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	Ingestion of ozone gas from the cooling system
D	Localized heating of the body from RF exposure in excess of the MPE limits

2. - E1A14

Except in some parts of Alaska, what is the maximum power permitted on the 630 meter band?

Select	Answer
A	5 watts EIRP
B	50 watts PEP
C	100 watts PEP
D	1 watt EIRP

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

4. - E1C14

How long must an operator wait after filing a notification with the Utilities Technology Council (UTC) before operating on the 2200 meter or 630 meter band?

Select	Answer
A	Operators must not operate until approval is received
B	Operators may not operate until a test signal has been transmitted in coordination with the local power company
C	Operators may operate after 30 days, providing they have not been told that their station is within 1 km of PLC systems using those frequencies
D	Operations may commence immediately, and may continue unless interference is reported by the UTC

5. - E1D01

What is the definition of telemetry?

Select	Answer
A	Two-way transmissions in excess of 1000 feet
B	Two-way transmissions of data
C	One-way transmission of measurements at a distance from the measuring instrument
D	One-way transmission that initiates, modifies, or terminates the functions of a device at a distance

6. - E1E07

What should a VE do if a candidate fails to comply with the examiner's instructions during an amateur operator license examination?

Select	Answer
A	Immediately terminate the candidate's examination
B	Warn the candidate that continued failure to comply will result in termination of the examination
C	Allow the candidate to complete the examination, but invalidate the results
D	Immediately terminate everyone's examination and close the session

7. - E1F01

On what frequencies are spread spectrum transmissions permitted?

Select	Answer
A	Only on amateur frequencies above 50 MHz
B	Only on amateur frequencies above 420 MHz
C	Only on amateur frequencies above 222 MHz
D	Only on amateur frequencies above 144 MHz

8. - E2A12

What is the purpose of digital store-and-forward functions on an amateur radio satellite?

Select	Answer
A	To delay download of telemetry between satellites
B	To relay messages between satellites
C	To store digital messages in the satellite for later download by other stations
D	To upload operational software for the transponder

9. - E2B09

What hardware, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM)?

Select	Answer
A	A special notch filter to remove synchronization pulses
B	A special front end limiter
C	No other hardware is needed
D	A special IF converter

10. - E2C02

Which of the following best describes the term self-spotting? in connection with HF contest operating?

Select	Answer
A	The often-prohibited practice of posting one's own call sign and frequency on a spotting network
B	The acceptable practice of manually posting the call signs of stations on a spotting network
C	A manual technique for rapidly zero beating or tuning to a station's frequency before calling that station
D	An automatic method for rapidly zero beating or tuning to a station's frequency before calling that station

11. - E2D09

What type of modulation is used for JT65 contacts?

Select	Answer
A	RTTY
B	Multi-tone AFSK
C	IEEE 802.11
D	PSK

12. - E2E07

Which of the following is a possible reason that attempts to initiate contact with a digital station on a clear frequency are unsuccessful?

Select	Answer
A	The protocol version you are using is not supported by the digital station
B	Your transmit frequency is incorrect
C	All these choices are correct
D	Another station you are unable to hear is using the frequency

13. - E3A07

Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?

Select	Answer
A	Bodies of water
B	Mountain ranges
C	Forests
D	Urban areas

14. - E3B12

What is the primary characteristic of chordal hop propagation?

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

15. - E3C07

Which of the following descriptors indicates the greatest solar flare intensity?

Select	Answer
A	Class M
B	Class A
C	Class X
D	Class B

16. - E4A08

Which of the following measures SWR?

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

17. - E4B07

What do the subscripts of S parameters represent?

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

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

19. - E4D09

What is the purpose of the preselector in a communications receiver?

Select	Answer
A	To allow selection of the optimum RF amplifier device
B	To store often-used frequencies
C	To increase rejection of signals outside the desired band
D	To provide a range of AGC time constants

20. - E4E08

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

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

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	315.6 Hz
B	157.8 Hz
C	47.3 kHz
D	23.67 kHz

22. - E5B09

What is the relationship between the AC current through a capacitor and the voltage across a capacitor?

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

23. - E5C02

How are impedances described in polar coordinates?

Select	Answer
A	By X and R values
B	By real and imaginary parts
C	By Y and G values
D	By phase angle and magnitude

24. - E5D08

How many watts are consumed in a circuit having a power factor of 0.6 if the input is 200VAC at 5 amperes?

Select	Answer
A	1600 watts
B	1000 watts
C	200 watts
D	600 watts

25. - E6A12

Why do many MOSFET devices have internally connected Zener diodes on the gates?

Select	Answer
A	To reduce the chance of static damage to the gate
B	To keep the gate voltage within specifications and prevent the device from overheating
C	To provide a voltage reference for the correct amount of reverse-bias gate voltage
D	To protect the substrate from excessive voltages

26. - E6B06

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

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

27. - E6C05

What is an advantage of CMOS logic devices over TTL devices?

