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

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1. - E0A11

Which of the following injuries can result from using high-power UHF or microwave transmitters?

Select	Answer
A	Localized heating of the body from RF exposure in excess of the MPE limits
B	Ingestion of ozone gas from the cooling system
C	Blood clotting from the intense magnetic field
D	Hearing loss caused by high voltage corona discharge

2. - E1A01

Which of the following carrier frequencies is illegal for LSB AFSK emissions on the 17 meter band RTTY and data segment of 18.068 to 18.110 MHz?

Select	Answer
A	18.100 MHz
B	18.068 MHz
C	18.110 MHz
D	18.107 MHz

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. - E1C04

What is meant by IARP?

Select	Answer
A	A forecast of intermittent aurora radio propagation
B	The internal amateur radio practices policy of the FCC
C	An international amateur radio permit that allows U.S. amateurs to operate in certain countries of the Americas
D	An indication of increased antenna reflected power

5. - E1D10

Which amateur stations are eligible to be telecommand stations of space stations (subject to the privileges of the class of operator license held by the control operator of the station)?

Select	Answer
A	All these choices are correct
B	Any amateur station so designated by the space station licensee
C	Any amateur station so designated by the ITU
D	Any amateur station designated by NASA

6. - E1E08

To which of the following examinees may a VE not administer an examination?

Select	Answer
A	Relatives of the VE as listed in the FCC rules
B	Employees of the VE
C	Friends of the VE
D	All these choices are correct

7. - E1F08

Which of the following types of amateur station communications are prohibited?

Select	Answer
A	Communications in a language other than English
B	Communications that have political content, except as allowed by the Fairness Doctrine
C	Communications transmitted for hire or material compensation, except as otherwise provided in the rules
D	Communications that have religious content

8. - E2A03

How is the signal inverted by an inverting linear transponder?

Select	Answer
A	The signal is passed through a mixer and the difference rather than the sum is transmitted
B	The signal is reduced to I and Q components and the Q component is filtered out
C	The signal is passed through a non-linear filter
D	The signal is detected and remodulated on the reverse sideband

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	120
D	90

10. - E2C11

How should you generally identify your station when attempting to contact a DX station during a contest or in a pileup?

Select	Answer
A	Send the call sign of the DX station three times, the words this is,then your call sign three times
B	Send only the last two letters of your call sign until you make contact
C	Send your full call sign and grid square
D	Send your full call sign once or twice

11. - E2D07

What digital protocol is used by APRS?

Select	Answer
A	AX.25
B	AMTOR
C	802.11
D	PACTOR

12. - E2E03

How is the timing of FT4 contacts organized?

Select	Answer
A	By exchanging ACK/NAK packets
B	Alternating transmissions at 7.5 second intervals
C	It depends on the lunar phase
D	Stations take turns on alternate days

13. - E3A12

What is the cause of auroral activity?

Select	Answer
A	An extreme low-pressure area in the polar regions
B	The interaction in the F2 layer between the solar wind and the Van Allen belt
C	The interaction in the E layer of charged particles from the Sun with the Earth's magnetic field
D	Meteor showers concentrated in the extreme northern and southern latitudes

14. - E3B07

What happens to linearly polarized radio waves that split into ordinary and extraordinary waves in the ionosphere?

Select	Answer
A	They become elliptically polarized
B	They become phase locked
C	They become depolarized
D	They are bent toward the magnetic poles

15. - E3C06

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

Select	Answer
A	By approximately twice the distance
B	By approximately 15 percent of the distance
C	By approximately four times the distance
D	By approximately 50 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	Excessive blanking occurs, which prevents display of the signal
C	All signals will have a DC offset
D	Calibration of the vertical scale is no longer valid

17. - E4B08

Which of the following can be used to measure the Q of a series-tuned circuit?

Select	Answer
A	The inductance to capacitance ratio
B	The resonant frequency of the circuit
C	The bandwidth of the circuit's frequency response
D	The frequency shift

18. - E4C05

What does a receiver noise floor of -174 dBm represent?

