PWM)Pulse modulation in which the duration of the pulses is varied by the modulating voltage [12].
PULSINGAllowing oscillations to occur for a specific period of time only during selected intervals [12].
PUMPElectrical source of the energy required to vary the capacitance of a parametric amplifier [11].
PUSH-PULL AMPLIFIERAn amplifier that uses two transistors (or electron tubes) whose output signals are in phase opposition [8].
Q(1) Figure of merit of efficiency of a circuit or coil. (2) Ratio of inductive reactance to resistance in servos. (3) Relationship between stored energy (capacitance) and rate of dissipation in certain types of electric elements, structures, or materials [2] [9].
QUALITY (OF SOUND)The factor that distinguishes tones of pitch and loudness [10].
QUANTIZED WAVEA wave created by the arbitrary division of the entire range of amplitude (or frequency, or phase) values of an analog wave into a series of standard values. Each sample takes the standard value nearest its actual value when modulated [12].
QUANTIZING NOISEA distortion introduced by quantizing the signal [12].
QUANTUM-MECHANICAL TUNNELINGThe action of an electron crossing a PN junction because of tunnel effect [7].
QUARTER-WAVE ANTENNASame as the MARCONI ANTENNA [10].
QUIESCENCE(1) The state of an amplifier with no signal applied. (2) The operating conditions that exist in a circuit when no input signal is applied to the circuit [6] [71 [13].
QUIESCENT STATEThe period during which a transistor, tube, or other circuit element is not performing an active function in the circuit [9] [13].
RADARAn acronym for RAdio Detecting And Ranging [18].
RADAR ALTIMETERAirborne radar that measures the distance of the aircraft above the ground [18].
RADAR BEAMThe space in front of a radar antenna where a target can be effectively detected or tracked. Defined by areas that contain half or more of the maximum power transmitted [18].
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RADAR DETECTORA detector that, in its simplest form, only needs to be capable of producing an output when RF energy (reflected from a target) is present at its input [12].
RADAR DISTRIBUTION SWITCHBOARDAn electrical switching panel used to connect inputs from any of several radars to repeaters (indicators) [18].
RADAR MILETime interval (12.36 microseconds) for RF energy to travel out from a radar to a target and back to the radar; radar nautical mile [18].
RADAR TEST SETA combination of several test circuits and equipment used to test various characteristics of a radar [18].
RADIATION FIELDThe electromagnetic field that radiates from an antenna and travels through space [10].
RADIATION LOSSESThe losses that occur when magnetic lines of force about a conductor are projected into space as radiation and are not returned to the conductor as the cycle alternates [10].
RADIATION PATTERNA plot of the radiated energy from an antenna [10].
RADIATION RESISTANCEThe resistance that if inserted in place of the antenna would consume the same amount of power as that radiated by the antenna [10].
RADIO COMMUNICATIONSThe term describing teletypewriter, voice, telegraphic, and facsimile communications. [17].
RADIO FREQUENCY (RF)(1) Any frequency of electromagnetic energy capable of propagation into space [2]. (2) The frequencies that fall between 3 kilohertz and 300 gigahertz used for radio communications [10].
RADIO FREQUENCY CARRIER SHIFTThe system that uses a keyer to shift a radio frequency signal above or below an assigned frequency. These shifts correspond to marks and spaces [17].
RADIO HORIZONThe boundary beyond the natural horizon in which radio waves cannot be propagated over the earth's surface [10].
RADIO SET CONTROL UNITEquipment used to remotely control certain transmitter and receiver functions [17].
RADIO WAVES(1) A form of radiant energy that can neither be seen nor felt. (2) An electromagnetic wave that is generated by a transmitter [10].
RADIXAlso called the base. The number of distinct symbols used in a number system. For example, since the decimal number system uses ten symbols (0, 1, 2, 3, 4, 5, 6, 7, 8, 9), the radix is 10. In the binary number system, the radix is 2 because it uses only two symbols (0, 1) [13].
RADIX POINTAlso called BINARY POINT, OCTAL POINT, DECIMAL POINT, and so forth, depending on the number system [13].
RANGEThe length of a straight line between a radar set and a target [11] [18].
RANGE-GATEA movable gate used to select radar echoes from a very short range interval [18].
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RANGE-HEIGHT INDICATORA radar display on which slant range is shown along the X axis and height along the Y axis [18].
RANGE MARKERA movable vertical pulse on an A-scope or a ring on a PPI scope used to measure the range of an echo or to calibrate the range scale [18].
RANGE RESOLUTIONAbility of a radar to distinguish between targets that are close together [18].
RANGESThe several upper limits a meter will measure as selectable by a switch or by jacks; for example, a voltmeter may have ranges of 1 volt, 2.5 volts, 10 volts, 25 volts, and 100 volts [3].
RANGE STEPOn an A-scope sweep, a vertical displacement used to measure the range of an echo [18].
RAREFIED WAVEA longitudinal wave that has been expanded or rarefied (made less dense) as it moves away from the source [10].
RATE GYROA gyro used to detect and measure angular rates of change [15].
RATIOThe value obtained when one number is divided by another. This value indicates the relative proportions of the two numbers [2].
RATIO DETECTORA detector that uses a double-tuned transformer to convert the instantaneous frequency variations of the FM input signal to instantaneous amplitude variations [12].
RATIO OF TRANSMITTED POWERSThe power ratio (FSK versus AM) that expresses the overall improvement of FSK transmission when compared to AM under rapid-fading and high-noise conditions [12].
RC CONSTANTTime constant of a resistor-capacitor circuit; equal in seconds to the resistance value in ohms multiplied by the capacitance value in farads [2] [9].
RC DIFFERENTIATORAn RC circuit in which the output is taken from the resistor [9].
RC FILTERA filter used in applications where load current is low and constant, and voltage regulation is not necessary [7].
RC INTEGRATORAn RC circuit in which the output is taken from the capacitor [9].
RC NETWORKA circuit containing resistance and capacitance arranged in a particular manner to perform a specific function [9].
RC OSCILLATORAn oscillator in which the frequency is determined by resistive and capacitive elements [9].
REACTANCEThe opposition offered to the flow of an alternating current by the inductance, capacitance, or both, in any circuit [2].
REACTANCE AMPLIFIERA low-noise amplifier that uses a nonlinear variable reactance as the active element instead of a variable resistance. Also called a parametric amplifier [11].
REACTANCE TUBEA tube connected in parallel with the tank circuit of an oscillator. Provides a signal that will either lag or lead the signal produced by the tank [12].
REACTANCE-TUBE MODULATORAn FM modulator that uses a reactance tube in parallel with the oscillator tank circuit [12].
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RECEIVER(1) The object that responds to the wave or disturbance. Same as DETECTOR [10]. (2) Equipment that converts electromagnetic energy into a visible or an audible form [17]. (3) In radar, a unit that converts RF echoes to video and/or audio signals [18].
RECEIVER SENSITIVITY(1) The degree to which a receiver can usefully detect a weak signal. (2) The lower limit of useful signal input to the receiver [18].
RECEIVER TRANSFER SWITCHBOARDEquipment used to transfer receiver audio outputs to remote control station audio circuits [17].
RECEIVING ANTENNAThe device used to pick up the RF signal from space [10].
RECEIVING ENDSee OUTPUT END [10].
RECEPTIONThe instant when an electromagnetic wave passes through a receiver antenna and induces a voltage in that antenna [17].
RECIPROCAL (OF A QUANTITY)The value obtained by dividing the number 1 by that quantity [1].
RECIPROCITYThe property of interchangeability of the same antenna for transmitting and receiving [10] [11].
RECOVERY TIMEIn a radar, the time interval between the end of the transmitted pulse and the time when echo signals are no longer attenuated by the tr gap [18].
RECTIFIERA device used to convert ac to pulsating dc [3] [6] [7].
RECTANGULAR-COORDINATE GRAPHA graph in which straight-line axes (horizontal and vertical) are perpendicular [10].
REDThe reference color of equipment that passes classified information. It normally refers to patch panels [17].
REFERENCE LINEThe position of zero displacement in a wave [10].
REFERENCE POINTA point in a circuit to which all other points in the circuit are compared [1].
