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

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1. - E0A08

What does SAR measure?

Select	Answer
A	The rate of RF energy reflected from stationary terrain
B	Signal Amplification Rating
C	Synthetic Aperture Ratio of the human body
D	The rate at which RF energy is absorbed by the body

2. - E1A03

What is the maximum legal carrier frequency on the 20 meter band for transmitting USB AFSK digital signals having a 1 kHz bandwidth?

Select	Answer
A	14.149 MHz
B	14.349 MHz
C	14.070 MHz
D	14.100 MHz

3. - E1B03

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

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

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 43 dB below
C	At least 73 dB below
D	At least 63 dB below

5. - E1D09

Which UHF amateur bands have frequencies authorized for space stations?

Select	Answer
A	33 cm and 13 cm
B	70 cm and 13 cm
C	70 cm and 33 cm
D	70 cm only

6. - E1E05

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

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

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	All these choices are correct
C	The transmitting station must be in an area regulated by the FCC or in a country that permits SS emissions
D	A station transmitting SS emission must not cause harmful interference to other stations employing other authorized emissions

8. - E2A03

How is the signal inverted by an inverting linear transponder?

Select	Answer
A	The signal is passed through a mixer and the difference rather than the sum is transmitted
B	The signal is reduced to I and Q components and the Q component is filtered out
C	The signal is detected and remodulated on the reverse sideband
D	The signal is passed through a non-linear filter

9. - E2B11

What is the function of the Vertical Interval Signaling (VIS) code sent as part of an SSTV transmission?

Select	Answer
A	To provide vertical synchronization
B	To lock the color burst oscillator in color SSTV images
C	To identify the SSTV mode being used
D	To identify the call sign of the station transmitting

10. - E2C11

How should you generally identify your station when attempting to contact a DX station during a contest or in a pileup?

Select	Answer
A	Send the call sign of the DX station three times, the words this is,then your call sign three times
B	Send your full call sign and grid square
C	Send only the last two letters of your call sign until you make contact
D	Send your full call sign once or twice

11. - E2D05

What is one advantage of the JT65 mode?

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

12. - E2E11

What is the difference between direct FSK and audio FSK?

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

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

14. - E3B11

At what time of day can sporadic E propagation occur?

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

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. - 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. - E4B08

Which of the following can be used to measure the Q of a series-tuned circuit?

Select	Answer
A	The inductance to capacitance ratio
B	The frequency shift
C	The resonant frequency of the circuit
D	The bandwidth of the circuit's frequency response

18. - E4C07

What does the MDS of a receiver represent?

Select	Answer
A	The meter display sensitivity
B	The maximum detectable spectrum
C	The minimum discernible signal
D	The multiplex distortion stability

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 provide a range of AGC time constants
C	To increase rejection of signals outside the desired band
D	To store often-used frequencies

20. - E4E01

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

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

21. - E5A02

What is resonance in an LC or RLC circuit?

Select	Answer
A	The highest frequency that will pass current
B	The lowest frequency that will pass current
C	The frequency at which the capacitive reactance equals the inductive reactance
D	The frequency at which the reactive impedance equals the resistive impedance

22. - E5B03

How is impedance in polar form converted to an equivalent admittance?

Select	Answer
A	Square the magnitude and subtract 90 degrees from the angle
B	Take the reciprocal of the magnitude and change the sign of the angle
C	Take the square root of the magnitude and add 180 degrees to the angle
D	Take the reciprocal of the angle and change the sign of the magnitude

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

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 multiplying the reactive power by the power factor
C	By multiplying the apparent power by the power factor
D	By dividing the reactive power by the power factor

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	Alpha cutoff frequency
C	Corner frequency
D	Beta cutoff frequency

26. - E6B10

In Figure E6-2, what is the schematic symbol for a light-emitting diode?

Select	Answer
A	6
B	7
C	1
D	5

27. - E6C01

What is the function of hysteresis in a comparator?

Select	Answer
A	To prevent input noise from causing unstable output signals
B	To increase the sensitivity
C	To cause the output to change states continually
D	To allow the comparator to be used with AC input signals

28. - E6D13

What is the primary cause of inductor self-resonance?

