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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?

SelectAnswer
ALocalized heating of the body from RF exposure in excess of the MPE limits
BBlood clotting from the intense magnetic field
CIngestion of ozone gas from the cooling system
DHearing loss caused by high voltage corona discharge

2. - E1A02

When using a transceiver that displays the carrier frequency of phone signals, which of the following displayed frequencies represents the lowest frequency at which a properly adjusted LSB emission will be totally within the band?

SelectAnswer
A300 Hz above the lower band edge
B3 kHz above the lower band edge
C1 kHz above the lower band edge
DThe exact lower band edge

3. - E1B05

What is the National Radio Quiet Zone?

SelectAnswer
AAn area surrounding the National Radio Astronomy Observatory
BAn area in New Mexico surrounding the White Sands Test Area
CAn area in Florida surrounding Cape Canaveral
DAn area in Puerto Rico surrounding the Arecibo Radio Telescope

4. - E1C05

When may an automatically controlled station originate third party communications?

SelectAnswer
AWhen approved by the National Telecommunication and Information Administration
BWhen agreed upon by the sending or receiving station
CNever
DOnly when transmitting RTTY or data emissions

5. - E1D02

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

SelectAnswer
AAuxiliary relay links carrying repeater audio
BBinary control characters
CTelecommand signals from a space telecommand station
DData containing personal information

6. - E1E12

What must the VE team do with the application form if the examinee does not pass the exam?

SelectAnswer
AMaintain the application form with the VEC's records
BReturn the application document to the examinee
CSend the application form to the FCC and inform the FCC of the grade
DDestroy the application form

7. - E1F10

Who may be the control operator of an auxiliary station?

SelectAnswer
AOnly Technician, General, Advanced or Amateur Extra Class operators
BAny licensed amateur operator
COnly General, Advanced or Amateur Extra Class operators
DOnly Amateur Extra Class operators

8. - E2A05

What do the letters in a satellite's mode designator specify?

SelectAnswer
AThe polarization of uplink and downlink signals
BThe location of the ground control station
CThe uplink and downlink frequency ranges
DPower limits for uplink and downlink transmissions

9. - E2B12

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

SelectAnswer
AElapsed time
BSpecific tone amplitudes
CA two-tone signal
DSpecific tone frequencies

10. - E2C12

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

SelectAnswer
AForward error correction and Viterbi codes
BCustom code plugs for the local trunking systems
CActing as store-and-forward digipeaters
DDiscovery and link establishment protocols

11. - E2D05

What is one advantage of the JT65 mode?

SelectAnswer
APermits fast-scan TV transmissions over narrow bandwidth
BThe ability to decode signals which have a very low signal-to-noise ratio
CEasily copied by ear if necessary
DUses only a 65 Hz bandwidth

12. - E2E12

How do ALE stations establish contact?

SelectAnswer
AALE radios monitor an internet site for the frequency they are being paged on
BALE constantly scans a list of frequencies, activating the radio when the designated call sign is received
CALE radios send a constant tone code to establish a frequency for future use
DALE radios activate when they hear their signal echoed by back scatter

13. - E3A02

What characterizes libration fading of an EME signal?

SelectAnswer
AA slow change in the pitch of the CW signal
BA gradual loss of signal as the sun rises
CA fluttery irregular fading
DThe returning echo is several hertz lower in frequency than the transmitted signal

14. - E3B03

What is the best time of day for transequatorial propagation?

SelectAnswer
AAfternoon or early evening
BMorning
CLate at night
DNoon

15. - E3C05

What orientation of Bz (B sub z) increases the likelihood that incoming particles from the sun will cause disturbed conditions?

SelectAnswer
AWestward
BSouthward
CEastward
DNorthward

16. - E4A07

Which of the following is an advantage of using an antenna analyzer compared to an SWR bridge to measure antenna SWR?

SelectAnswer
AAll these choices are correct
BAntenna analyzers automatically tune your antenna for resonance
CAntenna analyzers display a time-varying representation of the modulation envelope
DAntenna analyzers do not need an external RF source

17. - E4B05

What three test loads are used to calibrate an RF vector network analyzer?

SelectAnswer
A50 ohms, 75 ohms, and 90 ohms
BShort circuit, open circuit, and resonant circuit
CShort circuit, open circuit, and 50 ohms
D50 ohms through 1/8 wavelength, 1/4 wavelength, and 1/2 wavelength of coaxial cable

18. - E4C04

What is the noise figure of a receiver?

