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	By the odor
C	By the yellowish appearance of the gas
D	Only with a carbon monoxide detector

2. - E1A12

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

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

3. - E1B03

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

Select	Answer
A	3 miles
B	1 mile
C	30 miles
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 bring a copy of FCC Public Notice DA 16-1048
B	The U.S. embassy must approve of your operation
C	You must identify in the official language of the country in which you are operating
D	You must append "/CEPT" to your call sign

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

6. - E1E05

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

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

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. - E2A13

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

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

9. - E2B05

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

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

10. - E2C02

Which of the following best describes the term self-spotting? in connection with HF contest operating?

Select	Answer
A	An automatic method for rapidly zero beating or tuning to a station's frequency before calling that station
B	The often-prohibited practice of posting one's own call sign and frequency on a spotting network
C	The acceptable practice of manually posting the call signs of stations on a spotting network
D	A manual technique for rapidly zero beating or tuning to a station's frequency before calling that station

11. - E2D03

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

Select	Answer
A	MSK144
B	PACTOR III
C	JT65
D	Olivia

12. - E2E12

How do ALE stations establish contact?

Select	Answer
A	ALE radios activate when they hear their signal echoed by back scatter
B	ALE radios send a constant tone code to establish a frequency for future use
C	ALE radios monitor an internet site for the frequency they are being paged on
D	ALE constantly scans a list of frequencies, activating the radio when the designated call sign is received

13. - E3A02

What characterizes libration fading of an EME signal?

Select	Answer
A	A gradual loss of signal as the sun rises
B	A fluttery irregular fading
C	The returning echo is several hertz lower in frequency than the transmitted signal
D	A slow change in the pitch of the CW signal

14. - E3B04

What is meant by the terms "extraordinary" and "ordinary" waves?

Select	Answer
A	Long-path and short-path waves
B	Independent waves created in the ionosphere that are elliptically polarized
C	Refracted rays and reflected waves
D	Extraordinary waves describe rare long-skip propagation compared to ordinary waves, which travel shorter distances

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	Southward
B	Eastward
C	Northward
D	Westward

16. - E4A05

What is the purpose of the prescaler function on a frequency counter?

Select	Answer
A	It divides a higher frequency signal so a low-frequency counter can display the input frequency
B	It amplifies low-level signals for more accurate counting
C	It prevents oscillation in a low-frequency counter circuit
D	It multiplies a higher frequency signal so a low-frequency counter can display the operating frequency

17. - E4B10

Which of the following methods measures intermodulation distortion in an SSB transmitter?

Select	Answer
A	Modulate the transmitter using two RF signals having non-harmonically related frequencies and observe the RF output with a spectrum analyzer
B	Modulate the transmitter using two AF signals having non-harmonically related frequencies and observe the RF output with a spectrum analyzer
C	Modulate the transmitter using two AF signals having harmonically related frequencies and observe the RF output with a peak reading wattmeter
D	Modulate the transmitter using two RF signals having harmonically related frequencies and observe the RF output with a logic analyzer

18. - E4C13

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

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

19. - E4D01

What is meant by the blocking dynamic range of a receiver?

Select	Answer
A	The difference in dB between the noise floor and the level of an incoming signal that will cause 1 dB of gain compression
B	The minimum difference in dB between two signals which produce third-order intermodulation products greater than the noise floor
C	The minimum difference in dB between the levels of two FM signals that will cause one signal to block the other
D	The difference in dB between the noise floor and the third-order intercept point

20. - E4E05

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

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

21. - E5A07

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

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

22. - E5B06

What is susceptance?

Select	Answer
A	The imaginary part of admittance
B	A measure of the efficiency of a transformer
C	The ratio of magnetic field to electric field
D	The magnetic impedance of a circuit

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 7
B	Point 3
C	Point 1
D	Point 8

24. - E5D08

How many watts are consumed in a circuit having a power factor of 0.6 if the input is 200VAC at 5 amperes?

Select	Answer
A	1000 watts
B	600 watts
C	1600 watts
D	200 watts

25. - E6A08

What term indicates the frequency at which the grounded-base current gain of a transistor has decreased to 0.7 of the gain obtainable at 1 kHz?

