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

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1. - E0A02

When evaluating RF exposure levels from your station at a neighbor's home, what must you do?

Select	Answer
A	Ensure signals from your station are less than the controlled Maximum Permitted Emission (MPE) limits
B	Ensure signals from your station are less than the controlled Maximum Permitted Exposure (MPE) limits
C	Ensure signals from your station are less than the uncontrolled Maximum Permitted Emission (MPE) limits
D	Ensure signals from your station are less than the uncontrolled Maximum Permitted Exposure (MPE) limits

2. - E1A14

Except in some parts of Alaska, what is the maximum power permitted on the 630 meter band?

Select	Answer
A	5 watts EIRP
B	1 watt EIRP
C	50 watts PEP
D	100 watts PEP

3. - E1B10

What frequencies are authorized to an amateur station operating under RACES rules?

Select	Answer
A	Specific segments in the amateur service MF, HF, VHF and UHF bands
B	All amateur service frequencies authorized to the control operator
C	Specific local government channels
D	Military Auxiliary Radio System (MARS) channels

4. - E1C14

How long must an operator wait after filing a notification with the Utilities Technology Council (UTC) before operating on the 2200 meter or 630 meter band?

Select	Answer
A	Operators must not operate until approval is received
B	Operators may not operate until a test signal has been transmitted in coordination with the local power company
C	Operators may operate after 30 days, providing they have not been told that their station is within 1 km of PLC systems using those frequencies
D	Operations may commence immediately, and may continue unless interference is reported by the UTC

5. - E1D06

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

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

6. - E1E06

Who is responsible for the proper conduct and necessary supervision during an amateur operator license examination session?

Select	Answer
A	The VEC coordinating the session
B	Each administering VE
C	The FCC
D	The VE session manager

7. - E1F01

On what frequencies are spread spectrum transmissions permitted?

Select	Answer
A	Only on amateur frequencies above 144 MHz
B	Only on amateur frequencies above 222 MHz
C	Only on amateur frequencies above 50 MHz
D	Only on amateur frequencies above 420 MHz

8. - E2A08

Why should effective radiated power to a satellite that uses a linear transponder be limited?

Select	Answer
A	To prevent creating errors in the satellite telemetry
B	To avoid reducing the downlink power to all other users
C	To avoid interfering with terrestrial QSOs
D	To prevent the satellite from emitting out-of-band signals

9. - E2B01

How many times per second is a new frame transmitted in a fast-scan (NTSC) television system?

Select	Answer
A	60
B	30
C	90
D	120

10. - E2C10

Why might a DX station state that they are listening on another frequency?

Select	Answer
A	All these choices are correct
B	Because the DX station may be transmitting on a frequency that is prohibited to some responding stations
C	To improve operating efficiency by reducing interference
D	To separate the calling stations from the DX station

11. - E2D03

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

Select	Answer
A	Olivia
B	PACTOR III
C	MSK144
D	JT65

12. - E2E12

How do ALE stations establish contact?

Select	Answer
A	ALE radios monitor an internet site for the frequency they are being paged on
B	ALE radios send a constant tone code to establish a frequency for future use
C	ALE radios activate when they hear their signal echoed by back scatter
D	ALE constantly scans a list of frequencies, activating the radio when the designated call sign is received

13. - E3A02

What characterizes libration fading of an EME signal?

Select	Answer
A	A gradual loss of signal as the sun rises
B	A fluttery irregular fading
C	The returning echo is several hertz lower in frequency than the transmitted signal
D	A slow change in the pitch of the CW signal

14. - E3B12

What is the primary characteristic of chordal hop propagation?

Select	Answer
A	Successive ionospheric refractions without an intermediate reflection from the ground
B	Propagation across the geomagnetic equator
C	Signals reflected back toward the transmitting station
D	Propagation away from the great circle bearing between stations

15. - E3C06

By how much does the VHF/UHF radio horizon distance exceed the geometric horizon?

Select	Answer
A	By approximately four times the distance
B	By approximately twice the distance
C	By approximately 50 percent of the distance
D	By approximately 15 percent of the distance

16. - E4A06

What is the effect of aliasing on a digital oscilloscope caused by setting the time base too slow?

Select	Answer
A	A false, jittery low-frequency version of the signal is displayed
B	All signals will have a DC offset
C	Excessive blanking occurs, which prevents display of the signal
D	Calibration of the vertical scale is no longer valid

17. - E4B10

Which of the following methods measures intermodulation distortion in an SSB transmitter?