SelectAnswer
AThe ratio of thermal noise to atmospheric noise
BThe ratio of atmospheric noise to phase noise
CThe ratio in dB of the noise generated by the receiver to the theoretical minimum noise
DThe ratio of the noise bandwidth in hertz to the theoretical bandwidth of a resistive network

19. - E4D09

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

SelectAnswer
ATo increase rejection of signals outside the desired band
BTo allow selection of the optimum RF amplifier device
CTo provide a range of AGC time constants
DTo store often-used frequencies

20. - E4E02

Which of the following types of noise can often be reduced with a digital signal processing noise filter?

SelectAnswer
ABroadband white noise
BPower line noise
CAll these choices are correct
DIgnition noise

21. - E5A01

What can cause the voltage across reactances in a series RLC circuit to be higher than the voltage applied to the entire circuit?

SelectAnswer
AConductance
BResistance
CResonance
DCapacitance

22. - E5B11

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 25 ohms, R is 100 ohms, and XL is 50 ohms?

SelectAnswer
A14 degrees with the voltage leading the current
B14 degrees with the voltage lagging the current
C76 degrees with the voltage lagging the current
D76 degrees with the voltage leading the current

23. - E5C11

Which point in Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and an 18-microhenry inductor at 3.505 MHz?

SelectAnswer
APoint 3
BPoint 7
CPoint 1
DPoint 8

24. - E5D01

What is the result of skin effect?

SelectAnswer
AAs frequency decreases, RF current flows in a thinner layer of the conductor, closer to the surface
BAs frequency increases, RF current flows in a thinner layer of the conductor, closer to the surface
CThermal effects on the surface of the conductor increase the impedance
DThermal effects on the surface of the conductor decrease the impedance

25. - E6A06

What is the beta of a bipolar junction transistor?

SelectAnswer
AThe breakdown voltage of the base to collector junction
BThe switching speed
CThe change in collector current with respect to base current
DThe frequency at which the current gain is reduced to 0.707

26. - E6B04

What type of semiconductor device is designed for use as a voltage-controlled capacitor?

SelectAnswer
ASilicon-controlled rectifier
BZener diode
CVaractor diode
DTunnel diode

27. - E6C03

What is tri-state logic?

SelectAnswer
ALogic devices that utilize ternary math
BLogic devices with 0, 1, and high-impedance output states
CLow-power logic devices designed to operate at 3 volts
DProprietary logic devices manufactured by Tri-State Devices

28. - E6D06

What core material property determines the inductance of an inductor?

SelectAnswer
APermeability
BResistance
CThermal impedance
DReactivity

29. - E6E11

What is a characteristic of DIP packaging used for integrated circuits?

SelectAnswer
ALow leakage doubly insulated package
BA total of two rows of connecting pins placed on opposite sides of the package (Dual In-line Package)
CTwo chips in each package (Dual In Package)
DPackage mounts in a direct inverted position

30. - E6F08

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

SelectAnswer
AOptoisolators provide a very high degree of electrical isolation between a control circuit and the circuit being switched
BOptoisolators provide a low impedance link between a control circuit and a power circuit
COptoisolators provide impedance matching between the control circuit and power circuit
DOptoisolators eliminate the effects of reflected light in the control circuit

31. - E7A09

What logical operation is performed by an exclusive NOR gate?

SelectAnswer
AIt produces logic 0 at its output if only one input is logic 1
BIt produces logic 0 at its output only if all inputs are logic 0
CIt produces logic 1 at its output only if all inputs are logic 1
DIt produces logic 1 at its output if only one input is logic 1

32. - E7B15

What is one way to prevent thermal runaway in a bipolar transistor amplifier?

SelectAnswer
ANeutralization
BSelect transistors with high beta
CUse a resistor in series with the emitter
DAll these choices are correct

33. - E7C05

Which filter type is described as having ripple in the passband and a sharp cutoff?

SelectAnswer
AA passive op-amp filter
BAn active LC filter
CA Butterworth filter
DA Chebyshev filter

34. - E7D01

How does a linear electronic voltage regulator work?

SelectAnswer
AIt has a ramp voltage as its output
BThe control element duty cycle is proportional to the line or load conditions
CIt eliminates the need for a pass transistor
DThe conduction of a control element is varied to maintain a constant output voltage

35. - E7E04

What is one way a single-sideband phone signal can be generated?

