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

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1. - E0A08

What does SAR measure?

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

2. - E1A06

Where must the carrier frequency of a CW signal be set to comply with FCC rules for 60 meter operation?

Select	Answer
A	At the lowest frequency of the channel
B	On any frequency where the signal's sidebands are within the channel
C	At the highest frequency of the channel
D	At the center frequency of the channel

3. - E1B12

What must the control operator of a repeater operating in the 70 cm band do if a radiolocation system experiences interference from that repeater?

Select	Answer
A	File an FAA NOTAM (Notice to Airmen) with the repeater system's ERP, call sign, and six-character grid locator
B	All these choices are correct
C	Reduce the repeater antenna HAAT (Height Above Average Terrain)
D	Cease operation or make changes to the repeater to mitigate the interference

4. - E1C05

When may an automatically controlled station originate third party communications?

Select	Answer
A	Never
B	Only when transmitting RTTY or data emissions
C	When agreed upon by the sending or receiving station
D	When approved by the National Telecommunication and Information Administration

5. - E1D05

What must be posted at the station location of a station being operated by telecommand on or within 50 km of the earth's surface?

Select	Answer
A	A photocopy of the station license
B	A label with the name, address, and telephone number of the control operator
C	A label with the name, address, and telephone number of the station licensee
D	All these choices are correct

6. - E1E03

What is a Volunteer Examiner Coordinator?

Select	Answer
A	An organization that has entered into an agreement with the FCC to coordinate, prepare, and administer amateur operator license examinations
B	A person who has volunteered to administer amateur operator license examinations
C	A person who has volunteered to prepare amateur operator license examinations
D	The person who has entered into an agreement with the FCC to be the VE session manager

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 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 satisfy the FCC's spurious emission standards when operated at the lesser of 1500 watts or its full output power

8. - E2A10

What type of satellite appears to stay in one position in the sky?

Select	Answer
A	LEO
B	HEO
C	Geostationary
D	Geomagnetic

9. - E2B12

What signals SSTV receiving software to begin a new picture line?

Select	Answer
A	Elapsed time
B	Specific tone amplitudes
C	A two-tone signal
D	Specific tone frequencies

10. - E2C07

What is the Cabrillo format?

Select	Answer
A	The rules of order for meetings between contest sponsors
B	A method of exchanging information during a contest QSO
C	The most common set of contest rules
D	A standard for submission of electronic contest logs

11. - E2D01

Which of the following digital modes is designed for meteor scatter communications?

Select	Answer
A	MSK144
B	WSPR
C	APRS
D	Hellschreiber

12. - E2E05

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

Select	Answer
A	RTTY
B	PSK31
C	MFSK
D	PACTOR

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 slow change in the pitch of the CW signal
C	A gradual loss of signal as the sun rises
D	A fluttery irregular fading

14. - E3B12

What is the primary characteristic of chordal hop propagation?

Select	Answer
A	Propagation across the geomagnetic equator
B	Successive ionospheric refractions without an intermediate reflection from the ground
C	Signals reflected back toward the transmitting station
D	Propagation away from the great circle bearing between stations

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	Increased transequatorial propagation is likely
C	A solar flare has occurred
D	A temperature inversion has occurred

16. - E4A02

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

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

17. - E4B01

Which of the following factors most affects the accuracy of a frequency counter?

Select	Answer
A	Input attenuator accuracy
B	Temperature coefficient of the logic
C	Time base accuracy
D	Decade divider accuracy

18. - E4C15

What is reciprocal mixing?

Select	Answer
A	Two digital signals combining from alternate time slots
B	In-phase signals cancelling in a mixer resulting in loss of receiver sensitivity
C	Local oscillator phase noise mixing with adjacent strong signals to create interference to desired signals
D	Two out-of-band signals mixing to generate an in-band spurious signal

19. - E4D03

How can intermodulation interference between two repeaters occur?

Select	Answer
A	When the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmitters
B	When the signals from the transmitters are reflected out of phase from airplanes passing overhead
C	When the repeaters are in close proximity and the signals cause feedback in the final amplifier of one or both transmitters
D	When the signals from the transmitters are reflected in phase from airplanes passing overhead

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 across a wide bandwidth
C	Signals that appear at one IF but not another
D	Signals that are constant at all IF levels

21. - E5A02

What is resonance in an LC or RLC circuit?

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

22. - E5B03

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

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

23. - E5C08

What coordinate system is often used to display the phase angle of a circuit containing resistance, inductive and/or capacitive reactance?

Select	Answer
A	Faraday grid
B	Polar coordinates
C	Maidenhead grid
D	Elliptical coordinates

24. - E5D04

Why are short connections used at microwave frequencies?

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

25. - E6A01

In what application is gallium arsenide used as a semiconductor material?

Select	Answer
A	In high-current rectifier circuits
B	In very low-frequency RF circuits
C	In microwave circuits
D	In high-power audio circuits

26. - E6B06

Which of the following is a common use of a Schottky diode?

