US Amateur Radio - Amateur Extra (Element 4, 2020-2024) Practice Test

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1. - E0A07

How may dangerous levels of carbon monoxide from an emergency generator be detected?

Select	Answer
A	Only with a carbon monoxide detector
B	By the odor
C	Any ordinary smoke detector can be used
D	By the yellowish appearance of the gas

2. - E1A07

What is the maximum power permitted on the 2200 meter band?

Select	Answer
A	100 watts PEP
B	5 watts EIRP (Equivalent isotropic radiated power)
C	1 watt EIRP (Equivalent isotropic radiated power)
D	50 watts PEP

3. - E1B12

What must the control operator of a repeater operating in the 70 cm band do if a radiolocation system experiences interference from that repeater?

Select	Answer
A	All these choices are correct
B	File an FAA NOTAM (Notice to Airmen) with the repeater system's ERP, call sign, and six-character grid locator
C	Reduce the repeater antenna HAAT (Height Above Average Terrain)
D	Cease operation or make changes to the repeater to mitigate the interference

4. - E1C03

How do the control operator responsibilities of a station under automatic control differ from one under local control?

Select	Answer
A	Under automatic control there is no control operator
B	Under automatic control the control operator is not required to be present at the control point
C	Under local control a control operator is not required to be present at a control point
D	Under local control there is no control operator

5. - E1D06

What is the maximum permitted transmitter output power when operating a model craft by telecommand?

Select	Answer
A	100 watts
B	2 watts
C	1 watt
D	5 watts

6. - E1E11

What must the VE team do if an examinee scores a passing grade on all examination elements needed for an upgrade or new license?

Select	Answer
A	Three VEs must certify that the examinee is qualified for the license grant and that they have complied with the administering VE requirements
B	Issue the examinee the new or upgrade license
C	Photocopy all examination documents and forward them to the FCC for processing
D	All these choices are correct

7. - E1F04

Which of the following geographic descriptions approximately describes "Line A"?

Select	Answer
A	A line roughly parallel to and east of the U.S. Pacific coastline
B	A line roughly parallel to and north of the border between the U.S. and Mexico
C	A line roughly parallel to and south of the border between the U.S. and Canada
D	A line roughly parallel to and west of the U.S. Atlantic coastline

8. - E2A07

Which of the following types of signals can be relayed through a linear transponder?

Select	Answer
A	PSK and packet
B	All these choices are correct
C	SSB and SSTV
D	FM and CW

9. - E2B06

What is vestigial sideband modulation?

Select	Answer
A	A type of modulation in which one sideband is inverted
B	Amplitude modulation in which one complete sideband and a portion of the other are transmitted
C	Narrow-band FM modulation achieved by filtering one sideband from the audio before frequency modulating the carrier
D	Spread spectrum modulation achieved by applying FM modulation following single sideband amplitude modulation

10. - E2C12

What technique do individual nodes use to form a mesh network?

Select	Answer
A	Forward error correction and Viterbi codes
B	Acting as store-and-forward digipeaters
C	Discovery and link establishment protocols
D	Custom code plugs for the local trunking systems

11. - E2D03

Which of the following digital modes is especially useful for EME communications?

Select	Answer
A	MSK144
B	PACTOR III
C	JT65
D	Olivia

12. - E2E13

Which of these digital modes has the fastest data throughput under clear communication conditions?

Select	Answer
A	170 Hz shift, 45 baud RTTY
B	PSK31
C	AMTOR
D	300 baud packet

13. - E3A05

Tropospheric propagation of microwave signals often occurs in association with what phenomenon?

Select	Answer
A	Warm and cold fronts
B	Sprites and jets
C	Grayline
D	Lightning discharges

14. - E3B04

What is meant by the terms "extraordinary" and "ordinary" waves?

Select	Answer
A	Refracted rays and reflected waves
B	Independent waves created in the ionosphere that are elliptically polarized
C	Extraordinary waves describe rare long-skip propagation compared to ordinary waves, which travel shorter distances
D	Long-path and short-path waves

15. - E3C10

What does the 304A solar parameter measure?

Select	Answer
A	The solar emission at 304 GHz, correlated to x-ray flare levels
B	The ratio of x-ray flux to radio flux, correlated to sunspot number
C	UV emissions at 304 angstroms, correlated to the solar flux index
D	The solar wind velocity at 304 degrees from the solar equator, correlated to solar activity

16. - E4A03

Which of the following test instruments is used to display spurious signals and/or intermodulation distortion products generated by an SSB transmitter?

