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2009 Element 8 pool
300 / 300 questions need explanations
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What would be the most likely defective area when there is no target video in the center of the CRT and the blank spot gets smaller in diameter as your range scale is increased?
  • The TR (TRL) Cell. (17% chose this)
  • The local oscillator is misadjusted. (22% chose this)
  • Video amplifier circuit. (61% chose this)
  • The IF amplifier circuit. (0% chose this)
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An S-band RADAR operates in which frequency band?
  • 1 - 2 GHz. (4% chose this)
  • 4 - 8 GHz. (13% chose this)
  • 8 - 12 GHz. (9% chose this)
  • 2 - 4 GHz. (74% chose this)
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The following is true concerning waveguides:
  • Conduction is accomplished by the polarization of electromagnetic and electrostatic fields. (29% chose this)
  • Ancillary deflection is employed. (0% chose this)
  • The magnetic field is strongest at the center of the waveguide. (12% chose this)
  • The magnetic field is strongest at the edges of the waveguide. (59% chose this)
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In a RADAR system, waveguides should be installed:
  • Slightly bent for maximum gain. (0% chose this)
  • As straight as possible to reduce distortion. (75% chose this)
  • At 90 degree angles to improve resonance. (6% chose this)
  • As long as possible for system flexibility. (19% chose this)
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An advantage of resonant charging is that it:
  • Eliminates the need for a reverse current diode. (19% chose this)
  • Guarantees perfectly square output pulses. (0% chose this)
  • Reduces the high-voltage power supply requirements. (69% chose this)
  • Maintains a constant magnetron output frequency. (13% chose this)
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A right-angle bend in an X-band waveguide must have a radius greater than:
  • Three inches. (0% chose this)
  • Six inches. (13% chose this)
  • One inch. (20% chose this)
  • Two inches. (67% chose this)
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When monitoring the gate voltage of a power MOSFET in the switching power supply of a modern RADAR, you would expect to see the gate voltage change from "low" to "high" by how much?
  • 1 volt to 2 volts. (21% chose this)
  • 300 microvolts to 700 microvolts. (14% chose this)
  • Greater than 2 volts. (64% chose this)
  • 1.0 volt to 20.0 volts. (0% chose this)
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A rotary joint is used to:
  • Couple two waveguides together at right angles. (10% chose this)
  • Act as a switch between two waveguide runs. (10% chose this)
  • Connect a stationary waveguide to the antenna array. (80% chose this)
  • Maintain pressurization at the end of the waveguide. (0% chose this)
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Which of the following would not normally be an input to the video amplifier?
  • Fixed range rings. (0% chose this)
  • Variable range rings. (6% chose this)
  • Resolver signal. (72% chose this)
  • Low level video. (22% chose this)
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The TR box:
  • Prevents the received signal from entering the transmitter. (28% chose this)
  • Protects the receiver from the strong RADAR pulses. (6% chose this)
  • Turns off the receiver when the transmitter is on. (6% chose this)
  • Protects the receiver from the strong RADAR pulses and mutes the receiver when the transmitter is on. (61% chose this)
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What is the most important factor to consider in locating the antenna?
  • Allow the shortest cable/waveguide run. (13% chose this)
  • Maximum height for best long range operation. (19% chose this)
  • The antenna is in a location that is not shadowed by other structures. (69% chose this)
  • Easy access for maintenance. (0% chose this)
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An artificial transmission line is used for:
  • The transmission of RADAR pulses. (5% chose this)
  • Testing the RADAR unit, when actual targets are not available. (30% chose this)
  • Determining the shape and duration of pulses. (60% chose this)
  • Testing the delay time for artificial targets. (5% chose this)
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How many sequential memory cells with target returns are required to display the target?
  • 1 (7% chose this)
  • 2 (71% chose this)
  • 4 (14% chose this)
  • 8 (7% chose this)
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Silicon crystals:
  • Are very sensitive to static electric charges. (11% chose this)
  • Should be wrapped in lead foil for storage. (0% chose this)
  • Tolerate very low currents. (5% chose this)
  • All of these. (84% chose this)
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The indicated distance from your own vessel to a lighthouse is found to be in error. What circuit would you suspect?
  • Range ring oscillator. (54% chose this)
  • Video amplifier. (8% chose this)
  • STC circuit. (31% chose this)
  • FTC circuit. (8% chose this)
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For a range of 10 nautical miles, the RADAR pulse repetition frequency (PRF) should be:
  • Approximately 8.1 kHz or less. (63% chose this)
  • 900 Hz. (6% chose this)
  • 18.1 kHz or more. (19% chose this)
  • 120.3 microseconds. (13% chose this)
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Small targets are best detected by:
  • Short pulses transmitted at a fast rate. (33% chose this)
  • Using J band frequencies. (0% chose this)
  • Using a long pulse width with high output power. (52% chose this)
  • All of these answers are correct. (14% chose this)
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In a RADAR receiver, the RF power amplifier:
  • Is high gain. (13% chose this)
  • Is low gain. (6% chose this)
  • Does not exist. (63% chose this)
  • Requires wide bandwidth. (19% chose this)
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Prior to removing, servicing or making measurements on any solid state circuit boards from the RADAR set, the operator should ensure that:
  • The proper work surfaces and ESD grounding straps are in place to prevent damage to the boards from electrostatic discharge. (87% chose this)
  • The waveguide is detached from the antenna to prevent radiation. (7% chose this)
  • The magnetic field is present to prevent over-current damage or overheating from occurring in the magnetron. (0% chose this)
  • Only non-conductive tools and devices are used. (7% chose this)
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A pulse RADAR has a pulse repetition frequency (PRF) of 400 Hz, a pulse width of 1 microsecond, and a peak power of 100 kilowatts. The average power of the RADAR transmitter is:
  • 25 watts. (9% chose this)
  • 40 watts. (86% chose this)
  • 250 watts. (0% chose this)
  • 400 watts. (5% chose this)
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A microwave transmission line constructed of a center conductor suspended between parallel conductive ground planes is called:
  • Microstrip. (16% chose this)
  • Coax. (5% chose this)
  • Stripline. (47% chose this)
  • Waveguide. (32% chose this)
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Prior to making "power-on" measurements on a switching power supply, you should be familiar with the supply because of the following:
  • You need to know where the filter capacitors are so they can be discharged. (29% chose this)
  • If it does not use a line isolation transformer you may destroy the supply with grounded test equipment. (71% chose this)
  • It is not possible to cause a component failure by using ungrounded test equipment. (0% chose this)
  • So that measurements can be made without referring to the schematic. (0% chose this)
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The purpose of the variable range marker is to:
  • Provide an accurate means of determining the range of a moving target. (47% chose this)
  • Provide a bearing line between own ship and a moving target. (20% chose this)
  • Indicate the distance between two different targets. (27% chose this)
  • Provide a means of calibrating the fixed range rings. (7% chose this)
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What would be the frequency of a range ring marker oscillator generating range rings at intervals of 0.25 nautical miles?
  • 161 kHz (13% chose this)
  • 322 kHz (73% chose this)
  • 644 kHz (13% chose this)
  • 1288 kHz (0% chose this)
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While the vessel is docked the presentation of the pier is distorted near the center of the PPI with the pier appearing to bend in a concave fashion. This is a primary indication of what?
  • The deflection coils need adjusting. (10% chose this)
  • The centering magnets at the CRT neck need adjusting. (20% chose this)
  • The waveguide compensation delay line needs adjusting. (70% chose this)
  • The CRT filaments are weakening. (0% chose this)
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Timing circuits are used to provide what function?
  • Develop synchronizing pulses for the transmitter system. (93% chose this)
  • Synchronize the antenna and display system. (7% chose this)
  • Adjust the sea return. (0% chose this)
  • Control the North Up presentation. (0% chose this)
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The STC circuit:
  • Increases the sensitivity of the receiver for close targets. (31% chose this)
  • Decreases sea return on the PPI scope. (56% chose this)
  • Helps to increase the bearing resolution of targets. (13% chose this)
  • Increases sea return on the PPI scope. (0% chose this)
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In a fixed-frequency switching power supply, the pulse width of the switching circuit will increase when:
  • The load impedance decreases. (58% chose this)
  • The load current decreases. (11% chose this)
  • The output voltage increases. (16% chose this)
  • The input voltage increases. (16% chose this)
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Silicon crystals are used in RADAR mixer and detector stages. Using an ohmmeter, how might a crystal be checked to determine if it is functional?
  • Its resistance should be the same in both directions. (13% chose this)
  • Its resistance should be low in one direction and high in the opposite direction. (60% chose this)
  • Its resistance cannot be checked with a dc ohmmeter because the crystal acts as a rectifier. (13% chose this)
  • It would be more appropriate to use a VTVM and measure the voltage drop across the crystal. (13% chose this)
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What precautions should be taken with horizontal waveguide runs?
  • They should be sloped slightly downwards at the elbow and a small drain hole drilled in the elbow. (78% chose this)
  • They should be absolutely level. (0% chose this)
  • They should not exceed 10 feet in length. (11% chose this)
  • None of the above. (11% chose this)
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Which of the following statements about "true bearing" is correct?
  • The ship's heading flasher is at the top of the screen. (20% chose this)
  • True North is at the top of the screen and the heading flasher indicates the vessel's course. (73% chose this)
  • The true bearing of the nearest target is indicated. (7% chose this)
  • The relative bearing of the nearest target is indicated. (0% chose this)
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LCD patterns are formed when:
  • Current passes through the crystal causing them to align. (89% chose this)
  • When voltage is reduced to the raster scan display. (11% chose this)
  • When the deflection coils are resonant. (0% chose this)
  • When the ships antenna's bearing is true North. (0% chose this)
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The condition known as "glint" refers to a shifting of clutter with each RADAR pulse and can be caused by a:
  • Improperly functioning MTI filter. (46% chose this)
  • Memory failure. (0% chose this)
  • Low AFC voltage. (0% chose this)
  • Interference from electrical equipment. (54% chose this)
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The anode of a magnetron is normally maintained at ground potential:
  • Because it operates more efficiently that way. (6% chose this)
  • For safety purposes. (81% chose this)
  • Never. It must be highly positive to attract the electrons. (6% chose this)
  • Because greater peak-power ratings can be achieved. (6% chose this)
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In the circuit shown in Fig. 8A6, which of the following is true?
  • With A and B high, Q1 is saturated and Q2 is off. (5% chose this)
  • With either A or B low, Q1 is saturated and Q2 is off. (79% chose this)
  • With A and B low, Q2 is on and Q4 is off. (5% chose this)
  • With either A or B low, Q1 is off and Q2 is on. (11% chose this)
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The position of the PPI scope sweep must indicate the position of the antenna. The sweep and antenna positions are frequently kept in synchronization by the use of:
  • Synchro systems. (88% chose this)
  • Servo systems. (6% chose this)
  • DC positioning motors. (0% chose this)
  • Differential amplifiers. (6% chose this)
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The video (second) detector in a pulse modulated RADAR system would most likely use a/an:
  • Discriminator detector. (33% chose this)
  • Diode detector. (60% chose this)
  • Ratio detector. (0% chose this)
  • Infinite impedance detector. (7% chose this)
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Which of the following statements about most modern RADAR transmitter power supplies is false?
