Fcc Grol Element 8

Front 1

Choose the most correct statement containing the parameters which control the size of the target echo.
A. Transmitted power, antenna effective area, transmit and receive losses, RADAR cross section of the target, range to target.
B. Height of antenna, power radiated, size of the target, receiver gain, pulse width.
C. Power radiated, antenna gain, size of target, range to target, wave-guide loss.
D. Magnetron gain, antenna gain, size of target, range to target, wave-guide loss.

Back 1

A. Transmitted power, antenna effective area, transmit and receive losses, RADAR cross section of the target, range to target.

Front 2

Which of the following has NO effect on the maximum range capability?
A. Carrier frequency
B. Recovery time
C. Pulse repetition frequency
D. Receiver sensitivity

Back 2

B. Recovery time

Front 3

What type of transmitter power is measured over a period of time?
A. Average
B. Peak
C. Reciprocal
D. Return

Back 3

A. Average

Front 4

What RADAR component controls timing throughout the system?
A. Power Supply
B. Indicator
C. Synchronizer
D. Receiver

Back 4

C. Synchronizer

Front 5

Which of the following components allows the use of a single antenna for both transmitting and receiving?
A. Mixer
B. Duplexer
C. Synchronizer
D. Modulator

Back 5

B. Duplexer

Front 6

The sweep frequency of a RADAR indicator is determined by what parameter?
A. Carrier frequency
B. Pulse width
C. Duty cycle
D. Pulse repetition frequency

Back 6

D. Pulse repetition frequency

Front 7

A radio wave will travel a distance of three nautical miles in:
A. 6.17 µs
B. 37.0 µs
C. 22.76 µs
D. 18.51 µs

Back 7

D. 18.51 µs

Front 8

One RADAR mile is how many microseconds(µs)?
A. 6.2
B. 528.0
C. 12.34
D. 0.186

Back 8

C. 12.34

Front 9

RADAR range is measured by the constant:
A. 150 meters per microsecond
B. 150 yards per microsecond
C. 300 yards per microsecond
D. 18.6 miles per microsecond

Back 9

A. 150 meters per microsecond

Front 10

If a target os 5 miles away, how long does it take for the RADAR echo to be received back at the antenna?
A. 51.4 µs
B. 123 µs
C. 30.75 µs
D. 61.7 µs

Back 10

D. 61.7 µs

Front 11

How long would it take for a RADAR pulse to travel to a target 10 nautical miles away and return to the RADAR receiver?
A. 12.34 µs
B. 1.234 µs
C. 123.4 µs
D. 10 µs

Back 11

C. 123.4 µs

Front 12

What is the distance in nautical miles to the target if it takes 308.5 µs for the RADAR pulse to travel from the RADAR antenna to the target and back.
A. 12.5 nm
B. 25 nm
C. 50 nm
D. 2.5 nm

Back 12

B. 25 nm

Front 13

Frequencies generally used for marine RADAR are in the (blank) part of the radio spectrum.
A. UHF
B. EHF
C. SHF
D. VHF

Back 13

C. SHF

Front 14

Practical RADAR operation requires the use of microwave frequencies so that:
A. Stronger target echoes will be produced.
B. Ground clutter

Back 14

A. Stronger target echoes will be produced.

Front 15

An S-band RADAR operates in which frequency band?
A. 1 - 2 GHz
B. 4 - 8 GHz
C. 8 - 12 GHz
D. 2 - 4 GHz

Back 15

D. 2 - 4 GHz

Front 16

A RADAR operating at a frequency of 3 GHz has a wavelength of approximately:
A. 1 cm
B. 10 cm
C. 3 cm
D. 30 cm

Back 16

B. 10 cm

Front 17

The major advantage of an S-band RADAR over an X-band RADAR is:
A. It is less affected by weather conditions.
B. It has a greater bearing resolution.
C. It is mechanically less complex.
D. It has a higher power output.