Select	Answer
A	Alpha rejection frequency
B	Corner frequency
C	Beta cutoff frequency
D	Alpha cutoff frequency

26. - E6B11

What is used to control the attenuation of RF signals by a PIN diode?

Select	Answer
A	A sub-harmonic pump signal
B	Capacitance of an RF coupling capacitor
C	Reverse voltage larger than the RF signal
D	Forward DC bias current

27. - E6C06

Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply?

Select	Answer
A	Large bypass capacitance is inherent
B	The input switching threshold is about one-half the power supply voltage
C	Bandwidth is very limited
D	The input switching threshold is about two times the power supply voltage

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

29. - E6E01

Why is gallium arsenide (GaAs) useful for semiconductor devices operating at UHF and higher frequencies?

Select	Answer
A	Lower junction voltage drop
B	Lower transconductance
C	Higher noise figures
D	Higher electron mobility

30. - E6F06

Which of these materials is most commonly used to create photoconductive devices?

Select	Answer
A	An ordinary metal
B	A heavy metal
C	A crystalline semiconductor
D	A liquid semiconductor

31. - E7A07

What logical operation does a NAND gate perform?

Select	Answer
A	It produces logic 0 at its output if some but not all inputs are logic 1
B	It produces logic 1 at its output only when all inputs are logic 1
C	It produces logic 0 at its output only when all inputs are logic 0
D	It produces logic 0 at its output only when all inputs are logic 1

32. - E7B03

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

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

33. - E7C11

Which of the following describes a receiving filter's ability to reject signals occupying an adjacent channel?

Select	Answer
A	Shape factor
B	Noise factor
C	Passband ripple
D	Phase response

34. - E7D13

What is the equation for calculating power dissipated by a series linear voltage regulator?

Select	Answer
A	Input voltage divided by output current
B	Voltage difference from input to output multiplied by output current
C	Input voltage multiplied by input current
D	Output voltage multiplied by output current

35. - E7E11

Which type of detector circuit is used for demodulating SSB signals?

Select	Answer
A	Discriminator
B	Phase detector
C	Product detector
D	Phase comparator

36. - E7F03

What type of digital signal processing filter is used to generate an SSB signal?

Select	Answer
A	A notch filter
B	An elliptical filter
C	A Hilbert-transform filter
D	An adaptive filter

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	1
B	38
C	0.03
D	76

38. - E7H02

What is a microphonic?

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

39. - E8A11

Which of the following is a measure of the quality of an analog-to-digital converter?

Select	Answer
A	Power factor
B	Peak envelope power
C	Total harmonic distortion
D	Reciprocal mixing

40. - E8B10

What is frequency division multiplexing?

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

41. - E8C03

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

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

42. - E8D06

What is the advantage of including parity bits in ASCII characters?

Select	Answer
A	Faster transmission rate
B	Foreign language characters can be sent
C	The signal can overpower interfering signals
D	Some types of errors can be detected

43. - E9A09

What is antenna efficiency?

Select	Answer
A	Radiation resistance divided by transmission resistance
B	Effective radiated power divided by transmitter output
C	Total resistance divided by radiation resistance
D	Radiation resistance divided by total resistance

44. - E9B06

What is the elevation angle of peak response in the antenna radiation pattern shown in Figure E9-2?

Select	Answer
A	7.5 degrees
B	45 degrees
C	75 degrees
D	25 degrees

45. - E9C07

What is the approximate feed point impedance at the center of a two-wire folded dipole antenna?

Select	Answer
A	72 ohms
B	50 ohms
C	300 ohms
D	450 ohms

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. - E9E04

What is the purpose of the series capacitor in a gamma-type antenna matching network?

Select	Answer
A	To provide DC isolation between the feed line and the antenna
B	To provide a rejection notch that prevents the radiation of harmonics
C	To cancel the inductive reactance of the matching network
D	To transform the antenna impedance to a higher value

48. - E9F04

What impedance does a 1/2-wavelength transmission line present to a generator when the line is shorted at the far end?

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

49. - E9G11

How are the wavelength scales on a Smith chart calibrated?

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

50. - E9H11

What feature of a cardioid pattern antenna makes it useful for direction finding?

Select	Answer
A	A very sharp single null
B	High radiation angle
C	A very sharp peak
D	Broadband response

Figure E5-1

Figure E7-3

Figure E9-2