Select	Answer
A	Modulate the transmitter using two RF signals having non-harmonically related frequencies and observe the RF output with a spectrum analyzer
B	Modulate the transmitter using two RF signals having harmonically related frequencies and observe the RF output with a logic analyzer
C	Modulate the transmitter using two AF signals having non-harmonically related frequencies and observe the RF output with a spectrum analyzer
D	Modulate the transmitter using two AF signals having harmonically related frequencies and observe the RF output with a peak reading wattmeter

18. - E4C08

An SDR receiver is overloaded when input signals exceed what level?

Select	Answer
A	One-half the maximum sampling buffer size
B	The reference voltage of the analog-to-digital converter
C	One-half the maximum sample rate
D	The maximum count value of the analog-to-digital converter

19. - E4D08

What causes intermodulation in an electronic circuit?

Select	Answer
A	Too little gain
B	Nonlinear circuits or devices
C	Lack of neutralization
D	Positive feedback

20. - E4E05

How can radio frequency interference from an AC motor be suppressed?

Select	Answer
A	By installing a bypass capacitor in series with the motor leads
B	By using a ground-fault current interrupter in the circuit used to power the motor
C	By installing a brute-force AC-line filter in series with the motor leads
D	By installing a high-pass filter in series with the motor's power leads

21. - E5A12

What is the half-power bandwidth of a resonant circuit that has a resonant frequency of 3.7 MHz and a Q of 118?

Select	Answer
A	218.3 kHz
B	436.6 kHz
C	31.4 kHz
D	15.7 kHz

22. - E5B10

What is the relationship between the AC current through an inductor and the voltage across an inductor?

Select	Answer
A	Voltage and current are 180 degrees out of phase
B	Current leads voltage by 90 degrees
C	Voltage and current are in phase
D	Voltage leads current by 90 degrees

23. - E5C11

Which point in Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and an 18-microhenry inductor at 3.505 MHz?

Select	Answer
A	Point 3
B	Point 1
C	Point 7
D	Point 8

24. - E5D10

How can the true power be determined in an AC circuit where the voltage and current are out of phase?

Select	Answer
A	By multiplying the reactive power by the power factor
B	By dividing the apparent power by the power factor
C	By dividing the reactive power by the power factor
D	By multiplying the apparent power by the power factor

25. - E6A09

What is a depletion-mode FET?

Select	Answer
A	Any FET without a channel
B	An FET that exhibits a current flow between source and drain when no gate voltage is applied
C	An FET that has no current flow between source and drain when no gate voltage is applied
D	Any FET for which holes are the majority carriers

26. - E6B03

What type of bias is required for an LED to emit light?

Select	Answer
A	Forward bias
B	Inductive bias
C	Reverse bias
D	Zero bias

27. - E6C07

What best describes a pull-up or pull-down resistor?

Select	Answer
A	A resistor that ensures that an oscillator frequency does not drift
B	A resistor in a keying circuit used to reduce key clicks
C	A resistor connected to an op-amp output that prevents signals from exceeding the power supply voltage
D	A resistor connected to the positive or negative supply line used to establish a voltage when an input or output is an open circuit

28. - E6D08

What is one reason for using powdered-iron cores rather than ferrite cores in an inductor?

Select	Answer
A	Powdered-iron cores generally have greater initial permeability
B	Powdered-iron cores use smaller diameter wire for the same inductance
C	Powdered-iron cores generally maintain their characteristics at higher currents
D	Powdered-iron cores generally require fewer turns to produce a given inductance

29. - E6E04

Which is the most common input and output impedance of circuits that use MMICs?

Select	Answer
A	450 ohms
B	10 ohms
C	50 ohms
D	300 ohms

30. - E6F10

What is the most common type of photovoltaic cell used for electrical power generation?

Select	Answer
A	Selenium
B	Silicon
C	Cadmium Sulfide
D	Copper oxide

31. - E7A03

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

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

32. - E7B03

Which of the following components form the output of a class D amplifier circuit?

Select	Answer
A	A low-pass filter to remove switching signal components
B	A temperature compensating load resistor to improve linearity
C	A high-pass filter to compensate for low gain at low frequencies
D	A matched load resistor to prevent damage by switching transients

33. - E7C10

Which of the following filters would be the best choice for use in a 2 meter band repeater duplexer?

Select	Answer
A	A cavity filter
B	A DSP filter
C	An L-C filter
D	A crystal filter

34. - E7D12

What is the dropout voltage of an analog voltage regulator?

Select	Answer
A	Maximum that the output voltage may decrease at rated load
B	Minimum input-to-output voltage required to maintain regulation
C	Minimum input voltage for rated power dissipation
D	Maximum output voltage drops when the input voltage is varied over its specified range

35. - E7E08

What are the principal frequencies that appear at the output of a mixer circuit?