REFLECTED WAVE(1) The wave that reflects back from a medium. (2) The wave moving back to the source from the termination of a transmission line after reflection has occurred [10].
REFLECTING OBJECTIn radar a air or surface contact that provides an echo [18].
REFLECTION WAVESWaves that are neither transmitted nor absorbed, but are reflected from the surface of the medium they encounter [10].
REFLECTORThe parasitic element of an array that causes maximum energy radiation in a direction toward the driven element [10].
REFLEX KLYSTRONA klystron with a reflector (repeller) electrode in the place of a second resonant cavity used to redirect the velocity-modulated electrons back through the cavity that produced the modulation [11]. (2) A microwave oscillator that is tuned by changing the repealer voltage [18].
REFRACTIONThe changing of direction of a wave as it leaves one medium and enters another medium of a different density [10] [18].
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REFRACTIVE INDEXIn a wave-transmission medium, the ratio between the phase velocity in free space and in the medium [11] [18].
REGENERATIONSee FEEDBACK [18].
REGENERATIVE DETECTORA detector circuit that produces its own oscillations, heterodynes them with an incoming signal, and deflects them [12].
REGENERATIVE FEEDBACKThe process by which a portion of the output signal of an amplifying device is fed back in phase to reinforce the input. Also called POSITIVE FEEDBACK [8] [9].
REGULATORThe section in a basic power supply that maintains the output of the power supply at a constant level in spite of large changes in load current or input line voltage [6] [7].
RELATIVE BEARINGBearing of a target measured in a clockwise direction from "dead ahead" of a ship or plane [18].
RELAYAn electromagnetic device with one or more sets of contacts that change position by the magnetic attraction of a coil to an armature [3].
RELUCTANCEA measure of the opposition that a material offers to magnetic lines of force [1].
REMOTE-CUTOFF TUBEAn electron tube in which the control grid wires are farther apart at the centers than at the ends. This arrangement allows the tube to amplify large signals without being driven into cutoff. This tube is also called a VARIABLE-MU TUBE [6].
REPEATER(1) Another name for an active satellite [17]. (2) Also, a common name for remote radar indicators.
REPELLERSometimes called a REFLECTOR. An electrode in a reflex klystron with the primary purpose of reversing the direction of the electron beam [11].
REPERFORATOREquipment that converts the incoming TTY signal and stores it on paper tape [17].
REPRODUCTIONThe process of converting electrical signals to sound waves. This sound is speech, music, and so on [17].
REPULSIONThe mechanical force tending to separate bodies having like electrical charges or like magnetic polarity [1].
RERADIATIONThe reception and retransmission of radio waves that is caused by turbulence in the troposphere [10].
RESIDUAL MAGNETISMMagnetism remaining in a substance after removal of the magnetizing force [1].
RESISTANCE(1) The opposition a device or material offers to the flow of current. The effect of resistance is to raise the temperature of the material or device carrying the current. (2) A circuit element designed to offer a predetermined resistance to current flow. A resistance of 1 ohm will allow a current of 1 ampere to flow through it when a potential of 1 volt is applied. [1].
RESISTIVITYSee SPECIFIC RESISTANCE. The reciprocal of conductivity [4].
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RESISTORThe electrical component that offers resistance to the flow of current. It may be a coil of fine wire or a composition rod [1].
RESOLVERA rotary, electromechanical device used to perform trigonometric computations by varying the magnetic couplings between its primary and secondary windings. It is generally used in circuits that solve vector problems, such as analog computers and conversion equipment. The resolver solves three different type problems: (1) Resolution - separating a vector into two mutually perpendicular components; (2) Composition - combining two components of a vector to produce a vector sum; and (3) Combination - the process of resolution and composition taking place simultaneously [15].
RESONANCEThe condition in a circuit containing inductance and capacitance in which the inductive reactance is equal and opposite to the capacitive reactance. This condition occurs at only one frequency and the circuit in that condition is said to be in resonance [2] [9] [10].
RESONANCE CHAMBERSee ECHO BOX [18].
RESONANT CIRCUITA circuit that contains both inductance and capacitance and is resonant at one frequency (XL = XC) [9].
RESONANT FREQUENCYThat frequency in a given resonant circuit at which the inductive and capacitive reactance values are equal and cancel each other [9].
RESONANT LINEA transmission line that has standing waves of current and voltage [10].
REST FREQUENCYThe carrier frequency during the constant-amplitude portions of a phase modulation signal [12].
REST POSITIONSee REFERENCE LINE [10].
REST TIME (RT)The time when there is no pulse; nonpulse time [12].
RESULTANT MAGNETIC FIELDThe magnetic field produced in a synchro by the combined effects of the three stator magnetic fields [15].
RETENTIVITYThe ability of a material to retain its magnetism [1].
RETURNThe RF signal reflected back from a radar target; echo [18].
REVERBERATIONThe multiple reflections of sound waves [10].
REVERSE AGCThe type of AGC that causes an amplifier to be driven toward cut-off [17].
REVERSE BIASAn external voltage applied to a diode or semiconductor junction to reduce the flow of electrons across the junction. Also called BACK BIAS [7] [13].
RF RADIATION HAZARDA health hazard caused by exposure to electromagnetic radiation or high- energy particles (ions). Abbreviated RADHAZ [18].
RF (RADIO FREQUENCY) AMPLIFIERAn amplifier designed to amplify signals with frequencies between 10 kilohertz (10 kHz) and 100,000 megahertz (100,000 MHz) [8].
RF (RADIO FREQUENCY) TRANSFORMERA transformer specially designed for use with RF (radio frequencies). An RF transformer is wound onto a tube of nonmagnetic material and has a core of either powdered iron or air [8].
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RGKThe symbol used to express the resistance between the grid and the cathode of an electron tube [6].
RHEOSTATA variable resistor used for the purpose of adjusting the current in a circuit [1] [4].
RHOGreek letter "rho" (ρ). Used in the field of electricity and electronics to represent the specific resistance of a substance [4].
RHOMBIC ANTENNAA diamond-shaped antenna used widely for long-distance, high-frequency transmission and reception [10].
RIGID COAXIAL LINEA coaxial line consisting of a central insulated wire (inner conductor) mounted inside of a tubular outer conductor [10].
RIGIDITYThe tendency of the spin axis of a gyro wheel to remain in a fixed direction in space if no force is applied to it [15].
RINGINGRF oscillations caused by shock excitation of a resonant circuit or cavity [18].
RING TIMEIn radar, the time during which the output of an echo box remains above a specified level [18].
RIPPLE FREQUENCYThe frequency of the ripple current. In a full-wave rectifier it is twice the input- line frequency [6].
RIPPLE VOLTAGEThe alternating component of unidirectional voltage. (This component is small compared to the direct component.) [6]
RLC CIRCUITAn electrical circuit that has the properties of resistance, inductance, and capacitance [2].
RL DIFFERENTIATORAn RL circuit in which the output is taken from the inductor [9].
RL INTEGRATORAn RL circuit in which the output is taken from the resistor [9].
RMSAbbreviation of root mean square [2].
ROOT MEAN SQUARE (RMS)The equivalent heating value of an alternating current or voltage, as compared to a direct current or voltage. It is 0.707 times the peak value of a sine wave [2].
ROTARY CAPA spark gap, similar to a mechanically driven rotary switch, used to discharge a pulse- forming network [12].
ROTARY SWITCHA multicontact switch with contacts arranged in a circular or semicircular manner [3].
ROTATING FIELDThe magnetic field in a multiphase ac motor that is the result of field windings being energized by out-of-phase currents. In effect, the magnetic field is made to rotate electrically rather than mechanically [5].
ROTATING JOINTA joint that permits one section of a transmission line or waveguide to rotate continuously with respect to another while passing energy through the joint. Also called a rotary coupler [11].
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ROTOR(1) The revolving part of a rotating electrical machine. The rotor may be either the field or the armature, depending on the design of the machine [5]. (2) The rotating member of a synchro that consists of one or more coils of wire wound on a laminated core. Depending on the type of synchro, the rotor functions similarly to the primary or secondary winding of a transformer [15].
RPKThe symbol used to represent the resistance between the cathode and plate of a tube [6].
RUNNING OPENThe teletypewriter condition where the type hammer constantly strikes the type box but does not print or move across the page [17].
