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	Mica
B	Uranium Hexafluoride
C	Zinc oxide
D	Beryllium Oxide

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 holding an FCC issued amateur license or who is authorized for alien reciprocal operation
C	Any person named in an amateur station license grant or a person holding an unrestricted Radiotelephone Operator Permit
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	1 mile
D	3 miles

4. - E1C05

When may an automatically controlled station originate third party communications?

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

5. - E1D04

Which of the following is required in the identification transmissions from a balloon-borne telemetry station?

Select	Answer
A	All these choices are correct
B	The station's six-character Maidenhead grid locator
C	The output power of the balloon transmitter
D	Call sign

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 submit the application document to the coordinating VEC according to the coordinating VEC instructions
B	They must collect and send the documents to the NCVEC for grading
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. - 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 exhibit a gain of 0 dB or less over its full output range
B	It must be capable of external RF switching between its input and output networks
C	It must produce full legal output when driven by not more than 5 watts of mean RF input power
D	It must satisfy the FCC's spurious emission standards when operated at the lesser of 1500 watts or its full output power

8. - E2A08

Why should effective radiated power to a satellite that uses a linear transponder be limited?

Select	Answer
A	To avoid reducing the downlink power to all other users
B	To prevent the satellite from emitting out-of-band signals
C	To prevent creating errors in the satellite telemetry
D	To avoid interfering with terrestrial QSOs

9. - E2B01

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

Select	Answer
A	90
B	120
C	30
D	60

10. - E2C07

What is the Cabrillo format?

Select	Answer
A	A method of exchanging information during a contest QSO
B	The most common set of contest rules
C	The rules of order for meetings between contest sponsors
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	APRS
C	Hellschreiber
D	WSPR

12. - E2E13

Which of these digital modes has the fastest data throughput under clear communication conditions?

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

13. - E3A05

Tropospheric propagation of microwave signals often occurs in association with what phenomenon?

Select	Answer
A	Sprites and jets
B	Grayline
C	Warm and cold fronts
D	Lightning discharges

14. - E3B09

At what time of year is sporadic E propagation most likely to occur?

Select	Answer
A	Around the equinoxes, especially the fall equinox
B	Around the equinoxes, especially the spring equinox
C	Around the solstices, especially the summer solstice
D	Around the solstices, especially the winter solstice

15. - E3C04

What does the value of Bz (B sub Z) represent?

Select	Answer
A	Direction and strength of the interplanetary magnetic field
B	Critical frequency for vertical transmissions
C	Duration of long-delayed echoes
D	Geomagnetic field stability

16. - E4A11

How should an antenna analyzer be connected when measuring antenna resonance and feed point impedance?

Select	Answer
A	Connect the antenna feed line directly to the analyzer's connector
B	Loosely couple the analyzer near the antenna base
C	Connect the analyzer via a high-impedance transformer to the antenna
D	Loosely couple the antenna and a dummy load to the analyzer

17. - E4B09

What is indicated if the current reading on an RF ammeter placed in series with the antenna feed line of a transmitter increases as the transmitter is tuned to resonance?

Select	Answer
A	There is possibly a short to ground in the feed line
B	There is an impedance mismatch between the antenna and feed line
C	There is more power going into the antenna
D	The transmitter is not properly neutralized

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	-155 dBm
B	-148 dBm
C	-174 dBm
D	-164 dBm

19. - E4D08

What causes intermodulation in an electronic circuit?

Select	Answer
A	Too little gain
B	Positive feedback
C	Nonlinear circuits or devices
D	Lack of neutralization

20. - E4E11

What could cause local AM broadcast band signals to combine to generate spurious signals in the MF or HF bands?

Select	Answer
A	One or more of the broadcast stations is transmitting an over-modulated signal
B	Nearby corroded metal joints are mixing and re-radiating the broadcast signals
C	Your station receiver IF amplifier stage is defective
D	You are receiving skywave signals from a distant station

21. - E5A11

What is the half-power bandwidth of a resonant circuit that has a resonant frequency of 7.1 MHz and a Q of 150?

Select	Answer
A	23.67 kHz
B	315.6 Hz
C	157.8 Hz
D	47.3 kHz

22. - E5B04

What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors, all in parallel?

Select	Answer
A	110 seconds
B	220 seconds
C	55 seconds
D	440 seconds

23. - E5C12

Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and a 19-picofarad capacitor at 21.200 MHz?

Select	Answer
A	Point 8
B	Point 1
C	Point 7
D	Point 3

24. - E5D04

Why are short connections used at microwave frequencies?

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

25. - E6A01

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

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

26. - E6B02

What is an important characteristic of a Schottky diode as compared to an ordinary silicon diode when used as a power supply rectifier?