  • High voltage supplies may produce voltages in excess of 5,000 volts AC. (80% chose this)
  • There are usually separate low voltage and high voltage supplies. (5% chose this)
  • Low voltage supplies use switching circuits to deliver multiple voltages. (5% chose this)
  • Low voltage supplies may supply both AC and DC voltages. (10% chose this)
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Which of the following is not a method of analog-to-digital conversion?
  • Delta-sigma conversion. (9% chose this)
  • Dynamic-range conversion. (65% chose this)
  • Switched-capacitor conversion. (17% chose this)
  • Dual-slope integration. (9% chose this)
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If the magnetron is allowed to operate without the magnetic field in place:
  • Its output will be somewhat distorted. (0% chose this)
  • It will quickly destroy itself from excessive current flow. (100% chose this)
  • Its frequency will change slightly. (0% chose this)
  • Nothing serious will happen. (0% chose this)
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An RF mixer has what purpose in a RADAR system?
  • Mixes the CW transmitter output to form pulsed waves. (28% chose this)
  • Converts a low-level signal to a different frequency. (56% chose this)
  • Prevents microwave oscillations from reaching the antenna. (0% chose this)
  • Combines audio tones with RF to produce the RADAR signal. (17% chose this)
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In a RADAR receiver AGC and IAGC can vary between:
  • 10 and 15 db. (13% chose this)
  • 20 and 40 db. (50% chose this)
  • 30 and 60 db. (25% chose this)
  • 5 and 30 db. (13% chose this)
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What would be a common switching frequency for a display system power supply?
  • 18 kHz (57% chose this)
  • 120 Hz (14% chose this)
  • 60 kHz (21% chose this)
  • 120 kHz (7% chose this)
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In a circular resonant cavity with flat ends, the E-field and the H-field form with specific relationships. The:
  • E-lines are parallel to the top and bottom walls. (11% chose this)
  • E-lines are perpendicular to the end walls. (67% chose this)
  • H-lines are perpendicular to the side walls. (17% chose this)
  • H-lines are circular to the end walls. (6% chose this)
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How do you eliminate stationary objects such as trees, buildings, bridges, etc., from the PPI presentation?
  • Remove the discriminator from the unit. (14% chose this)
  • Use a discriminator as a second detector. (71% chose this)
  • Calibrate the IF circuit. (7% chose this)
  • Calibrate the local oscillator. (7% chose this)
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Which of the following would not be considered an input to the computer of a collision avoidance system?
  • Own ship's exact position from navigation satellite receiver. (6% chose this)
  • Own ship's gyrocompass heading. (6% chose this)
  • Own ship's speed from Doppler log. (6% chose this)
  • Own ship's wind velocity from an anemometer. (82% chose this)
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A radio wave will travel a distance of three nautical miles in:
  • 6.17 microseconds. (15% chose this)
  • 37.0 microseconds. (10% chose this)
  • 22.76 microseconds. (0% chose this)
  • 18.51 microseconds. (75% chose this)
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Operation of any RADAR system begins in the:
  • Triggering section. (65% chose this)
  • Magnetron. (29% chose this)
  • AFC. (0% chose this)
  • PFN. (6% chose this)
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A RADAR operating at a frequency of 3 GHz has a wavelength of approximately:
  • 1 centimeter. (9% chose this)
  • 10 centimeters. (65% chose this)
  • 3 centimeters. (26% chose this)
  • 30 centimeters. (0% chose this)
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Good bearing resolution largely depends upon:
  • A high transmitter output reading. (0% chose this)
  • A high duty cycle. (0% chose this)
  • A narrow antenna beam in the vertical plane. (13% chose this)
  • A narrow antenna beam in the horizontal plane. (88% chose this)
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What kind of display would indicate water in the waveguide?
  • Spoking. (25% chose this)
  • Large circular rings near the center. (56% chose this)
  • Loss of range rings. (6% chose this)
  • Wider than normal targets. (13% chose this)
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What device(s) could be used as the local oscillator in a RADAR receiver?
  • Thyratron (6% chose this)
  • Klystron (29% chose this)
  • Klystron and a Gunn Diode (59% chose this)
  • Gunn diode (6% chose this)
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In a solid-state RADAR modulator, the duration of the transmitted pulse is determined by:
  • The thyratron. (0% chose this)
  • The magnetron voltage. (5% chose this)
  • The pulse forming network. (77% chose this)
  • The trigger pulse. (18% chose this)
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RADAR interference on a communications receiver appears as:
  • A varying tone. (6% chose this)
  • Static. (22% chose this)
  • A hissing tone. (11% chose this)
  • A steady tone. (61% chose this)
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The AFC system is used to:
  • Control the frequency of the magnetron. (35% chose this)
  • Control the frequency of the klystron. (50% chose this)
  • Control the receiver gain. (5% chose this)
  • Control the frequency of the incoming pulses. (10% chose this)
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Choose the most correct statement:
  • The magnetron anode is a low voltage circuit. (16% chose this)
  • The anode of the magnetron carries high voltage. (16% chose this)
  • The filament of the magnetron carries dangerous voltages. (63% chose this)
  • The magnetron filament is a low voltage circuit. (5% chose this)
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What RADAR component controls timing throughout the system?
  • Power supply. (0% chose this)
  • Indicator. (0% chose this)
  • Synchronizer. (100% chose this)
  • Receiver. (0% chose this)
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If more light strikes the photodiode in Fig. 8A5, there will be:
  • Less diode current. (0% chose this)
  • No change in diode current. (0% chose this)
  • More diode current. (96% chose this)
  • There is wrong polarity on the diode. (4% chose this)
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When comparing a TTL and a CMOS NAND gate:
  • Both have active pull-up characteristics. (86% chose this)
  • Both have three output states. (10% chose this)
  • Both have comparable input power sourcing. (5% chose this)
  • Both employ Schmitt diodes for increased speed capabilities. (0% chose this)
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The purpose of the Pulse Forming Network is to:
  • Act as a low pass filter. (0% chose this)
  • Act as a high pass filter. (5% chose this)
  • Produce a pulse of the correct width. (74% chose this)
  • Regulate the pulse repetition rate. (21% chose this)
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The purpose of a modulator in the transmitter section of a RADAR is to:
  • Improve bearing resolution. (0% chose this)
  • Provide the correct waveform to the transmitter. (80% chose this)
  • Prevent sea return. (5% chose this)
  • Control magnetron power output. (15% chose this)
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What display system power supply output would use a tripler circuit?
  • The logic circuit supply. (13% chose this)
  • The sweep circuit supply. (7% chose this)
  • The HV supply for the CRT anode. (73% chose this)
  • The resolver drive (7% chose this)
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When the receiver employs an MTI circuit:
  • The receiver gain increases with time. (13% chose this)
  • Only moving targets will be displayed. (69% chose this)
  • The receiver AGC circuits are disabled. (0% chose this)
  • Ground clutter will be free of "rabbits." (19% chose this)
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Which of the following statements is true?
  • The front end of the receiver does not provide any amplification to the RADAR signal. (71% chose this)
  • The mixer provides a gain of at least 6 db. (6% chose this)
  • The I.F. amplifier is always a high gain, narrow bandwidth amplifier. (12% chose this)
  • None of the above. (12% chose this)
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The usual intermediate frequency of a shipboard RADAR unit is:
  • 455 kHz. (0% chose this)
  • 10.7 MHz. (6% chose this)
  • 30 or 60 MHz. (88% chose this)
  • 120 MHz. (6% chose this)
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An increase in magnetron current that coincides with a decrease in power output is an indication of what?
  • The pulse length decreasing. (13% chose this)
  • A high SWR. (13% chose this)
  • A high magnetron heater voltage. (6% chose this)
  • The external magnet weakening. (69% chose this)
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The error voltage from the discriminator is applied to the:
  • Repeller (reflector) of the klystron. (93% chose this)
  • Grids of the IF amplifier. (0% chose this)
  • Grids of the RF amplifiers. (7% chose this)
  • Magnetron. (0% chose this)
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Sea clutter on the RADAR scope cannot be effectively reduced using front panel controls. What circuit would you suspect is faulty?
  • Sensitivity Time Control (STC) circuit. (73% chose this)
  • False Target Eliminator (FTE) circuit. (13% chose this)
  • Fast Time Constant (FTC) circuit. (0% chose this)
  • Intermediate Frequency (IF) circuit. (13% chose this)
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The output of an RC integrator, when driven by a square wave with a period of much less than one time constant is a:
  • Sawtooth wave. (36% chose this)
  • Sine wave. (0% chose this)
  • Series of narrow spikes. (14% chose this)
  • Triangle wave. (50% chose this)
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Which of the following statements about the Variable Range Marker system is correct?
  • The VRM is an auxiliary output of the fixed range marker oscillator. (15% chose this)
  • The VRM system develops a single adjustable range ring. (62% chose this)
  • The VRM system is calibrated using a frequency counter. (0% chose this)
  • The VRM system is controlled by a crystal oscillator. (23% chose this)
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While removing a CRT from its operating casing, it is a good idea to:
  • Discharge the first anode. (21% chose this)
  • Test the second anode with your fingertip. (0% chose this)
  • Wear gloves and goggles. (71% chose this)
  • Set it down on a hard surface. (7% chose this)
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What is the most common type of antenna position indicating device used in modern RADARs?
  • Resolvers. (18% chose this)
  • Servo systems. (18% chose this)
  • Synchro transmitters. (64% chose this)
  • Step motors. (0% chose this)
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The triggering section is also known as the:
  • PFN. (9% chose this)
  • Timer circuit. (23% chose this)
  • Blocking oscillator. (9% chose this)
  • Synchronizer. (59% chose this)
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The raster scan RADAR display has missing video in a rectangular block on the screen. Where is the most likely problem area?
  • Horizontal sweep circuit. (8% chose this)
  • Power supply. (0% chose this)
  • Memory area failure. (77% chose this)
  • Vertical blanking pulse. (15% chose this)
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On a vessel with two RADARs, one has a different range indication on a specific target than the other. How would you determine which RADAR is incorrect?
  • Check the sweep and timing circuits of both indicators for correct readings. (81% chose this)
  • Triangulate target using the GPS and visual bearings. (13% chose this)
  • Check antenna parallax. (6% chose this)
  • Use the average of the two indications and adjust both for that amount. (0% chose this)
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An increase in the deflection on the magnetron current meter could likely be caused by:
  • Insufficient pulse amplitude from the modulator. (18% chose this)
  • Too high a B1 level on the magnetron. (12% chose this)
  • A decrease of the magnetic field strength. (71% chose this)
  • A lower duty cycle, as from 0.0003 to 0.0002. (0% chose this)
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To insert RF energy into or extract RF energy from a waveguide, which of the following would not be used?