SATELLITE ECLIPSEAn eclipse where the rays of the sun do not reach the satellite. This prevents recharging of the solar cells of the satellite and decreases the power to the transmitter [17].
SATELLITE-SUN CONJUNCTIONA period when the satellite and sun are close together and the noise from the sun prevents or hampers communications [17].
SATURABLE-CORE REACTORA coil in which the reactance is controlled by changing the permeability of the core [8].
SATURATION(1) The condition existing in any circuit in which an increase in the input signal produces no further change in the output [13]. (2) The operating point of a vacuum tube or transistor at which a further increase in grid or base current no longer produces an increase in plate or collector current [6] [7]. (3) In a magnetic core, the condition in which a magnetic material has reached a maximum flux density and the permeability has decreased to a value of (approximately) 1 [8].
SCALING FACTORThe term used to describe the use of unequal resistors in a servo's summing network to compensate for differences between input and output signal levels [15].
SCANNING(1) The process of subdividing a picture in an orderly manner into segments. This is used in facsimile transmission [17]. (2) Systematic movement of a radar beam to cover a definite pattern or area in space [18].
SCAT CODEA four-digit subcategory code used to identify the functional measurement parameters that can be satisfied by any one of many pieces of test equipment [16].
SCATTER ANGLEThe angle at which the receiving antenna must be aimed to capture the scattered energy of tropospheric scatter [10].
SCHEMATICA diagram which shows, by means of graphic symbols, the electrical connections and functions of a specific circuit arrangement [1] [4].
SCHEMATIC SYMBOLSA letter, abbreviation, or design used to represent specific characteristics or components on a schematic diagram [1].
SCINTILLATIONApparent change in target reflectivity. Motion of the target causes successive radar pulses to bounce off different parts of the target, such as fuselage and wingtip [18].
SCREEN GRIDA grid placed between a control grid and the plate and usually maintained at a fixed positive potential [6].
SCREENINGProcess of applying nonconductive or semiconductive materials to a substrate to form thick film components [14].
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SEA CLUTTERUnwanted echoes from the irregular surface of the sea that appear on a radar indicator [18].
SEARCH RADAR SYSTEMAn early-warning device that searches a fixed volume of space [18].
SECAS (SHIP EQUIPMENT CONFIGURATION ACCOUNTING SYSTEM)The Navy system that keeps track of the configuration of equipment in the fleet [16].
SECONDARYThe output coil of a transformer [2].
SECONDARY CELLA cell that can be recharged by a current being passed through the cell in a direction opposite to the discharge current [1].
SECONDARY EMISSIONThe liberation of electrons from an element, other than the cathode, as a result of being struck by other high-velocity electrons [6].
SECONDARY LOOPIn a cooling system, the loop that transfers the heat from the heat source, such as electronic equipment, to the primary loop; usually distilled water [18].
SECOND DETECTOR (DEMODULATOR)The part of the receiver that separates the audio or video component from the modulated intermediate frequency [18].
SECOND-SWEEP ECHOESSee AMBIGUOUS RETURNS [18].
SELECTIVITYThe ability of a receiver to select the desired signal and reject unwanted signals [9] [17].
SELENIUMA chemical element with light-sensitive properties that makes it useful as a semiconductor material in metallic rectifiers [7].
SELF-BIASIn a vacuum tube circuit, the voltage developed by the flow of current through a resistor in the grid or cathode leads [6].
SELF-EXCITED GENERATORSDC generators in which the generator output is fed to the field to produce field excitation [5].
SELF-EXCITED METERA term used to describe meters that operate from their own power sources [16].
SELF-INDUCTION(1) The production of a counterelectromotive force in a conductor when its own magnetic field collapses or expands with a change in current in the conductor [2]. (2) The phenomenon caused by the expanding and collapsing fields of an electron that encircle other electrons and retard the movement of the encircled electrons [10].
SELF-LUMINOUS BODIESObjects that produce their own light [10].
SELF-SYNCHRONIZED RADARA type of radar in which the timing pulses are generated within the transmitter [18].
SENDING ENDSee INPUT END [10].
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SENSITIVITY(1) For an ammeter, the amount of current that will cause full-scale deflection of the meter. (2) For a voltmeter, the ratio of the voltmeter resistance divided by the full-scale reading of the meter; expressed in ohms per volt [3] [16]. (3) The ability of a receiver to reproduce very weak signals. The greater the receiver sensitivity, the weaker the signal that can be reproduced [17]. (4) Efficiency of a microphone. Describes microphone power delivered to a matched-impedance load as compared to the sound level being converted. Usually expressed in terms of the electrical power level [12].
SENSITIVITY TIME CONTROL (STC)A circuit that varies the gain of a receiver as a function of time [18].
SERIES CIRCUITAn arrangement where electrical devices are connected so that the total current must flow through all the devices; electrons have one path to travel from the negative terminal to the positive terminal [1].
SERIES-CONNECTED DUPLEXERA configuration in which the tr spark gap is connected in series in one leg of the transmission line one-half wavelength away from the T-junction [18].
SERIES-DIODE DETECTORThe semiconductor diode in series with the input voltage and the load impedance. Sometimes called a VOLTAGE-DIODE DETECTOR [12].
SERIES-FED OSCILLATORAn oscillator in which dc power is supplied to the amplifier through the tank circuit or a portion of the tank circuit [9].
SERIES LIMITERA diode connected in series with the output, in which the output is taken across the resistor. Either the positive or negative alternation of the input wave is eliminated [9].
SERIES-NEGATIVE LIMITERA diode connected in series with the output, in which the output is taken across the resistor. It eliminates the negative alternation of the input wave [9].
SERIES-PARALLEL CIRCUITA circuit that consists of both series and parallel networks [1] [9].
SERIES PEAKINGA technique used to improve high-frequency response in which a peaking coil is placed in series with the output signal path [8].
SERIES-POSITIVE LIMITERA diode connected in series with the output, in which the output is taken across a resistor. It eliminates the positive alternation of the input wave [9].
SERIES-RESONANT CIRCUITA resonant circuit in which the source voltage is connected in series with a capacitor and an inductor (also in series) to furnish a low impedance at the frequency at which the circuit is resonant [9] [10].
SERIES VOLTAGE REGULATORA regulator with a regulating device that is in series with the load resistance [7].
SERIES-WOUND MOTORS AND GENERATORSMachines in which the armature and field windings are connected in series with each other [5].
SERVOAMPLIFIEREither ac or dc amplifiers used in servosystems to build up signal strength. These amplifiers usually have relatively flat gain versus frequency response, minimum phase shift, low output impedance, and low noise level [15].
SERVOMOTORAn ac or dc motor used in servosystems to move a load to a desired position or at a desired speed. The ac motor is usually used to drive light loads at a constant speed, while the dc motor is used to drive heavy loads at varying speeds [15].
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SERVOSYSTEMAn automatic feedback control system that compares a required condition (desired value, position, and so forth) with an actual condition and uses the difference to drive a control device to achieve the required condition [15].
SETA unit or units and the assemblies, subassemblies, and parts connected or associated together to perform a specific function [17].
SEXADECIMALSame as HEXADECIMAL [13].
SHADOWA dead spot (minimum radiation) caused by the physical obstruction of transmitted waves by a feed horn [18].
SHAPING CIRCUITA circuit that alters the shapes of input waveforms [9].
SHARP-CUTOFF TUBEThe opposite of a remote-cutoff tube. An electron tube that has evenly spaced grid wires. The amplification of the sharp-cutoff tube is limited by the bias voltage and tube characteristics [6].
SHELF LIFEThe period of time that a cell or battery may be stored and still be useful [1].
SHIELDED PAIRA line consisting of parallel conductors separated from each other and surrounded by a solid dielectric [10].
SHIELDING(1) A metallic covering used to prevent magnetic or electromagnetic fields from affecting an object [1]. (2) Technique designed to minimize internal and external interference [14].
SHORT CIRCUITAn unintentional current path between two components in a circuit or between a component and ground; usually caused by a circuit malfunction [1] [3] [16].
SHORT-CIRCUITED LINEA transmission line that has a terminating impedance equal to 0 [10].
SHUNTA resistive device placed in parallel with another component. Appreciable current may flow through it and an appreciable voltage may exist across it [12].