Select	Answer
A	Less forward voltage drop
B	Longer carrier retention time
C	More constant reverse avalanche voltage
D	Much higher reverse voltage breakdown

27. - E6C06

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

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

28. - E6D04

Which materials are commonly used as a core in an inductor?

Select	Answer
A	Polystyrene and polyethylene
B	Ferrite and brass
C	Teflon and Delrin
D	Cobalt and aluminum

29. - E6E06

What characteristics of the MMIC make it a popular choice for VHF through microwave circuits?

Select	Answer
A	Nearly infinite gain, very high input impedance, and very low output impedance
B	Controlled gain, low noise figure, and constant input and output impedance over the specified frequency range
C	The ability to retrieve information from a single signal even in the presence of other strong signals
D	Plate current that is controlled by a control grid

30. - E6F11

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

Select	Answer
A	0.5 V
B	1.5 V
C	12 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	J-K flip-flop
C	Astable multivibrator
D	Monostable multivibrator

32. - E7B05

What can be done to prevent unwanted oscillations in an RF power amplifier?

Select	Answer
A	Tune the stage for maximum SWR
B	Use a phase inverter in the output filter
C	Install parasitic suppressors and/or neutralize the stage
D	Tune both the input and output for maximum power

33. - E7C07

Which describes a Pi-L-network used for matching a vacuum tube final amplifier to a 50-ohm unbalanced output?

Select	Answer
A	A Phase Inverter Load network
B	A matching network in which all components are isolated from ground
C	A network with only three discrete parts
D	A Pi-network with an additional series inductor on the output

34. - E7D09

What is the main reason to use a charge controller with a solar power system?

Select	Answer
A	Control of electrolyte levels during battery discharge
B	Prevention of battery undercharge
C	Prevention of battery damage due to overcharge
D	Matching of day and night charge rates

35. - E7E09

What occurs when an excessive amount of signal energy reaches a mixer circuit?

Select	Answer
A	Spurious mixer products are generated
B	Mixer blanking occurs
C	A beat frequency is generated
D	Automatic limiting occurs

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

37. - E7G08

How does the gain of an ideal operational amplifier vary with frequency?

Select	Answer
A	It increases linearly with increasing frequency
B	It does not vary with frequency
C	It decreases linearly with increasing frequency
D	It decreases logarithmically with increasing frequency

38. - E7H14

What is a phase-locked loop circuit?

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

39. - E8A10

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

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

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	3
B	1/3
C	6000
D	2000

41. - E8C11

What is the relationship between symbol rate and baud?

Select	Answer
A	They are the same
B	Baud is twice the symbol rate
C	Symbol rate is only used for packet-based modes
D	Baud is only used for RTTY

42. - E8D01

Why are received spread spectrum signals resistant to interference?

Select	Answer
A	The receiver is always equipped with a digital blanker
B	Signals not using the spread spectrum algorithm are suppressed in the receiver
C	The high power used by a spread spectrum transmitter keeps its signal from being easily overpowered
D	If interference is detected by the receiver it will signal the transmitter to change frequencies

43. - E9A11

Which of the following factors determines ground losses for a ground-mounted vertical antenna operating in the 3 MHz to 30 MHz range?

Select	Answer
A	The standing wave ratio
B	Distance from the transmitter
C	Soil conductivity
D	Take-off angle

44. - E9B01

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

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

45. - E9C14

How does the performance of a horizontally polarized antenna mounted on the side of a hill compare with the same antenna mounted on flat ground?

Select	Answer
A	The horizontal beamwidth decreases in the downhill direction
B	The main lobe takeoff angle increases in the downhill direction
C	The horizontal beamwidth increases in the uphill direction
D	The main lobe takeoff angle decreases in the downhill direction

46. - E9D08

What happens as the Q of an antenna increases?

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

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	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
B	Insert a 1/2 wavelength piece of 300-ohm twinlead in series between the antenna terminals and the 50-ohm feed cable
C	Connect a 1/2 wavelength shorted stub of 75-ohm cable in parallel with the 50-ohm cable where it attaches to the antenna
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. - E9F06

What is the approximate physical length of an air-insulated, parallel conductor transmission line that is electrically 1/2 wavelength long at 14.10 MHz?

Select	Answer
A	7.0 meters
B	8.5 meters
C	10.6 meters
D	13.3 meters

49. - E9G01

Which of the following can be calculated using a Smith chart?

Select	Answer
A	Impedance along transmission lines
B	Antenna radiation pattern
C	Radiation resistance
D	Radio propagation

50. - E9H04

What is an advantage of placing a grounded electrostatic shield around a small loop direction-finding antenna?

Select	Answer
A	It adds capacitive loading, increasing the bandwidth of the antenna
B	It increases signal strength by providing a better match to the feed line
C	It eliminates tracking errors caused by strong out-of-band signals
D	It eliminates unbalanced capacitive coupling to the surroundings, improving the nulls

Figure E5-1

Figure E9-1