SelectAnswer
ABy driving a product detector with a DSB signal
BBy using a reactance modulator followed by a mixer
CBy using a balanced modulator followed by a filter
DBy using a loop modulator followed by a mixer

36. - E7F04

What is a common method of generating an SSB signal using digital signal processing?

SelectAnswer
AVarying quartz crystal characteristics emulated in digital form
BSignals are combined in quadrature phase relationship
CA frequency synthesizer removes the unwanted sidebands
DMixing products are converted to voltages and subtracted by adder circuits

37. - E7G02

What is ringing in a filter?

SelectAnswer
APartial cancellation of the signal over a range of frequencies
BUndesired oscillations added to the desired signal
CA reduction in high frequency response
DAn echo caused by a long time delay

38. - E7H06

Which of the following oscillator circuits are commonly used in VFOs?

SelectAnswer
AColpitts and Hartley
BPierce and Zener
CArmstrong and deForest
DNegative feedback and balanced feedback

39. - E8A08

Why would a direct or flash conversion analog-to-digital converter be useful for a software defined radio?

SelectAnswer
AVery high speed allows digitizing high frequencies
BVery low power consumption decreases frequency drift
CImmunity to out-of-sequence coding reduces spurious responses
DAll these choices are correct

40. - E8B08

What describes Orthogonal Frequency Division Multiplexing?

SelectAnswer
AA bandwidth compression technique using Fourier transforms
BA digital mode for narrow-band, slow-speed transmissions
CA frequency modulation technique that uses non-harmonically related frequencies
DA digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference

41. - E8C10

How may data rate be increased without increasing bandwidth?

SelectAnswer
AIt is impossible
BIncreasing analog-to-digital conversion resolution
CUsing a more efficient digital code
DUsing forward error correction

42. - E8D11

What is one advantage of using ASCII code for data communications?

SelectAnswer
AIt is possible to transmit both upper and lower case text
BIt uses one character as a shift code to send numeric and special characters
CIt contains fewer information bits per character than any other code
DIt includes built-in error correction features

43. - E9A03

What is the radiation resistance of an antenna?

SelectAnswer
AThe value of a resistance that would dissipate the same amount of power as that radiated from an antenna
BThe resistance in the atmosphere that an antenna must overcome to be able to radiate a signal
CThe specific impedance of the antenna
DThe combined losses of the antenna elements and feed line

44. - E9B01

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

SelectAnswer
A25 degrees
B75 degrees
C50 degrees
D30 degrees

45. - E9C06

What is the effect of adding a terminating resistor to a rhombic antenna?

SelectAnswer
AIt decreases the ground loss
BIt changes the radiation pattern from bidirectional to unidirectional
CIt reflects the standing waves on the antenna elements back to the transmitter
DIt changes the radiation pattern from horizontal to vertical polarization

46. - E9D02

How can linearly polarized Yagi antennas be used to produce circular polarization?

SelectAnswer
AStack two Yagis fed 90 degrees out of phase to form an array with the respective elements in parallel planes
BStack two Yagis fed in phase to form an array with the respective elements in parallel planes
CArrange two Yagis collinear to each other with the driven elements fed 180 degrees out of phase
DArrange two Yagis perpendicular to each other with the driven elements at the same point on the boom fed 90 degrees out of phase

47. - E9E07

What parameter describes the interactions at the load end of a mismatched transmission line?

SelectAnswer
ACharacteristic impedance
BDielectric constant
CReflection coefficient
DVelocity factor

48. - E9F01

What is the velocity factor of a transmission line?

SelectAnswer
AThe velocity of the wave in the transmission line multiplied by the velocity of light in a vacuum
BThe ratio of the characteristic impedance of the line to the terminating impedance
CThe velocity of the wave in the transmission line divided by the velocity of light in a vacuum
DThe index of shielding for coaxial cable

49. - E9G02

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

SelectAnswer
AResistance lines and reactance chords
BResistance circles and reactance arcs
CVoltage lines and current chords
DVoltage circles and current arcs

50. - E9H05

What is the main drawback of a small wire-loop antenna for direction finding?

SelectAnswer
AIt has no clearly defined null
BAll these choices are correct
CIt is practical for use only on VHF and higher bands
DIt has a bidirectional pattern

Figure E5-1

Figure E9-1