SHUNT-DIODE DETECTORA diode detector in which the diode is in parallel with the input voltage and the load impedance. Also known as a current detector because it operates with smaller input levels [12].
SHUNT-FED OSCILLATORAn oscillator that receives its dc power for the transistor or tube through a path both separate from and parallel to the tank circuit [9].
SHUNT PEAKINGA technique used to improve high-frequency response in which a peaking coil is placed in parallel (shunt) with the output signal path [8].
SHUNT RESISTORA resistor in parallel. In an ammeter, shunt resistors are used to provide multiple ranges [3].
SHUNT VOLTAGE REGULATORA regulator whose regulating device is in parallel with the load resistance [7].
SHUNT-WOUND MOTORS AND GENERATORSMachines in which the armature and field windings are connected in parallel (shunt) with each other [5].
SIEMENSThe new and preferred term for MHO [1].
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SIGNALA general term used to describe any ac or dc of interest in a circuit; for example, input signal [8] [15].
SIGNAL DISTORTIONAny unwanted change to the signal [12].
SIGNIFICANT SIDEBANDSThose sidebands with significantly large amplitude [12].
SILICONA metallic element which, in its pure state, is used as a semiconductor [7].
SILICON-CONTROLLED RECTIFIER (SCR)A semiconductor device that functions as an electrically controlled switch [7].
SINE WAVE(1) The curve traced by the projection on a uniform time scale of the end of a rotating arm, or vector. Also known as a sinusoidal wave [2]. (2) The basic synchronous alternating waveform for all complex waveforms [12].
SINGLE-ENDED MIXERSee UNBALANCED CRYSTAL MIXER [18].
SINGLE LINE DIAGRAMA diagram which shows, by means of single lines and graphic symbols, the course of an electric circuit or system of circuits and the component devices or parts used therein [4].
SINGLE, STATIONARY-LOBE SCANNING SYSTEMAntenna (with a single, stationary beam) that is rotated to obtain 360-degree coverage [18].
SINKSee OUTPUT END [10].
SKIN EFFECTThe tendency for alternating current to concentrate in the surface layer of a conductor. The effect increases with frequency and serves to increase the effective resistance of the conductor [10] [11].
SKIP DISTANCEThe distance from a transmitter to the point where the sky wave is first returned to earth [10].
SKIP ZONEA zone of silence between the point where the ground wave becomes too weak for reception and the sky wave is first returned to earth [10].
SKY WAVESRadio waves reflected back to earth from the ionosphere [10].
SLANT RANGESee RANGE [18].
SLIPThe difference between rotor speed and synchronous speed in an ac induction motor [5].
SLIP RINGSContacts that are mounted on the shaft of a motor or generator to which the rotor windings are connected and against which the brushes ride [5]. Devices for making electric connections between stationary and rotating contacts.
SLOPE DETECTORA tank circuit tuned to a frequency, either slightly above or below an FM carrier frequency, that is used to detect intelligence [12].
SLOTNarrow opening in a waveguide wall used to couple energy in or out of the waveguide. Also called an aperture or a window [11].
SNAP-ACTINGChanging position quickly with the aid of a spring [3].
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SOLENOIDAn electromagnetic device that changes electrical energy into mechanical motion; based upon the attraction of a movable iron plunger to the core of an electromagnet [3].
SOLIDOne of the three states of matter; it has definite volume and shape (ice is a solid) [1].
SOLID-STATE DEVICEAn electronic device that operates by the movement of elections within a solid piece of semiconductor material [7].
SONICPertaining to sounds capable of being heard by the human ear [10].
SOURCE(1) The object that produces the waves or disturbance. (2) The name given to them end of a two-wire transmission line that is connected to a source [10]. (3) The device which furnishes the electrical energy used by a load [1].
SOURCE, MAINTENANCE, AND RECOVERABILITY CODE (SM & R CODE)Specifies maintenance level for repair of components or assemblies [14].
SPACEAbsence of an RF signal in cw keying. Key-open condition or lack of data in communications systems. Also a period of no signal [12].
SPACE CHARGEAn electrical charge distributed throughout a volume or space [6].
SPACE DIVERSITYReception of radio waves by two or more antennas spaced some distance apart [10].
SPACE WAVERadio waves that travel directly from the transmitter to the receiver and remain in the troposphere [10].
SPACINGThe condition in teletypewriter operation where a circuit is open and no current flows [17].
SPARK-GAP MODULATORA modulator that consists of a circuit for storing energy, a circuit for rapidly discharging the storage circuit (spark gap), a pulse transformer, and a power source [12].
SPECIAL PURPOSE ELECTRONIC TEST EQUIPMENT (SPETE)Test equipment that is specifically designed to generate, modify, or measure a range of electronic functions of a specific or peculiar nature on a single system or equipment [16].
SPECIFIC GRAVITYThe ratio between the density of a substance and that of pure water at a given temperature [1].
SPECIFIC RESISTANCEThe resistance measured in ohms of a unit volume of a substance to the flow of electric current. (The unit volume used is generally the circular mil-foot.) [4]
SPECTRUM(1) The entire range of electromagnetic waves arranged in order of their frequencies. (2) The range of frequencies considered in a system [10].
SPECTRUM ANALYSISThe display of electromagnetic energy arranged according to wavelength or frequency [12].
SPECTRUM ANALYZERA test instrument that provides a visual display of the frequency distribution of an RF signal such as a transmitter output [18].
SPIN VECTORIn a gyro, a vector representing the angular velocity of the gyro rotor. The spin vector lies along the spin axis of the rotor [15].
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SPHERICAL WAVEFRONTSWaves of energy that spread out in concentric circles [18].
SPLATTERUnwanted sideband frequencies that are generated from overmodulation [12].
SPLICEA joint formed by the connecting of two or more conductors [4].
SPORADIC E LAYERIrregular, cloud-like patches of unusually high ionization. Often forms at heights near the normal E layer [10].
SPREADERInsulator used with transmission lines and antennas to keep the parallel wires separated [10].
SPROCKET TUNERA mechanical tuning device for magnetron tubes that changes the frequency of the cavities by changing the inductance. Also called a CROWN-OF-THORNS TUNER [11].
SQUARE MILThe area of a square, the sides of which are each equal to 1 mil. One square mil is equal to 1.2732 circular mils [4].
SQUELCHA circuit that cuts off the output of a receiver when there is no input [17].
SQUIRREL-CAGE WINDINGSA type of rotor winding in which heavy conductors are imbedded in the rotor body. The conductors are shorted together at the ends by continuous rings. It is widely applied in ac induction motors. Physically, it appears as a rotating squirrel-cage, thus the name [5].
STABILITYIn a magnetron, the ability to maintain normal operating characteristics [18].
STAGEOne of a series of circuits within a single device; for example, first stage of amplification [8].
STAGGER TUNINGA method of klystron tuning in which the resonant cavities are tuned to slightly different frequencies to increase the bandwidth of the amplifier [11].
STANDING WAVEThe distribution of voltage and current, formed by the incident and reflected waves, that has minimum and maximum points on a resultant wave that appear to stand still [10].
STANDING-WAVE RATIO (SWR)The ratio of the maximum (voltage, current) to the minimum (voltage, current) points of a transmission line. Indicates the impedance matching quality of the termination of the line [10] [11].
STARTThe first unit of a teletypewriter signal. It is always a space [17].
STATIC(1) A fixed nonvarying condition, without motion [13]. (2) Atmospheric noise, as in a receiver.
STATIC ELECTRICITYStationary electricity that is in the form of a charge. The accumulated electric charge on an object [1].
STATOR(1) The stationary part of a rotating electrical machine. The stator may be either the field or the armature, depending on the design of the machine [5]. (2) The stationary member of a synchro that consists of a cylindrical structure of slotted laminations on which three Y-connected coils are wound with their axes 120 degrees apart. Depending on the type of synchro, the stator's functions are similar to the primary or secondary windings of a transformer [15].
STATUTE MILE—5,280 feet [18].
STEP-BY-STEP COUNTERA counter that provides an output for each cycle of the input in one-step increments [9].
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STEP-TRANSMISSION SYSTEMA data transmission system that operates on direct current. It consists of a step transmitter (rotary switch) and a step motor interconnected to transmit data (information) between remote locations [15].