Select	Answer
A	The square root of the product of input frequencies
B	The two input frequencies along with their sum and difference frequencies
C	1.414 and 0.707 times the input frequency
D	Two and four times the original frequency

36. - E7F07

What function is performed by a Fast Fourier Transform?

Select	Answer
A	Converting analog signals to digital form
B	Converting 8-bit data to 16-bit data
C	Converting digital signals to analog form
D	Converting digital signals from the time domain to the frequency domain

37. - E7G07

What magnitude of voltage gain can be expected from the circuit in Figure E73 when R1 is 10 ohms and RF is 470 ohms?

Select	Answer
A	24
B	0.21
C	94
D	47

38. - E7H13

Which of the following is a technique for providing highly accurate and stable oscillators needed for microwave transmission and reception?

Select	Answer
A	All these choices are correct
B	Use a temperature-controlled high Q dielectric resonator
C	Use a rubidium stabilized reference oscillator
D	Use a GPS signal reference

39. - E8A08

Why would a direct or flash conversion analog-to-digital converter be useful for a software defined radio?

Select	Answer
A	All these choices are correct
B	Very low power consumption decreases frequency drift
C	Very high speed allows digitizing high frequencies
D	Immunity to out-of-sequence coding reduces spurious responses

40. - E8B08

What describes Orthogonal Frequency Division Multiplexing?

Select	Answer
A	A bandwidth compression technique using Fourier transforms
B	A frequency modulation technique that uses non-harmonically related frequencies
C	A digital mode for narrow-band, slow-speed transmissions
D	A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference

41. - E8C01

How is Forward Error Correction implemented?

Select	Answer
A	By the receiving station repeating each block of three data characters
B	By transmitting a special algorithm to the receiving station along with the data characters
C	By varying the frequency shift of the transmitted signal according to a predefined algorithm
D	By transmitting extra data that may be used to detect and correct transmission errors

42. - E8D03

How does the spread spectrum technique of frequency hopping work?

Select	Answer
A	If interference is detected by the receiver it will signal the transmitter to change frequencies
B	If interference is detected by the receiver it will signal the transmitter to wait until the frequency is clear
C	A binary bit stream is used to shift the phase of an RF carrier very rapidly in a pseudorandom sequence
D	The frequency of the transmitted signal is changed very rapidly according to a pseudorandom sequence also used by the receiving station

43. - E9A12

How much gain does an antenna have compared to a 1/2-wavelength dipole when it has 6 dB gain over an isotropic antenna?

Select	Answer
A	8.15 dB
B	6.0 dB
C	3.85 dB
D	2.79 dB

44. - E9B11

What is a disadvantage of decreasing the number of wire segments in an antenna model below 10 segments per half-wavelength?

Select	Answer
A	Ground conductivity will not be accurately modeled
B	The computed feed point impedance may be incorrect
C	The resulting design will favor radiation of harmonic energy
D	The antenna will become mechanically unstable

45. - E9C04

What happens to the radiation pattern of an unterminated long wire antenna as the wire length is increased?

Select	Answer
A	The lobes become more perpendicular to the wire
B	The vertical angle increases
C	The front-to-back ratio decreases
D	The lobes align more in the direction of the wire

46. - E9D03

Where should a high Q loading coil be placed to minimize losses in a shortened vertical antenna?

Select	Answer
A	At a voltage node
B	As close to the transmitter as possible
C	As low as possible on the vertical radiator
D	Near the center of the vertical radiator

47. - E9E04

What is the purpose of the series capacitor in a gamma-type antenna matching network?

Select	Answer
A	To cancel the inductive reactance of the matching network
B	To provide DC isolation between the feed line and the antenna
C	To provide a rejection notch that prevents the radiation of harmonics
D	To transform the antenna impedance to a higher value

48. - E9F02

Which of the following has the biggest effect on the velocity factor of a transmission line?

Select	Answer
A	The line length
B	Dielectric materials used in the line
C	The center conductor resistivity
D	The termination impedance

49. - E9G05

Which of the following is a common use for a Smith chart?

Select	Answer
A	Determine the gain of an antenna given the physical and electrical parameters
B	Determine the length and position of an impedance matching stub
C	Determine the impedance of a transmission line, given the physical dimensions
D	Determine the loss/100 feet of a transmission line, given the velocity factor and conductor materials

50. - E9H06

What is the triangulation method of direction finding?

Select	Answer
A	A fixed receiving station uses three different antennas to plot the location of the signal source
B	The geometric angles of sky waves from the source are used to determine its position
C	A fixed receiving station plots three headings to the signal source
D	Antenna headings from several different receiving locations are used to locate the signal source

Figure E5-1