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

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1. - E0A11

Which of the following injuries can result from using high-power UHF or microwave transmitters?

Select	Answer
A	Hearing loss caused by high voltage corona discharge
B	Blood clotting from the intense magnetic field
C	Localized heating of the body from RF exposure in excess of the MPE limits
D	Ingestion of ozone gas from the cooling system

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

3. - E1B07

To what type of regulations does PRB-1 apply?

Select	Answer
A	FAA tower height limits
B	Use of wireless devices in vehicles
C	Homeowners associations
D	State and local zoning

4. - E1C11

Which of the following operating arrangements allows an FCC-licensed U.S. citizen to operate in many European countries, and alien amateurs from many European countries to operate in the U.S.?

Select	Answer
A	IARP agreement
B	ITU reciprocal license
C	CEPT agreement
D	All these choices are correct

5. - E1D03

What is a space telecommand station?

Select	Answer
A	An amateur station that receives telemetry from a satellite or balloon more than 50 kilometers above the surface of the Earth
B	An amateur station located in a satellite or a balloon more than 50 kilometers above the surface of the Earth
C	An amateur station located on the surface of the Earth for communication with other Earth stations by means of Earth satellites
D	An amateur station that transmits communications to initiate, modify or terminate functions of a space station

6. - E1E01

For which types of out-of-pocket expenses do the Part 97 rules state that VEs and VECs may be reimbursed?

Select	Answer
A	No expenses are authorized for reimbursement
B	Preparing, processing, administering, and coordinating an examination for an amateur radio operator license
C	Providing amateur operator license examination preparation training materials
D	Teaching an amateur operator license examination preparation course

7. - E1F07

When may an amateur station send a message to a business?

Select	Answer
A	When transmitting international third-party communications
B	When the total money involved does not exceed $25
C	When the control operator is employed by the FCC or another government agency
D	When neither the amateur nor his or her employer has a pecuniary interest in the communications

8. - E2A06

What are Keplerian elements?

Select	Answer
A	Parameters that define the orbit of a satellite
B	Phase reversing elements in a Yagi antenna
C	High-emission heater filaments used in magnetron tubes
D	Encrypting codes used for spread spectrum modulation

9. - E2B12

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

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

10. - E2C12

What technique do individual nodes use to form a mesh network?

Select	Answer
A	Acting as store-and-forward digipeaters
B	Forward error correction and Viterbi codes
C	Custom code plugs for the local trunking systems
D	Discovery and link establishment protocols

11. - E2D01

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

Select	Answer
A	Hellschreiber
B	WSPR
C	MSK144
D	APRS

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	AMTOR
C	PSK31
D	300 baud packet

13. - E3A02

What characterizes libration fading of an EME signal?

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

14. - E3B05

Which amateur bands typically support long-path propagation?

Select	Answer
A	Only 160 meters to 40 meters
B	160 meters to 10 meters
C	6 meters to 2 meters
D	Only 30 meters to 10 meters

15. - E3C04

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

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

16. - E4A11

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

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

17. - E4B06

How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?

Select	Answer
A	125 watts
B	25 watts
C	75 watts
D	100 watts

18. - E4C08

An SDR receiver is overloaded when input signals exceed what level?

Select	Answer
A	The reference voltage of the analog-to-digital converter
B	One-half the maximum sampling buffer size
C	One-half the maximum sample rate
D	The maximum count value of the analog-to-digital converter

19. - E4D02

Which of the following describes problems caused by poor dynamic range in a receiver?

Select	Answer
A	Spurious signals caused by cross-modulation and desensitization from strong adjacent signals
B	Cross-modulation of the desired signal and insufficient audio power to operate the speaker
C	Oscillator instability and severe audio distortion of all but the strongest received signals
D	Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sideband

20. - E4E07

Which of the following can cause shielded cables to radiate or receive interference?

Select	Answer
A	Low inductance ground connections at both ends of the shield
B	Tying all ground connections to a common point resulting in differential-mode currents in the shield
C	Use of braided shielding material
D	Common-mode currents on the shield and conductors

21. - E5A08

What is the phase relationship between the current through and the voltage across a series resonant circuit at resonance?

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

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	440 seconds
B	220 seconds
C	55 seconds
D	110 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 3
C	Point 7
D	Point 1

24. - E5D04

Why are short connections used at microwave frequencies?