STICKOFF VOLTAGEA low voltage used in multispeed synchrosystems to prevent false synchronizations [15].
STOPThe last unit of a teletypewriter signal. It is always a mark [17].
STRANDED CONDUCTORA conductor composed of a group of wires. The wires in a stranded conductor are usually twisted together and not insulated from each other [4].
STRANDSFine metallic filaments twisted together to form a single wire [4].
STRATOSPHERELocated between the troposphere and the ionosphere; it has little effect on radio waves [10].
STROBOSCOPEAn instrument that allows viewing of rotating or reciprocating objects by producing the optical effect of a slowing down or stopping motion [16].
STUBShort section of a transmission line used to match the impedance of a transmission line to an antenna. Can also be used to produce desired phase relationships between connected elements of an antenna [10] [18].
SUBASSEMBLYConsists of two or more parts that form a portion of an assembly or a unit [17].
SUBHARMONICAn exact submultiple of the fundamental frequency. Even subharmonics are one-half, one-quarter, and so on. Odd subharmonics are one-third, one-fifth, and so on of the fundamental frequency [17].
SUBSTRATEMounting surface for integrated circuits. May be semiconductor or insulator material depending on type of IC [14].
SUDDEN IONOSPHERIC DISTURBANCEAn irregular ionospheric disturbance that can totally blank out hf radio communications [10].
SUMMING NETWORKA combination of two or more parallel resistors used in servosystems as an error detector. The output of the network is the algebraic sum of the inputs [15].
SUPERHETERODYNE RECEIVERA type of receiver that uses a mixer to convert the RF echo to an IF signal for amplification [18].
SUPERHIGH FREQUENCYThe band of frequencies from 3 gigahertz to 30 gigahertz [17].
SUPERSONIC(1) Speed greater than the speed of sound [10]. (2) Ultrasonic.
SUPPORT SYSTEMFor a radar, a system that provides an auxiliary input, such as dry air, electrical power, or liquid cooling [18].
SUPPRESSIONThe process of eliminating an undesired portion of a signal [17].
SURFACE WAVERadio waves that travel along the contours of the earth, thereby being highly attenuated [10].
SWAMPING RESISTORA resistor used to increase or "broaden" the bandwidth of a circuit [8].
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SWITCH(1) A device used to connect, disconnect, or change the connections in an electrical circuit [1]. (2) A device used to open or close a circuit [3].
SYMMETRICAL MULTIVIBRATORA circuit that generates square waves [18].
SYMPTOM ELABORATIONUsing built-in indicating instruments or other aids to define equipment malfunction [16].
SYMPTOM RECOGNITIONRecognition of a situation in equipment operation that is not normal [16].
SYNCHROA small motorlike analog device that operates like a variable transformer and is used primarily for the rapid and accurate transmission of data among equipments and stations [15].
SYNCHRO CAPACITORA unit containing three delta-connected capacitors. The synchro capacitor is used in synchro systems to increase the system's accuracy by cancelling or reducing the phase shift introduced by synchro inductance [15].
SYNCHRONIZERA circuit that supplies timing signals to other radar components [18].
SYNCHRONIZING NETWORKA circuit, also called a crossover or switching network, used in servosystems to sense how far the load is from the point of correspondence; it then functions to switch the appropriate signal into control [15].
SYNCHRONOUSA type of teletypewriter operation where both transmitter and receiver operate continuously [17].
SYNCHRONOUS MOTORAn ac motor whose rotor is activated by dc. It is characterized by constant speed and requires squirrel-cage windings or some other method to be self-starting [5].
SYNCHRONOUS ORBITAn orbit in which the satellite moves or rotates at the same speed as the earth [17].
SYNCHRONOUS SPEEDThe speed at which the rotating field in an ac motor revolves. This speed is a function of the number of poles in the field and the frequency of the applied voltage [5].
SYNCHRONOUS TUNINGIn a klystron amplifier, a method of tuning that tunes all the resonant cavities to the same frequency. High gain is achieved, but the bandwidth is narrow [11].
SYNCHRO SYSTEMTwo or more synchros interconnected electrically. The system is used to transmit data among equipments and stations [15].
SYNCHRO TESTERA synchro receiver with a calibrated dial. This receiver is used primarily for locating defective synchros. It can also be used for zeroing synchros [15].
SYSTEMA combination of sets, units, assemblies, subassemblies, and parts joined together to form a specific operational function or several functions [17].
TACHOMETER(1) A small ac or dc generator, sometimes referred to as a rate generator, that converts its shaft speed into an electrical output. The tachometer is frequently used in servosystems to sense the velocity of a load [15]. (2) An instrument that measures the rate at which a shaft is turning [16].
TANK CIRCUITA tuned circuit used to temporarily store energy. Also referred to as a parallel-resonant circuit [9].
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TAPPED RESISTORA wire-wound, fixed resistor having one or more additional terminals along its length, generally for voltage-divider applications [1].
TARGETIn radar, a specific object of radar search or detection [18].
TARGET RESOLUTIONThe ability of a radar to distinguish between two or more targets that are close to each other [18].
TELECOMMUNICATIONSThe transmission, emission, or reception of signs, signals, writings, images, or sounds. This is done by visual, oral, wire, radio, or other means [17].
TELETYPEWRITERA machine that can transmit and/or receive letters, numbers, or symbols. It may have a keyboard similar to a typewriter [17].
TEMPERATURE COEFFICIENTThe amount of change of resistance in a material per unit change in temperature [1] [4].
TEMPERATURE INVERSIONThe condition in which warm air is formed above a layer of cool air that is near the earth's surface [10].
TEMPESTA term normally used to describe compromising emanations. These emanations are unintentionally radiated signals that could disclose classified information [17].
TENSILE STRENGTHThe greatest stress a substance can withstand along its length without tearing apart [4].
TERMINALAn electrical connection [1] [4].
TERMINAL BOARDAlso called a terminal strip. An insulating base or slab equipped with terminals for connecting wiring [4].
TERMINAL DIAGRAMA diagram of a switch, relay, terminal board, or other component showing the connections to the equipment [4].
TERMINAL LUGA device attached to a conductor to permit connection to a terminal [4].
TEST EQUIPMENTA general term applied to devices used to test electrical and electronic circuits [3].
TEST EQUIPMENT INDEXThe Navy guide used to assist in identifying portable electrical/ electronic test equipment required for support of prime electrical/electronic, IC, weapons, and reactor instrumentation systems [16].
TEST POINTSLocations in equipment that are accessible to the technician's test probes where operating voltages or signals can be monitored [16].
TETRODE TUBEA four-electrode electron tube containing a plate, a cathode, a control grid, and a screen grid [6].
THERMAL INERTIAThe capacity of a soldering iron to generate and maintain a satisfactory soldering temperature while giving up heat to the material being soldered [4].
THERMAL-MAGNETIC TRIP ELEMENTA single circuit breaker trip element that combines the action of a thermal and a magnetic trip element [3].
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THERMAL RUNAWAYA conduction that exists when heat causes more electron-hole pairs to be generated, which, in turn, causes more heat and which may eventually cause diode destruction [7].
THERMAL TRIP ELEMENTA circuit breaker trip element that uses the increased bending of a bimetallic strip caused by increased current to open a circuit [3].
THERMIONIC EMISSIONEmission of electrons from a solid body as a result of elevated temperature [6].
THERMISTOR(1) A semiconductor device whose resistance varies with temperature [4]. (2) A type of bolometer characterized by a decrease in resistance as the dissipated power increases [16].
THERMOCOUPLEA junction of two dissimilar metals that produces a voltage when heated [1].
THERMOCOUPLE METER MOVEMENTA meter movement that uses the current induced in a thermocouple by the heating of a resistive element to measure the current in a circuit; used to measure ac or dc [3].
THERMOPLASTICA synthetic mixture of rosins that is flexible and used as an insulting material. Generally used as an insulator for low- and medium-range voltages [4].
THETAThe Greek letter (θ) used to represent phase angle [2].
THICK FILM COMPONENTSPassive circuit components (resistors and capacitors) having a thickness of 0.001 centimeter [14].
THIN FILM COMPONENTSPassive circuit elements (resistors and capacitors) deposited on a substrate to a thickness of 0.0001 centimeter [14].