Back 17

A. It is less affected by weather conditions.

Front 18

An X-band RADAR operates in which frequency band?
A. 1 - 2 GHz
B. 2 - 4 GHz
C. 4 - 8 GHz
D. 8 - 12 GHz

Back 18

D. 8 - 12 GHz

Front 19

A pulse RADAR has a pulse repetition frequency(PRF) of 400 Hz, a pulse width of 1 µs, and a peak power f 100 kilowatts. The average power of the RADAR transmitter is:
A. 25 watts
B. 40 watts
C. 250 watts
D. 400 watts

Back 19

B. 40 watts

Front 20

A shipboard RADAR transmitter has a pulse repetition frequency(PRF) of 1,000 Hz, a pulse width of 0.5 µs, peak power of 150 KW, and a minimum range of 75 meters. Its duty cycle is:
A. 0.5
B. 0.05
C. 0.005
D. 0.0005

Back 20

D. 0.0005

Front 21

A pulse RADAR transmits a 0.5 µs RF pulse with a peak power of 100 kilowatts every 1600 µs. This RADAR has:
A. An average power of 31.25 watts.
B. A PRF of 3,200.
C. A maximum range of 480 kilometers.
D. A duty cycle of 3.125 percent.

Back 21

A. An average power of 31.25 watts.

Front 22

If a RADAR transmitter has a pulse repetition frequency of 900 Hz, a pulse width if 0.5 µs, and a peak power of 15 kilowatts, what is its average power output?
A. 15 kilowatts
B. 13.5 kilowatts
C. 6.75 kilowatts
D. 166.67 kilowatts

Back 22

C. 6.75 kilowatts

Front 23

What is the average power if the RADAR set has a PRF of 1000 Hz, a pulse width of 1 µs, and a peak power rating of 100 kilowatts?
A. 10 watts
B. 100 watts
C. 1,000 watts
D. None of these

Back 23

B. 100 watts

Front 24

A search RADAR has a pulse width of 1.0 µs, a pulse repetition frequency of 900 Hz, and an average power of 18 watts. The unit's peak power is:
A. 200 kilowatts
B. 180 kilowatts
C. 20 kilowatts
D. 2 kilowatts

Back 24

C. 20 kilowatts

Front 25

For a range of 5 nm, the RADAR pulse repetition frequency should be:
A. 16.2 Hz or more
B. 16.2 MHz or less
C. 1.62 kHz or more
D. 16.2 kHz or less

Back 25

D. 16.2 kHz or less

Front 26

For a range of 100 nm, the RADAR pulse repetition frequency should be:
A. 8.1 kHz or less
B. 810 Hz or less
C. 8.1 kHz or more
D. 81 kHz or more

Back 26

B. 810 Hz or less

Front 27

The minimum range of a RADAR is determined by:
A. The frequency of the RADAR transmitter
B. The pulse repetition rate
C. The transmitted pulse width
D. The pulse repetition frequency

Back 27

C. The transmitted pulse width

Front 28

Short range RADARs would most likely transmit:
A. Narrow pulses at a fast rate
B. Narrow pulses at a slow rate
C. Wide pulses at a fast rate
D. Wide pulses at a slow rate

Back 28

A. Narrow pulses at a fast rate

Front 29

For a range of 30 nm, the RADAR pulse repetition frequency should be:
A. 0.27 kHz or less
B. 2.7 kHz or less
C. 27 kHz or more
D. 2.7 Hz or more

Back 29

B. 2.7 kHz or less

Front 30

For a range of 10 nm, the RADAR pulse repetition frequency(PRF) should be:
A. Approximately 8.1 kHz or less
B. 900 Hz
C. 18.1 kHz or more
D. 120.3 µs

Back 30

A. Approximately 8.1 kHz or less

Front 31

If the PRF is 2500 Hz, what is the PRI?
A. 40µs
B. 400µs
C. 250µs
D. 800µs

Back 31

B. 400µs

Front 32

If the pulse repetition frequency(PRF) is 2000 Hz, what is the pulse repetition interval(PRI)?
A. 0.05µs
B. 0.005µs
C. 0.0005µs
D. 0.00005µs

Back 32

C. 0.0005µs

Front 33

The pulse repetition rate refers to:
A. The reciprocal of the duty cycle.
B. The pulse rate of the local oscillator tube.
C. The pulse rate of the klystron.
D. The pulse rate of the magnetron.

Back 33

D. The pulse rate of the magnetron.

Front 34

If the RADAR unit has a pulse repetition frequency of 2000 Hz and a pulse width of 0.05µs, what is the duty cycle?
A. 0.0001
B. 0.0005
C. 0.05
D. 0.001

Back 34

A. 0.0001

Front 35

Small targets are best detected by:
A. Short pulses transmitted at a fast rate.
B. Using J band frequencies.
C. Using a long pulse width with high output power.
D. All of these answers are correct.