  • Coupling capacitance. (43% chose this)
  • Current loop. (7% chose this)
  • Aperture window. (29% chose this)
  • Voltage probe. (21% chose this)
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Resistive losses in a waveguide are very small because:
  • The inner surface of the waveguide is large. (67% chose this)
  • The inner surface of the waveguide is small. (13% chose this)
  • The waveguide does not require a ground connection. (20% chose this)
  • The heat remains in the waveguide and cannot dissipate. (0% chose this)
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How is the signal removed from a waveguide or magnetron?
  • With a thin wire called a T-hook. (7% chose this)
  • With a thin wire called a J-Hook. (93% chose this)
  • With a coaxial connector. (0% chose this)
  • With a waveguide flange joint. (0% chose this)
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Waveguides can be constructed from:
  • Brass. (0% chose this)
  • Aluminum. (0% chose this)
  • Copper. (0% chose this)
  • All of the above. (100% chose this)
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A typical shipboard RADAR antenna is a:
  • Rotary parabolic transducer. (8% chose this)
  • Slotted waveguide array. (83% chose this)
  • Phased planar array. (8% chose this)
  • Dipole. (0% chose this)
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Which of the following statements about antenna resolvers is correct?
  • Most resolvers contain a rotor winding and a delta stator winding. (8% chose this)
  • Resolvers consist of a two rotor windings and two stator windings that are 90 degrees apart. (25% chose this)
  • The basic resolver contains a rotor winding and two stator windings that are 90 degrees apart. (67% chose this)
  • Resolvers consist of a "Y" connected rotor winding and a delta connected stator winding. (0% chose this)
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A certain length of transmission line has a characteristic impedance of 72 ohms. If the line is cut at its center, each half of the transmission line will have a ZO of:
  • 36 ohms. (15% chose this)
  • 144 ohms. (8% chose this)
  • 72 ohms. (69% chose this)
  • The exact length must be known to determine Zo. (8% chose this)
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A waveguide is used at RADAR microwave frequencies because:
  • It is easier to install than other feedline types. (0% chose this)
  • It is more rugged than other feedline types. (5% chose this)
  • It is less expensive than other feedline types. (5% chose this)
  • It has lower transmission losses than other feedline types. (89% chose this)
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How does antenna length affect the horizontal beamwidth of the transmitted signal?
  • The longer the antenna the wider the horizontal beamwidth. (38% chose this)
  • The longer the antenna the narrower the horizontal beamwidth. (44% chose this)
  • The horizontal beamwidth is not affected by the antenna length. (13% chose this)
  • None of the above. (6% chose this)
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RADAR antenna direction must be sent to the display in all ARPAs or RADAR systems. How is this accomplished?
  • 3-phase synchros. (13% chose this)
  • 2-phase resolvers. (0% chose this)
  • Optical encoders. (13% chose this)
  • Any of the above. (73% chose this)
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Waveguide theory is based upon:
  • The movement of an electromagnetic field. (82% chose this)
  • Current flow through conductive wires. (12% chose this)
  • Inductance. (0% chose this)
  • Resonant charging. (6% chose this)
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Slotted waveguide arrays, when fed from one end exhibit:
  • Frequency scan. (38% chose this)
  • High VSWR. (15% chose this)
  • Poor performance in rain. (15% chose this)
  • A narrow elevation beam. (31% chose this)
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The center of the transmitted lobe from a slotted waveguide array is:
  • Several degrees offset from a line perpendicular to the antenna. (72% chose this)
  • Perpendicular to the antenna. (28% chose this)
  • Maximum at the right hand end. (0% chose this)
  • Maximum at the left hand end. (0% chose this)
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Waveguide theory is based on the principals of:
  • Ohm's Law. (23% chose this)
  • High standing waves. (0% chose this)
  • Skin effect and use of ¼ wave stubs. (69% chose this)
  • None of the above. (8% chose this)
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At microwave frequencies, waveguides are used instead of conventional coaxial transmission lines because:
  • They are smaller and easier to handle. (0% chose this)
  • They have considerably less loss. (92% chose this)
  • They are lighter since they have hollow centers. (8% chose this)
  • Moisture is never a problem with them. (0% chose this)
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If long-length transmission lines are not properly shielded and terminated:
  • The silicon crystals can be damaged. (0% chose this)
  • Communications receiver interference might result. (92% chose this)
  • Overmodulation might result. (8% chose this)
  • Minimal RF loss can result. (0% chose this)
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Standing waves on a transmission line may be an indication that:
  • All energy is being delivered to the load. (0% chose this)
  • Source and surge impedances are equal to ZO and ZL. (0% chose this)
  • The line is terminated in impedance equal to ZO. (0% chose this)
  • Some of the energy is not absorbed by the load. (100% chose this)
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The ferrite material in a circulator is used as a(an):
  • Electric switch. (5% chose this)
  • Saturated reactor. (15% chose this)
  • Loading element. (15% chose this)
  • Phase shifter. (65% chose this)
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A major consideration for the use of a switching regulator power supply over a linear regulator is:
  • The switching regulator has better regulation. (0% chose this)
  • The linear regulator does not require a transformer to step down AC line voltages to a usable level. (9% chose this)
  • The switching regulator can be used in nearly all applications requiring regulated voltage. (9% chose this)
  • The overall efficiency of a switching regulator is much higher than a linear power supply. (82% chose this)
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The purpose of the modulator is to:
  • Transmit the high voltage pulses to the antenna. (0% chose this)
  • Provide high voltage pulses of the proper shape and width to the magnetron. (74% chose this)
  • Adjust the pulse repetition rate. (16% chose this)
  • Tune the Magnetron to the proper frequency. (11% chose this)
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Pulse transformers and pulse-forming networks are commonly used to shape the microwave energy burst RADAR transmitter. The switching devices most often used in such pulse-forming circuits are:
  • Power MOSFETS and Triacs. (26% chose this)
  • Switching transistors. (0% chose this)
  • Thyratrons and BJT's. (0% chose this)
  • SCR's and Thyratrons. (74% chose this)
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A pulse-width modulator in a switching power supply is used to:
  • Provide the reference voltage for the regulator. (0% chose this)
  • Vary the frequency of the switching regulator to control the output voltage. (16% chose this)
  • Vary the duty cycle of the regulator switch to control the output voltage. (63% chose this)
  • Compare the reference voltage with the output voltage sample and produce an error voltage. (21% chose this)
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When a pulse RADAR is radiating, which elements in the TR box are energized?
  • The TR tube only. (11% chose this)
  • The ATR tube only. (17% chose this)
  • Both the TR and ATR tubes. (67% chose this)
  • Neither the TR nor ATR tubes. (6% chose this)
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What device(s) may act as the modulator of a RADAR system?
  • Magnetron. (9% chose this)
  • Klystron. (23% chose this)
  • Video amplifier. (0% chose this)
  • Thyratron or a silicon-controlled rectifier (SCR). (68% chose this)
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The ATR box:
  • Protects the receiver from strong RADAR signals. (11% chose this)
  • Prevents the received signal from entering the transmitter. (42% chose this)
  • Turns off the receiver when the transmitter is on. (0% chose this)
  • All of the above. (47% chose this)
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A DC keep-alive potential:
  • Is applied to a TR tube to make it more sensitive. (18% chose this)
  • Partially ionizes the gas in a TR tube, making it very sensitive to transmitter pulses. (0% chose this)
  • Fully ionizes the gas in a TR tube. (6% chose this)
  • Is applied to a TR tube to make it more sensitive and partially ionizes the gas in a TR tube. (76% chose this)
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The purpose of the Synchronizer is to:
  • Generate the modulating pulse to the magnetron. (12% chose this)
  • Generate a timing signal that establishes the pulse repetition rate. (71% chose this)
  • Insure that the TR tube conducts at the proper time. (12% chose this)
  • Control the pulse width. (6% chose this)
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The characteristic of the magnetron output pulse that relates to accurate range measurement is its:
  • Amplitude. (0% chose this)
  • Decay time. (21% chose this)
  • Rise time. (58% chose this)
  • Duration. (21% chose this)
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The characteristics of a field-effect transistor (FET) used in a modern RADAR switching power supply can be compared as follows:
  • "On" state compares to a bipolar transistor. "Off" state compares to a 1-Megohm resistor. (13% chose this)
  • "On" state compares to a pure resistor. "Off" state compares to a mechanical relay. (87% chose this)
  • "On" state compares to an low resistance inductor. "Off" state compares to a 10-Megohm resistor. (0% chose this)
  • "On" state compares to a resistor. "Off" state compares to a capacitor. (0% chose this)
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High voltage is applied to what element of the magnetron?
  • The waveguide. (4% chose this)
  • The anode. (35% chose this)
  • The plate cap. (4% chose this)
  • The cathode. (57% chose this)
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The magnetron is:
  • A type of diode that requires an internal magnetic field. (21% chose this)
  • A triode that requires an external magnetic field. (7% chose this)
  • Used as the local oscillator in the RADAR unit. (7% chose this)
  • A type of diode that requires an external magnetic field. (64% chose this)
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In a display system power supply what is the purpose of the chopper?
  • It acts as an electronic switch between the raw DC output and the inverter. (75% chose this)
  • It interrupts the AC supply line at a varying rate depending on the load demands. (13% chose this)
  • It regulates the 5 volt DC output. (13% chose this)
  • It pre-regulates the AC input. (0% chose this)
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In a pulse modulated magnetron what device determines the shape and width of the pulse?
