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

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1. - E0A08

What does SAR measure?

Select	Answer
A	The rate at which RF energy is absorbed by the body
B	Synthetic Aperture Ratio of the human body
C	The rate of RF energy reflected from stationary terrain
D	Signal Amplification Rating

2. - E1A04

With your transceiver displaying the carrier frequency of phone signals, you hear a DX station calling CQ on 3.601 MHz LSB. Is it legal to return the call using lower sideband on the same frequency?

Select	Answer
A	No, U.S. stations are not permitted to use phone emissions below 3.610 MHz
B	No, the sideband will extend beyond the edge of the phone band segment
C	Yes, because the displayed frequency is within the 75 meter phone band segment
D	Yes, because the DX station initiated the contact

3. - E1B07

To what type of regulations does PRB-1 apply?

Select	Answer
A	Homeowners associations
B	FAA tower height limits
C	State and local zoning
D	Use of wireless devices in vehicles

4. - E1C08

What is the maximum permissible duration of a remotely controlled station's transmissions if its control link malfunctions?

Select	Answer
A	3 minutes
B	30 seconds
C	5 minutes
D	10 minutes

5. - E1D12

Which of the following amateur stations may transmit one-way communications?

Select	Answer
A	A message forwarding station or automatically controlled digital station
B	A space station, beacon station, or telecommand station
C	A local repeater or linked repeater station
D	All these choices are correct

6. - E1E01

For which types of out-of-pocket expenses do the Part 97 rules state that VEs and VECs may be reimbursed?

Select	Answer
A	Providing amateur operator license examination preparation training materials
B	Preparing, processing, administering, and coordinating an examination for an amateur radio operator license
C	No expenses are authorized for reimbursement
D	Teaching an amateur operator license examination preparation course

7. - E1F11

Which of the following best describes one of the standards that must be met by an external RF power amplifier if it is to qualify for a grant of FCC certification?

Select	Answer
A	It must satisfy the FCC's spurious emission standards when operated at the lesser of 1500 watts or its full output power
B	It must be capable of external RF switching between its input and output networks
C	It must exhibit a gain of 0 dB or less over its full output range
D	It must produce full legal output when driven by not more than 5 watts of mean RF input power

8. - E2A11

What type of antenna can be used to minimize the effects of spin modulation and Faraday rotation?

Select	Answer
A	A log-periodic dipole array
B	A circularly polarized antenna
C	An isotropic antenna
D	A linearly polarized antenna

9. - E2B10

What aspect of an analog slow-scan television signal encodes the brightness of the picture?

Select	Answer
A	Tone frequency
B	Sync frequency
C	Sync amplitude
D	Tone amplitude

10. - E2C09

What type of equipment is commonly used to implement an amateur radio mesh network?

Select	Answer
A	A wireless router running custom firmware
B	An optical cable connection between the USB ports of 2 separate computers
C	A 2 meter VHF transceiver with a 1200 baud modem
D	A 440 MHz transceiver with a 9600 baud modem

11. - E2D07

What digital protocol is used by APRS?

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

12. - E2E05

Which of these digital modes does not support keyboard-to-keyboard operation?

Select	Answer
A	RTTY
B	MFSK
C	PSK31
D	PACTOR

13. - E3A12

What is the cause of auroral activity?

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

14. - E3B04

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

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

15. - E3C07

Which of the following descriptors indicates the greatest solar flare intensity?

Select	Answer
A	Class A
B	Class B
C	Class M
D	Class X

16. - E4A02

Which of the following parameters does a spectrum analyzer display on the vertical and horizontal axes?

Select	Answer
A	RF amplitude and frequency
B	SWR and time
C	SWR and frequency
D	RF amplitude and time

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S11
B	S21
C	S12
D	S22

18. - E4C06

A CW receiver with the AGC off has an equivalent input noise power density of -174 dBm/Hz. What would be the level of an unmodulated carrier input to this receiver that would yield an audio output SNR of 0 dB in a 400 Hz noise bandwidth?

Select	Answer
A	-164 dBm
B	-148 dBm
C	-155 dBm
D	-174 dBm

19. - E4D05

What transmitter frequencies would cause an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz?

Select	Answer
A	146.34 MHz and 146.61 MHz
B	146.88 MHz and 146.34 MHz
C	173.35 MHz and 139.40 MHz
D	146.10 MHz and 147.30 MHz

20. - E4E03

Which of the following signals might a receiver noise blanker be able to remove from desired signals?

Select	Answer
A	Signals that have a sharply peaked frequency distribution
B	Signals that appear at one IF but not another
C	Signals that are constant at all IF levels
D	Signals that appear across a wide bandwidth

21. - E5A09

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

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

22. - E5B06

What is susceptance?

Select	Answer
A	A measure of the efficiency of a transformer
B	The imaginary part of admittance
C	The magnetic impedance of a circuit
D	The ratio of magnetic field to electric field

23. - E5C01

Which of the following represents capacitive reactance in rectangular notation?

Select	Answer
A	-jX
B	Omega
C	+jX
D	Delta

24. - E5D04

Why are short connections used at microwave frequencies?

Select	Answer
A	To increase compensating capacitance
B	To reduce noise figure
C	To increase neutralizing resistance
D	To reduce phase shift along the connection

25. - E6A12

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

Select	Answer
A	To provide a voltage reference for the correct amount of reverse-bias gate voltage
B	To keep the gate voltage within specifications and prevent the device from overheating
C	To protect the substrate from excessive voltages
D	To reduce the chance of static damage to the gate

26. - E6B07

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

Select	Answer
A	Insufficient forward voltage
B	Charge carrier depletion
C	Excessive junction temperature
D	Excessive inverse voltage

27. - E6C01

What is the function of hysteresis in a comparator?