Back 35

C. Using a long pulse width with high output power.

Front 36

What is the relationship between pulse repetition rate and pulse width?
A. Higher PRR with wider pulse width.
B. The pulse repetition rate does not change with the pulse width.
C. The pulse width does not change with the pulse repetition rate.
D. Lower PRR with wider pulse width.

Back 36

D. Lower PRR with wider pulse width.

Front 37

What component of a RADAR receiver is represented by block 46 in fig. 8A1?
A. The ATR box.
B. The TR box.
C. The RF attenuator.
D. The crystal detector.

Back 37

B. The TR box.

Front 38

What component of a RADAR receiver is represented by block 47 in fig. 8A1?
A. The ATR box.
B. The TR box.
C. The RF attenuator.
D. The crystal detector.

Back 38

C. The RF attenuator.

Front 39

When comparing a TTL and a CMOS NAND gate:
A. Both have active pull-up characteristics.
B. Both have three output states.
C. Both have comparable input power sourcing.
D. Both employ Schmitt diodes for increased speed capabilities.

Back 39

A. Both have active pull-up characteristics.

Front 40

Silicon crystals:
A. Are very sensitive to static electric charges.
B. Should be wrapped in lead foil for storage.
C. Tolerate very low currents.
D. All of these.

Back 40

D. All of these.

Front 41

Which is the typical current for a silicon crystal used in a RADAR mixer or detector circuit?
A. 3mA
B. 15mA
C. 50mA
D. 100mA

Back 41

A. 3mA

Front 42

A basic sample-and-hold circuit contains:
A. An analog switch and an amplifier.
B. An analog switch, a capacitor, and an amplifier.
C. An analog multiplexer and a capacitor.
D. An analog switch, a capacitor, amplifiers and input and output buffers.

Back 42

D. An analog switch, a capacitor, amplifiers and input and output buffers.

Front 43

The basic frequency determining element in a Gunn oscillator is:
A. The power supply voltage.
B. The type of semiconductor used.
C. The resonant cavity.
D. The loading of the oscillator by the mixer.

Back 43

C. The resonant cavity.

Front 44

Which of the following is not a method of analog-to-digital conversion?
A. Delta-sigma conversion
B. Dynamic-range conversion
C. Switched-capacitor conversion
D. Dual-slope integration

Back 44

B. Dynamic-range conversion

Front 45

When comparing TTL and CMOS logic families, which of the following is true:
A. CMOS logic requires a supply voltage of 5 volts +-20%, whereas TTL logic requires 5 volts +-5%.
B. Unused inputs should be tied high or low as necessary especially in the CMOS family.
C. At higher operating frequencies, CMOS circuits consume almost as much power as TTL circuits.
D. When a CMOS input is held low, it sources current into whatever it drives.

Back 45

C. At higher operating frequencies, CMOS circuits consume almost as much power as TTL circuits.

Front 46

The primary operating frequency of a reflex klystron is controlled by the:
A. Dimensions of the resonant cavity.
B. Level of voltage on the control grid.
C. Voltage applied to the cavity grids.
D. Voltage applied to the repeller plate.

Back 46

A. Dimensions of the resonant cavity.

Front 47

A Gunn diode oscillator takes advantage of what effect?
A. Negative resistance
B. Avalanche transit time
C. Bulk-effect
D. Negative resistance and bulk-effect

Back 47

D. Negative resistance and bulk-effect

Front 48

Fine adjustments of a reflex klystron are accomplished by:
A. Adjusting the flexible wall of the cavity
B. Varying the repeller voltage
C. Adjusting the AFC control system
D. Varying the cavity grid potential

Back 48

B. Varying the repeller voltage

Front 49

Blocking oscillators operate on the formula of:
A. T=RxC
B. I=E/R
C. By using the receiver's AGC
D. None of the above are correct

Back 49

A. T=RxC

Front 50

The block diagram of a typical RADAR system microprocessor is shown in Fig 8A2. Choose the most correct statment regarding this system.
A. The ALU is used for address decoding
B. The Memory and I/O communicate with peripherals
C. The control unit executes arithmetic manipulations.
D. The internal bus is used by all units