  • Pulse Forming Network. (71% chose this)
  • Thyratron. (14% chose this)
  • LC parallel circuit. (0% chose this)
  • Dimensions of the magnetron cavity. (14% chose this)
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Bearing resolution is:
  • The ability to distinguish two adjacent targets of equal distance. (79% chose this)
  • The ability to distinguish two targets of different distances. (7% chose this)
  • The ability to distinguish two targets of different elevations. (0% chose this)
  • The ability to distinguish two targets of different size. (14% chose this)
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A keep-alive voltage is applied to:
  • The crystal detector. (0% chose this)
  • The ATR tube. (6% chose this)
  • The TR tube. (76% chose this)
  • The magnetron. (18% chose this)
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The variable range marker signal is normally fed to the input of the:
  • Sweep amplifier. (28% chose this)
  • Low voltage power supply regulator. (6% chose this)
  • Video amplifier. (44% chose this)
  • Range ring oscillator. (22% chose this)
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The purpose of the discriminator circuit in a RADAR set is to:
  • Discriminate against nearby objects. (0% chose this)
  • Discriminate against two objects with very similar bearings. (8% chose this)
  • Generate a corrective voltage for controlling the frequency of the klystron local oscillator. (62% chose this)
  • Demodulate or remove the intelligence from the FM signal. (31% chose this)
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The magnetron is used to:
  • Generate the output signal at the proper operating frequency. (86% chose this)
  • Determine the shape and width of the transmitted pulses. (5% chose this)
  • Modulate the pulse signal. (5% chose this)
  • Determine the pulse repetition rate. (5% chose this)
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In a RADAR unit, the mixer uses:
  • PIN diodes and silicon crystals. (73% chose this)
  • PIN diodes. (13% chose this)
  • Boettcher crystals. (13% chose this)
  • Silicon crystals. (0% chose this)
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Bearing information from the gyro is used to provide the following:
  • The heading of the nearest target. (9% chose this)
  • Range and bearing to the nearest target. (9% chose this)
  • Vessel's own heading. (82% chose this)
  • The range of a selected target. (0% chose this)
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The circuit that develops timing signals is called the:
  • Resolver. (0% chose this)
  • Synchronizer. (89% chose this)
  • Pulse forming network. (11% chose this)
  • Video amplifier. (0% chose this)
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The Electronic Bearing Line is:
  • The ships heading line. (20% chose this)
  • A line indicating True North. (5% chose this)
  • Used to mark a target to obtain the distance. (15% chose this)
  • A line from your own vessel to a specific target. (60% chose this)
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The major advantage of digitally processing a RADAR signal is:
  • Digital readouts appear on the RADAR display. (11% chose this)
  • Enhancement of weak target returns. (79% chose this)
  • An improved operator interface. (5% chose this)
  • Rectangular display geometry is far easier to read on the CRT. (5% chose this)
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In the circuit contained in Fig. 8F12, there are 5 volts present at points B and C, and there are zero volts present at points A and D. What is the voltage at point E?
  • -1.5 Volts. (60% chose this)
  • 3.75 Volts. (20% chose this)
  • 23.75 Volts. (7% chose this)
  • 4.5 Volts. (13% chose this)
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Long horizontal sections of waveguides are not desirable because:
  • Moisture can accumulate in the waveguide. (81% chose this)
  • The waveguide can sag, causing loss of signal. (6% chose this)
  • Excessive standing waves can occur. (0% chose this)
  • The polarization of the signal might shift. (13% chose this)
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A thick layer of rust and corrosion on the surface of the parabolic dish will have what effect?
  • No noticeable effect. (6% chose this)
  • Scatter and absorption of RADAR waves. (18% chose this)
  • Decrease in performance, especially for weak targets. (76% chose this)
  • Slightly out of focus PPI scope. (0% chose this)
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The echo box is used for:
  • Testing the wavelength of the incoming echo signal. (0% chose this)
  • Testing and tuning of the RADAR unit by providing artificial targets. (83% chose this)
  • Amplification of the echo signal. (17% chose this)
  • Detection of the echo pulses. (0% chose this)
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Before testing a RADAR transmitter, it would be a good idea to:
  • Make sure no one is on the deck. (7% chose this)
  • Make sure the magnetron's magnetic field is far away from the magnetron. (13% chose this)
  • Make sure there are no explosives or flammable cargo being loaded. (80% chose this)
  • Make sure the Coast Guard has been notified. (0% chose this)
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When you examine the RADAR you notice that there is no target video in the center of the CRT. The blank spot gets smaller in diameter as you increase the range scale. What operator front panel control could be misadjusted?
  • TUNE. (0% chose this)
  • Sensitivity Time Control (STC). (77% chose this)
  • Anti-Clutter Rain (ACR). (23% chose this)
  • False Target Elimination (FTE). (0% chose this)
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While making repairs or adjustments to RADAR units:
  • Wear fire-retardant clothing. (0% chose this)
  • Discharge all high-voltage capacitors to ground. (95% chose this)
  • Maintain the filament voltage. (0% chose this)
  • Reduce the magnetron voltage. (5% chose this)
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A defective crystal in the AFC section will cause:
  • No serious problems. (0% chose this)
  • Bright flashing pie sections on the PPI. (58% chose this)
  • Spiking on the PPI. (5% chose this)
  • Vertical spikes that constantly move across the screen. (37% chose this)
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Which of the following is the most useful instrument for RADAR servicing?
  • Oscilloscope. (92% chose this)
  • Frequency Counter. (0% chose this)
  • R. F. Wattmeter. (0% chose this)
  • Audio generator. (8% chose this)
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The VSWR of a microwave transmission line device might be measured using:
  • A dual directional coupler and a power meter. (25% chose this)
  • A network analyzer. (0% chose this)
  • A spectrum analyzer. (6% chose this)
  • A dual directional coupler, a power meter, and a network analyzer. (69% chose this)
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On a basic synchro system, the angular information is carried on the:
  • DC feedback signal. (13% chose this)
  • Stator lines. (73% chose this)
  • Deflection coils. (0% chose this)
  • Rotor lines. (13% chose this)
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What is the most common type of RADAR antenna used aboard commercial maritime vessels?
  • Parabolic. (6% chose this)
  • Truncated parabolic. (0% chose this)
  • Slotted waveguide array. (94% chose this)
  • Multi-element Yagi array. (0% chose this)
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An antenna synchro transmitter is composed of the following:
  • Three rotor and two stator windings. (19% chose this)
  • Two rotor and three stator windings. (50% chose this)
  • Three rotor and three stator windings. (6% chose this)
  • A single rotor and 3 stator windings. (25% chose this)
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The impedance total (ZO) of a transmission line can be calculated by ZO = √L/C when L and C are known. When a section of transmission line contains 250 microhenries of L and 1000 picofarads of C, its impedance total (ZO) will be:
  • 50 ohms. (25% chose this)
  • 250 ohms. (13% chose this)
  • 500 ohms. (56% chose this)
  • 1,000 ohms. (6% chose this)
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What device is located between the magnetron and the mixer and prevents received signals from entering the magnetron?
  • The ATR tube. (48% chose this)
  • The TR tube. (38% chose this)
  • The RF Attenuator. (10% chose this)
  • A resonant cavity. (5% chose this)
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Unblanking pulses are produced by the timer circuit. Where are they sent?
  • IF amplifiers. (10% chose this)
  • Mixer. (15% chose this)
  • CRT. (60% chose this)
  • Discriminator. (15% chose this)
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The block diagram of a typical RADAR system microprocessor is shown in Fig. 8A2. Choose the most correct statement regarding this system.
  • The ALU executes arithmetic manipulations. (68% chose this)
  • The ALU is used for address decoding. (5% chose this)
  • General registers are used for arithmetic manipulations. (18% chose this)
  • Address pointers are contained in the control unit. (9% chose this)
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Which of the following has NO effect on the maximum range capability?
  • Carrier frequency. (18% chose this)
  • Recovery time. (68% chose this)
  • Pulse repetition frequency. (0% chose this)
  • Receiver sensitivity. (14% chose this)
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What is the primary purpose of display system memory?
  • Eliminate fluctuating targets such as sea return. (73% chose this)
  • Display stationary targets. (0% chose this)
  • Display the last available targets prior to a power dropout. (13% chose this)
  • Store target bearings. (13% chose this)
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Select the statement, which is most correct regarding a raster scan display.
  • Raster displays are the same as conventional T.V. receivers. (0% chose this)
  • The scan rate for a RADAR system is 30 frames per second. (21% chose this)
  • Raster scanning is controlled by clock pulses and requires an address bus. (71% chose this)
  • Raster scanning is not used in RADAR systems. (7% chose this)
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What component of a RADAR receiver is represented by block 48 in Fig. 8A1?
  • Klystron (local oscillator). (76% chose this)
  • Discriminator. (6% chose this)
  • IF amplifier. (6% chose this)
  • Crystal detector. (12% chose this)
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The high-gain IF amplifiers in a RADAR receiver may amplify a 2 microvolt input signal to an output level of 2 volts. This amount of amplification represents a gain of:
  • 60 db. (13% chose this)
  • 100 db. (20% chose this)
  • 120 db. (67% chose this)
  • 1,000 db. (0% chose this)
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Which of the following components allows the use of a single antenna for both transmitting and receiving?
  • Mixer. (9% chose this)
  • Duplexer. (91% chose this)
  • Synchronizer. (0% chose this)
  • Modulator. (0% chose this)
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What would be the frequency of a range ring marker oscillator generating range rings at 10 nautical miles intervals?
  • 24 kHz (9% chose this)
  • 16 kHz (27% chose this)
  • 12 kHz (9% chose this)
  • 8 kHz (55% chose this)
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The purpose of the aquadag coating on the CRT is:
  • To protect the electrons from strong electric fields. (7% chose this)
  • To act as a second anode. (0% chose this)
  • To attract secondary emissions from the CRT screen. (0% chose this)
  • All of the above (93% chose this)
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A basic sample-and-hold circuit contains:
  • An analog switch and an amplifier. (0% chose this)
  • An analog switch, a capacitor, and an amplifier. (11% chose this)
  • An analog multiplexer and a capacitor. (0% chose this)
  • An analog switch, a capacitor, amplifiers and input and output buffers. (89% chose this)
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In a raster-type display, the electron beam is scanned:
  • From the center of the display to the outer edges. (8% chose this)
  • Horizontally and vertically across the CRT face. (77% chose this)
  • In a rotating pattern which follows the antenna position. (0% chose this)
  • From one specified X-Y coordinate to the next. (15% chose this)
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The STC circuit is used to:
  • Increase receiver stability. (0% chose this)
  • Increase receiver sensitivity. (12% chose this)
  • Increase receiver selectivity. (0% chose this)
  • Decrease sea return on a RADAR receiver. (88% chose this)
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Voltages used in CRT anode circuits are in what range of value?
  • 0.5-10 mV. (0% chose this)
  • 10-50 kV. (67% chose this)
  • 20-50 mV. (25% chose this)
  • 200-1000 V. (8% chose this)
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Accurate range markers must be developed using very narrow pulses. A circuit that could be used to provide these high-quality pulses for the CRT is a:
  • Ringing oscillator. (7% chose this)
  • Monostable multivibrator. (21% chose this)
  • Triggered bi-stable multivibrator. (14% chose this)
  • Blocking oscillator. (57% chose this)
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A directional coupler has an attenuation of -30 db. A measurement of 100 milliwatts at the coupler indicates the power of the line is:
  • 10 watts. (13% chose this)
  • 100 watts. (83% chose this)
  • 1,000 watts. (0% chose this)
  • 10,000 watts. (4% chose this)
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Short range RADARs would most likely transmit:
  • Narrow pulses at a fast rate. (68% chose this)
  • Narrow pulses at a slow rate. (10% chose this)
  • Wide pulses at a fast rate. (10% chose this)
  • Wide pulses at a slow rate. (13% chose this)
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The panel control for the variable range marker is normally a:
  • Variable resistor. (71% chose this)
  • Variable inductance. (6% chose this)
  • Variable capacitance. (0% chose this)
  • Variable resolver. (24% chose this)
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Targets displayed on the RADAR display are not on the same bearing as their visual bearing. What should you first suspect?