Select	Answer
A	The theoretical noise in a 1 Hz bandwidth at the input of a perfect receiver at room temperature
B	The minimum detectable signal as a function of receive frequency
C	The noise figure of a 1 Hz bandwidth receiver
D	The galactic noise contribution to minimum detectable signal

19. - E4D02

Which of the following describes problems caused by poor dynamic range in a receiver?

Select	Answer
A	Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sideband
B	Spurious signals caused by cross-modulation and desensitization from strong adjacent signals
C	Cross-modulation of the desired signal and insufficient audio power to operate the speaker
D	Oscillator instability and severe audio distortion of all but the strongest received signals

20. - E4E05

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

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

21. - E5A10

How is the Q of an RLC series resonant circuit calculated?

Select	Answer
A	Reactance of the inductance multiplied by the reactance of the capacitance
B	Reactance of either the inductance or capacitance divided by the resistance
C	Resistance divided by the reactance of either the inductance or capacitance
D	Reactance of either the inductance or capacitance multiplied by the resistance

22. - E5B03

How is impedance in polar form converted to an equivalent admittance?

Select	Answer
A	Take the square root of the magnitude and add 180 degrees to the angle
B	Square the magnitude and subtract 90 degrees from the angle
C	Take the reciprocal of the magnitude and change the sign of the angle
D	Take the reciprocal of the angle and change the sign of the magnitude

23. - E5C02

How are impedances described in polar coordinates?

Select	Answer
A	By real and imaginary parts
B	By Y and G values
C	By phase angle and magnitude
D	By X and R values

24. - E5D02

Why is it important to keep lead lengths short for components used in circuits for VHF and above?

Select	Answer
A	To increase the thermal time constant
B	To avoid unwanted inductive reactance
C	All these choices are correct
D	To maintain component lifetime

25. - E6A05

How does DC input impedance at the gate of a field-effect transistor compare with the DC input impedance of a bipolar transistor?

Select	Answer
A	They are both low impedance
B	An FET has higher input impedance
C	An FET has lower input impedance
D	They are both high impedance

26. - E6B11

What is used to control the attenuation of RF signals by a PIN diode?

Select	Answer
A	Forward DC bias current
B	A sub-harmonic pump signal
C	Reverse voltage larger than the RF signal
D	Capacitance of an RF coupling capacitor

27. - E6C05

What is an advantage of CMOS logic devices over TTL devices?

Select	Answer
A	Differential output capability
B	Lower power consumption
C	Lower distortion
D	Immune to damage from static discharge

28. - E6D13

What is the primary cause of inductor self-resonance?

Select	Answer
A	Inter-turn capacitance
B	Inductive kickback
C	Non-linear core hysteresis
D	The skin effect

29. - E6E03

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

Select	Answer
A	Silicon
B	Silicon dioxide
C	Silicon nitride
D	Gallium nitride

30. - E6F03

What is the most common configuration of an optoisolator or optocoupler?

Select	Answer
A	An LED and a phototransistor
B	A frequency modulated helium-neon laser
C	A lens and a photomultiplier
D	An amplitude modulated helium-neon laser

31. - E7A07

What logical operation does a NAND gate perform?

Select	Answer
A	It produces logic 0 at its output only when all inputs are logic 1
B	It produces logic 0 at its output if some but not all inputs are logic 1
C	It produces logic 0 at its output only when all inputs are logic 0
D	It produces logic 1 at its output only when all inputs are logic 1

32. - E7B02

What is a Class D amplifier?

Select	Answer
A	A low power amplifier that uses a differential amplifier for improved linearity
B	A type of amplifier that uses switching technology to achieve high efficiency
C	An amplifier that uses drift-mode FETs for high efficiency
D	A frequency doubling amplifier

33. - E7C12

What is one advantage of a Pi-matching network over an L-matching network consisting of a single inductor and a single capacitor?