Back 50

B. The Memory and I/O communicate with peripherals

Front 51

The phantastron circuit is capable of:
A. Stabilizing the magnetron
B. Preventing the saturation of the RADAR receiver
C. Being used to control the repeller voltage in the AFC system
D. Developing a linear ramp voltage when triggered by an external source

Back 51

D. Developing a linear ramp voltage when triggered by an external source

Front 52

The block diagram of a typical RADAR system microprocessor is shown in Fig 8A2. Choose the most correct statement regarding this system.
A. The ALU executes arithmetic manipulations
B. The ALU is used for address decoding
C. General registers are used for arithmetic manipulations
D. Address pointers are contained in the control unit

Back 52

A. The ALU executes arithmetic manipulations

Front 53

In the Line-Driver/Coaz/Line-Receiver circuit shown in Fig 8A3, what component is represented by the blank box marked "X"?
A. 25-ohm resistor
B. 51-ohm resistor
C. 10-microhm inductor
D. 20-microhm inductor

Back 53

B. 51-ohm resistor

Front 54

Choose the most correct statement:
A. The magnetron anode is a low voltage circuit
B. The anode of the magnetron carries high voltage
C. The filament of the magnetron carries dangerous voltages
D. The magnetrons filament is a low voltage circuit

Back 54

C. The filament of the magnetron carries dangerous voltages

Front 55

In this circuit shown in Fig. 8A4, U5 pins 1 and 4 are both 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?
A. Pin 5 low, Pin 9 low
B. Pin 5 high, Pin 9 low
C. Pin 5 low, Pin 9 high
D. Pin 5 high, Pin 9 high

Back 55

D. Pin 5 high, Pin 9 high

Front 56

If more light strikes the photodiode in Fig. 8A5 there will be:
A. Less diode current.
B. No change in diode current.
C. More diode current.
D. There is wrong polarity on the diode.

Back 56

C. More diode current.

Front 57

In the circuit shown in Fig. 8A6 which of the following is true?
A. With A and B high, Q1 is saturated and Q2 is off.
B. With either A or B low, Q1 is saturated and Q2 is off.
C. With A and B low, Q2 is on and Q4 is off.
D. With either A or B low, Q1 is off and Q2 is on.

Back 57

B. With either A or B low, Q1 is saturated and Q2 is off.

Front 58

What is the correct value of R(sub s) in Fig. 8A7, if the voltage across the LED is 1.9 volts with 5 volts applied and I(sub f) max equals 40 milliamps?
A. 4700 ohms
B. 155 ohms
C. 77 ohms
D. 10000 ohms

Back 58

C. 77 ohms

Front 59

The block diagram of a typical RADAR system microprocessor is shown in Fig. 8A2. Choose the most correct statement regarding this system.
A. The ALU is used for address decoding.
B. General registers are used for arithmetic manipulations.
C. The control unit executes arithmetic manipulations.
D. Address pointers are contained in the general registers.

Back 59

D. Address pointers are contained in the general registers.

Front 60

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?
A. D-type Flip-Flop, 3-State, Inverting.
B. Q-type Flip-Flop, Non-Inverting.
C. Q-type Directional Shift Register, Dual.
D. D to Q Convertor, 2-State.

Back 60

A. D-type Flip-Flop, 3-State, Inverting.

Front 61

The magnetron is used to:
A. Generate the output signal at the proper operating frequency.
B. Determine the shape and width of the transmitted pulses.
C. Modulate the pulse signal.
D. Determine the pulse repetition rate.

Back 61

A. Generate the output signal at the proper operating frequency.

Front 62

The purpose of the modulator is to:
A. Transmit the high voltage pulses to the antenna.
B. Provide high voltage pulses of the proper shape and width to the magnetron.
C. Adjust the pulse repetition rate.
D. Tune the magnetron to the proper frequency.

Back 62

B. Provide high voltage pulses of the proper shape and width to the magnetron.

Front 63

Which of the following statements about most modern RADAR transmitter power supplies is false?
A. High voltage supplies may produce voltages in excess of 5,000 volts AC.
B. There are usually separate low voltage and high voltage supplies.
C. Low voltage supplies use switching circuits to deliver multiple voltages.
D. Low voltage supplies may supply both AC and DC voltages.