  • A bad reed relay in the antenna pedestal. (0% chose this)
  • A sweep length misadjustment. (7% chose this)
  • One phase of the yoke assembly is open. (7% chose this)
  • Incorrect antenna position information. (86% chose this)
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How is the variable range marker usually adjusted for accuracy?
  • Adjusting the frequency of the VRM oscillator at the maximum range. (15% chose this)
  • Adjusting the frequency of the VRM oscillator at the minimum range. (15% chose this)
  • Adjusting the readout to match at the median range ring. (15% chose this)
  • The minimum and maximum ranges are aligned with the matching fixed range ring. (54% chose this)
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The synchronizer primarily affects the following circuit or function:
  • Mixer. (33% chose this)
  • Receiver. (13% chose this)
  • Modulator. (53% chose this)
  • I.F. Amplifier. (0% chose this)
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A RADAR transmitter is operating on 3.0 GHz and the reflex klystron local oscillator, operating at 3.060 GHz, develops a 60 MHz IF. If the magnetron drifts higher in frequency, the AFC system must cause the klystron repeller plate to become:
  • More positive. (13% chose this)
  • More negative. (60% chose this)
  • Less positive. (13% chose this)
  • Less negative. (13% chose this)
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The RADAR display has sectors of solid video (spoking). What would be the first thing to check?
  • Antenna information circuits failure. (0% chose this)
  • Frequency of raster scan. (7% chose this)
  • For interference from nearby ships. (47% chose this)
  • Constant velocity of antenna rotation. (47% chose this)
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In a RADAR unit, the local oscillator is a:
  • Hydrogen Thyratron. (19% chose this)
  • Klystron. (81% chose this)
  • Pentagrid converter tube. (0% chose this)
  • Reactance tube modulator. (0% chose this)
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The output from the synchronizer usually consists of a:
  • Sine wave. (9% chose this)
  • Pulse or square wave. (64% chose this)
  • Triangle wave. (27% chose this)
  • None of the above. (0% chose this)
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The primary operating frequency of a reflex klystron is controlled by the:
  • Dimensions of the resonant cavity. (63% chose this)
  • Level of voltage on the control grid. (16% chose this)
  • Voltage applied to the cavity grids. (5% chose this)
  • Voltage applied to the repeller plate. (16% chose this)
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In a RADAR unit, the mixer uses a:
  • Pentagrid converter tube. (14% chose this)
  • Field-effect transistor. (7% chose this)
  • Silicon crystal or PIN diode. (79% chose this)
  • Microwave transistor. (0% chose this)
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The major advantage of an S-band RADAR over an X-band RADAR is:
  • It is less affected by weather conditions. (87% chose this)
  • It has greater bearing resolution. (4% chose this)
  • It is mechanically less complex. (4% chose this)
  • It has greater power output. (4% chose this)
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Frequencies generally used for marine RADAR are in the ___ part of the radio spectrum.
  • UHF (4% chose this)
  • EHF (0% chose this)
  • SHF (91% chose this)
  • VHF (4% chose this)
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Which of the following characteristics are true of a power MOSFET used in a RADAR switching supply?
  • Low input impedance; failure mode can be gate punch-through. (5% chose this)
  • High input impedance; failure mode can be gate punch-through. (73% chose this)
  • High input impedance; failure mode can be thermal runaway. (14% chose this)
  • Low input impedance; failure mode can be gate breakdown. (9% chose this)
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When comparing TTL and CMOS logic families, which of the following is true:
  • CMOS logic requires a supply voltage of 5 volts ±20%, whereas TTL logic requires 5 volts ±5%. (16% chose this)
  • Unused inputs should be tied high or low as necessary especially in the CMOS family. (5% chose this)
  • At higher operating frequencies, CMOS circuits consume almost as much power as TTL circuits. (79% chose this)
  • When a CMOS input is held low, it sources current into whatever it drives. (0% chose this)
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An X band RADAR operates in which frequency band?
  • 1 - 2 GHz. (0% chose this)
  • 2 - 4 GHz. (13% chose this)
  • 4 - 8 GHz. (21% chose this)
  • 8 - 12 GHz. (67% chose this)
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What is the main difference between an analog and a digital receiver?
  • Special amplification circuitry. (0% chose this)
  • The presence of decision circuitry to distinguish between "on" and "off" signal levels. (85% chose this)
  • An AGC stage is not required in a digital receiver. (8% chose this)
  • Digital receivers produce no distortion. (8% chose this)
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What component of a RADAR receiver is represented by block 47 in Fig. 8A1?
  • The ATR box. (15% chose this)
  • The TR box. (15% chose this)
  • The RF Attenuator. (65% chose this)
  • The Crystal Detector. (5% chose this)
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What is the purpose or function of the "Trial Mode" used in most ARPA equipment?
  • It selects trial dots for targets' recent past positions. (0% chose this)
  • It is used to display target position and your own ship's data such as TCPA, CPA, etc. (29% chose this)
  • It is used to allow results of proposed maneuvers to be assessed. (53% chose this)
  • None of these. (18% chose this)
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The term DRAM stands for:
  • Digital refresh access memory. (0% chose this)
  • Digital recording access memory. (0% chose this)
  • Dynamic random access memory. (100% chose this)
  • Digital response area motion. (0% chose this)
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A circuit used to develop AFC voltage in a RADAR receiver is called the:
  • Peak detector. (0% chose this)
  • Crystal mixer. (0% chose this)
  • Second detector. (10% chose this)
  • Discriminator. (90% chose this)
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The shape and duration of the high-voltage pulse delivered to the magnetron is established by:
  • An RC network in the keyer stage. (13% chose this)
  • The duration of the modulator input trigger. (25% chose this)
  • An artificial delay line. (44% chose this)
  • The time required to saturate the pulse transformer. (19% chose this)
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What should be done to the interior surface of a waveguide in order to minimize signal loss?
  • Fill it with nitrogen gas. (29% chose this)
  • Paint it with nonconductive paint to prevent rust. (7% chose this)
  • Keep it as clean as possible. (64% chose this)
  • Fill it with a high-grade electrical oil. (0% chose this)
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What is the distance between range markers if the controlling oscillator is operating at 20 kHz?
  • 1 nautical miles. (20% chose this)
  • 2 nautical miles. (27% chose this)
  • 4 nautical miles. (53% chose this)
  • 8 nautical miles. (0% chose this)
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The main purpose of the video amplifier is to provide:
  • Composite video to the cathode of the CRT. (65% chose this)
  • Resolver signals (6% chose this)
  • Antenna X and Y signals. (0% chose this)
  • Provide the drive signal to the sweep amplifier. (29% chose this)
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What is the average power if the RADAR set has a PRF of 1000 Hz, a pulse width of 1 microsecond, and a peak power rating of 100 kilowatts?
  • 10 watts. (9% chose this)
  • 100 watts. (82% chose this)
  • 1,000 watts. (9% chose this)
  • None of these. (0% chose this)
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A Gunn diode oscillator takes advantage of what effect?
  • Negative resistance. (14% chose this)
  • Avalanche transit time. (9% chose this)
  • Bulk-effect. (5% chose this)
  • Negative resistance and bulk-effect. (73% chose this)
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In the receive mode, frequency conversion is generally accomplished by a:
  • Tunable wave-guide section. (13% chose this)
  • Pentagrid converter. (7% chose this)
  • Crystal diode. (60% chose this)
  • Ferrite device. (20% chose this)
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The nominal output high of the comparator shown in Fig. 8C11 is 4.5 volts. Choose the most correct statement which describes the trip points.
  • Upper trip point is 4.5 volts. Lower trip point is approximately 0 volts. (0% chose this)
  • Upper trip point is 2.5 volts. Lower trip point is approximately 2.0 volts. (15% chose this)
  • Upper trip point is 900 microvolts. Lower trip point is approximately 0 volts. (0% chose this)
  • Upper trip point is +1.285 volts. Lower trip point is -1.285 volts. (85% chose this)
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Which of the following is not part of the transmitting system?
  • Magnetron. (15% chose this)
  • Modulator. (0% chose this)
  • Pulse Forming Network. (25% chose this)
  • Klystron. (60% chose this)
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A negative voltage is commonly applied to the magnetron cathode rather than a positive voltage to the magnetron anode because:
  • The cathode must be made neutral to force electrons into the drift area. (12% chose this)
  • A positive voltage would tend to nullify or weaken the magnetic field. (6% chose this)
  • The anode can be operated at ground potential for safety reasons. (65% chose this)
  • The cavities might not be shock-excited into oscillation by a positive voltage. (18% chose this)
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Sea return is:
  • Sea water that gets into the antenna system. (6% chose this)
  • The return echo from a target at sea. (12% chose this)
  • The reflection of RADAR signals from nearby waves. (82% chose this)
  • None of the above. (0% chose this)
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Noise can:
  • Mask larger targets. (0% chose this)
  • Change bearings. (7% chose this)
  • Mask small targets. (87% chose this)
  • Increase RADAR transmitter interference. (7% chose this)
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If the PRF is 2500 Hz, what is the PRI?
  • 40 microseconds. (18% chose this)
  • 400 microseconds. (68% chose this)
  • 250 microseconds. (5% chose this)
  • 800 microseconds. (9% chose this)
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An ion discharge (TR) cell is used to:
  • Protect the transmitter from high SWRs. (23% chose this)
  • Lower the noise figure of the receiver. (0% chose this)
  • Tune the local oscillator of the RADAR receiver. (8% chose this)
  • Protect the receiver mixer during the transmit pulse. (69% chose this)
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What is the purpose or function of the RADAR duplexer/circulator?
  • An electronic switch that allows the use of one antenna for both transmission and reception. (88% chose this)
  • A coupling device that is used in the transition from a rectangular waveguide to a circular waveguide. (6% chose this)
  • A modified length of waveguide used to sample a portion of the transmitted energy for testing purposes. (0% chose this)
  • A dual section coupling device that allows the use of a magnetron as a transmitter. (6% chose this)
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How may the frequency of the klystron be varied?
  • Small changes can be made by adjusting the anode voltage. (12% chose this)
  • Large changes can be made by adjusting the frequency. (0% chose this)
  • By changing the phasing of the buncher grids (6% chose this)
  • Small changes can be made by adjusting the repeller voltage and large changes can be made by adjusting the size of the resonant cavity. (82% chose this)
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In a digitized RADAR, the 360 degree sweep is divided into how many digitized segments?
  • 16 (0% chose this)
  • 64 (0% chose this)
  • 255 (21% chose this)
  • 4,096 (79% chose this)
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The I.F. Amplifier bandwidth is:
  • Wide for short ranges and narrow for long ranges. (28% chose this)
  • Wide for long ranges and narrow for short ranges. (44% chose this)
  • Constant for all ranges. (17% chose this)
  • Adjustable from the control panel. (11% chose this)
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Practical RADAR operation requires the use of microwave frequencies so that:
  • Stronger target echoes will be produced. (73% chose this)
  • Ground clutter interference will be minimized. (0% chose this)
  • Interference to other communication systems will be eliminated. (18% chose this)
  • Non-directional antennas can be used for both transmitting and receiving. (9% chose this)
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What circuit controls the suppression of sea clutter?
