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AAS 2 > RF Circuits > Flashcards

RF Circuits Flashcards

1
Q

What is the effective radiated power of a repeater with 75 watts transmitter output power, 4 dB feedline loss, 3 dB duplexer/circulator loss, and 10 dB antenna gain (3-67J2)?

A

150 Watts

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2
Q

What component in a radio receives varying DC voltage from the detector and filters it to a steady DC voltage and then amplifies the voltage to use as a control for the RF amplifier?

A

AGC

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3
Q

What part of the electromagnetic spectrum includes wavelengths ranging from 700 nm to 400 nm?

A

Visible Light

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4
Q

What test equipment is used to test coaxial cables for shorts and opens and determine the location of those faults?

A

Time Domain Reflectometer

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5
Q

What is the surge impedance of aircraft coaxial cable?

A

50 Ohms

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6
Q

The _________ band includes frequencies between 300 kHz and 3 MHz.

A

Medium Frequency (MF)

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7
Q

What radio component is a device that releases RF signal in the form of an electromagnetic field?

A

Antenna

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8
Q

What happens to bandwidth if the modulating frequency is increased?

A

Bandwidth Increases

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9
Q

The __________ band includes frequencies ranging from 300 MHz to 3 GHz.

A

Ultra High Frequency (UHF)

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10
Q

Which antenna is considered to be a vertically polarized antenna?

A

Marconi

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11
Q

A radio wave is composed of an E-field and an H-field. Which of these is the magnetic field?

A

H-Field

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12
Q

What type of carrier wave does DME and transponders use?

A

On/Off Keyed

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13
Q

Using RC time constants, what happens to frequency when a long time constant is used?

A

Frequency Decreases

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14
Q

What type of hollow conductor works best for high energy applications?

A

Waveguide

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15
Q

In a super regenerative receiver, where can the bandpass filters be found?

A

At the RF section

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16
Q

What is the effective radiated power of a repeater with 100 watts transmitter output power, 5 dB feedline loss, 4 dB duplexer/ circulator loss, and 10 dB antenna gain (3-67J5)?

A

126 Watts

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17
Q

What radio component extracts the audio frequencies from the modulated RF signal?

A

Detector

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18
Q

What is sometimes installed in waveguides to prevent moisture from condensing?

A

Nitrogen

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19
Q

In a blocking oscillator the blocking condition is determined by the______?

A

Capacitor discharge

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20
Q

In modern avionics, what component/circuit can accomplish the same effect on an oscillator as a variable capacitor or variable inductor?

A

Frequency synthesizer

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21
Q

The __________ band includes frequencies ranging from 30 MHz to 300 MHz.

A

Very High Frequency (VHF)

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22
Q

What type of modulation is used for aircraft communications?

A

AM

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23
Q

The level at which the smallest or minimum discernible signal can pass to a receiver’s RF section is called what?

A

Noise Floor

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24
Q

Upper VHF band and above waves propagate as:

A

Space waves

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25
Q

What type of oscillator should be used to create square, sawtooth, rectangular, triangular, or any combination of these wave forms?

A

Non-sinusoidal oscillator

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26
Q

The largest tolerable signal a receiver’s detector/discriminator can safely process defines a receiver’s what?

A

Signal ceiling

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27
Q

When using a 555 timer as a multivibrator, the output frequency is controlled by varying what? (2)

A

Resistors and capacitors

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28
Q

In what type of receiver does an IF section filter out all frequencies except the difference between the RF and LO frequencies?

A

Super-Heterodyne/Dual Super-Heterodyne

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29
Q

How fast do ground waves travel?

A

At the speed of light

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30
Q

The difference between the upper and lower sidebands is known as:

A

The bandwidth

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31
Q

Which type of wave propagation is best suited for long distance communications beyond the visual horizon without “gaps” or dead spots?

A

Ground waves

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32
Q

__________________ is the duration of the pulse that the modulating signal varies.

A

Pulse width

33
Q

What radio transmitter component isolates the transmitter from the master oscillator?

A

Buffer

34
Q

What type(s) of wave form(s) is/are created with an astable multivibrator? (2)

A

Square and Rectangular

35
Q

________________ is the strength or magnitude of a waveform.

A

Amplitude

36
Q

What frequency range is typically associated with audio frequencies (AF)?

A

20Hz - 20kHz

37
Q

The main benefits of using the GaAsFET transistor in avionics equipment is:

A

High gain, Low noise

38
Q

Transmitter 1 has 12 watts of output power. Transmitter 2 has 14 watts of output power. How many dB greater is transmitter 2’s power level?