Select	Answer
A	Inter-turn capacitance
B	The skin effect
C	Non-linear core hysteresis
D	Inductive kickback

29. - E6E08

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

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

30. - E6F07

What is a solid-state relay?

Select	Answer
A	A mechanical relay that latches in the on or off state each time it is pulsed
B	A relay using transistors to drive the relay coil
C	A semiconductor passive delay line
D	A device that uses semiconductors to implement the functions of an electromechanical relay

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

32. - E7B06

Which of the following amplifier types reduces even-order harmonics?

Select	Answer
A	Class AB
B	Class C
C	Push-pull
D	Push-push

33. - E7C06

What are the distinguishing features of an elliptical filter?

Select	Answer
A	Gradual passband rolloff with minimal stop band ripple
B	Gradual passband rolloff with extreme stop band ripple
C	Extremely flat response over its pass band with gradually rounded stop band corners
D	Extremely sharp cutoff with one or more notches in the stop band

34. - E7D01

How does a linear electronic voltage regulator work?

Select	Answer
A	The control element duty cycle is proportional to the line or load conditions
B	It has a ramp voltage as its output
C	It eliminates the need for a pass transistor
D	The conduction of a control element is varied to maintain a constant output voltage

35. - E7E02

What is the function of a reactance modulator?

Select	Answer
A	To produce AM signals by using an electrically variable resistance
B	To produce PM or FM signals by using an electrically variable inductance or capacitance
C	To produce PM signals by using an electrically variable resistance
D	To produce AM signals by using an electrically variable inductance or capacitance

36. - E7F08

What is the function of decimation?

Select	Answer
A	Removing unnecessary significant digits
B	Converting data to binary code decimal form
C	Reducing the effective sample rate by removing samples
D	Attenuating the signal

37. - E7G01

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

Select	Answer
A	Very high
B	1000 ohms
C	Very low
D	100 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. - E8A02

Which of the following is a type of analog-to-digital conversion?

Select	Answer
A	Harmonic regeneration
B	Successive approximation
C	Phase reversal
D	Level shifting

40. - E8B08

What describes Orthogonal Frequency Division Multiplexing?

Select	Answer
A	A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference
B	A digital mode for narrow-band, slow-speed transmissions
C	A bandwidth compression technique using Fourier transforms
D	A frequency modulation technique that uses non-harmonically related frequencies

41. - E8C10

How may data rate be increased without increasing bandwidth?

Select	Answer
A	It is impossible
B	Using a more efficient digital code
C	Increasing analog-to-digital conversion resolution
D	Using forward error correction

42. - E8D10

What are some of the differences between the Baudot digital code and ASCII?

Select	Answer
A	Baudot uses 6 data bits per character, ASCII uses 7 or 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes
B	Baudot uses 7 data bits per character, ASCII uses 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes
C	Baudot uses 4 data bits per character, ASCII uses 7 or 8; Baudot uses 1 character as a letters/figures shift code, ASCII has no letters/figures code
D	Baudot uses 5 data bits per character, ASCII uses 7 or 8; Baudot uses 2 characters as letters/figures shift codes, ASCII has no letters/figures shift code

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	420 watts
B	286 watts
C	78.7 watts
D	1977 watts

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

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

46. - E9D12

Which of the following would provide the best RF ground for your station?

Select	Answer
A	A 50-ohm resistor connected to ground
B	An electrically short connection to a metal water pipe
C	An electrically short connection to 3 or 4 interconnected ground rods via a series RF choke
D	An electrically short connection to 3 or 4 interconnected ground rods driven into the Earth

47. - E9E03

What is the name of the matching system that uses a section of transmission line connected in parallel with the feed line at or near the feed point?

Select	Answer
A	The stub match
B	The delta match
C	The omega match
D	The gamma match

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	3.5 meters
B	4.3 meters
C	10.6 meters
D	5.3 meters

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	Prime axis
B	Polar axis
C	Reactance axis
D	Impedance axis

50. - E9H06

What is the triangulation method of direction finding?

Select	Answer
A	The geometric angles of sky waves from the source are used to determine its position
B	A fixed receiving station plots three headings to the signal source
C	A fixed receiving station uses three different antennas to plot the location of the signal source
D	Antenna headings from several different receiving locations are used to locate the signal source

Figure E6-2

Figure E9-3