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

Logging in (or registering) will help the system to select questions that you need to focus on.

1. - E0A11

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

Select	Answer
A	Localized heating of the body from RF exposure in excess of the MPE limits
B	Ingestion of ozone gas from the cooling system
C	Blood clotting from the intense magnetic field
D	Hearing 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?

Select	Answer
A	300 Hz above the lower band edge
B	The exact lower band edge
C	3 kHz above the lower band edge
D	1 kHz above the lower band edge

3. - E1B08

What limitations may the FCC place on an amateur station if its signal causes interference to domestic broadcast reception, assuming that the receivers involved are of good engineering design?

Select	Answer
A	The amateur station must avoid transmitting during certain hours on frequencies that cause the interference
B	The amateur station must cease operation on all frequencies below 30 MHz
C	The amateur station must cease operation on all frequencies above 30 MHz
D	The amateur station must cease operation

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

5. - E1D04

Which of the following is required in the identification transmissions from a balloon-borne telemetry station?

Select	Answer
A	The station's six-character Maidenhead grid locator
B	Call sign
C	All these choices are correct
D	The output power of the balloon transmitter

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

7. - E1F04

Which of the following geographic descriptions approximately describes "Line A"?

Select	Answer
A	A line roughly parallel to and east of the U.S. Pacific coastline
B	A line roughly parallel to and north of the border between the U.S. and Mexico
C	A line roughly parallel to and south of the border between the U.S. and Canada
D	A line roughly parallel to and west of the U.S. Atlantic coastline

8. - E2A05

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

Select	Answer
A	The polarization of uplink and downlink signals
B	The uplink and downlink frequency ranges
C	The location of the ground control station
D	Power limits for uplink and downlink transmissions

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. - E2C12

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

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

11. - E2D01

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

Select	Answer
A	WSPR
B	MSK144
C	Hellschreiber
D	APRS

12. - E2E10

Which of these digital modes has the narrowest bandwidth?

Select	Answer
A	170 Hz shift, 45-baud RTTY
B	MFSK16
C	300-baud packet
D	PSK31

13. - E3A08

When a meteor strikes the Earth's atmosphere, a cylindrical region of free electrons is formed at what layer of the ionosphere?

Select	Answer
A	The F2 layer
B	The F1 layer
C	The E layer
D	The D layer

14. - E3B07

What happens to linearly polarized radio waves that split into ordinary and extraordinary waves in the ionosphere?

Select	Answer
A	They become phase locked
B	They become depolarized
C	They become elliptically polarized
D	They are bent toward the magnetic poles

15. - E3C07

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

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

16. - E4A04

How is the compensation of an oscilloscope probe typically adjusted?

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

17. - E4B07

What do the subscripts of S parameters represent?

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

18. - E4C05

What does a receiver noise floor of -174 dBm represent?

Select	Answer
A	The noise figure of a 1 Hz bandwidth receiver
B	The theoretical noise in a 1 Hz bandwidth at the input of a perfect receiver at room temperature
C	The minimum detectable signal as a function of receive frequency
D	The galactic noise contribution to minimum detectable signal

19. - E4D09

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

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

20. - E4E03

Which of the following signals might a receiver noise blanker be able to remove from desired signals?

Select	Answer
A	Signals that are constant at all IF levels
B	Signals that have a sharply peaked frequency distribution
C	Signals that appear across a wide bandwidth
D	Signals that appear at one IF but not another

21. - E5A13

What is an effect of increasing Q in a series resonant circuit?

Select	Answer
A	Fewer components are needed for the same performance
B	Phase shift can become uncontrolled
C	Internal voltages increase
D	Parasitic effects are minimized

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?

Select	Answer
A	76 degrees with the voltage lagging the current
B	76 degrees with the voltage leading the current
C	14 degrees with the voltage lagging the current
D	14 degrees with the voltage leading the current

23. - E5C01

Which of the following represents capacitive reactance in rectangular notation?

Select	Answer
A	-jX
B	+jX
C	Omega
D	Delta

24. - E5D02

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

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

25. - E6A09

What is a depletion-mode FET?

Select	Answer
A	An FET that has no current flow between source and drain when no gate voltage is applied
B	Any FET without a channel
C	Any FET for which holes are the majority carriers
D	An FET that exhibits a current flow between source and drain when no gate voltage is applied

26. - E6B05

What characteristic of a PIN diode makes it useful as an RF switch?

Select	Answer
A	Low junction capacitance
B	Reverse bias controls its forward voltage drop
C	Ability to dissipate large amounts of power
D	Extremely high reverse breakdown voltage

27. - E6C07

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

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

28. - E6D13

What is the primary cause of inductor self-resonance?

