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

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1. - E0A07

How may dangerous levels of carbon monoxide from an emergency generator be detected?

Select	Answer
A	Any ordinary smoke detector can be used
B	Only with a carbon monoxide detector
C	By the yellowish appearance of the gas
D	By the odor

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 highest frequency of the channel
B	At the center frequency of the channel
C	At the lowest frequency of the channel
D	On any frequency where the signal's sidebands are within 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	Reasonable accommodations of amateur radio must be made
C	Use of wireless devices in a vehicle is exempt from regulation
D	No limitations may be placed on antenna size or placement

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	The U.S. embassy must approve of your operation
B	You must bring a copy of FCC Public Notice DA 16-1048
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. - E1D02

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

Select	Answer
A	Data containing personal information
B	Auxiliary relay links carrying repeater audio
C	Telecommand signals from a space telecommand station
D	Binary control characters

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

7. - E1F06

Under what circumstances might the FCC issue a Special Temporary Authority (STA) to an amateur station?

Select	Answer
A	To provide for experimental amateur communications
B	To provide additional spectrum for personal use
C	To provide temporary operation while awaiting normal licensing
D	To allow regular operation on Land Mobile channels

8. - E2A11

What type of antenna can be used to minimize the effects of spin modulation and Faraday rotation?

Select	Answer
A	A linearly polarized antenna
B	A log-periodic dipole array
C	An isotropic antenna
D	A circularly polarized antenna

9. - E2B02

How many horizontal lines make up a fast-scan (NTSC) television frame?

Select	Answer
A	30
B	525
C	60
D	1080

10. - E2C03

From which of the following bands is amateur radio contesting generally excluded?

Select	Answer
A	6 meters
B	33 centimeters
C	2 meters
D	30 meters

11. - E2D07

What digital protocol is used by APRS?

Select	Answer
A	802.11
B	PACTOR
C	AMTOR
D	AX.25

12. - E2E13

Which of these digital modes has the fastest data throughput under clear communication conditions?

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

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 F1 layer
B	The D layer
C	The E layer
D	The F2 layer

14. - E3B11

At what time of day can sporadic E propagation occur?

Select	Answer
A	Any time
B	Only around sunset and sunrise
C	Only in hours of darkness
D	Only around sunset

15. - E3C04

What does the value of Bz (B sub Z) represent?

Select	Answer
A	Direction and strength of the interplanetary magnetic field
B	Geomagnetic field stability
C	Critical frequency for vertical transmissions
D	Duration of long-delayed echoes

16. - E4A04

How is the compensation of an oscilloscope probe typically adjusted?

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

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S12
B	S11
C	S22
D	S21

18. - E4C08

An SDR receiver is overloaded when input signals exceed what level?

Select	Answer
A	One-half the maximum sampling buffer size
B	One-half the maximum sample rate
C	The reference voltage of the analog-to-digital converter
D	The maximum count value of the analog-to-digital converter

19. - E4D11

Why are odd-order intermodulation products, created within a receiver, of particular interest compared to other products?

Select	Answer
A	Odd-order intermodulation produces three products for every input signal within the band of interest
B	Odd-order products of two signals in the band of interest are also likely to be within the band
C	Odd-order products overload the IF filters
D	Odd-order products are an indication of poor image rejection

20. - E4E01

What problem can occur when using an automatic notch filter (ANF) to remove interfering carriers while receiving CW signals?

Select	Answer
A	Any nearby signal passing through the DSP system will overwhelm the desired signal
B	Received CW signals will appear to be modulated at the DSP clock frequency
C	Ringing in the DSP filter will completely remove the spaces between the CW characters
D	Removal of the CW signal as well as the interfering carrier

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. - 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	14 degrees with the voltage leading the current
B	14 degrees with the voltage lagging the current
C	76 degrees with the voltage lagging the current
D	76 degrees with the voltage leading the current

23. - E5C09

When using rectangular coordinates to graph the impedance of a circuit, what do the axes represent?

Select	Answer
A	The X axis represents the phase angle and the Y axis represents the magnitude
B	The X axis represents the resistive component and the Y axis represents the reactive component
C	The X axis represents the reactive component and the Y axis represents the resistive component
D	The X axis represents the magnitude and the Y axis represents the phase angle

24. - E5D14

What is reactive power?

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

25. - E6A03

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

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

26. - E6B09

What is a common use for point-contact diodes?

