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

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1. - E0A09

Which insulating material commonly used as a thermal conductor for some types of electronic devices is extremely toxic if broken or crushed and the particles are accidentally inhaled?

Select	Answer
A	Zinc oxide
B	Uranium Hexafluoride
C	Beryllium Oxide
D	Mica

2. - E1A09

What action or actions should you take if your digital message forwarding station inadvertently forwards a communication that violates FCC rules?

Select	Answer
A	Notify the originating station that the communication does not comply with FCC rules
B	All these choices are correct
C	Discontinue forwarding the communication as soon as you become aware of it
D	Notify the nearest FCC Field Engineers office

3. - E1B10

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

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

4. - E1C04

What is meant by IARP?

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

5. - E1D07

Which HF amateur bands have frequencies authorized for space stations?

Select	Answer
A	All HF bands
B	Only the 40, 20, 17, 15, and 10 meter bands
C	Only the 40, 20, 17, 15, 12, and 10 meter bands
D	Only the 40, 30, 20, 15, 12, and 10 meter bands

6. - E1E02

Who does Part 97 task with maintaining the pools of questions for all U.S. amateur license examinations?

Select	Answer
A	The VEs
B	The ARRL
C	The VECs
D	The FCC

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

8. - E2A09

What do the terms L band and S band specify regarding satellite communications?

Select	Answer
A	Which sideband to use
B	The 2 meter and 70 centimeter bands
C	The 23 centimeter and 13 centimeter bands
D	FM and Digital Store-and-Forward systems

9. - E2B03

How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?

Select	Answer
A	By scanning two fields simultaneously
B	By scanning each field from bottom to top
C	By scanning odd numbered lines in one field and even numbered lines in the next
D	By scanning lines from left to right in one field and right to left in the next

10. - E2C08

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

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

11. - E2D07

What digital protocol is used by APRS?

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

12. - E2E10

Which of these digital modes has the narrowest bandwidth?

Select	Answer
A	170 Hz shift, 45-baud RTTY
B	300-baud packet
C	MFSK16
D	PSK31

13. - E3A02

What characterizes libration fading of an EME signal?

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

14. - E3B11

At what time of day can sporadic E propagation occur?

Select	Answer
A	Only in hours of darkness
B	Only around sunset
C	Only around sunset and sunrise
D	Any time

15. - E3C14

Why does the radio-path horizon distance exceed the geometric horizon?

Select	Answer
A	D-region skip
B	Due to the Doppler effect
C	Downward bending due to density variations in the atmosphere
D	E-region skip

16. - E4A04

How is the compensation of an oscilloscope probe typically adjusted?

Select	Answer
A	A frequency standard is displayed and the probe is adjusted until the deflection time is accurate
B	A square wave is displayed and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible
C	A high frequency sine wave is displayed and the probe is adjusted for maximum amplitude
D	A DC voltage standard is displayed and the probe is adjusted until the displayed voltage is accurate

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S12
B	S21
C	S22
D	S11

18. - E4C11

Why can an attenuator be used to reduce receiver overload on the lower frequency HF bands with little or no impact on signal-to-noise ratio?

Select	Answer
A	Atmospheric noise is generally greater than internally generated noise even after attenuation
B	The attenuator has a low-pass filter to increase the strength of lower frequency signals
C	Signals are attenuated separately from the noise
D	The attenuator has a noise filter to suppress interference

19. - E4D11

Why are odd-order intermodulation products, created within a receiver, of particular interest compared to other products?

Select	Answer
A	Odd-order intermodulation produces three products for every input signal within the band of interest
B	Odd-order products overload the IF filters
C	Odd-order products of two signals in the band of interest are also likely to be within the band
D	Odd-order products are an indication of poor image rejection

20. - E4E08

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

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

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	15.7 kHz
D	31.4 kHz

22. - E5B10

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

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

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 8
B	Point 1
C	Point 3
D	Point 7

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	0.5
B	0.577
C	1.73
D	0.866

25. - E6A04

What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?

Select	Answer
A	Acceptor impurity
B	Insulator impurity
C	Donor impurity
D	N-type impurity

26. - E6B07

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

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

27. - E6C03

What is tri-state logic?

Select	Answer
A	Low-power logic devices designed to operate at 3 volts
B	Proprietary logic devices manufactured by Tri-State Devices
C	Logic devices with 0, 1, and high-impedance output states
D	Logic devices that utilize ternary math

28. - E6D02

What is the equivalent circuit of a quartz crystal?

Select	Answer
A	Motional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in parallel
B	Motional capacitance, motional inductance, and loss resistance in series, all in parallel with a shunt capacitor representing electrode and stray capacitance
C	Motional inductance and loss resistance in series, paralleled with motional capacitance and a capacitor representing electrode and stray capacitance
D	Motional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in series

29. - E6E01

Why is gallium arsenide (GaAs) useful for semiconductor devices operating at UHF and higher frequencies?

Select	Answer
A	Lower junction voltage drop
B	Higher electron mobility
C	Lower transconductance
D	Higher noise figures

30. - E6F08

Why are optoisolators often used in conjunction with solid-state circuits when switching 120 VAC?

