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

2. - E1A07

What is the maximum power permitted on the 2200 meter band?

Select	Answer
A	5 watts EIRP (Equivalent isotropic radiated power)
B	1 watt EIRP (Equivalent isotropic radiated power)
C	100 watts PEP
D	50 watts PEP

3. - E1B10

What frequencies are authorized to an amateur station operating under RACES rules?

Select	Answer
A	All amateur service frequencies authorized to the control operator
B	Specific local government channels
C	Military Auxiliary Radio System (MARS) channels
D	Specific segments in the amateur service MF, HF, VHF and UHF bands

4. - E1C10

What is the permitted mean power of any spurious emission relative to the mean power of the fundamental emission from a station transmitter or external RF amplifier installed after January 1, 2003 and transmitting on a frequency below 30 MHz?

Select	Answer
A	At least 53 dB below
B	At least 73 dB below
C	At least 63 dB below
D	At least 43 dB below

5. - E1D04

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

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

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. - E1F10

Who may be the control operator of an auxiliary station?

Select	Answer
A	Only Amateur Extra Class operators
B	Only Technician, General, Advanced or Amateur Extra Class operators
C	Any licensed amateur operator
D	Only General, Advanced or Amateur Extra Class operators

8. - E2A08

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

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

9. - E2B05

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

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

10. - E2C04

Which of the following frequencies are sometimes used for amateur radio mesh networks?

Select	Answer
A	Cable TV channels 41 through 43
B	Frequencies shared with various unlicensed wireless data services
C	The 60 meter band channel centered on 5373 kHz
D	HF frequencies where digital communications are permitted

11. - E2D09

What type of modulation is used for JT65 contacts?

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

12. - E2E04

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

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

13. - E3A10

Which type of atmospheric structure can create a path for microwave propagation?

Select	Answer
A	Dust devil
B	The jet stream
C	Temperature inversion
D	Wind shear

14. - E3B01

What is transequatorial propagation?

Select	Answer
A	Propagation between points at the same latitude
B	Propagation between points located on the magnetic equator
C	Propagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator
D	Propagation between a point on the equator and its antipodal point

15. - E3C04

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

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

16. - E4A11

How should an antenna analyzer be connected when measuring antenna resonance and feed point impedance?

Select	Answer
A	Connect the analyzer via a high-impedance transformer to the antenna
B	Connect the antenna feed line directly to the analyzer's connector
C	Loosely couple the analyzer near the antenna base
D	Loosely couple the antenna and a dummy load to the analyzer

17. - E4B06

How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?

Select	Answer
A	75 watts
B	100 watts
C	125 watts
D	25 watts

18. - E4C14

What transmit frequency might generate an image response signal in a receiver tuned to 14.300 MHz and that uses a 455 kHz IF frequency?

Select	Answer
A	15.210 MHz
B	13.845 MHz
C	14.445 MHz
D	14.755 MHz

19. - E4D04

Which of the following may reduce or eliminate intermodulation interference in a repeater caused by another transmitter operating in close proximity?

Select	Answer
A	Utilizing a Class D final amplifier
B	A band-pass filter in the feed line between the transmitter and receiver
C	A properly terminated circulator at the output of the repeater's transmitter
D	Utilizing a Class C final amplifier

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. - E5A03

What is the magnitude of the impedance of a series RLC circuit at resonance?

Select	Answer
A	Approximately equal to inductive reactance
B	Approximately equal to circuit resistance
C	High, as compared to the circuit resistance
D	Approximately equal to capacitive reactance

22. - E5B09

What is the relationship between the AC current through a capacitor and the voltage across a capacitor?

Select	Answer
A	Voltage and current are 180 degrees out of phase
B	Voltage and current are in phase
C	Voltage leads current by 90 degrees
D	Current leads voltage by 90 degrees

23. - E5C08

What coordinate system is often used to display the phase angle of a circuit containing resistance, inductive and/or capacitive reactance?

Select	Answer
A	Maidenhead grid
B	Polar coordinates
C	Faraday grid
D	Elliptical coordinates

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	200 watts
B	1000 watts
C	1600 watts
D	600 watts

25. - E6A01

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

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

26. - E6B09

What is a common use for point-contact diodes?

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

27. - E6C06

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

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

28. - E6D06

What core material property determines the inductance of an inductor?

Select	Answer
A	Permeability
B	Resistance
C	Reactivity
D	Thermal impedance

29. - E6E05

Which of the following noise figure values is typical of a low-noise UHF preamplifier?

Select	Answer
A	-20 dBm
B	2 dB
C	44 dBm
D	-10 dB

30. - E6F05

Which describes an optical shaft encoder?

