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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?

SelectAnswer
AOnly with a carbon monoxide detector
BBy the yellowish appearance of the gas
CBy the odor
DAny ordinary smoke detector can be used

2. - E1A14

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

SelectAnswer
A50 watts PEP
B1 watt EIRP
C100 watts PEP
D5 watts EIRP

3. - E1B06

Which of the following additional rules apply if you are installing an amateur station antenna at a site at or near a public use airport?

SelectAnswer
AYou may have to notify the Federal Aviation Administration and register it with the FCC as required by Part 17 of the FCC rules
BYou must file an Environmental Impact Statement with the EPA before construction begins
CYou must submit engineering drawings to the FAA
DYou must obtain a construction permit from the airport zoning authority

4. - E1C09

What is the highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz?

SelectAnswer
A0.5
B1.0
C3.0
D2.0

5. - E1D06

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

SelectAnswer
A1 watt
B2 watts
C100 watts
D5 watts

6. - E1E07

What should a VE do if a candidate fails to comply with the examiner's instructions during an amateur operator license examination?

SelectAnswer
AImmediately terminate the candidate's examination
BImmediately terminate everyone's examination and close the session
CAllow the candidate to complete the examination, but invalidate the results
DWarn the candidate that continued failure to comply will result in termination of the examination

7. - E1F01

On what frequencies are spread spectrum transmissions permitted?

SelectAnswer
AOnly on amateur frequencies above 420 MHz
BOnly on amateur frequencies above 50 MHz
COnly on amateur frequencies above 144 MHz
DOnly on amateur frequencies above 222 MHz

8. - E2A10

What type of satellite appears to stay in one position in the sky?

SelectAnswer
ALEO
BGeostationary
CGeomagnetic
DHEO

9. - E2B09

What hardware, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM)?

SelectAnswer
AA special notch filter to remove synchronization pulses
BNo other hardware is needed
CA special front end limiter
DA special IF converter

10. - E2C12

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

SelectAnswer
ADiscovery and link establishment protocols
BActing as store-and-forward digipeaters
CCustom code plugs for the local trunking systems
DForward error correction and Viterbi codes

11. - E2D09

What type of modulation is used for JT65 contacts?

SelectAnswer
AMulti-tone AFSK
BIEEE 802.11
CPSK
DRTTY

12. - E2E07

Which of the following is a possible reason that attempts to initiate contact with a digital station on a clear frequency are unsuccessful?

SelectAnswer
AYour transmit frequency is incorrect
BAnother station you are unable to hear is using the frequency
CAll these choices are correct
DThe protocol version you are using is not supported by the digital station

13. - E3A10

Which type of atmospheric structure can create a path for microwave propagation?

SelectAnswer
AWind shear
BThe jet stream
CTemperature inversion
DDust devil

14. - E3B01

What is transequatorial propagation?

SelectAnswer
APropagation between a point on the equator and its antipodal point
BPropagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator
CPropagation between points located on the magnetic equator
DPropagation between points at the same latitude

15. - E3C01

What does the radio communication term "ray tracing" describe?

SelectAnswer
AThe process in which an electronic display presents a pattern
BEvaluating high voltage sources for x-rays
CDetermining the radiation pattern from an array of antennas
DModeling a radio wave's path through the ionosphere

16. - E4A06

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

SelectAnswer
AA false, jittery low-frequency version of the signal is displayed
BCalibration of the vertical scale is no longer valid
CAll signals will have a DC offset
DExcessive blanking occurs, which prevents display of the signal

17. - E4B03

Which S parameter is equivalent to forward gain?

SelectAnswer
AS22
BS21
CS12
DS11

18. - E4C04

What is the noise figure of a receiver?

SelectAnswer
AThe ratio of thermal noise to atmospheric noise
BThe ratio of atmospheric noise to phase noise
CThe ratio in dB of the noise generated by the receiver to the theoretical minimum noise
DThe ratio of the noise bandwidth in hertz to the theoretical bandwidth of a resistive network

19. - E4D04

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

SelectAnswer
AUtilizing a Class C final amplifier
BUtilizing a Class D final amplifier
CA properly terminated circulator at the output of the repeater's transmitter
DA band-pass filter in the feed line between the transmitter and receiver

20. - E4E05

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

SelectAnswer
ABy using a ground-fault current interrupter in the circuit used to power the motor
BBy installing a bypass capacitor in series with the motor leads
CBy installing a brute-force AC-line filter in series with the motor leads
DBy installing a high-pass filter in series with the motor's power leads

21. - E5A11

What is the half-power bandwidth of a resonant circuit that has a resonant frequency of 7.1 MHz and a Q of 150?

