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

2. - E1A13

Who must be in physical control of the station apparatus of an amateur station aboard any vessel or craft that is documented or registered in the United States?

Select	Answer
A	Only a person named in an amateur station license grant
B	Any person named in an amateur station license grant or a person holding an unrestricted Radiotelephone Operator Permit
C	Any person holding an FCC issued amateur license or who is authorized for alien reciprocal operation
D	Only a person with an FCC Marine Radio license grant

3. - E1B03

Within what distance must an amateur station protect an FCC monitoring facility from harmful interference?

Select	Answer
A	30 miles
B	10 miles
C	3 miles
D	1 mile

4. - E1C02

Which of the following types of communications may be transmitted to amateur stations in foreign countries?

Select	Answer
A	Communications incidental to the purpose of the amateur service and remarks of a personal nature
B	Business-related messages for non-profit organizations
C	Messages intended for users of the maritime satellite service
D	All these choices are correct

5. - E1D02

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

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

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

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 transmitted for hire or material compensation, except as otherwise provided in the rules
C	Communications that have political content, except as allowed by the Fairness Doctrine
D	Communications that have religious content

8. - E2A07

Which of the following types of signals can be relayed through a linear transponder?

Select	Answer
A	PSK and packet
B	FM and CW
C	SSB and SSTV
D	All these choices are correct

9. - E2B01

How many times per second is a new frame transmitted in a fast-scan (NTSC) television system?

Select	Answer
A	60
B	120
C	30
D	90

10. - E2C06

During a VHF/UHF contest, in which band segment would you expect to find the highest level of SSB or CW activity?

Select	Answer
A	In the middle of each band, usually on the national calling frequency
B	In the weak signal segment of the band, with most of the activity near the calling frequency
C	At the top of each band, usually in a segment reserved for contests
D	In the middle of the band, usually 25 kHz above the national calling frequency

11. - E2D03

Which of the following digital modes is especially useful for EME communications?

Select	Answer
A	JT65
B	PACTOR III
C	MSK144
D	Olivia

12. - E2E03

How is the timing of FT4 contacts organized?

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

13. - E3A12

What is the cause of auroral activity?

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

14. - E3B03

What is the best time of day for transequatorial propagation?

Select	Answer
A	Morning
B	Late at night
C	Noon
D	Afternoon or early evening

15. - E3C02

What is indicated by a rising A or K index?

Select	Answer
A	Increasing disruption of the geomagnetic field
B	Higher levels of solar UV radiation
C	An increase in the critical frequency
D	Decreasing disruption of the geomagnetic field

16. - E4A08

Which of the following measures SWR?

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

17. - E4B07

What do the subscripts of S parameters represent?

Select	Answer
A	The port or ports at which measurements are made
B	Relative quality of the data
C	Frequency order of the measurements
D	The relative time between measurements

18. - E4C04

What is the noise figure of a receiver?

Select	Answer
A	The ratio in dB of the noise generated by the receiver to the theoretical minimum noise
B	The ratio of the noise bandwidth in hertz to the theoretical bandwidth of a resistive network
C	The ratio of thermal noise to atmospheric noise
D	The ratio of atmospheric noise to phase noise

19. - E4D01

What is meant by the blocking dynamic range of a receiver?

Select	Answer
A	The difference in dB between the noise floor and the third-order intercept point
B	The difference in dB between the noise floor and the level of an incoming signal that will cause 1 dB of gain compression
C	The minimum difference in dB between the levels of two FM signals that will cause one signal to block the other
D	The minimum difference in dB between two signals which produce third-order intermodulation products greater than the noise floor

20. - E4E03

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

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

21. - E5A02

What is resonance in an LC or RLC circuit?

Select	Answer
A	The highest frequency that will pass current
B	The frequency at which the capacitive reactance equals the inductive reactance
C	The frequency at which the reactive impedance equals the resistive impedance
D	The lowest frequency that will pass current

22. - E5B01

What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the applied voltage or to discharge to 36.8% of its initial voltage?

Select	Answer
A	One time constant
B	One exponential period
C	A time factor of one
D	An exponential rate of one

23. - E5C06

What does the impedance 50-j25 represent?

Select	Answer
A	50 ohms resistance in series with 25 ohms capacitive reactance
B	50 ohms resistance in series with 25 ohms inductive reactance
C	25 ohms resistance in series with 50 ohms inductive reactance
D	25 ohms resistance in series with 50 ohms capacitive reactance

24. - E5D15

What is the power factor of an RL circuit having a 45-degree phase angle between the voltage and the current?

Select	Answer
A	0.5
B	0.866
C	1.0
D	0.707

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. - E6B01

What is the most useful characteristic of a Zener diode?

Select	Answer
A	An internal capacitance that varies with the applied voltage
B	A constant voltage drop under conditions of varying current
C	A constant current drop under conditions of varying voltage
D	A negative resistance region

27. - E6C06

Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply?

Select	Answer
A	Large bypass capacitance is inherent
B	The input switching threshold is about two times the power supply voltage
C	Bandwidth is very limited
D	The input switching threshold is about one-half the power supply voltage

28. - E6D06

What core material property determines the inductance of an inductor?

