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

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1. - E0A03

Over what range of frequencies are the FCC human body RF exposure limits most restrictive?

Select	Answer
A	30 to 300 MHz
B	300 to 3000 MHz
C	3 to 30 MHz
D	300 kHz to 3 MHz

2. - E1A12

What special operating frequency restrictions are imposed on slow scan TV transmissions?

Select	Answer
A	They are restricted to phone band segments
B	They are restricted to 7.245 MHz, 14.245 MHz, 21.345 MHz, and 28.945 MHz
C	They are not permitted above 54 MHz
D	None; they are allowed on all amateur frequencies

3. - E1B03

Within what distance must an amateur station protect an FCC monitoring facility from harmful interference?

Select	Answer
A	3 miles
B	30 miles
C	1 mile
D	10 miles

4. - E1C06

Which of the following is required in order to operate in accordance with CEPT rules in foreign countries where permitted?

Select	Answer
A	You must append "/CEPT" to your call sign
B	You must identify in the official language of the country in which you are operating
C	You must bring a copy of FCC Public Notice DA 16-1048
D	The U.S. embassy must approve of your operation

5. - E1D12

Which of the following amateur stations may transmit one-way communications?

Select	Answer
A	All these choices are correct
B	A message forwarding station or automatically controlled digital station
C	A local repeater or linked repeater station
D	A space station, beacon station, or telecommand station

6. - E1E12

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

Select	Answer
A	Return the application document to the examinee
B	Send the application form to the FCC and inform the FCC of the grade
C	Destroy the application form
D	Maintain the application form with the VEC's records

7. - E1F09

Which of the following conditions apply when transmitting spread spectrum emissions?

Select	Answer
A	The transmitting station must be in an area regulated by the FCC or in a country that permits SS emissions
B	A station transmitting SS emission must not cause harmful interference to other stations employing other authorized emissions
C	The transmission must not be used to obscure the meaning of any communication
D	All these choices are correct

8. - E2A13

Which of the following techniques is normally used by low Earth orbiting digital satellites to relay messages around the world?

Select	Answer
A	Digipeating
B	Multi-satellite relaying
C	Node hopping
D	Store-and-forward

9. - E2B01

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

Select	Answer
A	60
B	90
C	120
D	30

10. - E2C05

What is the function of a DX QSL Manager?

Select	Answer
A	To run a net to allow many stations to contact a rare DX station
B	To relay calls to and from a DX station
C	To handle the receiving and sending of confirmation cards for a DX station
D	To allocate frequencies for DXpeditions

11. - E2D01

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

Select	Answer
A	Hellschreiber
B	WSPR
C	APRS
D	MSK144

12. - E2E01

Which of the following types of modulation is common for data emissions below 30 MHz?

Select	Answer
A	Spread spectrum
B	DTMF tones modulating an FM signal
C	FSK
D	Pulse modulation

13. - E3A11

What is a typical range for tropospheric propagation of microwave signals?

Select	Answer
A	2500 miles
B	10 miles to 50 miles
C	1200 miles
D	100 miles to 300 miles

14. - E3B12

What is the primary characteristic of chordal hop propagation?

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

15. - E3C06

By how much does the VHF/UHF radio horizon distance exceed the geometric horizon?

Select	Answer
A	By approximately 50 percent of the distance
B	By approximately twice the distance
C	By approximately four times the distance
D	By approximately 15 percent of the distance

16. - E4A04

How is the compensation of an oscilloscope probe typically adjusted?

Select	Answer
A	A square wave is displayed and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible
B	A high frequency sine wave is displayed and the probe is adjusted for maximum amplitude
C	A frequency standard is displayed and the probe is adjusted until the deflection time is accurate
D	A DC voltage standard is displayed and the probe is adjusted until the displayed voltage is accurate

17. - E4B02

What is the significance of voltmeter sensitivity expressed in ohms per volt?

Select	Answer
A	The full scale reading of the voltmeter multiplied by its ohms per volt rating will indicate the input impedance of the voltmeter
B	When used as an ammeter, the full scale reading in amps divided by ohms per volt rating will determine the size of shunt needed
C	When used as an ohmmeter, the reading in ohms divided by the ohms per volt rating will determine the voltage applied to the circuit
D	When used as a galvanometer, the reading in volts multiplied by the ohms per volt rating will determine the power drawn by the device under test

18. - E4C13

How does a narrow-band roofing filter affect receiver performance?

Select	Answer
A	All these choices are correct
B	It improves dynamic range by attenuating strong signals near the receive frequency
C	It improves intelligibility by using low Q circuitry to reduce ringing
D	It improves sensitivity by reducing front end noise

19. - E4D12

What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?

Select	Answer
A	Desensitization
B	Squelch gain rollback
C	Quieting
D	Cross-modulation interference

20. - E4E05

How can radio frequency interference from an AC motor be suppressed?

Select	Answer
A	By using a ground-fault current interrupter in the circuit used to power the motor
B	By installing a brute-force AC-line filter in series with the motor leads
C	By installing a high-pass filter in series with the motor's power leads
D	By installing a bypass capacitor in series with the motor leads

21. - E5A15

Which of the following increases Q for inductors and capacitors?