SelectAnswer
A157.8 Hz
B315.6 Hz
C47.3 kHz
D23.67 kHz

22. - E5B11

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 25 ohms, R is 100 ohms, and XL is 50 ohms?

SelectAnswer
A76 degrees with the voltage leading the current
B76 degrees with the voltage lagging the current
C14 degrees with the voltage leading the current
D14 degrees with the voltage lagging the current

23. - E5C02

How are impedances described in polar coordinates?

SelectAnswer
ABy real and imaginary parts
BBy Y and G values
CBy phase angle and magnitude
DBy X and R values

24. - E5D09

What happens to reactive power in an AC circuit that has both ideal inductors and ideal capacitors?

SelectAnswer
AIt is repeatedly exchanged between the associated magnetic and electric fields, but is not dissipated
BIt is dissipated in the formation of inductive and capacitive fields
CIt is dissipated as heat in the circuit
DIt is dissipated as kinetic energy in the circuit

25. - E6A12

Why do many MOSFET devices have internally connected Zener diodes on the gates?

SelectAnswer
ATo keep the gate voltage within specifications and prevent the device from overheating
BTo reduce the chance of static damage to the gate
CTo protect the substrate from excessive voltages
DTo provide a voltage reference for the correct amount of reverse-bias gate voltage

26. - E6B07

What is the failure mechanism when a junction diode fails due to excessive current?

SelectAnswer
AInsufficient forward voltage
BExcessive junction temperature
CCharge carrier depletion
DExcessive inverse voltage

27. - E6C04

Which of the following is an advantage of BiCMOS logic?

SelectAnswer
AAll these choices are correct
BIt is immune to electrostatic damage
CIt has the high input impedance of CMOS and the low output impedance of bipolar transistors
DIts simplicity results in much less expensive devices than standard CMOS

28. - E6D02

What is the equivalent circuit of a quartz crystal?

SelectAnswer
AMotional inductance and loss resistance in series, paralleled with motional capacitance and a capacitor representing electrode and stray capacitance
BMotional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in parallel
CMotional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in series
DMotional capacitance, motional inductance, and loss resistance in series, all in parallel with a shunt capacitor representing electrode and stray capacitance

29. - E6E03

Which of the following materials is likely to provide the highest frequency of operation when used in MMICs?

SelectAnswer
AGallium nitride
BSilicon
CSilicon nitride
DSilicon dioxide

30. - E6F06

Which of these materials is most commonly used to create photoconductive devices?

SelectAnswer
AA crystalline semiconductor
BA heavy metal
CAn ordinary metal
DA liquid semiconductor

31. - E7A07

What logical operation does a NAND gate perform?

SelectAnswer
AIt produces logic 0 at its output only when all inputs are logic 1
BIt produces logic 1 at its output only when all inputs are logic 1
CIt produces logic 0 at its output only when all inputs are logic 0
DIt produces logic 0 at its output if some but not all inputs are logic 1

32. - E7B06

Which of the following amplifier types reduces even-order harmonics?

SelectAnswer
AClass AB
BPush-pull
CClass C
DPush-push

33. - E7C01

How are the capacitors and inductors of a low-pass filter Pi-network arranged between the network's input and output?

SelectAnswer
ATwo capacitors are in series between the input and output, and an inductor is connected between the two capacitors and ground
BA capacitor is connected between the input and ground, another capacitor is connected between the output and ground, and an inductor is connected between input and output
CTwo inductors are in series between the input and output, and a capacitor is connected between the two inductors and ground
DAn inductor is connected between the input and ground, another inductor is connected between the output and ground, and a capacitor is connected between the input and output

34. - E7D11

What is the function of the pass transistor in a linear voltage regulator circuit?

SelectAnswer
AMaintains nearly constant output impedance over a wide range of load current
BPermits a wide range of output voltage settings
CProvides a stable input impedance over a wide range of source voltage
DMaintains nearly constant output voltage over a wide range of load current

35. - E7E04

What is one way a single-sideband phone signal can be generated?