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

25. - E6A10

In Figure E6-1, what is the schematic symbol for an N-channel dual-gate MOSFET?

Select	Answer
A	6
B	2
C	4
D	5

26. - E6B10

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

Select	Answer
A	1
B	5
C	7
D	6

27. - E6C04

Which of the following is an advantage of BiCMOS logic?

Select	Answer
A	Its simplicity results in much less expensive devices than standard CMOS
B	It is immune to electrostatic damage
C	It has the high input impedance of CMOS and the low output impedance of bipolar transistors
D	All these choices are correct

28. - E6D03

Which of the following is an aspect of the piezoelectric effect?

Select	Answer
A	Generation of electrical energy in the presence of light
B	Increased conductivity in the presence of light
C	Mechanical deformation of material by the application of a voltage
D	Mechanical deformation of material by the application of a magnetic field

29. - E6E05

Which of the following noise figure values is typical of a low-noise UHF preamplifier?

Select	Answer
A	-10 dB
B	-20 dBm
C	2 dB
D	44 dBm

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

31. - E7A11

What type of logic defines "1" as a high voltage?

Select	Answer
A	Reverse Logic
B	Negative logic
C	Positive Logic
D	Assertive Logic

32. - E7B08

How can an RF power amplifier be neutralized?

Select	Answer
A	By reducing the driving power
B	By feeding an in-phase component of the output back to the input
C	By increasing the driving power
D	By feeding a 180-degree out-of-phase portion of the output back to the input

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

34. - E7D08

What type of circuit is shown in Figure E7-2?

Select	Answer
A	Grounded emitter amplifier
B	Switching voltage regulator
C	Linear voltage regulator
D	Monostable multivibrator

35. - E7E06

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

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

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	An adaptive filter
C	A Hilbert-transform filter
D	A crystal-lattice filter

37. - E7G02

What is ringing in a filter?

Select	Answer
A	Undesired oscillations added to the desired signal
B	Partial cancellation of the signal over a range of frequencies
C	A reduction in high frequency response
D	An echo caused by a long time delay

38. - E7H04

How is positive feedback supplied in a Colpitts oscillator?

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

39. - E8A04

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

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

40. - E8B07

Orthogonal Frequency Division Multiplexing is a technique used for which type of amateur communication?

Select	Answer
A	EME
B	High-speed digital modes
C	Extremely low-power contacts
D	OFDM signals are not allowed on amateur bands

41. - E8C01

How is Forward Error Correction implemented?

Select	Answer
A	By varying the frequency shift of the transmitted signal according to a predefined algorithm
B	By the receiving station repeating each block of three data characters
C	By transmitting extra data that may be used to detect and correct transmission errors
D	By transmitting a special algorithm to the receiving station along with the data characters

42. - E8D07

What is a common cause of overmodulation of AFSK signals?

Select	Answer
A	Excessive numbers of retries
B	Excessive transmit audio levels
C	Ground loops
D	Bit errors in the modem

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

44. - E9B02

In the antenna radiation pattern shown in Figure E9-1, what is the front-to-back ratio?

Select	Answer
A	18 dB
B	14 dB
C	24 dB
D	36 dB

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

46. - E9D01

How much does the gain of an ideal parabolic dish antenna change when the operating frequency is doubled?

Select	Answer
A	6 dB
B	3 dB
C	2 dB
D	4 dB

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	Connect a 1/2 wavelength shorted stub of 75-ohm cable in parallel with the 50-ohm cable where it attaches to the antenna
C	Insert a 1/2 wavelength piece of 300-ohm twinlead 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. - E9F09

What is the approximate physical length of a foam polyethylene dielectric coaxial transmission line that is electrically 1/4 wavelength long at 7.2 MHz?

Select	Answer
A	10.4 meters
B	6.9 meters
C	5.2 meters
D	8.3 meters

49. - E9G02

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

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

50. - E9H07

Why is RF attenuation used when direction-finding?

Select	Answer
A	To compensate for isotropic directivity and the antenna effect of feed lines
B	To prevent receiver overload which reduces pattern nulls
C	To increase receiver sensitivity
D	To narrow the receiver bandwidth

Figure E5-1

Figure E6-1

Figure E6-2

Figure E7-2

Figure E9-1