Select	Answer
A	A time-domain reflectometer
B	A logic analyzer
C	A spectrum analyzer
D	A wattmeter

17. - E4B07

What do the subscripts of S parameters represent?

Select	Answer
A	The port or ports at which measurements are made
B	Relative quality of the data
C	Frequency order of the measurements
D	The relative time between measurements

18. - E4C11

Why can an attenuator be used to reduce receiver overload on the lower frequency HF bands with little or no impact on signal-to-noise ratio?

Select	Answer
A	The attenuator has a low-pass filter to increase the strength of lower frequency signals
B	Atmospheric noise is generally greater than internally generated noise even after attenuation
C	Signals are attenuated separately from the noise
D	The attenuator has a noise filter to suppress interference

19. - E4D04

Which of the following may reduce or eliminate intermodulation interference in a repeater caused by another transmitter operating in close proximity?

Select	Answer
A	Utilizing a Class D final amplifier
B	A properly terminated circulator at the output of the repeater's transmitter
C	A band-pass filter in the feed line between the transmitter and receiver
D	Utilizing a Class C final amplifier

20. - E4E04

How can conducted and radiated noise caused by an automobile alternator be suppressed?

Select	Answer
A	By installing filter capacitors in series with the DC power lead and a blocking capacitor in the field lead
B	By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads
C	By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead
D	By installing a noise suppression resistor and a blocking capacitor in both leads

21. - E5A16

What is the resonant frequency of an RLC circuit if R is 33 ohms, L is 50 microhenries and C is 10 picofarads?

Select	Answer
A	23.5 kHz
B	7.12 kHz
C	23.5 MHz
D	7.12 MHz

22. - E5B05

What happens to the magnitude of a pure reactance when it is converted to a susceptance?

Select	Answer
A	It is unchanged
B	It is shifted by 90 degrees
C	The sign is reversed
D	It becomes the reciprocal

23. - E5C04

What coordinate system is often used to display the resistive, inductive, and/or capacitive reactance components of impedance?

Select	Answer
A	Maidenhead grid
B	Rectangular coordinates
C	Faraday grid
D	Elliptical coordinates

24. - E5D13

How many watts are consumed in a circuit consisting of a 100-ohm resistor in series with a 100-ohm inductive reactance drawing 1 ampere?

Select	Answer
A	100 watts
B	200 watts
C	141.4 watts
D	70.7 watts

25. - E6A10

In Figure E6-1, what is the schematic symbol for an N-channel dual-gate MOSFET?

Select	Answer
A	6
B	2
C	4
D	5

26. - E6B09

What is a common use for point-contact diodes?

Select	Answer
A	As a high-voltage rectifier
B	As a constant current source
C	As an RF detector
D	As a constant voltage source

27. - E6C03

What is tri-state logic?

Select	Answer
A	Proprietary logic devices manufactured by Tri-State Devices
B	Low-power logic devices designed to operate at 3 volts
C	Logic devices with 0, 1, and high-impedance output states
D	Logic devices that utilize ternary math

28. - E6D02

What is the equivalent circuit of a quartz crystal?

Select	Answer
A	Motional capacitance, motional inductance, and loss resistance in series, all in parallel with a shunt capacitor representing electrode and stray capacitance
B	Motional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in parallel
C	Motional inductance and loss resistance in series, paralleled with motional capacitance and a capacitor representing electrode and stray capacitance
D	Motional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in series

29. - E6E01

Why is gallium arsenide (GaAs) useful for semiconductor devices operating at UHF and higher frequencies?

Select	Answer
A	Lower transconductance
B	Higher electron mobility
C	Lower junction voltage drop
D	Higher noise figures

30. - E6F08

Why are optoisolators often used in conjunction with solid-state circuits when switching 120 VAC?

Select	Answer
A	Optoisolators eliminate the effects of reflected light in the control circuit
B	Optoisolators provide a low impedance link between a control circuit and a power circuit
C	Optoisolators provide a very high degree of electrical isolation between a control circuit and the circuit being switched
D	Optoisolators provide impedance matching between the control circuit and power circuit

31. - E7A03

Which of the following can divide the frequency of a pulse train by 2?

Select	Answer
A	An OR gate
B	An XOR gate
C	A flip-flop
D	A multiplexer

32. - E7B10

In Figure E7-1, what is the purpose of R1 and R2?

Select	Answer
A	Voltage divider bias
B	Feedback
C	Self bias
D	Load resistors

33. - E7C05

Which filter type is described as having ripple in the passband and a sharp cutoff?

