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

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1. - E0A03

Over what range of frequencies are the FCC human body RF exposure limits most restrictive?

Select	Answer
A	300 kHz to 3 MHz
B	300 to 3000 MHz
C	3 to 30 MHz
D	30 to 300 MHz

2. - E1A12

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

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

3. - E1B05

What is the National Radio Quiet Zone?

Select	Answer
A	An area in Puerto Rico surrounding the Arecibo Radio Telescope
B	An area in Florida surrounding Cape Canaveral
C	An area in New Mexico surrounding the White Sands Test Area
D	An area surrounding the National Radio Astronomy Observatory

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. - E1D12

Which of the following amateur stations may transmit one-way communications?

Select	Answer
A	A message forwarding station or automatically controlled digital station
B	A space station, beacon station, or telecommand station
C	All these choices are correct
D	A local repeater or linked repeater station

6. - E1E10

What must the administering VEs do after the administration of a successful examination for an amateur operator license?

Select	Answer
A	They must collect and send the documents to the FCC according to instructions
B	They must collect and send the documents to the NCVEC for grading
C	They must collect and submit the documents to the coordinating VEC for grading
D	They must submit the application document to the coordinating VEC according to the coordinating VEC instructions

7. - E1F07

When may an amateur station send a message to a business?

Select	Answer
A	When the total money involved does not exceed $25
B	When neither the amateur nor his or her employer has a pecuniary interest in the communications
C	When the control operator is employed by the FCC or another government agency
D	When transmitting international third-party communications

8. - E2A01

What is the direction of an ascending pass for an amateur satellite?

Select	Answer
A	From north to south
B	From west to east
C	From east to west
D	From south to north

9. - E2B04

How is color information sent in analog SSTV?

Select	Answer
A	Color is amplitude modulated on the frequency modulated intensity signal
B	Color information is sent on a 2.8 kHz subcarrier
C	Color lines are sent sequentially
D	Color is sent in a color burst at the end of each line

10. - E2C03

From which of the following bands is amateur radio contesting generally excluded?

Select	Answer
A	30 meters
B	6 meters
C	33 centimeters
D	2 meters

11. - E2D02

Which of the following is a good technique for making meteor scatter contacts?

Select	Answer
A	Use of special digital modes
B	15-second timed transmission sequences with stations alternating based on location
C	Short transmissions with rapidly repeated call signs and signal reports
D	All these choices are correct

12. - E2E10

Which of these digital modes has the narrowest bandwidth?

Select	Answer
A	PSK31
B	170 Hz shift, 45-baud RTTY
C	MFSK16
D	300-baud packet

13. - E3A01

What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?

Select	Answer
A	12,000 miles, if the moon is visible by both stations
B	5000 miles, if the moon is at perigee
C	2000 miles, if the moon is at apogee
D	500 miles, if the moon is at perigee

14. - E3B11

At what time of day can sporadic E propagation occur?

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

15. - E3C09

How does the intensity of an X3 flare compare to that of an X2 flare?

Select	Answer
A	50 percent greater
B	Twice as great
C	10 percent greater
D	Four times as great

16. - E4A05

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

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

17. - E4B11

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

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

18. - E4C10

What is an advantage of having a variety of receiver IF bandwidths from which to select?

Select	Answer
A	Multiple frequencies can be received simultaneously if desired
B	Receive bandwidth can be set to match the modulation bandwidth, maximizing signal-to-noise ratio and minimizing interference
C	The noise figure of the RF amplifier can be adjusted to match the modulation type, thus increasing receiver sensitivity
D	Receiver power consumption can be reduced when wider bandwidth is not required

19. - E4D08

What causes intermodulation in an electronic circuit?

Select	Answer
A	Lack of neutralization
B	Nonlinear circuits or devices
C	Positive feedback
D	Too little gain

20. - E4E09

What undesirable effect can occur when using an IF noise blanker?

Select	Answer
A	Received audio in the speech range might have an echo effect
B	Nearby signals may appear to be excessively wide even if they meet emission standards
C	FM signals can no longer be demodulated
D	The audio frequency bandwidth of the received signal might be compressed

21. - E5A07

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

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

22. - E5B11

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 25 ohms, R is 100 ohms, and XL is 50 ohms?

Select	Answer
A	14 degrees with the voltage lagging the current
B	76 degrees with the voltage leading the current
C	76 degrees with the voltage lagging the current
D	14 degrees with the voltage leading the current

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

24. - E5D05

What is the power factor of an RL circuit having a 30-degree phase angle between the voltage and the current?

Select	Answer
A	0.5
B	0.866
C	1.73
D	0.577

25. - E6A06

What is the beta of a bipolar junction transistor?

Select	Answer
A	The frequency at which the current gain is reduced to 0.707
B	The change in collector current with respect to base current
C	The switching speed
D	The breakdown voltage of the base to collector junction

26. - E6B03

What type of bias is required for an LED to emit light?