SelectAnswer
ABy using a balanced modulator followed by a filter
BBy using a loop modulator followed by a mixer
CBy using a reactance modulator followed by a mixer
DBy driving a product detector with a DSB signal

36. - E7F05

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

SelectAnswer
AAt four times the rate of the highest frequency component of the signal
BAt least half the rate of the highest frequency component of the signal
CAt least twice the rate of the highest frequency component of the signal
DAt the same rate as the highest frequency component of the signal

37. - E7G10

What absolute voltage gain can be expected from the circuit in Figure E7-3 when R1 is 1800 ohms and RF is 68 kilohms?

SelectAnswer
A0.03
B1
C76
D38

38. - E7H14

What is a phase-locked loop circuit?

SelectAnswer
AAn electronic circuit also known as a monostable multivibrator
BAn electronic circuit consisting of a precision push-pull amplifier with a differential input
CAn electronic servo loop consisting of a phase detector, a low-pass filter, a voltage-controlled oscillator, and a stable reference oscillator
DAn electronic servo loop consisting of a ratio detector, reactance modulator, and voltage-controlled oscillator

39. - E8A04

What is "dither" with respect to analog-to-digital converters?

SelectAnswer
AA small amount of noise added to the input signal to allow more precise representation of a signal over time
BAn error caused by irregular quantization step size
CA method of decimation by randomly skipping samples
DAn abnormal condition where the converter cannot settle on a value to represent the signal

40. - E8B01

What is the modulation index of an FM signal?

SelectAnswer
AThe ratio of frequency deviation to modulating signal frequency
BThe bandwidth of the transmitted signal divided by the modulating signal frequency
CThe ratio of modulating signal amplitude to frequency deviation
DThe type of modulation used by the transmitter

41. - E8C10

How may data rate be increased without increasing bandwidth?

SelectAnswer
AUsing forward error correction
BUsing a more efficient digital code
CIt is impossible
DIncreasing analog-to-digital conversion resolution

42. - E8D08

What parameter evaluates distortion of an AFSK signal caused by excessive input audio levels?

SelectAnswer
ABaud rate
BSignal-to-noise ratio
CRepeat Request Rate (RRR)
DIntermodulation Distortion (IMD)

43. - E9A09

What is antenna efficiency?

SelectAnswer
ARadiation resistance divided by total resistance
BRadiation resistance divided by transmission resistance
CEffective radiated power divided by transmitter output
DTotal resistance divided by radiation resistance

44. - E9B05

What type of antenna pattern is shown in Figure E9-2?

SelectAnswer
AAzimuth
BPolarization
CRadiation resistance
DElevation

45. - E9C06

What is the effect of adding a terminating resistor to a rhombic antenna?

SelectAnswer
AIt reflects the standing waves on the antenna elements back to the transmitter
BIt decreases the ground loss
CIt changes the radiation pattern from horizontal to vertical polarization
DIt changes the radiation pattern from bidirectional to unidirectional

46. - E9D11

Which of the following conductors would be best for minimizing losses in a station's RF ground system?

SelectAnswer
ASolid wire
BWide flat copper strap
CResistive wire, such as spark plug wire
DStranded wire

47. - E9E11

What is the primary purpose of phasing lines when used with an antenna having multiple driven elements?

SelectAnswer
AIt creates a low-angle radiation pattern
BIt allows single-band antennas to operate on other bands
CIt ensures that each driven element operates in concert with the others to create the desired antenna pattern
DIt prevents reflected power from traveling back down the feed line and causing harmonic radiation from the transmitter

48. - E9F08

Which of the following is a significant difference between foam dielectric coaxial cable and solid dielectric cable, assuming all other parameters are the same?

SelectAnswer
AAll these choices are correct
BFoam dielectric has lower loss per unit of length
CFoam dielectric has higher velocity factor
DFoam dielectric has lower safe operating voltage limits

49. - E9G03

Which of the following is often determined using a Smith chart?

SelectAnswer
AImpedance and SWR values in transmission lines
BSatellite azimuth and elevation bearings
CBeam headings and radiation patterns
DTrigonometric functions

50. - E9H01

When constructing a Beverage antenna, which of the following factors should be included in the design to achieve good performance at the desired frequency?

SelectAnswer
AIt should be one or more wavelengths long
BIts overall length must not exceed 1/4 wavelength
CIt should be configured as a four-sided loop
DIt must be mounted more than 1 wavelength above ground

Figure E7-3

Figure E9-2