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. - E0A07

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

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

2. - E1A14

Except in some parts of Alaska, what is the maximum power permitted on the 630 meter band?

Select	Answer
A	1 watt EIRP
B	100 watts PEP
C	50 watts PEP
D	5 watts EIRP

3. - E1B03

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

Select	Answer
A	3 miles
B	30 miles
C	10 miles
D	1 mile

4. - E1C03

How do the control operator responsibilities of a station under automatic control differ from one under local control?

Select	Answer
A	Under local control a control operator is not required to be present at a control point
B	Under local control there is no control operator
C	Under automatic control there is no control operator
D	Under automatic control the control operator is not required to be present at the control point

5. - E1D08

Which VHF amateur bands have frequencies authorized for space stations?

Select	Answer
A	6 meters, 2 meters, and 1.25 meters
B	6 meters and 2 meters
C	2 meters
D	2 meters and 1.25 meters

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 77%
D	Minimum passing score of 80%

7. - E1F09

Which of the following conditions apply when transmitting spread spectrum emissions?

Select	Answer
A	The transmission must not be used to obscure the meaning of any communication
B	A station transmitting SS emission must not cause harmful interference to other stations employing other authorized emissions
C	All these choices are correct
D	The transmitting station must be in an area regulated by the FCC or in a country that permits SS emissions

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	Multi-satellite relaying
C	Store-and-forward
D	Digipeating

9. - E2B06

What is vestigial sideband modulation?

Select	Answer
A	A type of modulation in which one sideband is inverted
B	Amplitude modulation in which one complete sideband and a portion of the other are transmitted
C	Spread spectrum modulation achieved by applying FM modulation following single sideband amplitude modulation
D	Narrow-band FM modulation achieved by filtering one sideband from the audio before frequency modulating the carrier

10. - E2C06

During a VHF/UHF contest, in which band segment would you expect to find the highest level of SSB or CW activity?

Select	Answer
A	In the middle of the band, usually 25 kHz above the national calling frequency
B	At the top of each band, usually in a segment reserved for contests
C	In the middle of each band, usually on the national calling frequency
D	In the weak signal segment of the band, with most of the activity near the calling frequency

11. - E2D05

What is one advantage of the JT65 mode?

Select	Answer
A	Easily copied by ear if necessary
B	Permits fast-scan TV transmissions over narrow bandwidth
C	The ability to decode signals which have a very low signal-to-noise ratio
D	Uses only a 65 Hz bandwidth

12. - E2E11

What is the difference between direct FSK and audio FSK?

Select	Answer
A	Direct FSK applies the data signal to the transmitter VFO, while AFSK transmits tones via phone
B	Direct FSK occupies less bandwidth
C	Only direct FSK can be decoded by computer
D	Direct FSK can transmit faster baud rates

13. - E3A03

When scheduling EME contacts, which of these conditions will generally result in the least path loss?

Select	Answer
A	When the moon is at perigee
B	When the moon is at apogee
C	When the moon is full
D	When the MUF is above 30 MHz

14. - E3B02

What is the approximate maximum range for signals using transequatorial propagation?

Select	Answer
A	1000 miles
B	7500 miles
C	2500 miles
D	5000 miles

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. - E4A01

Which of the following limits the highest frequency signal that can be accurately displayed on a digital oscilloscope?

Select	Answer
A	Q of the circuit
B	All these choices are correct
C	Sampling rate of the analog-to-digital converter
D	Amount of memory

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S21
B	S22
C	S11
D	S12

18. - E4C03

What is the term for the suppression in an FM receiver of one signal by another stronger signal on the same frequency?

Select	Answer
A	Capture effect
B	Frequency discrimination
C	Desensitization
D	Cross-modulation interference

19. - E4D09

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

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

20. - E4E01

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

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

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	Parasitic effects are minimized
C	Phase shift can become uncontrolled
D	Internal voltages increase

22. - E5B12

What is admittance?

Select	Answer
A	The term for the gain of a field effect transistor
B	The inverse of impedance
C	The inverse of Q factor
D	The turns ratio of a transformer

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 3
B	Point 7
C	Point 8
D	Point 1

24. - E5D10

How can the true power be determined in an AC circuit where the voltage and current are out of phase?