Select	Answer
A	To increase the sensitivity
B	To cause the output to change states continually
C	To prevent input noise from causing unstable output signals
D	To allow the comparator to be used with AC input signals

28. - E6D05

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

Select	Answer
A	Ferrite toroids generally have better temperature stability
B	Ferrite toroids generally require fewer turns to produce a given inductance value
C	Ferrite toroids generally have lower initial permeability
D	Ferrite toroids are easier to use with surface mount technology

29. - E6E08

How is power supplied to the most common type of MMIC?

Select	Answer
A	Through a resistor and/or RF choke connected to the amplifier output lead
B	MMICs require no operating bias
C	Directly to the bias voltage (VCC IN) lead
D	Through a capacitor and RF choke connected to the amplifier input lead

30. - E6F04

What is the photovoltaic effect?

Select	Answer
A	The conversion of electrical energy to mechanical energy
B	The tendency of a battery to discharge when exposed to light
C	The conversion of light to electrical energy
D	The conversion of voltage to current when exposed to light

31. - E7A05

Which of the following is a circuit that continuously alternates between two states without an external clock?

Select	Answer
A	Astable multivibrator
B	Monostable multivibrator
C	T flip-flop
D	J-K flip-flop

32. - E7B07

Which of the following is a likely result when a Class C amplifier is used to amplify a single-sideband phone signal?

Select	Answer
A	Signal distortion and excessive bandwidth
B	Reduced intermodulation products
C	Signal inversion
D	Increased overall intelligibility

33. - E7C02

Which of the following is a property of a T-network with series capacitors and a parallel shunt inductor?

Select	Answer
A	It is a notch filter
B	It is a high-pass filter
C	It is a band-pass filter
D	It is a low-pass filter

34. - E7D02

What is a characteristic of a switching electronic voltage regulator?

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

35. - E7E01

Which of the following can be used to generate FM phone emissions?

Select	Answer
A	A balanced modulator on the oscillator
B	A reactance modulator on the final amplifier
C	A reactance modulator on the oscillator
D	A balanced modulator on the audio amplifier

36. - E7F08

What is the function of decimation?

Select	Answer
A	Removing unnecessary significant digits
B	Reducing the effective sample rate by removing samples
C	Attenuating the signal
D	Converting data to binary code decimal form

37. - E7G06

What is the gain-bandwidth of an operational amplifier?

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

38. - E7H12

Which of the following must be done to ensure that a crystal oscillator provides the frequency specified by the crystal manufacturer?

Select	Answer
A	Provide the crystal with a specified parallel inductance
B	Bias the crystal at a specified voltage
C	Provide the crystal with a specified parallel capacitance
D	Bias the crystal at a specified current

39. - E8A01

What is the name of the process that shows that a square wave is made up of a sine wave plus all its odd harmonics?

Select	Answer
A	Vector analysis
B	Differential analysis
C	Numerical analysis
D	Fourier analysis

40. - E8B04

What is the modulation index of an FM-phone signal having a maximum carrier deviation of plus or minus 6 kHz when modulated with a 2 kHz modulating frequency?

Select	Answer
A	1/3
B	2000
C	6000
D	3

41. - E8C09

Which digital code allows only one bit to change between sequential code values?

Select	Answer
A	Gray code
B	Excess 3 code
C	Binary Coded Decimal Code
D	Extended Binary Coded Decimal Interchange Code

42. - E8D09

What is considered an acceptable maximum IMD level for an idling PSK signal?

Select	Answer
A	+15 dB
B	+10 dB
C	-20 dB
D	-30 dB

43. - E9A07

What is the effective isotropic radiated power of a repeater station with 200 watts transmitter power output, 2 dB feed line loss, 2.8 dB duplexer loss, 1.2 dB circulator loss, and 7 dBi antenna gain?

Select	Answer
A	252 watts
B	63.2 watts
C	632 watts
D	159 watts

44. - E9B10

What is the principle of a Method of Moments analysis?

Select	Answer
A	A wire is modeled as a single sine-wave current generator
B	A wire is modeled as a series of segments, each having a distinct value of voltage across it
C	A wire is modeled as a series of segments, each having a uniform value of current
D	A wire is modeled as a single sine-wave voltage source

45. - E9C08

What is a folded dipole antenna?

Select	Answer
A	A dipole configured to provide forward gain
B	A dipole one-quarter wavelength long
C	A half-wave dipole with an additional parallel wire connecting its two ends
D	A type of ground-plane antenna

46. - E9D07

What is an advantage of using top loading in a shortened HF vertical antenna?

Select	Answer
A	Improved radiation efficiency
B	Greater structural strength
C	Higher losses
D	Lower Q

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. - E9F10

What impedance does a 1/8-wavelength transmission line present to a generator when the line is shorted at the far end?

Select	Answer
A	A capacitive reactance
B	Zero
C	An inductive reactance
D	The same as the characteristic impedance of the line

49. - E9G10

What do the arcs on a Smith chart represent?

Select	Answer
A	SWR
B	Points with constant resistance
C	Points with constant reactance
D	Frequency

50. - E9H08

What is the function of a sense antenna?

Select	Answer
A	It modifies the pattern of a DF antenna array to provide a null in one direction
B	It provides diversity reception that cancels multipath signals
C	It increases the sensitivity of a DF antenna array
D	It allows DF antennas to receive signals at different vertical angles