THREE-ELEMENT ARRAYAn array with two parasitic elements (reflector and director) and a driven element [10].
THREE-DIMENSIONAL RADAR (3D)A radar set that measures the range, bearing and altitudes of a target [18].
THROWIn a switch, the number of different circuits each pole can control; for example, single throw and double throw [3].
THYRATRONA gas tube used as a modulator switching device [18].
THYRATRON TUBEA gas-filled triode in which a sufficiently large positive pulse applied to the control grid ionizes the gas and causes the tube to conduct, after which the control grid has no effect in conduction [6] [12].
TICKLER COILA small coil connected in series with the collector or plate circuit of a transistor or tube and inductively coupled to the base or grid-circuit coil to establish feedback (regeneration) [9].
TIME CONSTANTTime required for an exponential quantity to change by an amount equal to 63.2 percent of the total change that can occur [2] [9].
TIME-DIVISION MULTIPLEXINGThe process that periodically samples the full 360 degrees of each sine wave. The sample can be of a received signal or of a signal to be transmitted [17].
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TIME LAGThe delay in a servosystem between the application of the input signal and the actual movement of the load [15].
TIMERSee SYNCHRONIZER [18].
TINNINGThe process of applying a thin coat of solder to materials prior to their being soldered; for example, application of a light coat of solder to the filaments of a conductor to hold the filaments in place prior to soldering of the conductor [4].
TOLERANCE(1) The maximum permissible error or variation from the standard in a measuring instrument. (2) A maximum electrical or mechanical variation of specifications that can be tolerated without impairing the operation of a device [1].
TONESMusical sounds [10].
TONE-TERMINAL SETEquipment that converts TTY dc pulses into audio tones for modulation of a transmitter in audio-frequency-tone shift transmissions [17].
TOP-HATAn antenna that is center-fed and capacitively loaded [17].
 This measurement is expressed either in ounce-inches for torque synchro systems or in pound-feet for heavy machinery [15].
TORQUE DIFFERENTIAL RECEIVER (TDR)A type of differential synchro that takes two electrical inputs, one to the rotor and one to the stator, and produces a mechanical output. The output is the angular position of the rotor that represents the algebraic sum or difference of the two electrical inputs [15].
TORQUE DIFFERENTIAL SYNCHRO SYSTEMA synchro system containing either a TDX or a TDR. This system is used in applications where it is necessary to compare two signals, add or subtract the signals, and furnish an output proportional to the sum or difference between the two signals [15].
TORQUE DIFFERENTIAL TRANSMITTER (TDX)This type of synchro is functionally the same as the CDX, except that it is used in torque systems rather than control systems [15].
TORQUE GRADIENTA term used in the rating of torque synchros. It is expressed in the number of inch-ounces of torque required to pull a specific synchro 1 degree away from its normal position; for example, 0.4 inch-ounce per degree [15].
TORQUE RECEIVER (TR)A type of synchro that converts the electrical input supplied to its stator back to a mechanical angular output through the movement of its rotor [15].
TORQUE SYNCHRO SYSTEMA synchro system that uses torque synchros to move light loads such as dials, pointers, and other similar devices [15].
TORQUE TRANSMITTER (TX)This type of synchro is functionally the same as the CX, except that it is used in torque synchro systems [15].
TORQUE VECTORIn a gyro, a vector representing the rotary motion applied to change the direction of the rotor axis. The torque vector represents the axis about which the applied force is felt [15].
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TOTAL RESISTANCE(RT) The equivalent resistance of an entire circuit. For a series circuit: RT = R1 + R2 + R3 ...Rn. For parallel circuits:
TOXIC VAPORSVapors emitted by a substance that can do bodily harm [4].
TR RECOVERY TIMETime required for a fired tr or atr tube to deionize to a normal level of conductance [18].
TRACKOperational phase of a fire-control or track radar during which the radar beam is kept on the target [18].
TRACK RADARRadar that provides continuous range, bearing, and elevation data by keeping the RF beam on the target [18].
TRANSCONDUCTANCETransconductance is a ratio of the change in plate current to a change in grid voltage with the plate voltage held constant. Transconductance (gm) is usually expressed in micromhos or millimhos. Mathematically,
transfer energy from one circuit to another [2].
TRANSFORMER EFFICIENCYThe ratio of output power to input power, generally expressed as a percentage.
secondary winding is less than the number of turns in the primary winding. This construction will provide less voltage in the secondary circuit than in the primary circuit [2].
TRANSFORMER, STEP-UPA transformer so constructed that the number of turns in the secondary winding is more than the number of turns in the primary winding. This construction will provide more voltage in the secondary circuit than in the primary circuit [2].
TRANSISTORA semiconductor device with three or more elements [7].
TRANSITIONThe time it takes to shift from a mark to a space condition or from a space to a mark condition [17].
TRANSIT TIMEThe time an electron takes to cross the distance between the cathode and the plate [6] [11].
1-78
TRANSLATIONIn a gyro, a force acting through the center of gravity of the gyro that causes no torque on the gyro rotor. Translation forces do not change the angle of the plane of rotation but move the gyroscope as a unit [15].
TRANSLUCENTThose substances, such as frosted glass, through which some light rays can pass but through which objects cannot be seen clearly [10].
TRANSMISSION LINEA device designed to guide electrical or electromagnetic energy from one point to another [10].
TRANSMISSION MEDIUMA means of transferring intelligence from point to point; includes light, smoke, sound, wire lines, and radio-frequency waves [10] [12].
TRANSMIT-RECEIVE TUBE (TR)A gas-filled RF switch that is used as a duplexer [18].
TRANSMITTEREquipment that generates and amplifies an RF carrier, modulates the RF carrier with intelligence, and radiates the signal into space [17] [18].
TRANSMITTER DISTRIBUTORA device that reads Baudot code from paper tape and allows a message to be printed on a page printer [17].
TRANSMITTER ENDSee INPUT END [10].
TRANSMITTER FREQUENCY (CARRIER FREQUENCY)The frequency of the unmodulated output of a transmitter [18].
TRANSMITTER TRANSFER SWITCHBOARDEquipment that selectively transfers remote station functions and signals to transmitters [17].
TRANSMITTING ANTENNAThe device used to send the transmitted signal energy into space [10].
TRANSPARENTThose substances, such as glass, that pass almost all of the light waves falling upon them [10].
TRANSVERSE ELECTRIC MODEA waveguide mode in which the entire electric field is perpendicular to the wide dimension and the magnetic field is parallel to the length. Also called the TE mode [11].
TRANSVERSE MAGNETIC MODEA waveguide mode in which the entire magnetic field is perpendicular to the wide dimension and some portion of the electric field is parallel to the length. Also called the TM mode [11].
TRANSVERSE WAVE MOTIONThe up and down motion of a wave as the wave moves outward [10].
TRAVERSE (BEARING) SIGNALIn a monopulse radar system, the combination of individual lobe signals that represents target-offset direction and amplitude from the antenna axis [18].
TREMENDOUSLY HIGH FREQUENCYThe band of frequencies from 300 gigahertz to 3,000 gigahertz.
TRIACA three-terminal device that is similar to two SCRs back to back with a common gate and common terminals. Although similar in construction and operation to the SCR, the triac controls and conducts current flow during both alternations of an ac cycle [7].
1-79
TRIATICA special type of monopole antenna array [17].
TRIGGERA short pulse, either positive or negative, that can be used to cause an electronic function to take place [9].
TRIGGER GENERATORSee SYNCHRONIZER [18].
TRIGGER PULSESIn radar, pulses that are used to initiate specific events [18].
TRIODE TUBEA three-electrode electron tube containing a plate, a cathode, and a control grid [6].
TRIP-ELEMENTThe part of a circuit breaker that senses any overload condition and causes the circuit breaker to open the circuit [3].
TRIP-FREE CIRCUIT BREAKERA circuit breaker that will open a circuit even if the operating mechanism is held in the ON position [3].
TRIVALENT IMPURITYAcceptor impurities containing only three valence electrons [7].
TROPOSPHEREThe portion of the atmosphere, closest to the earth's surface, where all weather phenomena take place [10].
TROPOSPHERIC SCATTERThe propagation of radio waves in the troposphere by means of scatter [10].