Select	Answer
A	As a variable capacitance in an automatic frequency control circuit
B	As a VHF/UHF mixer or detector
C	As a constant voltage reference in a power supply
D	As a rectifier in high current power supplies

27. - E6C06

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

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

28. - E6D07

What is current in the primary winding of a transformer called if no load is attached to the secondary?

Select	Answer
A	Stabilizing current
B	Direct current
C	Magnetizing current
D	Excitation current

29. - E6E08

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

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

30. - E6F02

What happens to the conductivity of a photoconductive material when light shines on it?

Select	Answer
A	It stays the same
B	It increases
C	It decreases
D	It becomes unstable

31. - E7A09

What logical operation is performed by an exclusive NOR gate?

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

32. - E7B12

What type of amplifier circuit is shown in Figure E7-1?

Select	Answer
A	Common base
B	Common emitter
C	Emitter follower
D	Common collector

33. - E7C03

What advantage does a series-L Pi-L-network have over a series-L Pi-network for impedance matching between the final amplifier of a vacuum-tube transmitter and an antenna?

Select	Answer
A	Greater transformation range
B	Does not require a capacitor
C	Greater harmonic suppression
D	Higher efficiency

34. - E7D14

What is the purpose of connecting equal-value resistors across power supply filter capacitors connected in series?

Select	Answer
A	Provide a minimum load on the supply
B	Equalize the voltage across each capacitor
C	All these choices are correct
D	Discharge the capacitors when voltage is removed

35. - E7E10

How does a diode envelope detector function?

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

36. - E7F07

What function is performed by a Fast Fourier Transform?

Select	Answer
A	Converting analog signals to digital form
B	Converting digital signals from the time domain to the frequency domain
C	Converting 8-bit data to 16-bit data
D	Converting digital signals to analog form

37. - E7G07

What magnitude of voltage gain can be expected from the circuit in Figure E73 when R1 is 10 ohms and RF is 470 ohms?

Select	Answer
A	94
B	47
C	0.21
D	24

38. - E7H10

What information is contained in the lookup table of a direct digital synthesizer (DDS)?

Select	Answer
A	The phase relationship between a reference oscillator and the output waveform
B	Amplitude values that represent the desired waveform
C	Frequently used receiver and transmitter frequencies
D	The phase relationship between a voltage-controlled oscillator and the output waveform

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	Fourier analysis
B	Vector analysis
C	Differential analysis
D	Numerical analysis

40. - E8B06

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?

Select	Answer
A	0.214
B	47
C	0.47
D	2.14

41. - E8C02

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

Select	Answer
A	The duration of each bit in a message sent over the air
B	The number of characters carried per second by the station-to-station link
C	The number of control characters in a message packet
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 change frequencies
B	The frequency of the transmitted signal is changed very rapidly according to a pseudorandom sequence also used by the receiving station
C	If interference is detected by the receiver it will signal the transmitter to wait until the frequency is clear
D	A binary bit stream is used to shift the phase of an RF carrier very rapidly in a pseudorandom sequence

43. - E9A08

What is antenna bandwidth?

Select	Answer
A	The frequency range over which an antenna satisfies a performance requirement
B	Antenna length divided by the number of elements
C	The angle between the half-power radiation points
D	The angle formed between two imaginary lines drawn through the element ends

44. - E9B04

What is the front-to-back ratio of the radiation pattern shown in Figure E92?

Select	Answer
A	38 dB
B	28 dB
C	15 dB
D	3 dB

45. - E9C05

Which of the following is a type of OCFD antenna?

Select	Answer
A	A multiband dipole antenna using one-way circular polarization for frequency diversity
B	A remotely tunable dipole antenna using orthogonally controlled frequency diversity
C	A dipole fed approximately 1/3 the way from one end with a 4:1 balun to provide multiband operation
D	A folded dipole center-fed with 300-ohm transmission line

46. - E9D07

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

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

47. - E9E10

Which of these choices is an effective way to match an antenna with a 100-ohm feed point impedance to a 50-ohm coaxial cable feed line?

Select	Answer
A	Connect a 1/2 wavelength shorted stub of 75-ohm cable in parallel with the 50-ohm cable where it attaches to the antenna
B	Insert a 1/2 wavelength piece of 300-ohm twinlead in series between the antenna terminals and the 50-ohm feed cable
C	Insert a 1/4-wavelength piece of 75-ohm coaxial cable transmission line in series between the antenna terminals and the 50-ohm feed cable
D	Connect a 1/4-wavelength open stub of 300-ohm twinlead in parallel with the coaxial feed line where it connects to the antenna

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 loss per unit of length
C	All these choices are correct
D	Foam dielectric has lower safe operating voltage limits

49. - E9G04

What are the two families of circles and arcs that make up a Smith chart?

Select	Answer
A	Resistance and voltage
B	Voltage and impedance
C	Resistance and reactance
D	Reactance and voltage

50. - E9H09

What is a Pennant antenna?

Select	Answer
A	A small, vertically oriented receiving antenna consisting of a triangular loop terminated in approximately 900 ohms
B	A stealth antenna built to look like a flagpole
C	A form of rhombic antenna terminated in a variable capacitor to provide frequency diversity
D	A four-element, high-gain vertical array invented by George Pennant

Figure E7-1