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

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	14.100 MHz
B	14.149 MHz
C	14.070 MHz
D	14.349 MHz

3. - E1B12

What must the control operator of a repeater operating in the 70 cm band do if a radiolocation system experiences interference from that repeater?

Select	Answer
A	Cease operation or make changes to the repeater to mitigate the interference
B	All these choices are correct
C	File an FAA NOTAM (Notice to Airmen) with the repeater system's ERP, call sign, and six-character grid locator
D	Reduce the repeater antenna HAAT (Height Above Average Terrain)

4. - E1C09

What is the highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz?

Select	Answer
A	3.0
B	0.5
C	2.0
D	1.0

5. - E1D10

Which amateur stations are eligible to be telecommand stations of space stations (subject to the privileges of the class of operator license held by the control operator of the station)?

Select	Answer
A	Any amateur station so designated by the space station licensee
B	Any amateur station designated by NASA
C	Any amateur station so designated by the ITU
D	All these choices are correct

6. - E1E05

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

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

7. - E1F10

Who may be the control operator of an auxiliary station?

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

8. - E2A06

What are Keplerian elements?

Select	Answer
A	Encrypting codes used for spread spectrum modulation
B	High-emission heater filaments used in magnetron tubes
C	Parameters that define the orbit of a satellite
D	Phase reversing elements in a Yagi antenna

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 contains chroma information
C	The vestigial sideband carries the audio information
D	Vestigial sideband reduces bandwidth while allowing for simple video detector circuitry

10. - E2C12

What technique do individual nodes use to form a mesh network?

Select	Answer
A	Custom code plugs for the local trunking systems
B	Acting as store-and-forward digipeaters
C	Discovery and link establishment protocols
D	Forward error correction and Viterbi codes

11. - E2D08

What type of packet frame is used to transmit APRS beacon data?

Select	Answer
A	Unnumbered Information
B	Connect
C	Disconnect
D	Acknowledgement

12. - E2E04

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

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

13. - E3A07

Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?

Select	Answer
A	Urban areas
B	Bodies of water
C	Mountain ranges
D	Forests

14. - E3B04

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

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

15. - E3C08

What does the space weather term G5 mean?

Select	Answer
A	Waning sunspot numbers
B	Moderate solar wind
C	Very low solar activity
D	An extreme geomagnetic storm

16. - E4A09

Which of the following is good practice when using an oscilloscope probe?

Select	Answer
A	Never use a DC-coupled probe to measure an AC circuit
B	All these choices are correct
C	Never use a high-impedance probe to measure a low-impedance circuit
D	Keep the signal ground connection of the probe as short as possible

17. - E4B11

Which of the following can be measured with a vector network analyzer?

Select	Answer
A	Output impedance
B	Reflection coefficient
C	All these choices are correct
D	Input impedance

18. - E4C04

What is the noise figure of a receiver?

Select	Answer
A	The ratio in dB of the noise generated by the receiver to the theoretical minimum noise
B	The ratio of atmospheric noise to phase noise
C	The ratio of the noise bandwidth in hertz to the theoretical bandwidth of a resistive network
D	The ratio of thermal noise to atmospheric noise

19. - E4D09

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

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

20. - E4E11

What could cause local AM broadcast band signals to combine to generate spurious signals in the MF or HF bands?

Select	Answer
A	You are receiving skywave signals from a distant station
B	One or more of the broadcast stations is transmitting an over-modulated signal
C	Nearby corroded metal joints are mixing and re-radiating the broadcast signals
D	Your station receiver IF amplifier stage is defective

21. - E5A09

How is the Q of an RLC parallel resonant circuit calculated?

Select	Answer
A	Reactance of either the inductance or capacitance multiplied by the resistance
B	Resistance divided by the reactance of either the inductance or capacitance
C	Reactance of either the inductance or capacitance divided by the resistance
D	Reactance of the inductance multiplied by the reactance of the capacitance

22. - E5B05

What happens to the magnitude of a pure reactance when it is converted to a susceptance?

Select	Answer
A	It is shifted by 90 degrees
B	It is unchanged
C	It becomes the reciprocal
D	The sign is reversed

23. - E5C02

How are impedances described in polar coordinates?

Select	Answer
A	By phase angle and magnitude
B	By X and R values
C	By Y and G values
D	By real and imaginary parts

24. - E5D02

Why is it important to keep lead lengths short for components used in circuits for VHF and above?

Select	Answer
A	All these choices are correct
B	To avoid unwanted inductive reactance
C	To increase the thermal time constant
D	To maintain component lifetime

25. - E6A10

In Figure E6-1, what is the schematic symbol for an N-channel dual-gate MOSFET?