TROUBLE INDICATORSSignal lights used to aid maintenance personnel in locating troubles quickly [15].
TROUBLESHOOTINGThe process of locating and diagnosing faults in equipment by means of systematic checking or analysis [3] [15] [16].
TROUBLE TABLESTables of trouble symptoms and probable causes, furnished by many manufacturers to help technicians isolate problems [15].
TROUGH (BOTTOM)The peak of the negative alternation (maximum value below the line) of a sine wave [10].
TRUE BEARINGAngle between a target and true north measured clockwise in the horizontal plane [18].
TRUE NORTHGeographic north [18].
TRUE POWERThe power dissipated in the resistance of the circuit, or the power actually used in the circuit [2].
TRUNCATED PARABOLOIDA paraboloid reflector that has been cut away at the top and bottom to increase beam width in the vertical plane [18].
TRUTH TABLEA table that describes a logic function by listing all possible combinations of input values and indicating, for each combination, the true output values [13].
TUBE DYNAMIC CONDITIONRefers to the testing condition in which a vacuum tube is actually performing its function [16].
TUBE STATIC CONDITIONRefers to the testing condition in which a tube has certain voltages applied but is not in its normal operating condition [16].
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TUNED CIRCUIT(1) A circuit consisting of inductance and capacitance that can be adjusted for resonance at a desired frequency [9]. (2) A circuit that is used as a filter which passes or rejects specific frequecies [16]. (3) An LC circuit used as a frequency-determining device [8].
TUNED LINEAnother name for the resonant line. This line uses tuning devices to eliminate the reactance and transfer maximum power from the source to the line [10].
TUNNEL DIODEA heavily doped semiconductor device that has high gain and fast switching capabilities [7]. See NEGATIVE-RESISTANCE ELEMENT [11].
TUNNELINGThe piercing of a potential barrier in a semiconductor by a particle (current carrier) that does not have sufficient energy to go over the barrier [11].
TURNOne complete loop of a conductor about a core [2].
TURNS RATIOThe ratio of the number of turns in the primary winding to the number of turns in the secondary winding of a transformer [2].
TURNSTILE ANTENNAA type of antenna used in vhf communications that is omnidirectional and consists of two horizontal half-wave antennas mounted at right angles to each other in the horizontal plane [10].
TWISTED PAIRA line consisting of two insulated wires twisted together to form a flexible line without the use of spacers [10].
TWO-DIMENSIONAL RADAR (2D)Measures the range and bearing to a target [18].
TWO-M (2M)Miniature/microminiature repair program [14].
TWO-WIRE OPEN LINEA parallel line consisting of two wires that are generally spaced from 2 to 6 inches apart by insulating spacers [10].
TWO-WIRE RIBBON (TWIN LEAD)A parallel two-wire line in which uniform spacing is assured by two wires imbedded in a low-loss dielectric [10].
ULTRAHIGH FREQUENCYThe band of frequencies from 300 megahertz to 3 gigahertz [17].
ULTRASONIC(1) Sounds above 20,000 hertz [10]. (2) Supersonic.
UNBALANCED CRYSTAL MIXERA circuit consisting of a section of coaxial transmission line one-half wavelength long that is tuned to the difference (intermediate) frequency between the local oscillator and RF echo signals [18].
UNIDIRECTIONALIn one direction only [1].
UNIDIRECTIONAL ARRAYAn antenna array that radiates in only one general direction [10].
UNIJUNCTION TRANSISTOR (UJT)A three-terminal, semiconductor device with a negative resistance characteristic that is used in switching circuits, oscillators, and wave-shaping circuits [7].
UNIT(1) An assembly or any combination of parts, subassemblies, and assemblies mounted together. Normally capable of independent operation [17]. (2) A single object or thing [13].
UNIT SIZEThe standards adopted to make comparisons between things of like value (for example, the unit size for conductors is the mil-foot) [4].
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UNIVERSAL TIME CONSTANT CHARTA chart used to find the time constant of a circuit if the impressed voltage and the values of R and C or R and L are known [2].
UNTUNED LINEAnother name for the flat or nonresonant line [10].
UP LINKThe frequency used to transmit a signal from earth to a satellite [17].
UPPER-FREQUENCY CUTOFFThe highest frequency a circuit can pass [9].
UPPER SIDEBANDAll of the sum frequencies above the carrier [12].
VACUUM EVAPORATIONProcess of producing thin film components [14].
VALENCEThe measure of the extent to which an atom is able to combine directly with other atoms. It generally depends on the number and arrangement of the electrons in the outermost shell of the atom [1].
VALENCE SHELLThe electrons that form the outermost shell of an atom [1].
V ANTENNAA bidirectional antenna, shaped like a V, which is widely used for communications [10].
VARAbbreviation for volt-amperes reactive [2].
VARACTORA PN junction semiconductor, designed for microwave frequencies, in which the capacitance varies with the applied voltage [7] [11] [12].
VARACTOR FM MODULATORAn FM modulator that uses a voltage-variable capacitor (varactor) [12].
VARIABLEA representative symbol that can assume any of a given set of values [13].
VARIABLE ATTENUATORAn attenuator for reducing the strength of an ac signal either continuously or in steps, without causing signal distortion [11].
VARIABLE-MU-TUBESame as REMOTE-CUTOFF TUBE [6].
VARIABLE RESISTORA wire-wound or composition resistor, the value of which may be changed over a designed range [1].
VARNISHED CAMBRICCotton cloth coated with insulation varnish. An insulation used on high- voltage conductors [4].
VECTORA line used to represent both direction and magnitude [2] [12].
VEITCH DIAGRAMA diagram consisting of joined squares, which is used to give a graphic representation of basic logic relations [13].
VELOCITYThe rate at which a disturbance travels through a medium [10].
VELOCITY MODULATIONModification of the velocity of an electron beam by the alternate acceleration and deceleration of electrons [11].
VELOCITY SERVOSYSTEMA servosystem which controls the speed of the load it is driving [15].
VERTICAL AXISOn a graph, the straight line axis that is plotted from bottom to top [10].
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VERTICAL DEFLECTION PLATESA pair of parallel electrodes in a CRT that moves the electron beam up and down [6].
VERTICAL PATTERNThe part of a radiation pattern that is radiated in the vertical plane [10].
VERTICAL PLANEAn imaginary plane that is perpendicular to the horizontal plane [11] [18].
VERTICALLY POLARIZEDWaves that are radiated with the E field component perpendicular to the earth's surface [10].
VERY HIGH FREQUENCYThe band of frequencies from 30 megahertz to 300 megahertz [17].
VERY LARGE SCALE INTEGRATION (vlsi)An integrated circuit containing over 2,000 logic gates or 64,000 bits of memory [14].
VERY LOW FREQUENCYThe band of frequencies from 3 kilohertz to 30 kilohertz [17].
VIDEO AMPLIFIERAn amplifier designed to amplify the entire band of frequencies from 10 hertz (10 Hz) to 6 megahertz (6 MHz). Also called a WIDE-BAND AMPLIFIER [8].
VIDEO ENHANCEMENT FEATURESSee ANTIJAMMING CIRCUITS [18].
VINCULAPlural of vinculum (see below) [13].
VINCULUMA straight horizontal line placed over one or more members of a compound logic expression to negate or complement. Also, used to join two or more members together [13].
VIRTUAL GROUNDA point in a circuit that is at ground potential (0 V) but is not connected to ground [8].
VOLTThe unit of electromotive force or electrical pressure. One volt is the pressure required to send 1 ampere of current through a resistance of 1 ohm [1].
VOLTAGE(1) The term used to signify electrical pressure. Voltage is a force that causes current to flow through an electrical conductor. (2) The voltage of a circuit is the greatest effective difference of potential between any two conductors of the circuit [1].
VOLTAGE AMPLIFIERAn amplifier in which the output-signal voltage is greater than the input-signal voltage [8].
VOLTAGE-DIODE DETECTORA series-diode detector in which the diode is in series with the input voltage and the load impedance [12].
VOLTAGE DIVIDERA series network in which desired portions of the source voltage may be tapped off for use in the circuit [1].
VOLTAGE DROPThe difference in voltage between two points. It is the result of the loss of electrical pressure as a current flows through a resistance [1] [4].