Select	Answer
A	Immune to damage from static discharge
B	Lower power consumption
C	Differential output capability
D	Lower distortion

28. - E6D10

What is a primary advantage of using a toroidal core instead of a solenoidal core in an inductor?

Select	Answer
A	Toroidal cores exhibit greater hysteresis
B	Toroidal cores confine most of the magnetic field within the core material
C	Toroidal cores have lower Q characteristics
D	Toroidal cores make it easier to couple the magnetic energy into other components

29. - E6E01

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

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

30. - E6F08

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

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

31. - E7A09

What logical operation is performed by an exclusive NOR gate?

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

32. - E7B12

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

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

33. - E7C01

How are the capacitors and inductors of a low-pass filter Pi-network arranged between the network's input and output?

Select	Answer
A	An inductor is connected between the input and ground, another inductor is connected between the output and ground, and a capacitor is connected between the input and output
B	Two inductors are in series between the input and output, and a capacitor is connected between the two inductors and ground
C	Two capacitors are in series between the input and output, and an inductor is connected between the two capacitors and ground
D	A capacitor is connected between the input and ground, another capacitor is connected between the output and ground, and an inductor is connected between input and output

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

35. - E7E11

Which type of detector circuit is used for demodulating SSB signals?

Select	Answer
A	Discriminator
B	Phase comparator
C	Product detector
D	Phase detector

36. - E7F01

What is meant by direct digital conversion as applied to software defined radios?

Select	Answer
A	Incoming RF is digitized by an analog-to-digital converter without being mixed with a local oscillator signal
B	A switching mixer is used to generate I and Q signals directly from the RF input
C	Software is converted from source code to object code during operation of the receiver
D	Incoming RF is converted to a control voltage for a voltage controlled oscillator

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	0.07
B	14
C	28
D	7

38. - E7H02

What is a microphonic?

Select	Answer
A	Excess loading of the microphone by an oscillator
B	Changes in oscillator frequency due to mechanical vibration
C	Distortion caused by RF pickup on the microphone cable
D	An IC used for amplifying microphone signals

39. - E8A11

Which of the following is a measure of the quality of an analog-to-digital converter?

Select	Answer
A	Reciprocal mixing
B	Total harmonic distortion
C	Power factor
D	Peak envelope power

40. - E8B11

What is digital time division multiplexing?

Select	Answer
A	Two or more data streams share the same channel by transmitting time of transmission as the sub-carrier
B	Two or more signals are arranged to share discrete time slots of a data transmission
C	Two or more data streams are assigned to discrete sub-carriers on an FM transmitter
D	Two or more signals are quadrature modulated to increase bandwidth efficiency

41. - E8C09

Which digital code allows only one bit to change between sequential code values?

Select	Answer
A	Binary Coded Decimal Code
B	Excess 3 code
C	Gray code
D	Extended Binary Coded Decimal Interchange Code

42. - E8D06

What is the advantage of including parity bits in ASCII characters?

Select	Answer
A	Foreign language characters can be sent
B	Some types of errors can be detected
C	The signal can overpower interfering signals
D	Faster transmission rate

43. - E9A03

What is the radiation resistance of an antenna?

Select	Answer
A	The specific impedance of the antenna
B	The value of a resistance that would dissipate the same amount of power as that radiated from an antenna
C	The combined losses of the antenna elements and feed line
D	The resistance in the atmosphere that an antenna must overcome to be able to radiate a signal

44. - E9B05

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

Select	Answer
A	Elevation
B	Radiation resistance
C	Polarization
D	Azimuth

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

46. - E9D11

Which of the following conductors would be best for minimizing losses in a station's RF ground system?

Select	Answer
A	Resistive wire, such as spark plug wire
B	Solid wire
C	Stranded wire
D	Wide flat copper strap

47. - E9E08

What is a use for a Wilkinson divider?

Select	Answer
A	It is used to divide power equally between two 50-ohm loads while maintaining 50-ohm input impedance
B	It is used to feed high-impedance antennas from a low-impedance source
C	It is used to feed low-impedance loads from a high-impedance source
D	It divides the operating frequency of a transmitter signal so it can be used on a lower frequency band

48. - E9F02

Which of the following has the biggest effect on the velocity factor of a transmission line?

Select	Answer
A	The line length
B	The termination impedance
C	Dielectric materials used in the line
D	The center conductor resistivity

49. - E9G08

What is the process of normalization with regard to a Smith chart?

Select	Answer
A	Reassigning reactance values with regard to the resistance axis
B	Reassigning resistance values with regard to the reactance axis
C	Reassigning impedance values with regard to the prime center
D	Reassigning prime center with regard to the reactance axis

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 provides diversity reception that cancels multipath signals
C	It increases the sensitivity of a DF antenna array
D	It modifies the pattern of a DF antenna array to provide a null in one direction

Figure E7-1

Figure E7-3

Figure E9-2