Select	Answer
A	Lower reactance
B	Lower self-resonant frequency
C	Lower losses
D	Higher self-resonant frequency

22. - E5B03

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

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

23. - E5C04

What coordinate system is often used to display the resistive, inductive, and/or capacitive reactance components of impedance?

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

24. - E5D02

Why is it important to keep lead lengths short for components used in circuits for VHF and above?

Select	Answer
A	To avoid unwanted inductive reactance
B	All these choices are correct
C	To maintain component lifetime
D	To increase the thermal time constant

25. - E6A03

Why does a PN-junction diode not conduct current when reverse biased?

Select	Answer
A	Holes in P-type material and electrons in the N-type material are separated by the applied voltage, widening the depletion region
B	Excess holes in P-type material combine with the electrons in N-type material, converting the entire diode into an insulator
C	Only N-type semiconductor material can conduct current
D	Only P-type semiconductor material can conduct current

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 rectifier in high current power supplies
D	As a variable capacitance in an automatic frequency control circuit

27. - E6C02

What happens when the level of a comparator's input signal crosses the threshold?

Select	Answer
A	The IC input can be damaged
B	The comparator enters latch-up
C	The comparator changes its output state
D	The feedback loop becomes unstable

28. - E6D08

What is one reason for using powdered-iron cores rather than ferrite cores in an inductor?

Select	Answer
A	Powdered-iron cores use smaller diameter wire for the same inductance
B	Powdered-iron cores generally require fewer turns to produce a given inductance
C	Powdered-iron cores generally have greater initial permeability
D	Powdered-iron cores generally maintain their characteristics at higher currents

29. - E6E05

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

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

30. - E6F02

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

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

31. - E7A10

What is a truth table?

Select	Answer
A	A table of logic symbols that indicate the logic states of an op-amp
B	A diagram showing logic states when the digital device output is true
C	A table of logic symbols that indicate the high logic states of an op-amp
D	A list of inputs and corresponding outputs for a digital device

32. - E7B03

Which of the following components form the output of a class D amplifier circuit?

Select	Answer
A	A temperature compensating load resistor to improve linearity
B	A matched load resistor to prevent damage by switching transients
C	A low-pass filter to remove switching signal components
D	A high-pass filter to compensate for low gain at low frequencies

33. - E7C05

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

Select	Answer
A	A Chebyshev filter
B	A Butterworth filter
C	A passive op-amp filter
D	An active LC filter

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

35. - E7E01

Which of the following can be used to generate FM phone emissions?

Select	Answer
A	A reactance modulator on the oscillator
B	A balanced modulator on the oscillator
C	A reactance modulator on the final amplifier
D	A balanced modulator on the audio amplifier

36. - E7F07

What function is performed by a Fast Fourier Transform?

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

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. - E7H11

What are the major spectral impurity components of direct digital synthesizers?

Select	Answer
A	Spurious signals at discrete frequencies
B	Digital conversion noise
C	Nyquist limit noise
D	Broadband noise

39. - E8A02

Which of the following is a type of analog-to-digital conversion?

Select	Answer
A	Phase reversal
B	Harmonic regeneration
C	Level shifting
D	Successive approximation

40. - E8B01

What is the modulation index of an FM signal?

Select	Answer
A	The bandwidth of the transmitted signal divided by the modulating signal frequency
B	The type of modulation used by the transmitter
C	The ratio of frequency deviation to modulating signal frequency
D	The ratio of modulating signal amplitude to frequency deviation

41. - E8C08

How does ARQ accomplish error correction?

Select	Answer
A	Special polynomial codes provide automatic correction
B	Special binary codes provide automatic correction
C	If errors are detected, a retransmission is requested
D	If errors are detected, redundant data is substituted

42. - E8D01

Why are received spread spectrum signals resistant to interference?

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

43. - E9A01

What is an isotropic antenna?

Select	Answer
A	A theoretical, omnidirectional antenna used as a reference for antenna gain
B	A spacecraft antenna used to direct signals toward Earth
C	A horizontally polarized antenna used to compare Yagi antennas
D	A grounded antenna used to measure Earth conductivity

44. - E9B04

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

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

45. - E9C13

How does the radiation pattern of a horizontally polarized 3-element beam antenna vary with increasing height above ground?

Select	Answer
A	The takeoff angle of the lowest elevation lobe increases
B	The takeoff angle of the lowest elevation lobe decreases
C	The horizontal beamwidth decreases
D	The horizontal beamwidth increases

46. - E9D08

What happens as the Q of an antenna increases?

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

47. - E9E06

Which of these feed line impedances would be suitable for constructing a quarter-wave Q-section for matching a 100-ohm loop to 50-ohm feed line?

Select	Answer
A	450 ohms
B	75 ohms
C	50 ohms
D	62 ohms

48. - E9F07

How does ladder line compare to small-diameter coaxial cable such as RG-58 at 50 MHz?

Select	Answer
A	Smaller reflection coefficient
B	Lower loss
C	Lower velocity factor
D	Higher SWR

49. - E9G10

What do the arcs on a Smith chart represent?

Select	Answer
A	Points with constant reactance
B	Points with constant resistance
C	SWR
D	Frequency

50. - E9H03

What is Receiving Directivity Factor (RDF)?

Select	Answer
A	Relative directivity compared to isotropic
B	Forward gain compared to average gain over the entire hemisphere
C	Relative directivity compared to a dipole
D	Forward gain compared to the gain in the reverse direction