Select	Answer
A	Optoisolators provide impedance matching between the control circuit and power circuit
B	Optoisolators eliminate the effects of reflected light in the control circuit
C	Optoisolators provide a very high degree of electrical isolation between a control circuit and the circuit being switched
D	Optoisolators provide a low impedance link between a control circuit and a power circuit

31. - E7A08

What logical operation does an OR gate perform?

Select	Answer
A	It produces logic 0 at its output if all inputs are logic 1
B	It produces logic 1 at its output if all inputs are logic 0
C	It produces logic 1 at its output if any or all inputs are logic 1
D	It only produces logic 0 at its output when all inputs are logic 1

32. - E7B10

In Figure E7-1, what is the purpose of R1 and R2?

Select	Answer
A	Self bias
B	Feedback
C	Load resistors
D	Voltage divider bias

33. - E7C04

How does an impedance-matching circuit transform a complex impedance to a resistive impedance?

Select	Answer
A	It cancels the reactive part of the impedance and changes the resistive part to a desired value
B	Reactive currents are dissipated in matched resistances
C	It introduces transconductance to cancel the reactive part of impedance
D	It introduces negative resistance to cancel the resistive part of impedance

34. - E7D13

What is the equation for calculating power dissipated by a series linear voltage regulator?

Select	Answer
A	Output voltage multiplied by output current
B	Voltage difference from input to output multiplied by output current
C	Input voltage divided by output current
D	Input voltage multiplied by input current

35. - E7E03

What is a frequency discriminator stage in a FM receiver?

Select	Answer
A	An FM generator circuit
B	An automatic band-switching circuit
C	A circuit for detecting FM signals
D	A circuit for filtering two closely adjacent signals

36. - E7F12

Which of the following is an advantage of a Finite Impulse Response (FIR) filter vs an Infinite Impulse Response (IIR) digital filter?

Select	Answer
A	FIR filters are easier to implement for a given set of passband rolloff requirements
B	FIR filters can delay all frequency components of the signal by the same amount
C	All these choices are correct
D	FIR filters can respond faster to impulses

37. - E7G11

What absolute voltage gain can be expected from the circuit in Figure E7-3 when R1 is 3300 ohms and RF is 47 kilohms?

Select	Answer
A	14
B	28
C	7
D	0.07

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

39. - E8A04

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

Select	Answer
A	An error caused by irregular quantization step size
B	A small amount of noise added to the input signal to allow more precise representation of a signal over time
C	An abnormal condition where the converter cannot settle on a value to represent the signal
D	A method of decimation by randomly skipping samples

40. - E8B02

How does the modulation index of a phase-modulated emission vary with RF carrier frequency?

Select	Answer
A	It decreases as the RF carrier frequency increases
B	It varies with the square root of the RF carrier frequency
C	It increases as the RF carrier frequency increases
D	It does not depend on the RF carrier frequency

41. - E8C07

What is the bandwidth of a 4800-Hz frequency shift, 9600-baud ASCII FM transmission?

Select	Answer
A	5.76 kHz
B	9.6 kHz
C	15.36 kHz
D	4.8 kHz

42. - E8D09

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

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

43. - E9A01

What is an isotropic antenna?

Select	Answer
A	A grounded antenna used to measure Earth conductivity
B	A spacecraft antenna used to direct signals toward Earth
C	A theoretical, omnidirectional antenna used as a reference for antenna gain
D	A horizontally polarized antenna used to compare Yagi antennas

44. - E9B01

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

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

45. - E9C13

How does the radiation pattern of a horizontally polarized 3-element beam antenna vary with increasing height above ground?

Select	Answer
A	The takeoff angle of the lowest elevation lobe decreases
B	The horizontal beamwidth decreases
C	The horizontal beamwidth increases
D	The takeoff angle of the lowest elevation lobe increases

46. - E9D10

What happens to feed-point impedance at the base of a fixed length HF mobile antenna when operated below its resonant frequency?

Select	Answer
A	The radiation resistance decreases and the capacitive reactance decreases
B	The radiation resistance increases and the capacitive reactance increases
C	The radiation resistance decreases and the capacitive reactance increases
D	The radiation resistance increases and the capacitive reactance decreases

47. - E9E06

Which of these feed line impedances would be suitable for constructing a quarter-wave Q-section for matching a 100-ohm loop to 50-ohm feed line?

Select	Answer
A	50 ohms
B	450 ohms
C	62 ohms
D	75 ohms

48. - E9F03

Why is the physical length of a coaxial cable transmission line shorter than its electrical length?

Select	Answer
A	The surge impedance is higher in a parallel feed line
B	Skin effect is less pronounced in the coaxial cable
C	The characteristic impedance is higher in a parallel feed line
D	Electrical signals move more slowly in a coaxial cable than in air

49. - E9G02

What type of coordinate system is used in a Smith chart?

Select	Answer
A	Voltage circles and current arcs
B	Voltage lines and current chords
C	Resistance lines and reactance chords
D	Resistance circles and reactance arcs

50. - E9H06

What is the triangulation method of direction finding?

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

Figure E5-1

Figure E7-1

Figure E7-3

Figure E9-1