Back 63

A. High voltage supplies may produce voltages in excess of 5,000 volts AC.

Front 64

The purpose of the Pulse Forming Network is to:
A. Act as a low pass filter.
B. Act as a high pass filter.
C. Produce a pulse of the correct width.
D. Regulate the pulse repetition rate.

Back 64

C. Produce a pulse of the correct width.

Front 65

The purpose of the Synchronizer is to:
A. Generate the modulating pulse to the magnetron.
B. Generate the timing signal that establishes the pulse repetition rate.
C. Insure that the TR tube conducts at the proper time.
D. Control the pulse width.

Back 65

B. Generate the timing signal that establishes the pulse repetition rate.

Front 66

Which of the following is not part of the transmitting system?
A. Magnetron
B. Modulator
C. Pulse Forming Network
D. Klystron

Back 66

D. Klystron

Front 67

High voltage is applied to what element of the magnetron?
A. The waveguide
B. The anode
C. The plate cap
D. The cathode

Back 67

D. The cathode

Front 68

The characteristic of the magnetron output pulse that relates to accurate range measurement is its:
A. Amplitude
B. Decay time
C. Rise time
D. Duration

Back 68

C. Rise time

Front 69

What device is used as a transmitter in a marine RADAR system?
A. Magnetron
B. Klystron
C. Beam-powered pentode
D. Thyratron

Back 69

A. Magnetron

Front 70

The magnetron is:
A. A type of diode that requires an internal magnetic field.
B. A triode that requires an external magnetic field.
C. Used as the local oscillator in the RADAR unit.
D. A type of diode that requires an external magnetic field.

Back 70

D. A type of diode that requires an external magnetic field.

Front 71

A negative voltage is commonly applied to the magnetron cathode rather than a positive voltage to the magnetron anode because:
A. The cathode must be made neutral to force electrons into the drift area.
B. A positive voltage would tend to nullify or weaken the magnetic field.
C. The anode can be operated at ground potential for safety reasons.
D. The cavities might not be shock-excited into oscillation by a positive voltage.

Back 71

C. The anode can be operated at ground potential for safety reasons.

Front 72

The anode of a magnetron is normally maintained at ground potential:
A. Because it operates more efficiently that way.
B. For safety purposes.
C. Never. It must be highly positive to attract the electrons.
D. Because greater peak-power ratings can be achieved.

Back 72

B. For safety purposes.

Front 73

In a solid-state RADAR modulator, the duration of the transmitted pulse is determined by:
A. The thyratron.
B. The magnetron voltage.
C. The pulse forming network.
D. The trigger pulse.

Back 73

C. The pulse forming network.

Front 74

The modulation frequency of most RADAR systems is between:
A. 60 and 500 Hz.
B. 3000 and 6000 Hz.
C. 1500 and 7500 Hz.
D. 1000 and 3000 Hz.

Back 74

A. 60 and 500 Hz.

Front 75

A shipboard RADAR uses a PFN driving a magnetron cathode through a step-up transformer. This results in which type of modulation?
A. Frequency modulation.
B. Amplitude modulation.
C. Continuous Wave (CW) modulation.
D. Pulse modulation.

Back 75

D. Pulse modulation.

Front 76

In a pulse modulated magnetron what device determines the shape and width of the pulse?
A. Pulse Forming Network.
B. Thyratron.
C. LC parallel circuit.
D. Dimensions of the magnetron cavity.

Back 76

A. Pulse Forming Network.

Front 77

What device(s) may act as the modulator of a RADAR system?
A. Magnetron.
B. Klystron.
C. Video amplifier.
D. Thyratron or a silicon-controlled rectifier (SCR).

Back 77

D. Thyratron or a silicon-controlled rectifier (SCR).

Front 78

The purpose of a modulator in the transmitter section of a RADAR is to:
A. Improve bearing resolution.
B. Provide the correct waveform to the transmitter.
C. Prevent sea return.
D. Control magnetron power output.

Back 78

B. Provide the correct waveform to the transmitter.

Front 79

The pulse developed by the modulator may have an amplitude greater than the supply voltage. This is possible by:
A. Using a voltage multiplier circuit.
B. Employing a resonant charging choke.
C. Discharging a capacitor through an inductor.
D. Discharging two capacitors in series and combining their charges.