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

31. - E7A07

What logical operation does a NAND gate perform?

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

32. - E7B01

For what portion of the signal cycle does each active element in a push-pull Class AB amplifier conduct?

Select	Answer
A	Less than 180 degrees
B	Exactly 180 degrees
C	More than 180 degrees but less than 360 degrees
D	The entire cycle

33. - E7C12

What is one advantage of a Pi-matching network over an L-matching network consisting of a single inductor and a single capacitor?

Select	Answer
A	L-networks cannot perform impedance transformation
B	Pi-networks provide balanced input and output
C	Pi-networks are more stable
D	The Q of Pi-networks can be controlled

34. - E7D04

Which of the following types of linear voltage regulator usually make the most efficient use of the primary power source?

Select	Answer
A	A series regulator
B	A series current source
C	A shunt current source
D	A shunt regulator

35. - E7E04

What is one way a single-sideband phone signal can be generated?

Select	Answer
A	By driving a product detector with a DSB signal
B	By using a loop modulator followed by a mixer
C	By using a balanced modulator followed by a filter
D	By using a reactance modulator followed by a mixer

36. - E7F04

What is a common method of generating an SSB signal using digital signal processing?

Select	Answer
A	A frequency synthesizer removes the unwanted sidebands
B	Signals are combined in quadrature phase relationship
C	Mixing products are converted to voltages and subtracted by adder circuits
D	Varying quartz crystal characteristics emulated in digital form

37. - E7G03

What is the typical input impedance of an op-amp?

Select	Answer
A	Very high
B	Very low
C	100 ohms
D	1000 ohms

38. - E7H06

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

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

39. - E8A01

What is the name of the process that shows that a square wave is made up of a sine wave plus all its odd harmonics?

Select	Answer
A	Differential analysis
B	Fourier analysis
C	Numerical analysis
D	Vector analysis

40. - E8B03

What is the modulation index of an FM-phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency when the modulating frequency is 1000 Hz?

Select	Answer
A	3000
B	3
C	0.3
D	1000

41. - E8C01

How is Forward Error Correction implemented?

Select	Answer
A	By transmitting a special algorithm to the receiving station along with the data characters
B	By the receiving station repeating each block of three data characters
C	By transmitting extra data that may be used to detect and correct transmission errors
D	By varying the frequency shift of the transmitted signal according to a predefined algorithm

42. - E8D07

What is a common cause of overmodulation of AFSK signals?

Select	Answer
A	Bit errors in the modem
B	Excessive transmit audio levels
C	Excessive numbers of retries
D	Ground loops

43. - E9A05

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

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

44. - E9B04

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

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

45. - E9C14

How does the performance of a horizontally polarized antenna mounted on the side of a hill compare with the same antenna mounted on flat ground?

Select	Answer
A	The horizontal beamwidth increases in the uphill direction
B	The main lobe takeoff angle increases in the downhill direction
C	The main lobe takeoff angle decreases in the downhill direction
D	The horizontal beamwidth decreases in the downhill direction

46. - E9D10

What happens to feed-point impedance at the base of a fixed length HF mobile antenna when operated below its resonant frequency?

Select	Answer
A	The radiation resistance decreases and the capacitive reactance decreases
B	The radiation resistance decreases and the capacitive reactance increases
C	The radiation resistance increases and the capacitive reactance decreases
D	The radiation resistance increases and the capacitive reactance increases

47. - E9E11

What is the primary purpose of phasing lines when used with an antenna having multiple driven elements?

Select	Answer
A	It prevents reflected power from traveling back down the feed line and causing harmonic radiation from the transmitter
B	It allows single-band antennas to operate on other bands
C	It ensures that each driven element operates in concert with the others to create the desired antenna pattern
D	It creates a low-angle radiation pattern

48. - E9F06

What is the approximate physical length of an air-insulated, parallel conductor transmission line that is electrically 1/2 wavelength long at 14.10 MHz?

Select	Answer
A	7.0 meters
B	8.5 meters
C	10.6 meters
D	13.3 meters

49. - E9G01

Which of the following can be calculated using a Smith chart?

Select	Answer
A	Antenna radiation pattern
B	Impedance along transmission lines
C	Radio propagation
D	Radiation resistance

50. - E9H09

What is a Pennant antenna?

Select	Answer
A	A stealth antenna built to look like a flagpole
B	A small, vertically oriented receiving antenna consisting of a triangular loop terminated in approximately 900 ohms
C	A form of rhombic antenna terminated in a variable capacitor to provide frequency diversity
D	A four-element, high-gain vertical array invented by George Pennant