Select	Answer
A	By dividing the apparent power by the power factor
B	By dividing the reactive power by the power factor
C	By multiplying the apparent power by the power factor
D	By multiplying the reactive power by the power factor

25. - E6A04

What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?

Select	Answer
A	N-type impurity
B	Insulator impurity
C	Acceptor impurity
D	Donor impurity

26. - E6B09

What is a common use for point-contact diodes?

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

27. - E6C07

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

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

28. - E6D11

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

Select	Answer
A	Ceramic
B	Brass
C	Powdered iron
D	Ferrite

29. - E6E09

Which of the following component package types would be most suitable for use at frequencies above the HF range?

Select	Answer
A	Surface mount
B	Axial lead
C	Radial lead
D	TO-220

30. - E6F02

What happens to the conductivity of a photoconductive material when light shines on it?

Select	Answer
A	It increases
B	It decreases
C	It becomes unstable
D	It stays the same

31. - E7A06

What is a characteristic of a monostable multivibrator?

Select	Answer
A	It produces a continuous square wave oscillating between 1 and 0
B	It maintains a constant output voltage, regardless of variations in the input voltage
C	It stores one bit of data in either a 0 or 1 state
D	It switches momentarily to the opposite binary state and then returns to its original state after a set time

32. - E7B14

Why are switching amplifiers more efficient than linear amplifiers?

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

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

34. - E7D15

What is the purpose of a step-start circuit in a high-voltage power supply?

Select	Answer
A	To compensate for variations of the incoming line voltage
B	To allow for remote control of the power supply
C	To allow the filter capacitors to charge gradually
D	To provide a dual-voltage output for reduced power applications

35. - E7E05

What circuit is added to an FM transmitter to boost the higher audio frequencies?

Select	Answer
A	A pre-emphasis network
B	A heterodyne suppressor
C	A de-emphasis network
D	A heterodyne enhancer

36. - E7F03

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

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

37. - E7G03

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

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

38. - E7H05

How is positive feedback supplied in a Pierce oscillator?

Select	Answer
A	Through a neutralizing capacitor
B	Through link coupling
C	Through a quartz crystal
D	Through a tapped coil

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 divided by the gain of the input amplifier
C	8
D	256

40. - E8B10

What is frequency division multiplexing?

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

41. - E8C08

How does ARQ accomplish error correction?

Select	Answer
A	Special binary codes provide automatic correction
B	Special polynomial codes provide automatic correction
C	If errors are detected, redundant data is substituted
D	If errors are detected, a retransmission is requested

42. - E8D05

What is the most common method of reducing key clicks?

Select	Answer
A	High-pass filters at the transmitter output
B	Increase keying waveform rise and fall times
C	Reduce keying waveform rise and fall times
D	Low-pass filters at the transmitter output

43. - E9A02

What is the effective radiated power relative to a dipole of a repeater station with 150 watts transmitter power output, 2 dB feed line loss, 2.2 dB duplexer loss, and 7 dBd antenna gain?

Select	Answer
A	1977 watts
B	420 watts
C	78.7 watts
D	286 watts

44. - E9B01

In the antenna radiation pattern shown in Figure E9-1, what is the beamwidth?

Select	Answer
A	75 degrees
B	30 degrees
C	50 degrees
D	25 degrees

45. - E9C01

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed 180 degrees out of phase?

Select	Answer
A	Omni-directional
B	A figure-8 broadside to the axis of the array
C	Cardioid
D	A figure-8 oriented along the axis of the array

46. - E9D09

What is the function of a loading coil used as part of an HF mobile antenna?

Select	Answer
A	To lower the losses
B	To increase the SWR bandwidth
C	To cancel capacitive reactance
D	To lower the Q

47. - E9E08

What is a use for a Wilkinson divider?

Select	Answer
A	It is used to divide power equally between two 50-ohm loads while maintaining 50-ohm input impedance
B	It divides the operating frequency of a transmitter signal so it can be used on a lower frequency band
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	10.6 meters
B	4.3 meters
C	5.3 meters
D	3.5 meters

49. - E9G01

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

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

50. - E9H03

What is Receiving Directivity Factor (RDF)?

Select	Answer
A	Forward gain compared to average gain over the entire hemisphere
B	Forward gain compared to the gain in the reverse direction
C	Relative directivity compared to isotropic
D	Relative directivity compared to a dipole

Figure E5-1

Figure E9-1