Back 79

B. Employing a resonant charging choke.

Front 80

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:
A. Power MOSFETS and Triacs.
B. Switching transistors.
C. Thyratrons and BJT’s.
D. SCR’s and Thyratrons.

Back 80

D. SCR’s and Thyratrons.

Front 81

The purpose of the pulse-forming network is to:
A. Determine the width of the modulating pulses.
B. Determine the pulse repetition rate.
C. Act as a high pass filter.
D. Act as a log pass filter.

Back 81

A. Determine the width of the modulating pulses.

Front 82

The shape and duration of the high-voltage pulse delivered to the magnetron is established by:
A. An RC network in the keyer stage.
B. The duration of the modulator input trigger.
C. An artificial delay line.
D. The time required to saturate the pulse transformer.

Back 82

C. An artificial delay line.

Front 83

Pulse-forming networks are usually composed of the following:
A. Series capacitors and shunt inductors.
B. Series inductors and shunt capacitors.
C. Resonant circuit with an inductor and capacitor.
D. None of the above.

Back 83

B. Series inductors and shunt capacitors.

Front 84

An artificial transmission line is used for:
A. The transmission of RADAR pulses.
B. Testing the RADAR unit, when actual targets are not available.
C. Determining the shape and duration of pulses.
D. Testing the delay time for artificial targets.

Back 84

C. Determining the shape and duration of pulses.

Front 85

The ferrite material in a circulator is used as a(an):
A. Electric switch.
B. Saturated reactor.
C. Loading element.
D. Phase shifter.

Back 85

D. Phase shifter.

Front 86

In a circular resonant cavity with flat ends, the E-field and the H-field form with specific relationships. The:
A. E-lines are parallel to the top and bottom walls.
B. E-lines are perpendicular to the end walls.
C. H-lines are perpendicular to the side walls.
D. H-lines are circular to the end walls.

Back 86

B. E-lines are perpendicular to the end walls.

Front 87

A ferrite circulator is most commonly used in what portion of a RADAR system?
A. The antenna.
B. The modulator.
C. The duplexer.
D. The receiver.

Back 87

C. The duplexer.

Front 88

A circulator provides what function in the RF section of a RADAR system?
A. It replaces the TR cell and functions as a duplexer.
B. It cools the magnetron by forcing a flow of circulating air.
C. It permits tests to be made to the thyristors while in use.
D. It transmits antenna position to the indicator during operation.

Back 88

A. It replaces the TR cell and functions as a duplexer.

Front 89

A directional coupler has an attenuation of -30 db. A measurement of 100 milliwatts at the coupler indicates the power of the line is:
A. 10 watts.
B. 100 watts.
C. 1,000 watts.
D. 10,000 watts.

Back 89

B. 100 watts.

Front 90

What is the purpose or function of the RADAR duplexer/circulator?
A. An electronic switch that allows the use of one antenna for both transmission and reception.
B. A coupling device that is used in the transition from a rectangular waveguide to a circular waveguide.
C. A modified length of waveguide used to sample a portion of the transmitted energy for testing purposes.
D. A dual section coupling device that allows the use of a magnetron as a transmitter.

Back 90

A. An electronic switch that allows the use of one antenna for both transmission and reception.

Front 91

The ATR box:
A. Protects the receiver from strong RADAR signals.
B. Prevents the received signal from entering the transmitter.
C. Turns off the receiver when the transmitter is on.
D. All of the above.

Back 91

B. Prevents the received signal from entering the transmitter.

Front 92

When a pulse RADAR is radiating, which elements in the TR box are energized?
A. The TR tube only.
B. The ATR tube only.
C. Both the TR and ATR tubes.
D. Neither the TR nor ATR tubes.

Back 92

C. Both the TR and ATR tubes.

Front 93

The TR box:
A. Prevents the received signal from entering the transmitter.
B. Protects the receiver from the strong RADAR pulses.
C. Turns off the receiver when the transmitter is on.
D. Protects the receiver from the strong RADAR pulses and mutes the receiver when the transmitter is on.

Back 93

D. Protects the receiver from the strong RADAR pulses and mutes the receiver when the transmitter is on.

Front 94

What device is located between the magnetron and the mixer and prevents received signals from entering the magnetron?
A. The ATR tube.
B. The TR tube.
C. The RF Attenuator.
D. A resonant cavity.