  • EBL circuit. (0% chose this)
  • STC circuit. (100% chose this)
  • Local oscillator. (0% chose this)
  • Audio amplifier. (0% chose this)
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The minimum range of a RADAR is determined by:
  • The frequency of the RADAR transmitter. (0% chose this)
  • The pulse repetition rate. (25% chose this)
  • The transmitted pulse width. (65% chose this)
  • The pulse repetition frequency. (10% chose this)
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RADAR interference to a communications receiver is eliminated by:
  • Not operating other devices when RADAR is in use. (0% chose this)
  • Properly grounding, bonding, and shielding all units. (94% chose this)
  • Using a high pass filter on the power line. (6% chose this)
  • Using a link coupling. (0% chose this)
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The phantastron circuit is capable of:
  • Stabilizing the magnetron. (11% chose this)
  • Preventing saturation of the RADAR receiver. (17% chose this)
  • Being used to control repeller voltage in the AFC system. (6% chose this)
  • Developing a linear ramp voltage when triggered by an external source. (67% chose this)
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The basic frequency determining element in a Gunn oscillator is:
  • The power supply voltage. (14% chose this)
  • The type of semiconductor used. (0% chose this)
  • The resonant cavity. (67% chose this)
  • The loading of the oscillator by the mixer. (19% chose this)
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The heading flash is a momentary intensification of the sweep line on the PPI presentation. Its function is to:
  • Alert the operator when a target is within range. (22% chose this)
  • Alert the operator when shallow water is near. (0% chose this)
  • Inform the operator of the dead-ahead position on the PPI scope. (61% chose this)
  • Inform the operator when the antenna is pointed to the rear of the ship. (17% chose this)
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The circuit shown in Fig. 8C10 is the output of a switching power supply. Measuring from the junction of CR6, CR7 and L1 to ground with an oscilloscope, what waveform would you expect to see?
  • Filtered DC. (23% chose this)
  • Pulsating DC at line frequency. (8% chose this)
  • AC at line frequency. (8% chose this)
  • Pulsating DC much higher than line frequency. (62% chose this)
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What does the term ARPA/CAS refer to?
  • The basic RADAR system in operation. (0% chose this)
  • The device which displays the optional U.S.C.G. Acquisition and Search RADAR information on a CRT display. (29% chose this)
  • The device which acquires and tracks targets that are displayed on the RADAR indicator's CRT. (71% chose this)
  • The device which allows the ship to automatically steer around potential hazards. (0% chose this)
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Overcoupling in a RADAR receiver will cause?
  • Improved target returns. (8% chose this)
  • Increase the range of the IAGC. (8% chose this)
  • Decrease noise. (8% chose this)
  • Oscillations. (75% chose this)
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A pulse RADAR transmits a 0.5 microsecond RF pulse with a peak power of 100 kilowatts every 1600 microseconds. This RADAR has:
  • An average power of 31.25 watts. (68% chose this)
  • A PRF of 3,200. (16% chose this)
  • A maximum range of 480 kilometers. (0% chose this)
  • A duty cycle of 3.125 percent. (16% chose this)
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A logarithmic IF amplifier is preferable to a linear IF amplifier in a RADAR receiver because it:
  • Has higher gain. (0% chose this)
  • Is more easily aligned. (6% chose this)
  • Has a lower noise figure. (0% chose this)
  • Has a greater dynamic range. (94% chose this)
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In a display system power supply, what is the purpose of the inverter?
  • Inverts the polarity of the DC voltage applied to the voltage regulators. (25% chose this)
  • Provides the dual polarity 12 volt DC supply. (19% chose this)
  • Acts as the voltage regulator for the 5 volt DC supply. (0% chose this)
  • Produces the pulsed DC input voltage to the power transformer. (56% chose this)
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RADAR receivers are similar to:
  • FM receivers. (0% chose this)
  • HF receivers. (0% chose this)
  • T.V. receivers. (7% chose this)
  • Microwave receivers. (93% chose this)
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Which of the following signals are usually an input to the video amplifier?
  • Range. (6% chose this)
  • Brilliance. (0% chose this)
  • Contrast. (0% chose this)
  • All of the above. (94% chose this)
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Video amplifiers in pulse RADAR receivers must have a broad bandwidth because:
  • Weak pulses must be amplified. (55% chose this)
  • High frequency sine waves must be amplified. (0% chose this)
  • The RADARs operate at PRFs above 100. (18% chose this)
  • The pulses produced are normally too wide for video amplification. (27% chose this)
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A circulator provides what function in the RF section of a RADAR system?
  • It replaces the TR cell and functions as a duplexer. (75% chose this)
  • It cools the magnetron by forcing a flow of circulating air. (5% chose this)
  • It permits tests to be made to the thyristors while in use. (0% chose this)
  • It transmits antenna position to the indicator during operation. (20% chose this)
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A constant frequency switching power supply regulator with an input voltage of 165 volts DC, and a switching frequency of 20 kHz, has an "ON" time of 27 microseconds when supplying 1 ampere to its load. What is the output voltage across the load?
  • It cannot be determined with the information given. (11% chose this)
  • 305.55 volts DC. (0% chose this)
  • 89.1 volts DC. (67% chose this)
  • 165 volts DC. (22% chose this)
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Where is a RF attenuator used in a RADAR unit?
  • Between the antenna and the receiver. (18% chose this)
  • Between the magnetron and the antenna. (24% chose this)
  • Between the magnetron and the AFC section of the receiver. (53% chose this)
  • Between the AFC section and the klystron. (6% chose this)
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The modulation frequency of most RADAR systems is between:
  • 60 and 500 Hz. (63% chose this)
  • 3000 and 6000 Hz. (16% chose this)
  • 1500 and 7500 Hz. (11% chose this)
  • 1000 and 3000 Hz. (11% chose this)
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Range rings on the PPI indicator are oval in shape. Which circuit would you suspect is faulty?
  • Timing circuit. (14% chose this)
  • Video amplifier circuit. (29% chose this)
  • Range marker circuit. (29% chose this)
  • Sweep generation circuit. (29% chose this)
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The klystron local oscillator is constantly kept on frequency by:
  • Constant manual adjustments. (0% chose this)
  • The Automatic Frequency Control circuit. (64% chose this)
  • A feedback loop from the crystal detector. (21% chose this)
  • A feedback loop from the TR box. (14% chose this)
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For a range of 30 nautical miles, the RADAR pulse repetition frequency should be:
  • 0.27 kHz or less. (5% chose this)
  • 2.7 kHz or less. (85% chose this)
  • 27 kHz or more. (5% chose this)
  • 2.7 Hz or more. (5% chose this)
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The display power supply provides the following:
  • 5 volts DC for logic circuits. (23% chose this)
  • ± 12 volts DC for analog and sweep circuits. (15% chose this)
  • 17kV DC for the CRT HV anode. (8% chose this)
  • All of the above (54% chose this)
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Which is typical current for a silicon crystal used in a RADAR mixer or detector circuit?
  • 3 mA (76% chose this)
  • 15 mA (10% chose this)
  • 50 mA (10% chose this)
  • 100 mA (5% chose this)
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Choose the most correct statement with respect to component damage from electrostatic discharge:
  • ESD damage occurs primarily in passive components which are easily identified and replaced. (8% chose this)
  • ESD damage occurs primarily in active components which are easily identified and replaced. (0% chose this)
  • The technician will feel a small static shock and recognize that ESD damage has occurred to the circuit. (0% chose this)
  • ESD damage may cause immediate circuit failures, but may also cause failures much later at times when the RADAR set is critically needed. (92% chose this)
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If a CRT is dropped:
  • Most likely nothing will happen because they are built with durability in mind. (7% chose this)
  • It might go out of calibration. (0% chose this)
  • The phosphor might break loose. (7% chose this)
  • It might implode, causing damage to workers and equipment. (87% chose this)
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In the Line-Driver/Coax/Line-receiver circuit shown in Fig. 8A3, what component is represented by the blank box marked "X"?
  • 25-ohm resistor. (4% chose this)
  • 51-ohm resistor. (81% chose this)
  • 10-microhm inductor. (0% chose this)
  • 20-microhm inductor. (15% chose this)
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The block diagram of a typical RADAR system microprocessor is shown in Fig. 8A2. Choose the most correct statement regarding this system.
  • The ALU is used for address decoding. (19% chose this)
  • The Memory and I/O communicate with peripherals. (67% chose this)
  • The control unit executes arithmetic manipulations. (5% chose this)
  • The internal bus is used simultaneously by all units. (10% chose this)
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The display power supply provides the following:
  • +18 volts DC for the pulse forming network. (0% chose this)
  • 5 volts DC for logic circuits and ± 12 volts DC for analog and sweep circuits. (56% chose this)
  • 80 volts AC for the antenna resolver circuits. (0% chose this)
  • All of the above (44% chose this)
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In a marine RADAR set, a high VSWR is indicated at the magnetron output. The waveguide and rotary joint appear to be functioning properly. What component may be malfunctioning?
  • The magnetron (17% chose this)
  • The waveform generator (0% chose this)
  • The STC circuit (17% chose this)
  • The waveguide array termination (67% chose this)
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Which of the following functions is not affected by the timing circuit?
  • Resolver output. (50% chose this)
  • Pulse repetition frequency. (13% chose this)
  • Sweep drive. (19% chose this)
  • Modulation. (19% chose this)
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Noise can appear on the LCD as:
  • Erratic video and sharp changes in intensity. (73% chose this)
  • Black spots on the screen. (7% chose this)
  • Changes in bearings. (0% chose this)
  • None of the above. (20% chose this)
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Which of the following signals is not usually an input to the video amplifier?
  • Resolver. (82% chose this)
  • Range. (12% chose this)
  • Brilliance. (6% chose this)
  • Contrast. (0% chose this)
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In a RADAR unit, if the crystal mixer becomes defective, replace the:
  • Crystal only. (20% chose this)
  • The crystal and the ATR tube. (20% chose this)
  • The crystal and the TR tube. (50% chose this)
  • The crystal and the klystron. (10% chose this)
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A gated LC oscillator, operating at 27 kHz, is being used to develop range markers. If each cycle is converted to a range mark, the range between markers will be:
  • 3 nautical miles. (60% chose this)
  • 6 nautical miles. (0% chose this)
  • 8 nautical miles. (13% chose this)
  • 12 nautical miles. (27% chose this)
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Choose the most correct statement containing the parameters which control the size of the target echo.
