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	Blood clotting from the intense magnetic field
B	Hearing loss caused by high voltage corona discharge
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. - E1A06

Where must the carrier frequency of a CW signal be set to comply with FCC rules for 60 meter operation?

Select	Answer
A	At the center frequency of the channel
B	At the lowest frequency of the channel
C	On any frequency where the signal's sidebands are within the channel
D	At the highest frequency of the channel

3. - E1B11

What does PRB-1 require of regulations affecting amateur radio?

Select	Answer
A	Amateur radio operations must be permitted in any private residence
B	Use of wireless devices in a vehicle is exempt from regulation
C	No limitations may be placed on antenna size or placement
D	Reasonable accommodations of amateur radio must be made

4. - E1C03

How do the control operator responsibilities of a station under automatic control differ from one under local control?

Select	Answer
A	Under local control there is no control operator
B	Under local control a control operator is not required to be present at a control point
C	Under automatic control there is no control operator
D	Under automatic control the control operator is not required to be present at the control point

5. - E1D01

What is the definition of telemetry?

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

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

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. - E2A08

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

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

9. - E2B05

Which of the following describes the use of vestigial sideband in analog fast-scan TV transmissions?

Select	Answer
A	The vestigial sideband contains chroma information
B	Vestigial sideband provides high frequency emphasis to sharpen the picture
C	The vestigial sideband carries the audio information
D	Vestigial sideband reduces bandwidth while allowing for simple video detector circuitry

10. - E2C07

What is the Cabrillo format?

Select	Answer
A	A standard for submission of electronic contest logs
B	A method of exchanging information during a contest QSO
C	The rules of order for meetings between contest sponsors
D	The most common set of contest rules

11. - E2D09

What type of modulation is used for JT65 contacts?

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

12. - E2E04

What is indicated when one of the ellipses in an FSK crossed-ellipse display suddenly disappears?

Select	Answer
A	The mark and space signal have been inverted
B	One of the signal filters is saturated
C	The receiver has drifted 5 kHz from the desired receive frequency
D	Selective fading has occurred

13. - E3A05

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

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

14. - E3B10

Why is chordal hop propagation desirable?

Select	Answer
A	Signals travel faster along ionospheric chords
B	The MUF for chordal hop propagation is much lower than for normal skip propagation
C	Atmospheric noise is lower in the direction of chordal hop propagation
D	The signal experiences less loss compared to multi-hop using Earth as a reflector

15. - E3C05

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

Select	Answer
A	Westward
B	Eastward
C	Northward
D	Southward

16. - E4A02

Which of the following parameters does a spectrum analyzer display on the vertical and horizontal axes?

Select	Answer
A	SWR and frequency
B	SWR and time
C	RF amplitude and frequency
D	RF amplitude and time

17. - E4B07

What do the subscripts of S parameters represent?

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

18. - E4C04

What is the noise figure of a receiver?

Select	Answer
A	The ratio of the noise bandwidth in hertz to the theoretical bandwidth of a resistive network
B	The ratio of atmospheric noise to phase noise
C	The ratio of thermal noise to atmospheric noise
D	The ratio in dB of the noise generated by the receiver to the theoretical minimum noise

19. - E4D05

What transmitter frequencies would cause an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz?

Select	Answer
A	146.10 MHz and 147.30 MHz
B	173.35 MHz and 139.40 MHz
C	146.34 MHz and 146.61 MHz
D	146.88 MHz and 146.34 MHz

20. - E4E07

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

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

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	157.8 Hz
B	47.3 kHz
C	315.6 Hz
D	23.67 kHz

22. - E5B12

What is admittance?

Select	Answer
A	The turns ratio of a transformer
B	The inverse of Q factor
C	The inverse of impedance
D	The term for the gain of a field effect transistor

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. - E5D14

What is reactive power?

Select	Answer
A	Wattless, nonproductive power
B	Power lost because of capacitor leakage
C	Power consumed in circuit Q
D	Power consumed in wire resistance in an inductor

25. - E6A12

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

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

26. - E6B10

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

Select	Answer
A	5
B	1
C	7
D	6

27. - E6C07

What best describes a pull-up or pull-down resistor?

Select	Answer
A	A resistor that ensures that an oscillator frequency does not drift
B	A resistor connected to an op-amp output that prevents signals from exceeding the power supply voltage
C	A resistor in a keying circuit used to reduce key clicks
D	A resistor connected to the positive or negative supply line used to establish a voltage when an input or output is an open circuit

28. - E6D13

What is the primary cause of inductor self-resonance?

Select	Answer
A	Non-linear core hysteresis
B	Inductive kickback
C	The skin effect
D	Inter-turn capacitance

29. - E6E07

What type of transmission line is used for connections to MMICs?

Select	Answer
A	Parallel wire
B	Microstrip
C	Miniature coax
D	Circular waveguide

30. - E6F02

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

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

31. - E7A03

Which of the following can divide the frequency of a pulse train by 2?