Select	Answer
A	Reactivity
B	Permeability
C	Thermal impedance
D	Resistance

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	Gallium nitride
D	Silicon nitride

30. - E6F06

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

Select	Answer
A	A liquid semiconductor
B	A heavy metal
C	A crystalline semiconductor
D	An ordinary metal

31. - E7A09

What logical operation is performed by an exclusive NOR gate?

Select	Answer
A	It produces logic 0 at its output if only one input is logic 1
B	It produces logic 1 at its output if only one input is logic 1
C	It produces logic 0 at its output only if all inputs are logic 0
D	It produces logic 1 at its output only if all inputs are logic 1

32. - E7B14

Why are switching amplifiers more efficient than linear amplifiers?

Select	Answer
A	The power transistor is at saturation or cutoff most of the time
B	Switching amplifiers operate at higher voltages
C	Linear amplifiers have high gain resulting in higher harmonic content
D	Switching amplifiers use push-pull circuits

33. - E7C08

Which of the following factors has the greatest effect on the bandwidth and response shape of a crystal ladder filter?

Select	Answer
A	The gain of the RF stage preceding the filter
B	The amplitude of the signals passing through the filter
C	The DC voltage applied to the quartz crystal
D	The relative frequencies of the individual crystals

34. - E7D10

What is the primary reason that a high-frequency switching type high-voltage power supply can be both less expensive and lighter in weight than a conventional power supply?

Select	Answer
A	The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output
B	The inverter design does not require any output filtering
C	It uses a diode bridge rectifier for increased output
D	It uses a large power factor compensation capacitor to recover power from the unused portion of the AC cycle

35. - E7E08

What are the principal frequencies that appear at the output of a mixer circuit?

Select	Answer
A	The two input frequencies along with their sum and difference frequencies
B	The square root of the product of input frequencies
C	1.414 and 0.707 times the input frequency
D	Two and four times the original frequency

36. - E7F02

What kind of digital signal processing audio filter is used to remove unwanted noise from a received SSB signal?

Select	Answer
A	A phase-inverting filter
B	A crystal-lattice filter
C	A Hilbert-transform filter
D	An adaptive filter

37. - E7G03

What is the typical input impedance of an op-amp?

Select	Answer
A	Very low
B	1000 ohms
C	100 ohms
D	Very high

38. - E7H04

How is positive feedback supplied in a Colpitts oscillator?

Select	Answer
A	Through link coupling
B	Through a capacitive divider
C	Through a neutralizing capacitor
D	Through a tapped coil

39. - E8A05

What of the following instruments would be the most accurate for measuring the RMS voltage of a complex waveform?

Select	Answer
A	An absorption wave meter
B	A D'Arsonval meter
C	A true-RMS calculating meter
D	A grid dip meter

40. - E8B01

What is the modulation index of an FM signal?

Select	Answer
A	The type of modulation used by the transmitter
B	The ratio of modulating signal amplitude to frequency deviation
C	The ratio of frequency deviation to modulating signal frequency
D	The bandwidth of the transmitted signal divided by the modulating signal frequency

41. - E8C03

Why should phase-shifting of a PSK signal be done at the zero crossing of the RF signal?

Select	Answer
A	To simplify modulation
B	To minimize bandwidth
C	All these choices are correct
D	To improve carrier suppression

42. - E8D10

What are some of the differences between the Baudot digital code and ASCII?

Select	Answer
A	Baudot uses 4 data bits per character, ASCII uses 7 or 8; Baudot uses 1 character as a letters/figures shift code, ASCII has no letters/figures code
B	Baudot uses 5 data bits per character, ASCII uses 7 or 8; Baudot uses 2 characters as letters/figures shift codes, ASCII has no letters/figures shift code
C	Baudot uses 7 data bits per character, ASCII uses 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes
D	Baudot uses 6 data bits per character, ASCII uses 7 or 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes

43. - E9A09

What is antenna efficiency?

Select	Answer
A	Radiation resistance divided by transmission resistance
B	Total resistance divided by radiation resistance
C	Effective radiated power divided by transmitter output
D	Radiation resistance divided by total resistance

44. - E9B05

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

Select	Answer
A	Azimuth
B	Polarization
C	Elevation
D	Radiation resistance

45. - E9C08

What is a folded dipole antenna?

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

46. - E9D08

What happens as the Q of an antenna increases?

Select	Answer
A	Gain is reduced
B	More common-mode current is present on the feed line
C	SWR bandwidth increases
D	SWR bandwidth decreases

47. - E9E04

What is the purpose of the series capacitor in a gamma-type antenna matching network?

Select	Answer
A	To provide a rejection notch that prevents the radiation of harmonics
B	To provide DC isolation between the feed line and the antenna
C	To cancel the inductive reactance of the matching network
D	To transform the antenna impedance to a higher value

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?

Select	Answer
A	Foam dielectric has higher velocity factor
B	Foam dielectric has lower safe operating voltage limits
C	Foam dielectric has lower loss per unit of length
D	All these choices are correct

49. - E9G05

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

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

50. - E9H08

What is the function of a sense antenna?

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

Figure E9-2