Electronics (Mike Jaroch)
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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]. | ||
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]. | ||
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]. | ||
SECASSHIP EQUIPMENT CONFIGURATION ACCOUNTING SYSTEM —The Navy system that keeps track of the configuration of equipment in the fleet [16]. | ||
SECOND DETECTORThe part of the receiver that separates the audio or video component from the modulated intermediate frequency [18]. | ||
SECOND-SWEEP ECHOESSee AMBIGUOUS RETURNS [18]. | ||
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]. | ||
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]. | ||
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 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 PEAKINGA technique used to improve high-frequency response in which a peaking coil is placed in series with the output signal path [8]. | ||
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-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-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-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]. | ||
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 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-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-WOUND MOTORS AND GENERATORSMachines in which the armature and field windings are connected in parallel (shunt) with each other [5]. | ||
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 RECTIFIERA 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 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]. | |
SINGLE-ENDED MIXERSee UNBALANCED CRYSTAL MIXER [18]. | ||
SINKSee OUTPUT END [10]. | ||
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]. | ||
SM & R CODESOURCE, MAINTENANCE, AND RECOVERABILITY CODE (SM & R CODE)—Specifies maintenance level for repair of components or assemblies [14]. | ||
SNAP-ACTINGChanging position quickly with the aid of a spring [3]. | ||
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]. | ||
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]. | ||
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]. | ||
SPETETest 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]. | ||
SPHERICAL WAVEFRONTSWaves of energy that spread out in concentric circles [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]. | ||
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]. | ||
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 MILE5,280 feet [18]. | ||
STEP-BY-STEP COUNTERA counter that provides an output for each cycle of the input in one-step increments [9]. | ||
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]. | ||
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]. | ||
SWR(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]. | ||
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]. | ||
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]. | ||
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]. | ||
SYSTEMA combination of sets, units, assemblies, subassemblies, and parts joined together to form a specific operational function or several functions [17]. | ||