A

+0.669 dB

39
Q

HF and lower band VHF waves travel as:

A

Sky waves

40
Q

The __________ band includes frequencies ranging from 30 GHz to 300 GHz.

A

Extremely High Frequency (EHF)

41
Q

In a super heterodyne receiver, which section filters out all the frequencies except the difference between the RF and LO frequencies?

A

IF section

42
Q

What is the effective radiated power of a repeater with 75 watts of transmitter power output, 5 dB feedline loss, 4 dB duplexer/circulator loss, and 6 dB antenna gain (3-67J3)?

A

37.6 Watts

43
Q

What is the metal braiding in coaxial cable known as?

A

Shielding

44
Q

What type of transmission line consists of a center conductor surrounded with a dielectric?

A

Coaxial Cable

45
Q

What type of theoretical radiator transmits well in all directions in a spheroid pattern?

A

Isotropic radiator

46
Q

A power change of a factor of 10 is equal to decibel level change of:

A

10 dB

47
Q

What term describes the tendency for Radio Frequency (RF) AC current to be greater on the surface of a conductor or transmission line than near the center?

A

Skin-effect

48
Q

A radio receiver is expected to operate normally between its Minimum Discernible and Largest Tolerable signals. This is called the receiver’s ______________________.

A

Dynamic range

49
Q

What test equipment is used to test and determine a transmission line’s forward and reflected power? (Two answers)

A

In-line wattmeter & VSWR meter

50
Q

What is the effective radiated power of a repeater with 50 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer/circulator loss, and 7 dB antenna gain (3-67J6)?

A

31.5 Watts

51
Q

In a free-running multivibrator, what determines the frequency?

A

The coupling circuit

52
Q

The sum of the modulating frequency and the carrier frequency is known as:

A

Upper sideband

53
Q

What component in a FM receiver performs the same function as the detector found in an AM receiver?

A

Discriminator

54
Q

The relationship between the E-field and H-field is that they travel:

A

At right angles to each other

55
Q

Using RC time constant, what happens to frequency when a short time constant is used?

A

Frequency increases

56
Q

Which antenna consists of two 1/4 wavelength wires placed end to end?

A

Hertzian

57
Q

What part of the electromagnetic spectrum includes wavelengths ranging from 1 mm to 700 nm?

A

Infrared Radiation

58
Q

What radio component is a relaxation oscillator that can function in either of two temporarily stable conditions and is capable of rapidly shifting from one temporary state to another?

A

Multivibrators

59
Q

In order to get the best reception possible, antennas should:

A

Have the same polarization

60
Q

The __________ band includes frequencies ranging from 3 GHz to 30 GHz.

A

Super High Frequency (SHF)

61
Q

The _________ band includes frequencies between 3 MHz and 30 MHz.

A

High Frequency (HF)

62
Q

What radio component is used to decrease the gain of the RF amplifier?

A

AGC

63
Q

________________ is the distance between any point on a wave and the equivalent point on the next wave.

A

Wavelength

64
Q

Which frequency bands does a Yagi-Uda antenna typically operate in? (Three answers)

A

HF, VHF, & UHF

65
Q

In FM, what is used to control the frequency of the oscillator?

A

An audio wave

66
Q

A change in power by a factor of two is approximately equivalent to a decibel change of:

A

3 dB

67
Q

What is the effective radiated power of a repeater with 100 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer/circulator loss, and 7 dB antenna gain (3-67J4)?

A

100 Watts

68
Q

What band on the electromagnetic spectrum does the audio frequency (AF) range fall in?

A

Very low frequency (VLF)

69
Q

The _________ band includes frequencies between 30 kHz and 300 kHz.

A

Low frequency (LF)

70
Q

Which portion of a wave carries the information?

A

The carrier signal

71
Q

What frequencies are present in the mixer stage of a receiver?

A

RF, LO, Sum, Difference

72
Q

What is another name for a “Blocking” Oscillator?

A

Quench oscillator

73
Q

What is the result when a received signal is in-phase and adds to the reference signal in a Receiver/Transmitter using Phase Shift Keying (PSK) modulation?

A

A digital “one”

74
Q

The difference between the modulated frequency and the carrier frequency is known as:

A

Lower sideband

75
Q

What radio component reduces strong signals which might overload the detector?

A

AGC

76
Q

What radio transmitter component provides the basic carrier wave?

A

Stabilized master oscillator

77
Q

What is the effective radiated power (ERP) of a repeater with 50 watts transmitter output power, 4 dB feedline loss, 3 dB duplexer/circulator loss, and 6 dB antenna gain (3-67J1)?

A

39.7 Watts

78
Q

What type of cable is most commonly used as aircraft transmission lines?

A

Coaxial Cable

AAS 2 (6 decks)

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