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

2. - E1A10

If an amateur station is installed aboard a ship or aircraft, what condition must be met before the station is operated?

Select	Answer
A	The amateur station must have a power supply that is completely independent of the main ship or aircraft power supply
B	The amateur operator must have an FCC Marine or Aircraft endorsement on his or her amateur license
C	Its operation must be approved by the master of the ship or the pilot in command of the aircraft
D	The amateur station operator must agree not to transmit when the main radio of the ship or aircraft is in use

3. - E1B09

Which amateur stations may be operated under RACES rules?

Select	Answer
A	Any FCC-licensed amateur station except a Technician Class
B	Any FCC-licensed amateur station participating in the Military Auxiliary Radio System (MARS)
C	Only those club stations licensed to Amateur Extra Class operators
D	Any FCC-licensed amateur station certified by the responsible civil defense organization for the area served

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	5 minutes
C	30 seconds
D	10 minutes

5. - E1D02

Which of the following may transmit special codes intended to obscure the meaning of messages?

Select	Answer
A	Data containing personal information
B	Auxiliary relay links carrying repeater audio
C	Binary control characters
D	Telecommand signals from a space telecommand station

6. - E1E10

What must the administering VEs do after the administration of a successful examination for an amateur operator license?

Select	Answer
A	They must collect and submit the documents to the coordinating VEC for grading
B	They must collect and send the documents to the FCC according to instructions
C	They must submit the application document to the coordinating VEC according to the coordinating VEC instructions
D	They must collect and send the documents to the NCVEC for grading

7. - E1F04

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

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

8. - E2A03

How is the signal inverted by an inverting linear transponder?

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

9. - E2B02

How many horizontal lines make up a fast-scan (NTSC) television frame?

Select	Answer
A	30
B	60
C	1080
D	525

10. - E2C08

Which of the following contacts may be confirmed through the U.S. QSL bureau system?

Select	Answer
A	Contacts between a U.S. station and a non-U.S. station
B	Contacts using tactical call signs
C	Repeater contacts between U.S. club members
D	Special event contacts between stations in the U.S.

11. - E2D02

Which of the following is a good technique for making meteor scatter contacts?

Select	Answer
A	All these choices are correct
B	Use of special digital modes
C	Short transmissions with rapidly repeated call signs and signal reports
D	15-second timed transmission sequences with stations alternating based on location

12. - E2E08

Which of the following HF digital modes can be used to transfer binary files?

Select	Answer
A	PACTOR
B	Hellschreiber
C	RTTY
D	AMTOR

13. - E3A03

When scheduling EME contacts, which of these conditions will generally result in the least path loss?

Select	Answer
A	When the moon is at apogee
B	When the MUF is above 30 MHz
C	When the moon is at perigee
D	When the moon is full

14. - E3B01

What is transequatorial propagation?

Select	Answer
A	Propagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator
B	Propagation between points located on the magnetic equator
C	Propagation between a point on the equator and its antipodal point
D	Propagation between points at the same latitude

15. - E3C15

What might be indicated by a sudden rise in radio background noise across a large portion of the HF spectrum?

Select	Answer
A	Long-path propagation is likely
B	A temperature inversion has occurred
C	A solar flare has occurred
D	Increased transequatorial propagation is likely

16. - E4A08

Which of the following measures SWR?

Select	Answer
A	An ohmmeter
B	A Q meter
C	An antenna analyzer
D	A spectrum analyzer

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S12
B	S11
C	S21
D	S22

18. - E4C03

What is the term for the suppression in an FM receiver of one signal by another stronger signal on the same frequency?

Select	Answer
A	Desensitization
B	Frequency discrimination
C	Capture effect
D	Cross-modulation interference

19. - E4D09

What is the purpose of the preselector in a communications receiver?

Select	Answer
A	To allow selection of the optimum RF amplifier device
B	To provide a range of AGC time constants
C	To store often-used frequencies
D	To increase rejection of signals outside the desired band

20. - E4E08

What current flows equally on all conductors of an unshielded multi-conductor cable?

Select	Answer
A	Common-mode current
B	Reactive current only
C	Differential-mode current
D	Return current

21. - E5A10

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

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

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?

Select	Answer
A	14 degrees with the voltage leading the current
B	14 degrees with the voltage lagging the current
C	76 degrees with the voltage lagging the current
D	76 degrees with the voltage leading the current

23. - E5C09

When using rectangular coordinates to graph the impedance of a circuit, what do the axes represent?