  • Transmitted power, antenna effective area, transmit and receive losses, RADAR cross section of the target, range to target. (72% chose this)
  • Height of antenna, power radiated, size of target, receiver gain, pulse width. (11% chose this)
  • Power radiated, antenna gain, size of target, shape of target, pulse width, receiver gain. (17% chose this)
  • Magnetron gain, antenna gain, size of target, range to target, wave-guide loss. (0% chose this)
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In order to ensure that a practical filter is able to remove undesired components from the output of an analog-to-digital converter, the sampling frequency should be:
  • The same as the lowest component of the analog frequency. (8% chose this)
  • Two times the highest component of the analog frequency. (38% chose this)
  • Greater than two times the highest component of the sampled frequency. (46% chose this)
  • The same as the highest component of the sampled frequency. (8% chose this)
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Pulse RADARs require precise timing for their operation. Which type circuit below might best be used to provide these accurate timing pulses?
  • Single-swing blocking oscillator. (80% chose this)
  • AFC controlled sinewave oscillator. (0% chose this)
  • Non-symmetrical astable multivibrator. (13% chose this)
  • Triggered flip-flop type multivibrator. (7% chose this)
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What section of the receiving system sends signals to the display system?
  • Video amplifier. (89% chose this)
  • Audio amplifier. (0% chose this)
  • I.F. Amplifier. (0% chose this)
  • Resolver. (11% chose this)
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One RADAR mile is how many microseconds?
  • 6.2 (5% chose this)
  • 528.0 (0% chose this)
  • 12.34 (86% chose this)
  • 0.186 (10% chose this)
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The sensitivity time control (STC) circuit:
  • Decreases the sensitivity of the receiver for close objects. (42% chose this)
  • Increases the sensitivity of the receiver for close objects. (8% chose this)
  • Increases the sensitivity of the receiver for distant objects. (33% chose this)
  • Decreases the sensitivity of the transmitter for close objects. (17% chose this)
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What RADAR circuit determines the pulse repetition rate (PRR)?
  • Discriminator. (0% chose this)
  • Timer (synchronizer circuit). (83% chose this)
  • Artificial transmission line. (4% chose this)
  • Pulse-rate-indicator circuit. (13% chose this)
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The purpose of the Electronic Bearing Line is to:
  • Indicate your own vessel's heading. (24% chose this)
  • Measure the bearing of a specific target. (47% chose this)
  • Indicate True North. (18% chose this)
  • Display the range of a specific target. (12% chose this)
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An important component of the VRM system is the:
  • Resolver. (9% chose this)
  • Interference rejection circuit. (9% chose this)
  • STC sensitivity control. (36% chose this)
  • Shift register. (45% chose this)
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The sweep drive is initiated by what circuit?
  • Resolver. (31% chose this)
  • Sweep amplifier. (19% chose this)
  • Video amplifier. (6% chose this)
  • Synchronizer. (44% chose this)
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Why is coaxial cable often used for S-band installations instead of a waveguide?
  • Losses can be kept reasonable at S-band frequencies and the installation cost is lower. (79% chose this)
  • A waveguide will not support the power density required for modern S-band RADAR transmitters. (7% chose this)
  • S-band waveguide flanges show too much leakage and are unsafe for use near personnel. (7% chose this)
  • Dimensions for S-band waveguide do not permit a rugged enough installation for use by ships at sea. (7% chose this)
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Low or no mixer current could be caused by:
  • Local oscillator frequency misadjustment. (8% chose this)
  • TR cell failure. (8% chose this)
  • Mixer diode degradation. (8% chose this)
  • All of the above. (75% chose this)
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For a range of 5 nautical miles, the RADAR pulse repetition frequency should be:
  • 16.2 Hz or more. (0% chose this)
  • 16.2 MHz or less. (11% chose this)
  • 1.62 kHz or more. (11% chose this)
  • 16.2 kHz or less. (78% chose this)
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What component of a RADAR receiver is represented by block 49 in Fig. 8A1?
  • Discriminator. (7% chose this)
  • IF amplifier. (0% chose this)
  • Klystron. (14% chose this)
  • Crystal detector (the mixer). (79% chose this)
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Which answer best describes a line on the display which indicates a target's position. The speed is shown by the length of the line and the course by the direction of the line.
  • Vector. (67% chose this)
  • Electronic Bearing Line. (20% chose this)
  • Range Marker. (0% chose this)
  • Heading Marker. (13% chose this)
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Loss of distant targets during and immediately after wet weather indicates:
  • A leak in waveguide or rotary joint. (73% chose this)
  • High atmospheric absorption. (13% chose this)
  • Dirt or soot on the rotary joint. (0% chose this)
  • High humidity in the transmitter causing power supply loading. (13% chose this)
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A high magnetron current indicates a/an:
  • Defective AFC crystal. (6% chose this)
  • Increase in duty cycle. (6% chose this)
  • Defective external magnetic field. (88% chose this)
  • High standing wave ratio (SWR). (0% chose this)
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What component is block 50 in Fig. 8A1?
  • IF amplifier. (7% chose this)
  • AFC amplifier. (20% chose this)
  • Discriminator. (67% chose this)
  • Crystal detector. (7% chose this)
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If a target is 5 miles away, how long does it take for the RADAR echo to be received back at the antenna?
  • 51.4 microseconds. (4% chose this)
  • 123 microseconds. (4% chose this)
  • 30.75 microseconds. (4% chose this)
  • 61.7 microseconds. (87% chose this)
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An AFC system keeps the receiver tuned to the transmitted signal by varying the frequency of the:
  • Magnetron. (13% chose this)
  • IF amplifier stage. (7% chose this)
  • Local oscillator. (80% chose this)
  • Cavity duplexer. (0% chose this)
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What is the distance in nautical miles to a target if it takes 308.5 microseconds for the RADAR pulse to travel from the RADAR antenna to the target and back.
  • 12.5 nautical miles. (12% chose this)
  • 25 nautical miles. (80% chose this)
  • 50 nautical miles. (4% chose this)
  • 2.5 nautical miles. (4% chose this)
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The block diagram of a typical RADAR system microprocessor is shown in Fig. 8A2. Choose the most correct statement regarding this system.
  • The ALU is used for address decoding. (8% chose this)
  • General registers are used for arithmetic manipulations. (17% chose this)
  • The control unit executes arithmetic manipulations. (8% chose this)
  • Address pointers are contained in the general registers. (67% chose this)
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If the TR tube malfunctions:
  • The transmitter might be damaged. (6% chose this)
  • The receiver might be damaged. (53% chose this)
  • The klystron might be damaged. (24% chose this)
  • Magnetron current will increase. (18% chose this)
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In the circuit shown in Fig. 8A4, U5 pins 1 and 4 are high and both are in the reset state. Assume one clock cycle occurs of Clk A followed by one cycle of Clk B. What are the output states of the two D-type flip flops?
  • Pin 5 low, Pin 9 low. (10% chose this)
  • Pin 5 high, Pin 9 low. (5% chose this)
  • Pin 5 low, Pin 9 high. (15% chose this)
  • Pin 5 high, Pin 9 high. (70% chose this)
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Which of the following statements is correct?
  • The video amplifier is located between the mixer and the I.F. amplifier. (6% chose this)
  • The video amplifier operates between 60 MHz and 120 Mhz. (6% chose this)
  • The video amplifier is located between the I.F. amplifier and the display system. (78% chose this)
  • The video amplifier is located between the local oscillator and the mixer. (11% chose this)
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A ferrite circulator is most commonly used in what portion of a RADAR system?
  • The antenna. (6% chose this)
  • The modulator. (13% chose this)
  • The duplexer. (75% chose this)
  • The receiver. (6% chose this)
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A true bearing presentation appears as follows:
  • The bow of the vessel always points up. (15% chose this)
  • The course of the five closest targets is displayed. (0% chose this)
  • North is at the top of the display and the ship's heading flasher indicates the vessel's course. (80% chose this)
  • The course and distance of the closest target is displayed. (5% chose this)
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You are troubleshooting a component on a printed circuit board in a RADAR system while referencing the Truth Table in Fig. 8A8. What kind of integrated circuit is the component?
  • D-type Flip-Flop, 3-State, Inverting. (74% chose this)
  • Q-type Flip-Flop, Non-Inverting. (11% chose this)
  • Q-type Directional Shift Register, Dual. (16% chose this)
  • D to Q Convertor, 2-State. (0% chose this)
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One of the best methods of reducing noise in a RADAR receiver is?
  • Changing the frequency. (19% chose this)
  • Isolation. (75% chose this)
  • Replacing the resonant cavity. (6% chose this)
  • Changing the IF strip. (0% chose this)
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A non-magnetic screwdriver should always be used when replacing what component?
  • TR tube. (17% chose this)
  • Mixer. (0% chose this)
  • Video amplifier. (0% chose this)
  • Magnetron. (83% chose this)
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Fine adjustments of a reflex klystron are accomplished by:
  • Adjusting the flexible wall of the cavity. (18% chose this)
  • Varying the repeller voltage. (68% chose this)
  • Adjusting the AFC control system. (0% chose this)
  • Varying the cavity grid potential. (14% chose this)
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The MTI circuit:
  • Acts as a mixer in a RADAR receiver. (0% chose this)
  • Is a filter, which blocks out stationary targets, allowing only moving targets to be detected. (86% chose this)
  • Is used to monitor transmitter interference. (7% chose this)
  • Will pick up targets, which are not in motion. (7% chose this)
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The sweep frequency of a RADAR indicator is determined by what parameter?
  • Carrier frequency. (5% chose this)
  • Pulse width. (10% chose this)
  • Duty cycle. (5% chose this)
  • Pulse repetition frequency. (80% chose this)
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The ship's speed indication on the ARPA display can be set manually, but does not change with changes in the vessel's speed. What other indication would point to a related equipment failure?
  • "GYRO OUT" is displayed on the ARPA indicator. (17% chose this)
  • "LOG OUT" is displayed on the ARPA indicator. (83% chose this)
  • "TARGET LOST" is displayed on the ARPA indicator. (0% chose this)
  • "NORTH UP" is displayed on the ARPA indicator. (0% chose this)
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If the RADAR unit has a pulse repetition frequency (PRF) of 2000 Hz and a pulse width of 0.05 microseconds, what is the duty cycle?
  • 0.0001 (45% chose this)
  • 0.0005 (41% chose this)
  • 0.05 (9% chose this)
  • 0.001 (5% chose this)
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The timer circuit:
  • Determines the pulse repetition rate (PRR). (20% chose this)
  • Determines range markers. (0% chose this)
  • Provides blanking and unblanking signals for the CRT. (5% chose this)
  • All of the above (75% chose this)
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The purpose of the pulse-forming network is to:
  • Determine the width of the modulating pulses. (69% chose this)
  • Determine the pulse repetition rate. (31% chose this)
  • Act as a high pass filter. (0% chose this)
  • Act as a log pass filter. (0% chose this)
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Which of the following inputs is required to indicate azimuth?