VOLTAGE-FEED METHODSame as END-FEED METHOD [10].
VOLTAGE GAINThe ratio of output voltage to input voltage in an amplifier [6].
VOLTAGE MULTIPLIERSMethods of increasing voltages; used primarily where low current is required [7].
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VOLTAGE REGULATIONA measure of the ability of a generator or power supply to maintain a constant output voltage from no-load to full-load operation. Expressed as a percentage of full-load voltage; the better the regulation, the lower the percent [5].
VOLTAGE STANDING WAVE RATIO (VSWR)In a waveguide, the ratio of the electric field (voltage) at a maximum point to that of an adjacent minimum point [10] [18].
VOLTMETERA meter used to measure voltage [3] [16].
WAFERA slice of semiconductor material upon which monolithic ICs are produced [14].
WAFER SWITCHA rotary switch in which the contacts are arranged on levels. Each level (wafer) is electrically independent but mechanically connected by the shaft of the switch [3].
WATTThe unit of electrical power that is the product of voltage and current [16].
WATTAGE RATINGA rating expressing the maximum power that a device can safely handle [1].
WATT-HOURA practical unit of electrical energy equal to one watt of power for one hour [1].
WATT-HOUR METERA meter used to measure electrical energy [3].
WATTMETERA meter used to measure electrical power [3] [16].
WAVE ANTENNASame as BEVERAGE ANTENNA [10].
WAVEFORMThe shape of the wave obtained when instantaneous values of an ac quantity are plotted against time in rectangular coordinates [2].
WAVEFORM ANALYSISObservation displays of voltage and current variations with respect to time or by harmonic analysis of complex signals [16].
WAVEFRONTA small section of an expanding sphere of electromagnetic radiation that is perpendicular to the direction of travel of the energy [10].
WAVEGUIDEA rectangular, circular, or elliptical metal pipe designed to transport electromagnetic waves through its interior [10] [11].
WAVEGUIDE DUPLEXERTR and atr tubes housed in a resonant cavity attached to a waveguide system.
WAVEGUIDE MODE OF OPERATIONAny particular field configuration in a waveguide that satisfies the boundary conditions. Usually divided into two broad types: the transverse electric (TE) and the transverse magnetic (TM) modes [11].
WAVEGUIDE POSTA rod of conductive material used as impedance changing devices in waveguides [11].
WAVEGUIDE SCREWA screw that projects into a waveguide for the purpose of changing the impedance [11].
WAVELENGTHThe distance, usually expressed in meters, traveled by a wave during the time interval of one complete cycle. It is equal to the velocity divided by the frequency [2] [10] [12].
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WAVEMETERSCalibrated resonant circuits that are used to measure frequency [16]. An instrument for measuring the wavelength of an RF wave [18].
WAVE MOTIONA recurring disturbance advancing through space with or without the use of a physical medium [10].
WAVE TRAINA continuous series of waves with the same amplitude and wavelength [10].
WAVE WINDINGAn armature winding in which the two ends of each coil are connected to commutator segments separated by the distance between poles [5].
WEBER'S THEORYA theory of magnetism which assumes that all magnetic material is composed of many tiny magnets. A piece of magnetic material that is magnetized has all of the tiny magnets aligned so that the north pole of each magnet points in one direction [1].
WHEATSTONE BRIDGEAn ac bridge circuit used to measure unknown values of resistance, inductance, or capacitance [16].
WIDE-BAND AMPLIFIERAn amplifier designed to pass an extremely wide band of frequencies, such as a video amplifier [8].
WINDOWSee SLOT [11].
WIREAn insulated conductor, with low resistance to current flow, that is either solid or stranded [1] [4].
WIRING DIAGRAMA diagram that shows the connections of an equipment or its component devices or parts. It may cover internal or external connections, or both, and contains such detail as is needed to make or trace connections that are involved [4].
WOBBLE FREQUENCYThe frequency at which an electron wobbles on its axis under the influence of an external magnetic field of a given strength [11].
WORDS-PER-MINUTEAn approximate rate of speed. It means the number of five letter words with a space between them that can be transmitted or received in a one-minute period [17].
WORKThe product of force and motion [1].
WORKING VOLTAGEThe maximum voltage that a capacitor may operate at without the risk of damage [2].
WYE (Y)A 3-phase connection in which one end of each phase winding is connected to a common point. Each free end is connected to a separate phase wire. The diagram of this connection often resembles the letter Y [5].
X-AXISIn a gyro, the spin axis of the gyro [15].
X-RAY EMISSIONPenetrating radiation similar to light, but with shorter wavelength, that can penetrate human tissue [18].
YAGI ANTENNAA multielement parasitic array. The elements lie in the same plane as those of the end- fire array [10].
Y-AXISIn a gyro, an axis through the center of gravity and perpendicular to the spin axis [15].
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Z-AXISIn a gyro, an axis through the center of gravity and mutually perpendicular to both the X (spin) and Y axes [15].
ZENER DIODEA PN-junction diode designed to operate in the reverse-bias breakdown region [7].
ZENER EFFECTA reverse breakdown effect in diodes in which breakdown occurs at reverse voltages below 5 volts. The presence of a high energy field at the junction of a semiconductor produces the breakdown [7].
ZEROINGThe process of adjusting a synchro to its electrical zero position [15].
ZONE OF MUTUAL VISIBILITYThe area where the satellite can be seen by both the up- and down- link earth terminals [17].


Sherlock
Sherlock Holmes and Dr Watson's adventures in 21st Century London. A thrilling, funny, fast-paced contemporary remake of the Arthur Conan Doyle classic. Each season consists of 3 90 minute episodes.
Sherlock Holmes and Dr Watson's adventures in 21st Century London. A thrilling, funny, fast-paced contemporary remake of the Arthur Conan Doyle classic. Each season consists of 3 90 minute episodes.
Mr. Robot centers on a young programmer, Elliot (Rami Malek), who suffers from a debilitating anti-social disorder and decides that he can only connect to people by hacking them. He finds himself in the intersection between a cybersecurity firm he works for and the underworld organizations that are recruiting him to bring down corporate America. Slater plays Mr. Robot, a mysterious anarchist who recruits Elliot. Anonymous Content’s Steve Golin (“True Detective”) and Chad Hamilton (“Breakup at a Wedding”) also executive produce.
“Doctor Who” is the continuing saga of a mysterious time traveler who picks up human companions and faces evil foes with little more than his wits and a sonic screwdriver while he journeys throughout time and space in the TARDIS—a unique craft disguised as a police call box.
Fringe follows the exploits of FBI Special Agent Olivia Dunham, scientist Walter Bishop, and his son Peter as they investigate aspects of fringe science (telepathy, levitation, invisibility, reanimation, genetic mutation, etc).
An ex-CIA agent connects up with a mysterious man with a state of the art machine that predicts who will be involved in a violent crime. Together they will try to prevent the crimes from happening.
Based upon characters published by DC Comics, through a freak accident, scientist Barry Allen (Grant Gustin) is given the power of super speed that transforms him into the Fastest Man Alive.
DC Comics hero the Green Arrow comes to television in this drama starring Stephen Amell as Oliver Queen, billionaire playboy-turned arrow-wielding vigilante. After a shipwreck in which he's presumed dead, he returns home and ventures on a quest to right the wrongs of his past, and save the city of Starling from a rising tide of crime.
Sense8 is centered around eight characters that live in different cities around the world who experience a violent vision, and soon find themselves mentally connected by this experience. They are suddenly able to see and talk to each other as though they were in the same place, and have access to each other's deepest secrets. Not only must these eight adapt to this new ability and to each other, they must figure out what happened and why and what it means for the future of humanity, while being hunted by an organization out to capture, kill or vivisect them.
In the series, a young boy vanishes into thin air. As friends, family, and local police search for answers, they are drawn into an extraordinary mystery involving top secret experiments, terrifying supernatural forces, and one very strange little girl. The series, set in Indiana, is a love letter to the ‘80s classics that captivated a generation.
Anthony Hopkins will star as Dr. Robert Ford, the head of a futuristic theme park where robots go crazy and attack the guests. James Marsden, Ed Harris, Evan Rachel Wood, Thandie Newton, Jeffrey Wright and Miranda Otto will co-star.