Back 94

A. The ATR tube.

Front 95

A keep-alive voltage is applied to:
A. The crystal detector.
B. The ATR tube.
C. The TR tube.
D. The magnetron.

Back 95

C. The TR tube.

Front 96

A DC keep-alive potential:
A. Is applied to a TR tube to make it more sensitive.
B. Partially ionizes the gas in a TR tube, making it very sensitive to transmitter pulses.
C. Fully ionizes the gas in a TR tube.
D. Is applied to a TR tube to make it more sensitive and partially ionizes the gas in a TR tube.

Back 96

D. Is applied to a TR tube to make it more sensitive and partially ionizes the gas in a TR tube.

Front 97

What RADAR circuit determines the pulse repetition rate (PRR)?
A. Discriminator.
B. Timer (synchronizer circuit).
C. Artificial transmission line.
D. Pulse-rate-indicator circuit.

Back 97

B. Timer (synchronizer circuit).

Front 98

The triggering section is also known as the:
A. PFN.
B. Timer circuit.
C. Blocking oscillator.
D. Synchronizer.

Back 98

D. Synchronizer.

Front 99

Operation of any RADAR system begins in the:
A. Triggering section.
B. Magnetron.
C. AFC.
D. PFN.

Back 99

A. Triggering section.

Front 100

The timer circuit:
A. Determines the pulse repetition rate (PRR).
B. Determines range markers.
C. Provides blanking and unblanking signals for the CRT.
D. All of the above

Back 100

D. All of the above

Front 101

Pulse RADARs require precise timing for their operation. Which type circuit below might best be used to provide these accurate timing pulses?
A. Single-swing blocking oscillator.
B. AFC controlled sinewave oscillator.
C. Non-symmetrical astable multivibrator.
D. Triggered flip-flop type multivibrator.

Back 101

A. Single-swing blocking oscillator.

Front 102

Unblanking pulses are produced by the timer circuit. Where are they sent?
A. IF amplifiers.
B. Mixer.
C. CRT.
D. Discriminator.

Back 102

C. CRT.

Front 103

An advantage of resonant charging is that it:
A. Eliminates the need for a reverse current diode.
B. Guarantees perfectly square output pulses.
C. Reduces the high-voltage power supply requirements.
D. Maintains a constant magnetron output frequency.

Back 103

C. Reduces the high-voltage power supply requirements.

Front 104

The characteristics of a field-effect transistor (FET) used in a modern RADAR switching power supply can be compared as follows:
A. “On” state compares to a bipolar transistor. “Off” state compares to a 1-Megohm resistor.
B. “On” state compares to a pure resistor. “Off” state compares to a mechanical relay.
C. “On” state compares to an low resistance inductor. “Off” state compares to a 10-Megohm resistor.
D. “On” state compares to a resistor. “Off” state compares to a capacitor.

Back 104

B. “On” state compares to a pure resistor. “Off” state compares to a mechanical relay.

Front 105

A pulse-width modulator in a switching power supply is used to:
A. Provide the reference voltage for the regulator.
B. Vary the frequency of the switching regulator to control the output voltage.
C. Vary the duty cycle of the regulator switch to control the output voltage.
D. Compare the reference voltage with the output voltage sample and produce an error voltage.

Back 105

C. Vary the duty cycle of the regulator switch to control the output voltage.

Front 106

In a fixed-frequency switching power supply, the pulse width of the switching circuit will increase when:
A. The load impedance decreases.
B. The load current decreases.
C. The output voltage increases.
D. The input voltage increases.

Back 106

A. The load impedance decreases.

Front 107

A major consideration for the use of a switching regulator power supply over a linear regulator is:
A. The switching regulator has better regulation.
B. The linear regulator does not require a transformer to step down AC line voltages to a usable level.
C. The switching regulator can be used in nearly all applications requiring regulated voltage.
D. The overall efficiency of a switching regulator is much higher than a linear power supply.

Back 107

D. The overall efficiency of a switching regulator is much higher than a linear power supply.

Front 108

Which of the following characteristics are true of a power MOSFET used in a RADAR switching supply?
A. Low input impedance; failure mode can be gate punch-through.
B. High input impedance; failure mode can be gate punch-through.
C. High input impedance; failure mode can be thermal runaway.
D. Low input impedance; failure mode can be gate breakdown.

Back 108

B. High input impedance; failure mode can be gate punch-through.