  • Gyro signals. (62% chose this)
  • Synchronizer (0% chose this)
  • Resolver. (15% chose this)
  • Range rings. (23% chose this)
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A search RADAR has a pulse width of 1.0 microsecond, a pulse repetition frequency (PRF) of 900 Hz, and an average power of 18 watts. The unit's peak power is:
  • 200 kilowatts. (15% chose this)
  • 180 kilowatts. (10% chose this)
  • 20 kilowatts. (65% chose this)
  • 2 kilowatts. (10% chose this)
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Logarithmic receivers:
  • Can't be damaged. (0% chose this)
  • Can't be saturated. (64% chose this)
  • Should not be used in RADAR systems. (27% chose this)
  • Have low sensitivity. (9% chose this)
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The pulse developed by the modulator may have an amplitude greater than the supply voltage. This is possible by:
  • Using a voltage multiplier circuit. (7% chose this)
  • Employing a resonant charging choke. (79% chose this)
  • Discharging a capacitor through an inductor. (0% chose this)
  • Discharging two capacitors in series and combining their charges. (14% chose this)
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The purpose of the sweep amplifier is to:
  • Increase the power of the video amplifier. (6% chose this)
  • Drive the CRT deflection coils. (25% chose this)
  • Drive the resolver coils. (6% chose this)
  • All of the above. (63% chose this)
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If a RADAR transmitter has a pulse repetition frequency (PRF) of 900 Hz, a pulse width of 0.5 microseconds and a peak power of 15 kilowatts, what is its average power output?
  • 15 kilowatts. (17% chose this)
  • 13.5 watts. (0% chose this)
  • 6.75 watts. (74% chose this)
  • 166.67 watts. (9% chose this)
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The primary cause of noise in a RADAR receiver can be attributed to:
  • Electrical causes. (14% chose this)
  • Atmospheric changes. (14% chose this)
  • Poor grounding. (21% chose this)
  • Thermal noise caused by RADAR receiver components. (50% chose this)
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The pulse repetition rate (PRR) refers to:
  • The reciprocal of the duty cycle. (0% chose this)
  • The pulse rate of the local oscillator tube. (10% chose this)
  • The pulse rate of the klystron. (14% chose this)
  • The pulse rate of the magnetron. (76% chose this)
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It is reported that the RADAR is not receiving small targets. The most likely causes are:
  • Magnetron, IF amplifier, or receiver tuning. (59% chose this)
  • PFN, crystals, or processor memory. (12% chose this)
  • Crystals, local oscillator tuning, or power supply. (24% chose this)
  • Fuse blown, IF amp, or video processor. (6% chose this)
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How long would it take for a RADAR pulse to travel to a target 10 nautical miles away and return to the RADAR receiver?
  • 12.34 microseconds. (10% chose this)
  • 1.234 microseconds. (0% chose this)
  • 123.4 microseconds. (90% chose this)
  • 10 microseconds. (0% chose this)
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RADAR range is measured by the constant:
  • 150 meters per microsecond. (78% chose this)
  • 150 yards per microsecond. (6% chose this)
  • 300 yards per microsecond. (6% chose this)
  • 18.6 miles per microsecond. (11% chose this)
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In the AFC system, the discriminator compares the frequencies of the:
  • Magnetron and klystron. (53% chose this)
  • PRR generator and magnetron. (7% chose this)
  • Magnetron and crystal detector. (33% chose this)
  • Magnetron and video amplifier. (7% chose this)
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For a range of 100 nautical miles, the RADAR pulse repetition frequency should be:
  • 8.1 kHz or less. (18% chose this)
  • 810 Hz or less. (71% chose this)
  • 8.1 kHz or more. (6% chose this)
  • 81 kHz or more. (6% chose this)
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The main purpose of the sweep generator is to provide:
  • Antenna information. (7% chose this)
  • Range rings. (20% chose this)
  • Composite video to the cathode of the CRT. (27% chose this)
  • The drive signal to the sweep amplifier. (47% chose this)
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Pulse-forming networks are usually composed of the following:
  • Series capacitors and shunt inductors. (7% chose this)
  • Series inductors and shunt capacitors. (60% chose this)
  • Resonant circuit with an inductor and capacitor. (33% chose this)
  • None of the above. (0% chose this)
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What component of a RADAR receiver is represented by block 46 in Fig. 8A1?
  • The ATR box. (14% chose this)
  • The TR box. (62% chose this)
  • The RF Attenuator. (19% chose this)
  • The Crystal Detector. (5% chose this)
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What type of transmitter power is measured over a period of time?
  • Average. (87% chose this)
  • Peak. (7% chose this)
  • Reciprocal. (0% chose this)
  • Return. (7% chose this)
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In video amplifiers, compensation for the input and output stage capacitances must be accomplished to prevent distorting the video pulses. This compensation is normally accomplished by connecting:
  • Inductors in parallel with both the input and output capacitances. (17% chose this)
  • Resistances in parallel with both the input and output capacitances. (8% chose this)
  • An inductor in parallel with the input capacitance and an inductor in series with the output capacitance. (17% chose this)
  • An inductor in series with the input capacitance and an inductor in parallel with the output capacitance. (58% chose this)
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A shipboard RADAR uses a PFN driving a magnetron cathode through a step-up transformer. This results in which type of modulation?
  • Frequency modulation. (11% chose this)
  • Amplitude modulation. (0% chose this)
  • Continuous Wave (CW) modulation. (11% chose this)
  • Pulse modulation. (78% chose this)
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A circuit card in a RADAR system has just been replaced with a spare card. You notice the voltage level at point E in Fig. 8F12 is negative 4.75 volts when the inputs are all at 5 volts. The problem is:
  • The 25 K resistor is open. (0% chose this)
  • The 100 K resistor has been mistakenly replaced with a 50 K resistor. (22% chose this)
  • The op amp is at the rail voltage. (0% chose this)
  • The 50 K resistor has been mistakenly replaced with a 25 K resistor. (78% chose this)
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What device is used as a transmitter in a marine RADAR system?
  • Magnetron. (94% chose this)
  • Klystron. (0% chose this)
  • Beam-powered pentode. (6% chose this)
  • Thyratron. (0% chose this)
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How does the dual memory function reduce sea clutter?
  • Successive sweeps are digitized and compared. Only signals appearing in both sweeps are displayed. (100% chose this)
  • The dual memory system makes the desired targets larger. (0% chose this)
  • It reduces receiver gain for closer signals. (0% chose this)
  • It increases receiver gain for real targets. (0% chose this)
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If the pulse repetition frequency (PRF) is 2000 Hz, what is the pulse repetition interval (PRI)?
  • 0.05 seconds. (6% chose this)
  • 0.005 seconds. (22% chose this)
  • 0.0005 seconds. (61% chose this)
  • 0.00005 seconds. (11% chose this)
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The diagram in Fig. 8C9 shows a simplified RADAR mixer circuit using a crystal diode as the first detector. What is the output of the circuit when no echoes are being received?
  • 60 MHz CW. (7% chose this)
  • 4095 MHz CW. (0% chose this)
  • 4155 MHz CW. (7% chose this)
  • No output is developed. (86% chose this)
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Blocking oscillators operate on the formula of:
  • T = R x C. (88% chose this)
  • I = E/R. (6% chose this)
  • By using the receiver's AGC. (6% chose this)
  • None of the above are correct. (0% chose this)
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In a RADAR receiver the most common types of interference are?
  • Weather and sea return. (71% chose this)
  • Sea return and thermal. (0% chose this)
  • Weather and electrical. (29% chose this)
  • Jamming and electrical. (0% chose this)
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What is the relationship between pulse repetition rate and pulse width?
  • Higher PRR with wider pulse width. (0% chose this)
  • The pulse repetition rate does not change with the pulse width. (12% chose this)
  • The pulse width does not change with the pulse repetition rate. (12% chose this)
  • Lower PRR with wider pulse width. (76% chose this)
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A shipboard RADAR transmitter has a pulse repetition frequency (PRF) of 1,000 Hz, a pulse width of 0.5 microseconds, peak power of 150 KW, and a minimum range of 75 meters. Its duty cycle is:
  • 0.5 (5% chose this)
  • 0.05 (15% chose this)
  • 0.005 (40% chose this)
  • 0.0005 (40% chose this)
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While troubleshooting a memory problem in a raster scan RADAR, you discover that the "REFRESH" cycle is not operating correctly. What type of memory circuit are you working on?
  • SRAM (7% chose this)
  • DRAM (87% chose this)
  • ROM (7% chose this)
  • PROM (0% chose this)
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Why should long horizontal runs of waveguide be avoided?
  • They must be insulated to prevent electric shock. (0% chose this)
  • To prevent damage from shipboard personnel. (0% chose this)
  • To minimize reception of horizontally polarized returns. (20% chose this)
  • To prevent accumulation of condensation. (80% chose this)
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The ARPA term CPA refers to:
  • The furthest point a ship or target will get to your own ship's bow. (9% chose this)
  • Direction of target relative to your own ship's direction. (18% chose this)
  • The combined detection and processing of targets. (18% chose this)
  • The closest point a ship or target will approach your own ship. (55% chose this)
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What are the usual input signals to the video amplifier?
  • Low level video. (0% chose this)
  • Fixed range rings. (0% chose this)
  • Variable range rings. (0% chose this)
  • All of the above. (100% chose this)
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How many deflection coils are driven by the sweep amplifier?
  • 4 (13% chose this)
  • 3 (13% chose this)
  • 2 (75% chose this)
  • 1 (0% chose this)
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Range markers are determined by:
  • The CRT. (31% chose this)
  • The magnetron. (8% chose this)
  • The timer. (46% chose this)
  • The video amplifier. (15% chose this)
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What is the correct value of RS in Fig. 8A7, if the voltage across the LED is 1.9 Volts with 5 Volts applied and If max equals 40 milliamps?
  • 4,700 ohms. (11% chose this)
  • 155 ohms. (11% chose this)
  • 77 ohms. (79% chose this)
  • 10,000 ohms. (0% chose this)
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Modern liquid crystal displays have a pixel count of:
  • Greater than 200 pixels per inch. (80% chose this)
  • Greater than 50 pixels per inch. (13% chose this)
  • Can have no more than 125 pixels per inch. (0% chose this)
  • Can implement 1,000 pixels per inch. (7% chose this)
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With regard to the comparator shown in Fig. 8C11, the input is a sinusoid. Nominal high level output of the comparator is 4.5 volts. Choose the most correct statement regarding the input and output.
  • The leading edge of the output waveform occurs 180 degrees after positive zero crossing of the input waveform. (78% chose this)
  • The rising edge of the output waveform trails the positive zero crossing of the input waveform by 45 degrees. (11% chose this)
  • The rising edge of the output waveform trails the negative zero crossing of the input waveform by 45 degrees. (0% chose this)
  • The rising edge of the output waveform trails the positive peak of the input waveform by 45 degrees. (11% chose this)
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In a RADAR using digital video processing, a bright, wide ring appears at a fixed distance from the center of the display on all digital ranges. The transmitter is operating normally. What receiver circuit would you suspect is causing the problem?
  • VRM circuit. (0% chose this)
  • Video storage RAM or shift register. (64% chose this)
  • Range ring generator. (36% chose this)
  • EBL circuit. (0% chose this)
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