Select	Answer
A	A passive op-amp filter
B	An active LC filter
C	A Chebyshev filter
D	A Butterworth filter

34. - E7D08

What type of circuit is shown in Figure E7-2?

Select	Answer
A	Grounded emitter amplifier
B	Switching voltage regulator
C	Linear voltage regulator
D	Monostable multivibrator

35. - E7E07

What is meant by the term "baseband" in radio communications?

Select	Answer
A	The lowest frequency band that the transmitter or receiver covers
B	The unmodulated bandwidth of the transmitted signal
C	The basic oscillator frequency in an FM transmitter that is multiplied to increase the deviation and carrier frequency
D	The frequency range occupied by a message signal prior to modulation

36. - E7F05

How frequently must an analog signal be sampled by an analog-to-digital converter so that the signal can be accurately reproduced?

Select	Answer
A	At four times the rate of the highest frequency component of the signal
B	At least half the rate of the highest frequency component of the signal
C	At least twice the rate of the highest frequency component of the signal
D	At the same rate as the highest frequency component of the signal

37. - E7G06

What is the gain-bandwidth of an operational amplifier?

Select	Answer
A	The frequency at which the amplifier's offset voltage is zero
B	The gain of the amplifier at a filter's cutoff frequency
C	The maximum frequency for a filter circuit using that type of amplifier
D	The frequency at which the open-loop gain of the amplifier equals one

38. - E7H10

What information is contained in the lookup table of a direct digital synthesizer (DDS)?

Select	Answer
A	Amplitude values that represent the desired waveform
B	The phase relationship between a reference oscillator and the output waveform
C	The phase relationship between a voltage-controlled oscillator and the output waveform
D	Frequently used receiver and transmitter frequencies

39. - E8A09

How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?

Select	Answer
A	256 divided by the gain of the input amplifier
B	8
C	8 multiplied by the gain of the input amplifier
D	256

40. - E8B06

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?

Select	Answer
A	0.214
B	0.47
C	2.14
D	47

41. - E8C07

What is the bandwidth of a 4800-Hz frequency shift, 9600-baud ASCII FM transmission?

Select	Answer
A	9.6 kHz
B	15.36 kHz
C	5.76 kHz
D	4.8 kHz

42. - E8D05

What is the most common method of reducing key clicks?

Select	Answer
A	High-pass filters at the transmitter output
B	Reduce keying waveform rise and fall times
C	Low-pass filters at the transmitter output
D	Increase keying waveform rise and fall times

43. - E9A03

What is the radiation resistance of an antenna?

Select	Answer
A	The resistance in the atmosphere that an antenna must overcome to be able to radiate a signal
B	The combined losses of the antenna elements and feed line
C	The value of a resistance that would dissipate the same amount of power as that radiated from an antenna
D	The specific impedance of the antenna

44. - E9B04

What is the front-to-back ratio of the radiation pattern shown in Figure E92?

Select	Answer
A	28 dB
B	15 dB
C	38 dB
D	3 dB

45. - E9C07

What is the approximate feed point impedance at the center of a two-wire folded dipole antenna?

Select	Answer
A	450 ohms
B	300 ohms
C	72 ohms
D	50 ohms

46. - E9D09

What is the function of a loading coil used as part of an HF mobile antenna?

Select	Answer
A	To lower the losses
B	To lower the Q
C	To increase the SWR bandwidth
D	To cancel capacitive reactance

47. - E9E02

What is the name of an antenna matching system that matches an unbalanced feed line to an antenna by feeding the driven element both at the center of the element and at a fraction of a wavelength to one side of center?

Select	Answer
A	The delta match
B	The epsilon match
C	The gamma match
D	The stub match

48. - E9F05

What is the approximate physical length of a solid polyethylene dielectric coaxial transmission line that is electrically 1/4 wavelength long at 14.1 MHz?

Select	Answer
A	10.6 meters
B	3.5 meters
C	4.3 meters
D	5.3 meters

49. - E9G04

What are the two families of circles and arcs that make up a Smith chart?

Select	Answer
A	Resistance and voltage
B	Voltage and impedance
C	Reactance and voltage
D	Resistance and reactance

50. - E9H10

How can the output voltage of a multiple-turn receiving loop antenna be increased?

Select	Answer
A	By winding adjacent turns in opposing directions
B	By reducing the permeability of the loop shield
C	By utilizing high impedance wire for the coupling loop
D	By increasing the number of turns and/or the area

Figure E6-1

Figure E7-1

Figure E7-2