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

2. - E1A11

Which of the following describes authorization or licensing required when operating an amateur station aboard a U.S.-registered vessel in international waters?

Select	Answer
A	Any FCC-issued amateur license
B	Any amateur license with an FCC Marine or Aircraft endorsement
C	An unrestricted Radiotelephone Operator Permit
D	Only General Class or higher amateur licenses

3. - E1B11

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

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

4. - E1C12

On what portion of the 630 meter band are phone emissions permitted?

Select	Answer
A	Only the bottom 3 kHz
B	The entire band
C	Only the top 3 kHz
D	None

5. - E1D05

What must be posted at the station location of a station being operated by telecommand on or within 50 km of the earth's surface?

Select	Answer
A	All these choices are correct
B	A photocopy of the station license
C	A label with the name, address, and telephone number of the control operator
D	A label with the name, address, and telephone number of the station licensee

6. - E1E05

What is the minimum passing score on all amateur operator license examinations?

Select	Answer
A	Minimum passing score of 70%
B	Minimum passing score of 74%
C	Minimum passing score of 80%
D	Minimum passing score of 77%

7. - E1F08

Which of the following types of amateur station communications are prohibited?

Select	Answer
A	Communications that have religious content
B	Communications transmitted for hire or material compensation, except as otherwise provided in the rules
C	Communications in a language other than English
D	Communications that have political content, except as allowed by the Fairness Doctrine

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

9. - E2B08

What technique allows commercial analog TV receivers to be used for fast-scan TV operations on the 70 cm band?

Select	Answer
A	Using USB and demodulating the signal with a computer sound card
B	Transmitting on channels shared with cable TV
C	Transmitting on the abandoned TV channel 2
D	Using converted satellite TV dishes

10. - E2C07

What is the Cabrillo format?

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

11. - E2D03

Which of the following digital modes is especially useful for EME communications?

Select	Answer
A	PACTOR III
B	Olivia
C	JT65
D	MSK144

12. - E2E07

Which of the following is a possible reason that attempts to initiate contact with a digital station on a clear frequency are unsuccessful?

Select	Answer
A	The protocol version you are using is not supported by the digital station
B	All these choices are correct
C	Your transmit frequency is incorrect
D	Another station you are unable to hear is using the frequency

13. - E3A11

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

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

14. - E3B11

At what time of day can sporadic E propagation occur?

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

15. - E3C06

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

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

16. - E4A03

Which of the following test instruments is used to display spurious signals and/or intermodulation distortion products generated by an SSB transmitter?

Select	Answer
A	A logic analyzer
B	A wattmeter
C	A time-domain reflectometer
D	A spectrum analyzer

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S11
B	S12
C	S21
D	S22

18. - E4C01

What is an effect of excessive phase noise in a receiver's local oscillator?

Select	Answer
A	It decreases receiver third-order intercept point
B	It limits the receiver's ability to receive strong signals
C	It can affect the receiver's frequency calibration
D	It can combine with strong signals on nearby frequencies to generate interference

19. - E4D11

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

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

20. - E4E05

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

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

21. - E5A07

What is the magnitude of the current at the input of a parallel RLC circuit at resonance?

Select	Answer
A	Minimum
B	L/R
C	Maximum
D	R/L

22. - E5B04

What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors, all in parallel?

Select	Answer
A	220 seconds
B	440 seconds
C	110 seconds
D	55 seconds

23. - E5C03

Which of the following represents an inductive reactance in polar coordinates?

Select	Answer
A	A negative phase angle
B	A positive phase angle
C	A negative magnitude
D	A positive magnitude

24. - E5D03

What is microstrip?

Select	Answer
A	Short lengths of coax mounted on printed circuit boards to minimize time delay between microwave circuits
B	Lightweight transmission line made of common zip cord
C	Miniature coax used for low power applications
D	Precision printed circuit conductors above a ground plane that provide constant impedance interconnects at microwave frequencies

25. - E6A01

In what application is gallium arsenide used as a semiconductor material?

Select	Answer
A	In microwave circuits
B	In very low-frequency RF circuits
C	In high-current rectifier circuits
D	In high-power audio circuits

26. - E6B03

What type of bias is required for an LED to emit light?

Select	Answer
A	Forward bias
B	Reverse bias
C	Zero bias
D	Inductive bias

27. - E6C09

What is a Programmable Logic Device (PLD)?

Select	Answer
A	A logic circuit that can be modified during use
B	A type of transistor whose gain can be changed by digital logic circuits
C	Programmable equipment used for testing digital logic integrated circuits
D	A programmable collection of logic gates and circuits in a single integrated circuit

28. - E6D10

What is a primary advantage of using a toroidal core instead of a solenoidal core in an inductor?

Select	Answer
A	Toroidal cores make it easier to couple the magnetic energy into other components
B	Toroidal cores have lower Q characteristics
C	Toroidal cores confine most of the magnetic field within the core material
D	Toroidal cores exhibit greater hysteresis

29. - E6E08

How is power supplied to the most common type of MMIC?

Select	Answer
A	Directly to the bias voltage (VCC IN) lead
B	Through a resistor and/or RF choke connected to the amplifier output lead
C	MMICs require no operating bias
D	Through a capacitor and RF choke connected to the amplifier input lead

30. - E6F05

Which describes an optical shaft encoder?