Select	Answer
A	An XOR gate
B	A multiplexer
C	A flip-flop
D	An OR gate

32. - E7B10

In Figure E7-1, what is the purpose of R1 and R2?

Select	Answer
A	Self bias
B	Voltage divider bias
C	Feedback
D	Load resistors

33. - E7C04

How does an impedance-matching circuit transform a complex impedance to a resistive impedance?

Select	Answer
A	It introduces negative resistance to cancel the resistive part of impedance
B	Reactive currents are dissipated in matched resistances
C	It introduces transconductance to cancel the reactive part of impedance
D	It cancels the reactive part of the impedance and changes the resistive part to a desired value

34. - E7D08

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

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

35. - E7E02

What is the function of a reactance modulator?

Select	Answer
A	To produce PM signals by using an electrically variable resistance
B	To produce AM signals by using an electrically variable resistance
C	To produce PM or FM signals by using an electrically variable inductance or capacitance
D	To produce AM signals by using an electrically variable inductance or capacitance

36. - E7F09

Why is an anti-aliasing digital filter required in a digital decimator?

Select	Answer
A	It peaks the response of the decimator, improving bandwidth
B	It removes low-frequency signal components to eliminate the need for DC restoration
C	It notches out the sampling frequency to avoid sampling errors
D	It removes high-frequency signal components that would otherwise be reproduced as lower frequency components

37. - E7G10

What absolute voltage gain can be expected from the circuit in Figure E7-3 when R1 is 1800 ohms and RF is 68 kilohms?

Select	Answer
A	38
B	1
C	0.03
D	76

38. - E7H11

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

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

39. - E8A09

How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?

Select	Answer
A	8
B	256 divided by the gain of the input amplifier
C	256
D	8 multiplied by the gain of the input amplifier

40. - E8B05

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus-or-minus 5 kHz when the maximum modulation frequency is 3 kHz?

Select	Answer
A	60
B	0.6
C	0.167
D	1.67

41. - E8C03

Why should phase-shifting of a PSK signal be done at the zero crossing of the RF signal?

Select	Answer
A	All these choices are correct
B	To minimize bandwidth
C	To simplify modulation
D	To improve carrier suppression

42. - E8D10

What are some of the differences between the Baudot digital code and ASCII?

Select	Answer
A	Baudot uses 5 data bits per character, ASCII uses 7 or 8; Baudot uses 2 characters as letters/figures shift codes, ASCII has no letters/figures shift code
B	Baudot uses 4 data bits per character, ASCII uses 7 or 8; Baudot uses 1 character as a letters/figures shift code, ASCII has no letters/figures code
C	Baudot uses 6 data bits per character, ASCII uses 7 or 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes
D	Baudot uses 7 data bits per character, ASCII uses 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes

43. - E9A05

What is included in the total resistance of an antenna system?

Select	Answer
A	Transmission-line resistance plus radiation resistance
B	Radiation resistance plus space impedance
C	Radiation resistance plus transmission resistance
D	Radiation resistance plus loss resistance

44. - E9B10

What is the principle of a Method of Moments analysis?

Select	Answer
A	A wire is modeled as a series of segments, each having a uniform value of current
B	A wire is modeled as a series of segments, each having a distinct value of voltage across it
C	A wire is modeled as a single sine-wave voltage source
D	A wire is modeled as a single sine-wave current generator

45. - E9C08

What is a folded dipole antenna?

Select	Answer
A	A dipole one-quarter wavelength long
B	A dipole configured to provide forward gain
C	A half-wave dipole with an additional parallel wire connecting its two ends
D	A type of ground-plane antenna

46. - E9D01

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

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

47. - E9E05

How must an antenna's driven element be tuned to use a hairpin matching system?

Select	Answer
A	The driven element reactance must be capacitive
B	The driven element reactance must be inductive
C	The driven element radiation resistance must be higher than the characteristic impedance of the transmission line
D	The driven element resonance must be lower than the operating frequency

48. - E9F13

What impedance does a 1/4-wavelength transmission line present to a generator when the line is shorted at the far end?

Select	Answer
A	Very low impedance
B	Very high impedance
C	The same as the generator output impedance
D	The same as the characteristic impedance of the transmission line

49. - E9G04

What are the two families of circles and arcs that make up a Smith chart?

Select	Answer
A	Resistance and reactance
B	Resistance and voltage
C	Voltage and impedance
D	Reactance and voltage

50. - E9H06

What is the triangulation method of direction finding?

Select	Answer
A	A fixed receiving station plots three headings to the signal source
B	The geometric angles of sky waves from the source are used to determine its position
C	Antenna headings from several different receiving locations are used to locate the signal source
D	A fixed receiving station uses three different antennas to plot the location of the signal source

Figure E5-1

Figure E6-2

Figure E7-1

Figure E7-2

Figure E7-3