Select	Answer
A	The X axis represents the resistive component and the Y axis represents the reactive component
B	The X axis represents the reactive component and the Y axis represents the resistive component
C	The X axis represents the phase angle and the Y axis represents the magnitude
D	The X axis represents the magnitude and the Y axis represents the phase angle

24. - E5D05

What is the power factor of an RL circuit having a 30-degree phase angle between the voltage and the current?

Select	Answer
A	0.577
B	0.5
C	1.73
D	0.866

25. - E6A12

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

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

26. - E6B10

In Figure E6-2, what is the schematic symbol for a light-emitting diode?

Select	Answer
A	6
B	1
C	7
D	5

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

29. - E6E04

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

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

30. - E6F11

What is the approximate open-circuit voltage produced by a fully illuminated silicon photovoltaic cell?

Select	Answer
A	1.5 V
B	12 V
C	0.5 V
D	0.1 V

31. - E7A05

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

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

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 frequency doubling amplifier
C	An amplifier that uses drift-mode FETs for high efficiency
D	A type of amplifier that uses switching technology to achieve high efficiency

33. - E7C05

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

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

34. - E7D04

Which of the following types of linear voltage regulator usually make the most efficient use of the primary power source?

Select	Answer
A	A series current source
B	A shunt current source
C	A series regulator
D	A shunt regulator

35. - E7E06

Why is de-emphasis commonly used in FM communications receivers?

Select	Answer
A	To reduce impulse noise reception
B	For higher efficiency
C	To remove third-order distortion products
D	For compatibility with transmitters using phase modulation

36. - E7F14

Which of the following would allow a digital signal processing filter to create a sharper filter response?

Select	Answer
A	More taps
B	Double-precision math routines
C	Complex phasor representations
D	Higher data rate

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?

Select	Answer
A	0.03
B	76
C	38
D	1

38. - E7H14

What is a phase-locked loop circuit?

Select	Answer
A	An electronic circuit consisting of a precision push-pull amplifier with a differential input
B	An electronic circuit also known as a monostable multivibrator
C	An electronic servo loop consisting of a phase detector, a low-pass filter, a voltage-controlled oscillator, and a stable reference oscillator
D	An electronic servo loop consisting of a ratio detector, reactance modulator, and voltage-controlled oscillator

39. - E8A10

What is the purpose of a low-pass filter used in conjunction with a digital-to-analog converter?

Select	Answer
A	Improve accuracy by removing out-of-sequence codes from the input
B	Remove harmonics from the output caused by the discrete analog levels generated
C	All these choices are correct
D	Lower the input bandwidth to increase the effective resolution

40. - E8B05

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus-or-minus 5 kHz when the maximum modulation frequency is 3 kHz?

Select	Answer
A	0.6
B	1.67
C	60
D	0.167

41. - E8C02

What is the definition of symbol rate in a digital transmission?

Select	Answer
A	The number of control characters in a message packet
B	The duration of each bit in a message sent over the air
C	The number of characters carried per second by the station-to-station link
D	The rate at which the waveform changes to convey information

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 wait until the frequency is clear
B	A binary bit stream is used to shift the phase of an RF carrier very rapidly in a pseudorandom sequence
C	If interference is detected by the receiver it will signal the transmitter to change frequencies
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	2.79 dB
B	3.85 dB
C	6.0 dB
D	8.15 dB

44. - E9B08

What is the far field of an antenna?

Select	Answer
A	The region of the ionosphere where radiated power is not refracted
B	The region where radiated power dissipates over a specified time period
C	The region where the shape of the antenna pattern is independent of distance
D	The region where radiated field strengths are constant

45. - E9C12

Which of the following describes an Extended Double Zepp antenna?

Select	Answer
A	A wideband vertical antenna constructed from precisely tapered aluminum tubing
B	A portable antenna erected using two push support poles
C	An end-fed folded dipole antenna
D	A center-fed 1.25-wavelength antenna (two 5/8-wave elements in phase)

46. - E9D07

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

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

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 epsilon match
B	The stub match
C	The delta match
D	The gamma 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	The same as the generator output impedance
B	Very low impedance
C	The same as the characteristic impedance of the transmission line
D	Very high impedance

49. - E9G07

On the Smith chart shown in Figure E9-3, what is the only straight line shown?

Select	Answer
A	The resistance axis
B	The voltage axis
C	The current axis
D	The reactance axis

50. - E9H08

What is the function of a sense antenna?

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

Figure E6-2

Figure E7-3

Figure E9-3