Select	Answer
A	5
B	2
C	4
D	6

26. - E6B09

What is a common use for point-contact diodes?

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

27. - E6C08

In Figure E6-3, what is the schematic symbol for a NAND gate?

Select	Answer
A	3
B	2
C	1
D	4

28. - E6D04

Which materials are commonly used as a core in an inductor?

Select	Answer
A	Polystyrene and polyethylene
B	Teflon and Delrin
C	Cobalt and aluminum
D	Ferrite and brass

29. - E6E05

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

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

30. - E6F04

What is the photovoltaic effect?

Select	Answer
A	The tendency of a battery to discharge when exposed to light
B	The conversion of voltage to current when exposed to light
C	The conversion of light to electrical energy
D	The conversion of electrical energy to mechanical energy

31. - E7A04

How many flip-flops are required to divide a signal frequency by 4?

Select	Answer
A	8
B	1
C	4
D	2

32. - E7B08

How can an RF power amplifier be neutralized?

Select	Answer
A	By increasing the driving power
B	By feeding a 180-degree out-of-phase portion of the output back to the input
C	By reducing the driving power
D	By feeding an in-phase component of the output back to the input

33. - E7C02

Which of the following is a property of a T-network with series capacitors and a parallel shunt inductor?

Select	Answer
A	It is a band-pass filter
B	It is a low-pass filter
C	It is a notch filter
D	It is a high-pass filter

34. - E7D05

Which of the following types of linear voltage regulator places a constant load on the unregulated voltage source?

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

35. - E7E08

What are the principal frequencies that appear at the output of a mixer circuit?

Select	Answer
A	1.414 and 0.707 times the input frequency
B	The square root of the product of input frequencies
C	The two input frequencies along with their sum and difference frequencies
D	Two and four times the original frequency

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	6 bits
B	8 bits
C	10 bits
D	4 bits

37. - E7G05

How can unwanted ringing and audio instability be prevented in an op-amp RC audio filter circuit?

Select	Answer
A	Restrict gain but increase Q
B	Restrict both gain and Q
C	Increase both gain and Q
D	Restrict Q but increase gain

38. - E7H02

What is a microphonic?

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

39. - E8A04

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

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

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 bandwidth compression technique using Fourier transforms
C	A frequency modulation technique that uses non-harmonically related frequencies
D	A digital mode for narrow-band, slow-speed transmissions

41. - E8C11

What is the relationship between symbol rate and baud?

Select	Answer
A	Baud is twice the symbol rate
B	They are the same
C	Baud is only used for RTTY
D	Symbol rate is only used for packet-based modes

42. - E8D02

What spread spectrum communications technique uses a high-speed binary bit stream to shift the phase of an RF carrier?

Select	Answer
A	Direct sequence
B	Phase compandored spread spectrum
C	Frequency hopping
D	Binary phase-shift keying

43. - E9A07

What is the effective isotropic radiated power of a repeater station with 200 watts transmitter power output, 2 dB feed line loss, 2.8 dB duplexer loss, 1.2 dB circulator loss, and 7 dBi antenna gain?

Select	Answer
A	252 watts
B	159 watts
C	632 watts
D	63.2 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	The total amount of radiation from the directional antenna is stronger by its front-to-back ratio
B	They are the same
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 increased by the gain of the antenna

45. - E9C06

What is the effect of adding a terminating resistor to a rhombic antenna?

Select	Answer
A	It reflects the standing waves on the antenna elements back to the transmitter
B	It changes the radiation pattern from horizontal to vertical polarization
C	It decreases the ground loss
D	It changes the radiation pattern from bidirectional to unidirectional

46. - E9D01

How much does the gain of an ideal parabolic dish antenna change when the operating frequency is doubled?

Select	Answer
A	4 dB
B	2 dB
C	6 dB
D	3 dB

47. - E9E09

Which of the following is used to shunt-feed a grounded tower at its base?

Select	Answer
A	Gamma match
B	Double-bazooka match
C	Hairpin match
D	All these choices are correct

48. - E9F10

What impedance does a 1/8-wavelength transmission line present to a generator when the line is shorted at the far end?

Select	Answer
A	The same as the characteristic impedance of the line
B	Zero
C	A capacitive reactance
D	An inductive reactance

49. - E9G02

What type of coordinate system is used in a Smith chart?

Select	Answer
A	Voltage lines and current chords
B	Voltage circles and current arcs
C	Resistance circles and reactance arcs
D	Resistance lines and reactance chords

50. - E9H05

What is the main drawback of a small wire-loop antenna for direction finding?

Select	Answer
A	It is practical for use only on VHF and higher bands
B	It has no clearly defined null
C	It has a bidirectional pattern
D	All these choices are correct

Figure E6-1

Figure E6-3