Select	Answer
A	A device that measures the strength of a beam of light using analog to digital conversion
B	A device that detects rotation of a control by interrupting a light source with a patterned wheel
C	A device for generating RTTY signals by means of a rotating light source
D	A digital encryption device often used to encrypt spacecraft control signals

31. - E7A03

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

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

32. - E7B15

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

Select	Answer
A	Neutralization
B	Use a resistor in series with the emitter
C	All these choices are correct
D	Select transistors with high beta

33. - E7C04

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

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

34. - E7D09

What is the main reason to use a charge controller with a solar power system?

Select	Answer
A	Matching of day and night charge rates
B	Control of electrolyte levels during battery discharge
C	Prevention of battery undercharge
D	Prevention of battery damage due to overcharge

35. - E7E07

What is meant by the term "baseband" in radio communications?

Select	Answer
A	The frequency range occupied by a message signal prior to modulation
B	The unmodulated bandwidth of the transmitted signal
C	The basic oscillator frequency in an FM transmitter that is multiplied to increase the deviation and carrier frequency
D	The lowest frequency band that the transmitter or receiver covers

36. - E7F06

What is the minimum number of bits required for an analog-to-digital converter to sample a signal with a range of 1 volt at a resolution of 1 millivolt?

Select	Answer
A	10 bits
B	4 bits
C	8 bits
D	6 bits

37. - E7G06

What is the gain-bandwidth of an operational amplifier?

Select	Answer
A	The gain of the amplifier at a filter's cutoff frequency
B	The frequency at which the open-loop gain of the amplifier equals one
C	The frequency at which the amplifier's offset voltage is zero
D	The maximum frequency for a filter circuit using that type of amplifier

38. - E7H06

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

Select	Answer
A	Negative feedback and balanced feedback
B	Colpitts and Hartley
C	Armstrong and deForest
D	Pierce and Zener

39. - E8A04

What is "dither" with respect to analog-to-digital converters?

Select	Answer
A	An abnormal condition where the converter cannot settle on a value to represent the signal
B	An error caused by irregular quantization step size
C	A small amount of noise added to the input signal to allow more precise representation of a signal over time
D	A method of decimation by randomly skipping samples

40. - E8B10

What is frequency division multiplexing?

Select	Answer
A	Two or more information streams are merged into a digital combiner, which then pulse position modulates the transmitter
B	Two or more information streams are merged into a baseband, which then modulates the transmitter
C	The transmitted signal is divided into packets of information
D	The transmitted signal jumps from band to band at a predetermined rate

41. - E8C09

Which digital code allows only one bit to change between sequential code values?

Select	Answer
A	Binary Coded Decimal Code
B	Extended Binary Coded Decimal Interchange Code
C	Excess 3 code
D	Gray code

42. - E8D09

What is considered an acceptable maximum IMD level for an idling PSK signal?

Select	Answer
A	+15 dB
B	-30 dB
C	+10 dB
D	-20 dB

43. - E9A05

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

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

44. - E9B07

How does the total amount of radiation emitted by a directional gain antenna compare with the total amount of radiation emitted from a theoretical isotropic antenna, assuming each is driven by the same amount of power?

Select	Answer
A	The total amount of radiation from the directional antenna is stronger by its front-to-back ratio
B	They are the same
C	The total amount of radiation from the directional antenna is increased by the gain of the antenna
D	The radiation from the isotropic antenna is 2.15 dB stronger than that from the directional antenna

45. - E9C04

What happens to the radiation pattern of an unterminated long wire antenna as the wire length is increased?

Select	Answer
A	The vertical angle increases
B	The lobes align more in the direction of the wire
C	The front-to-back ratio decreases
D	The lobes become more perpendicular to the wire

46. - E9D03

Where should a high Q loading coil be placed to minimize losses in a shortened vertical antenna?

Select	Answer
A	At a voltage node
B	As close to the transmitter as possible
C	Near the center of the vertical radiator
D	As low as possible on the vertical radiator

47. - E9E08

What is a use for a Wilkinson divider?

Select	Answer
A	It divides the operating frequency of a transmitter signal so it can be used on a lower frequency band
B	It is used to divide power equally between two 50-ohm loads while maintaining 50-ohm input impedance
C	It is used to feed low-impedance loads from a high-impedance source
D	It is used to feed high-impedance antennas from a low-impedance source

48. - E9F05

What is the approximate physical length of a solid polyethylene dielectric coaxial transmission line that is electrically 1/4 wavelength long at 14.1 MHz?

Select	Answer
A	5.3 meters
B	10.6 meters
C	4.3 meters
D	3.5 meters

49. - E9G11

How are the wavelength scales on a Smith chart calibrated?

Select	Answer
A	In fractions of transmission line electrical frequency
B	In fractions of transmission line electrical wavelength
C	In fractions of antenna electrical wavelength
D	In fractions of antenna electrical frequency

50. - E9H04

What is an advantage of placing a grounded electrostatic shield around a small loop direction-finding antenna?

Select	Answer
A	It eliminates unbalanced capacitive coupling to the surroundings, improving the nulls
B	It increases signal strength by providing a better match to the feed line
C	It adds capacitive loading, increasing the bandwidth of the antenna
D	It eliminates tracking errors caused by strong out-of-band signals