Select	Answer
A	As a constant voltage source
B	As a high-voltage rectifier
C	As a constant current source
D	As an RF detector

27. - E6C08

In Figure E6-3, what is the schematic symbol for a NAND gate?

Select	Answer
A	2
B	3
C	4
D	1

28. - E6D11

Which type of core material decreases inductance when inserted into a coil?

Select	Answer
A	Powdered iron
B	Ferrite
C	Ceramic
D	Brass

29. - E6E06

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

Select	Answer
A	Plate current that is controlled by a control grid
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	The ability to retrieve information from a single signal even in the presence of other strong signals

30. - E6F03

What is the most common configuration of an optoisolator or optocoupler?

Select	Answer
A	A lens and a photomultiplier
B	An amplitude modulated helium-neon laser
C	An LED and a phototransistor
D	A frequency modulated helium-neon laser

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. - E7B04

Where on the load line of a Class A common emitter amplifier would bias normally be set?

Select	Answer
A	Where the load line intersects the voltage axis
B	Approximately halfway between saturation and cutoff
C	At a point where the load line intersects the zero bias current curve
D	At a point where the bias resistor equals the load resistor

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

34. - E7D06

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

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

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 PM signals by using an electrically variable resistance
C	To produce AM signals by using an electrically variable resistance
D	To produce AM signals by using an electrically variable inductance or capacitance

36. - E7F12

Which of the following is an advantage of a Finite Impulse Response (FIR) filter vs an Infinite Impulse Response (IIR) digital filter?

Select	Answer
A	FIR filters can respond faster to impulses
B	All these choices are correct
C	FIR filters are easier to implement for a given set of passband rolloff requirements
D	FIR filters can delay all frequency components of the signal by the same amount

37. - E7G07

What magnitude of voltage gain can be expected from the circuit in Figure E73 when R1 is 10 ohms and RF is 470 ohms?

Select	Answer
A	47
B	94
C	0.21
D	24

38. - E7H02

What is a microphonic?

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

39. - E8A08

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

Select	Answer
A	Very low power consumption decreases frequency drift
B	Immunity to out-of-sequence coding reduces spurious responses
C	All these choices are correct
D	Very high speed allows digitizing high frequencies

40. - E8B06

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?

Select	Answer
A	0.214
B	0.47
C	47
D	2.14

41. - E8C11

What is the relationship between symbol rate and baud?

Select	Answer
A	Baud is twice the symbol rate
B	Baud is only used for RTTY
C	Symbol rate is only used for packet-based modes
D	They are the same

42. - E8D03

How does the spread spectrum technique of frequency hopping work?

Select	Answer
A	If interference is detected by the receiver it will signal the transmitter to change frequencies
B	The frequency of the transmitted signal is changed very rapidly according to a pseudorandom sequence also used by the receiving station
C	If interference is detected by the receiver it will signal the transmitter to wait until the frequency is clear
D	A binary bit stream is used to shift the phase of an RF carrier very rapidly in a pseudorandom sequence

43. - E9A10

Which of the following improves the efficiency of a ground-mounted quarter-wave vertical antenna?

Select	Answer
A	Isolating the coax shield from ground
B	All these choices are correct
C	Shortening the radiating element
D	Installing a radial system

44. - E9B09

What type of computer program technique is commonly used for modeling antennas?

Select	Answer
A	Graphical analysis
B	Mutual impedance analysis
C	Method of Moments
D	Calculus differentiation with respect to physical properties

45. - E9C06

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

Select	Answer
A	It changes the radiation pattern from horizontal to vertical polarization
B	It changes the radiation pattern from bidirectional to unidirectional
C	It decreases the ground loss
D	It reflects the standing waves on the antenna elements back to the transmitter

46. - E9D06

What happens to the SWR bandwidth when one or more loading coils are used to resonate an electrically short antenna?

Select	Answer
A	It is increased
B	It is unchanged if the loading coil is located at a voltage maximum point
C	It is unchanged if the loading coil is located at the feed point
D	It is decreased

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	50 ohms
C	62 ohms
D	75 ohms

48. - E9F12

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

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

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	Impedance axis
B	Prime axis
C	Reactance axis
D	Polar axis

50. - E9H10

How can the output voltage of a multiple-turn receiving loop antenna be increased?

Select	Answer
A	By winding adjacent turns in opposing directions
B	By utilizing high impedance wire for the coupling loop
C	By reducing the permeability of the loop shield
D	By increasing the number of turns and/or the area

Figure E6-3

Figure E7-2

Figure E9-3