Select	Answer
A	Pi-networks provide balanced input and output
B	L-networks cannot perform impedance transformation
C	Pi-networks are more stable
D	The Q of Pi-networks can be controlled

34. - E7D02

What is a characteristic of a switching electronic voltage regulator?

Select	Answer
A	The resistance of a control element is varied in direct proportion to the line voltage or load current
B	The controlled device's duty cycle is changed to produce a constant average output voltage
C	It gives a ramp voltage at its output
D	It is generally less efficient than a linear regulator

35. - E7E10

How does a diode envelope detector function?

Select	Answer
A	By sensing the change of reactance in the diode with respect to frequency
B	By rectification and filtering of RF signals
C	By mixing signals with noise in the transition region of the diode
D	By breakdown of the Zener voltage

36. - E7F04

What is a common method of generating an SSB signal using digital signal processing?

Select	Answer
A	Varying quartz crystal characteristics emulated in digital form
B	Signals are combined in quadrature phase relationship
C	A frequency synthesizer removes the unwanted sidebands
D	Mixing products are converted to voltages and subtracted by adder circuits

37. - E7G04

What is meant by the "op-amp input offset voltage"?

Select	Answer
A	The output voltage of the op-amp minus its input voltage
B	The potential between the amplifier input terminals of the op-amp in an open loop condition
C	The differential input voltage needed to bring the open loop output voltage to zero
D	The difference between the output voltage of the op-amp and the input voltage required in the immediately following stage

38. - E7H09

What type of frequency synthesizer circuit uses a phase accumulator, lookup table, digital to analog converter, and a low-pass anti-alias filter?

Select	Answer
A	A direct digital synthesizer
B	A phase-locked loop synthesizer
C	A hybrid synthesizer
D	A diode-switching matrix synthesizer

39. - E8A11

Which of the following is a measure of the quality of an analog-to-digital converter?

Select	Answer
A	Peak envelope power
B	Power factor
C	Reciprocal mixing
D	Total harmonic distortion

40. - E8B08

What describes Orthogonal Frequency Division Multiplexing?

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

41. - E8C05

What is the approximate bandwidth of a 13-WPM International Morse Code transmission?

Select	Answer
A	13 Hz
B	104 Hz
C	26 Hz
D	52 Hz

42. - E8D05

What is the most common method of reducing key clicks?

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

43. - E9A06

What is the effective radiated power relative to a dipole of a repeater station with 200 watts transmitter power output, 4 dB feed line loss, 3.2 dB duplexer loss, 0.8 dB circulator loss, and 10 dBd antenna gain?

Select	Answer
A	2000 watts
B	317 watts
C	126 watts
D	300 watts

44. - E9B01

In the antenna radiation pattern shown in Figure E9-1, what is the beamwidth?

Select	Answer
A	30 degrees
B	75 degrees
C	25 degrees
D	50 degrees

45. - E9C11

How is the far-field elevation pattern of a vertically polarized antenna affected by being mounted over seawater versus soil?

Select	Answer
A	The low-angle radiation increases
B	Additional higher vertical angle lobes will appear
C	The low-angle radiation decreases
D	Fewer vertical angle lobes will be present

46. - E9D11

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

Select	Answer
A	Solid wire
B	Resistive wire, such as spark plug wire
C	Stranded wire
D	Wide flat copper strap

47. - E9E09

Which of the following is used to shunt-feed a grounded tower at its base?

Select	Answer
A	Gamma match
B	All these choices are correct
C	Hairpin match
D	Double-bazooka match

48. - E9F13

What impedance does a 1/4-wavelength transmission line present to a generator when the line is shorted at the far end?

Select	Answer
A	Very high impedance
B	The same as the generator output impedance
C	Very low impedance
D	The same as the characteristic impedance of the transmission line

49. - E9G05

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

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

50. - E9H05

What is the main drawback of a small wire-loop antenna for direction finding?

Select	Answer
A	It has no clearly defined null
B	All these choices are correct
C	It has a bidirectional pattern
D	It is practical for use only on VHF and higher bands

Figure E9-1