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

29. - E6E06

What characteristics of the MMIC make it a popular choice for VHF through microwave circuits?

Select	Answer
A	The ability to retrieve information from a single signal even in the presence of other strong signals
B	Controlled gain, low noise figure, and constant input and output impedance over the specified frequency range
C	Nearly infinite gain, very high input impedance, and very low output impedance
D	Plate current that is controlled by a control grid

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

31. - E7A04

How many flip-flops are required to divide a signal frequency by 4?

Select	Answer
A	4
B	8
C	2
D	1

32. - E7B14

Why are switching amplifiers more efficient than linear amplifiers?

Select	Answer
A	The power transistor is at saturation or cutoff most of the time
B	Linear amplifiers have high gain resulting in higher harmonic content
C	Switching amplifiers use push-pull circuits
D	Switching amplifiers operate at higher voltages

33. - E7C03

What advantage does a series-L Pi-L-network have over a series-L Pi-network for impedance matching between the final amplifier of a vacuum-tube transmitter and an antenna?

Select	Answer
A	Greater harmonic suppression
B	Higher efficiency
C	Does not require a capacitor
D	Greater transformation range

34. - E7D06

What is the purpose of Q1 in the circuit shown in Figure E7-2?

Select	Answer
A	It provides a constant load for the voltage source
B	It controls the current supplied to the load
C	It provides D1 with current
D	It provides negative feedback to improve regulation

35. - E7E02

What is the function of a reactance modulator?

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

36. - E7F01

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

Select	Answer
A	A switching mixer is used to generate I and Q signals directly from the RF input
B	Software is converted from source code to object code during operation of the receiver
C	Incoming RF is digitized by an analog-to-digital converter without being mixed with a local oscillator signal
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	28
C	14
D	7

38. - E7H04

How is positive feedback supplied in a Colpitts oscillator?

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

39. - E8A09

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

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

40. - E8B08

What describes Orthogonal Frequency Division Multiplexing?

Select	Answer
A	A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference
B	A bandwidth compression technique using Fourier transforms
C	A digital mode for narrow-band, slow-speed transmissions
D	A frequency modulation technique that uses non-harmonically related frequencies

41. - E8C04

What technique minimizes the bandwidth of a PSK31 signal?

Select	Answer
A	Zero-sum character encoding
B	Use of trapezoidal data pulses
C	Reed-Solomon character encoding
D	Use of sinusoidal data pulses

42. - E8D08

What parameter evaluates distortion of an AFSK signal caused by excessive input audio levels?

Select	Answer
A	Intermodulation Distortion (IMD)
B	Baud rate
C	Repeat Request Rate (RRR)
D	Signal-to-noise ratio

43. - E9A01

What is an isotropic antenna?

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

44. - E9B04

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

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

45. - E9C09

Which of the following describes a G5RV antenna?

Select	Answer
A	A phased array antenna consisting of multiple loops
B	A multi-band trap antenna
C	A multi-band dipole antenna fed with coax and a balun through a selected length of open wire transmission line
D	A wide band dipole using shorted coaxial cable for the radiating elements and fed with a�4:1 balun

46. - E9D02

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

Select	Answer
A	Stack two Yagis fed in phase to form an array with the respective elements in parallel planes
B	Stack two Yagis fed 90 degrees out of phase to form an array with the respective elements in parallel planes
C	Arrange two Yagis perpendicular to each other with the driven elements at the same point on the boom fed 90 degrees out of phase
D	Arrange two Yagis collinear to each other with the driven elements fed 180 degrees out of phase

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	62 ohms
B	50 ohms
C	450 ohms
D	75 ohms

48. - E9F10

What impedance does a 1/8-wavelength transmission line present to a generator when the line is shorted at the far end?

Select	Answer
A	Zero
B	An inductive reactance
C	The same as the characteristic impedance of the line
D	A capacitive reactance

49. - E9G06

On the Smith chart shown in Figure E9-3, what is the name for the large outer circle on which the reactance arcs terminate?

Select	Answer
A	Polar axis
B	Impedance axis
C	Prime axis
D	Reactance axis

50. - E9H08

What is the function of a sense antenna?

Select	Answer
A	It provides diversity reception that cancels multipath signals
B	It allows DF antennas to receive signals at different vertical angles
C	It modifies the pattern of a DF antenna array to provide a null in one direction
D	It increases the sensitivity of a DF antenna array

Figure E7-2

Figure E7-3

Figure E9-3