Select	Answer
A	Forward bias
B	Zero bias
C	Reverse bias
D	Inductive bias

27. - E6C05

What is an advantage of CMOS logic devices over TTL devices?

Select	Answer
A	Lower power consumption
B	Immune to damage from static discharge
C	Differential output capability
D	Lower distortion

28. - E6D09

What devices are commonly used as VHF and UHF parasitic suppressors at the input and output terminals of a transistor HF amplifier?

Select	Answer
A	Steel-core toroids
B	Ferrite beads
C	Electrolytic capacitors
D	Butterworth filters

29. - E6E09

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

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

30. - E6F08

Why are optoisolators often used in conjunction with solid-state circuits when switching 120 VAC?

Select	Answer
A	Optoisolators provide a low impedance link between a control circuit and a power circuit
B	Optoisolators provide impedance matching between the control circuit and power circuit
C	Optoisolators provide a very high degree of electrical isolation between a control circuit and the circuit being switched
D	Optoisolators eliminate the effects of reflected light in the control circuit

31. - E7A10

What is a truth table?

Select	Answer
A	A diagram showing logic states when the digital device output is true
B	A table of logic symbols that indicate the high logic states of an op-amp
C	A table of logic symbols that indicate the logic states of an op-amp
D	A list of inputs and corresponding outputs for a digital device

32. - E7B02

What is a Class D amplifier?

Select	Answer
A	A type of amplifier that uses switching technology to achieve high efficiency
B	An amplifier that uses drift-mode FETs for high efficiency
C	A low power amplifier that uses a differential amplifier for improved linearity
D	A frequency doubling amplifier

33. - E7C08

Which of the following factors has the greatest effect on the bandwidth and response shape of a crystal ladder filter?

Select	Answer
A	The gain of the RF stage preceding the filter
B	The relative frequencies of the individual crystals
C	The amplitude of the signals passing through the filter
D	The DC voltage applied to the quartz crystal

34. - E7D03

What device is typically used as a stable voltage reference in a linear voltage regulator?

Select	Answer
A	A tunnel diode
B	A varactor diode
C	A Zener diode
D	An SCR

35. - E7E02

What is the function of a reactance modulator?

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

36. - E7F11

What sets the minimum detectable signal level for a direct-sampling SDR receiver in the absence of atmospheric or thermal noise?

Select	Answer
A	Reference voltage level and sample width in bits
B	Sample clock phase noise
C	Missing codes and jitter
D	Data storage transfer rate

37. - E7G09

What will be the output voltage of the circuit shown in Figure E7-3 if R1 is 1000 ohms, RF is 10,000 ohms, and 0.23 volts DC is applied to the input?

Select	Answer
A	-2.3 volts
B	0.23 volts
C	-0.23 volts
D	2.3 volts

38. - E7H03

How is positive feedback supplied in a Hartley oscillator?

Select	Answer
A	Through link coupling
B	Through a capacitive divider
C	Through a tapped coil
D	Through a neutralizing capacitor

39. - E8A06

What is the approximate ratio of PEP-to-average power in a typical single-sideband phone signal?

Select	Answer
A	2.5 to 1
B	100 to 1
C	25 to 1
D	1 to 1

40. - E8B11

What is digital time division multiplexing?

Select	Answer
A	Two or more data streams are assigned to discrete sub-carriers on an FM transmitter
B	Two or more signals are quadrature modulated to increase bandwidth efficiency
C	Two or more data streams share the same channel by transmitting time of transmission as the sub-carrier
D	Two or more signals are arranged to share discrete time slots of a data transmission

41. - E8C03

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

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

42. - E8D04

What is the primary effect of extremely short rise or fall time on a CW signal?

Select	Answer
A	The generation of RF harmonics
B	More difficult to copy
C	The generation of key clicks
D	Limits data speed

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	63.2 watts
C	159 watts
D	632 watts

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	25 degrees
C	75 degrees
D	45 degrees

45. - E9C05

Which of the following is a type of OCFD antenna?

Select	Answer
A	A multiband dipole antenna using one-way circular polarization for frequency diversity
B	A folded dipole center-fed with 300-ohm transmission line
C	A remotely tunable dipole antenna using orthogonally controlled frequency diversity
D	A dipole fed approximately 1/3 the way from one end with a 4:1 balun to provide multiband operation

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

47. - E9E08

What is a use for a Wilkinson divider?

Select	Answer
A	It is used to feed low-impedance loads from a high-impedance source
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 divide power equally between two 50-ohm loads while maintaining 50-ohm input impedance
D	It is used to feed high-impedance antennas from a low-impedance source

48. - E9F11

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

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

49. - E9G07

On the Smith chart shown in Figure E9-3, what is the only straight line shown?

Select	Answer
A	The reactance axis
B	The current axis
C	The voltage axis
D	The resistance axis

50. - E9H11

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

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

Figure E7-3

Figure E9-2

Figure E9-3