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. - E0A11

Which of the following injuries can result from using high-power UHF or microwave transmitters?

Select	Answer
A	Localized heating of the body from RF exposure in excess of the MPE limits
B	Blood clotting from the intense magnetic field
C	Ingestion of ozone gas from the cooling system
D	Hearing loss caused by high voltage corona discharge

2. - E1A12

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

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

3. - E1B08

What limitations may the FCC place on an amateur station if its signal causes interference to domestic broadcast reception, assuming that the receivers involved are of good engineering design?

Select	Answer
A	The amateur station must avoid transmitting during certain hours on frequencies that cause the interference
B	The amateur station must cease operation on all frequencies below 30 MHz
C	The amateur station must cease operation on all frequencies above 30 MHz
D	The amateur station must cease operation

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 43 dB below
D	At least 63 dB below

5. - E1D03

What is a space telecommand station?

Select	Answer
A	An amateur station located in a satellite or a balloon more than 50 kilometers above the surface of the Earth
B	An amateur station that receives telemetry from a satellite or balloon more than 50 kilometers above the surface of the Earth
C	An amateur station that transmits communications to initiate, modify or terminate functions of a space station
D	An amateur station located on the surface of the Earth for communication with other Earth stations by means of Earth satellites

6. - E1E07

What should a VE do if a candidate fails to comply with the examiner's instructions during an amateur operator license examination?

Select	Answer
A	Allow the candidate to complete the examination, but invalidate the results
B	Immediately terminate everyone's examination and close the session
C	Immediately terminate the candidate's examination
D	Warn the candidate that continued failure to comply will result in termination of the examination

7. - E1F07

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

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

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 the satellite from emitting out-of-band signals
C	To prevent creating errors in the satellite telemetry
D	To avoid reducing the downlink power to all other users

9. - E2B08

What technique allows commercial analog TV receivers to be used for fast-scan TV operations on the 70 cm band?

Select	Answer
A	Using converted satellite TV dishes
B	Transmitting on the abandoned TV channel 2
C	Using USB and demodulating the signal with a computer sound card
D	Transmitting on channels shared with cable TV

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

11. - E2D02

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

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

12. - E2E10

Which of these digital modes has the narrowest bandwidth?

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

13. - E3A11

What is a typical range for tropospheric propagation of microwave signals?

Select	Answer
A	10 miles to 50 miles
B	2500 miles
C	100 miles to 300 miles
D	1200 miles

14. - E3B03

What is the best time of day for transequatorial propagation?

Select	Answer
A	Afternoon or early evening
B	Noon
C	Morning
D	Late at night

15. - E3C02

What is indicated by a rising A or K index?

Select	Answer
A	Decreasing disruption of the geomagnetic field
B	An increase in the critical frequency
C	Increasing disruption of the geomagnetic field
D	Higher levels of solar UV radiation

16. - E4A04

How is the compensation of an oscilloscope probe typically adjusted?

Select	Answer
A	A square wave is displayed and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible
B	A frequency standard is displayed and the probe is adjusted until the deflection time is accurate
C	A DC voltage standard is displayed and the probe is adjusted until the displayed voltage is accurate
D	A high frequency sine wave is displayed and the probe is adjusted for maximum amplitude

17. - E4B09

What is indicated if the current reading on an RF ammeter placed in series with the antenna feed line of a transmitter increases as the transmitter is tuned to resonance?

Select	Answer
A	There is more power going into the antenna
B	The transmitter is not properly neutralized
C	There is possibly a short to ground in the feed line
D	There is an impedance mismatch between the antenna and feed line

18. - E4C11

Why can an attenuator be used to reduce receiver overload on the lower frequency HF bands with little or no impact on signal-to-noise ratio?

Select	Answer
A	Atmospheric noise is generally greater than internally generated noise even after attenuation
B	Signals are attenuated separately from the noise
C	The attenuator has a low-pass filter to increase the strength of lower frequency signals
D	The attenuator has a noise filter to suppress interference

19. - E4D02

Which of the following describes problems caused by poor dynamic range in a receiver?

Select	Answer
A	Oscillator instability and severe audio distortion of all but the strongest received signals
B	Cross-modulation of the desired signal and insufficient audio power to operate the speaker
C	Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sideband
D	Spurious signals caused by cross-modulation and desensitization from strong adjacent signals

20. - E4E08

What current flows equally on all conductors of an unshielded multi-conductor cable?

Select	Answer
A	Common-mode current
B	Return current
C	Differential-mode current
D	Reactive current only

21. - E5A05

What is the result of increasing the Q of an impedance-matching circuit?

Select	Answer
A	Matching range is increased
B	Matching bandwidth is decreased
C	Matching bandwidth is increased
D	It has no effect on impedance matching

22. - E5B04

What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors, all in parallel?

Select	Answer
A	440 seconds
B	110 seconds
C	220 seconds
D	55 seconds

23. - E5C10

Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 400-ohm resistor and a 38-picofarad capacitor at 14 MHz?

Select	Answer
A	Point 2
B	Point 4
C	Point 6
D	Point 5

24. - E5D06

In what direction is the magnetic field oriented about a conductor in relation to the direction of electron flow?

Select	Answer
A	In a direction opposite to the current
B	In a circle around the conductor
C	In the same direction as the current
D	In all directions; omni-directional

25. - E6A05

How does DC input impedance at the gate of a field-effect transistor compare with the DC input impedance of a bipolar transistor?

Select	Answer
A	An FET has lower input impedance
B	An FET has higher input impedance
C	They are both high impedance
D	They are both low impedance

26. - E6B08

Which of the following is a Schottky barrier diode?

Select	Answer
A	Metal-semiconductor junction
B	Electrolytic rectifier
C	Thermionic emission diode
D	PIN junction

27. - E6C02

What happens when the level of a comparator's input signal crosses the threshold?

Select	Answer
A	The feedback loop becomes unstable
B	The comparator enters latch-up
C	The comparator changes its output state
D	The IC input can be damaged

28. - E6D12

What is inductor saturation?

Select	Answer
A	The inductor windings are over-coupled
B	Adjacent inductors become over-coupled
C	The inductor's voltage rating is exceeded causing a flashover
D	The ability of the inductor's core to store magnetic energy has been exceeded

29. - E6E08

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

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

30. - E6F08

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

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

31. - E7A06

What is a characteristic of a monostable multivibrator?

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

32. - E7B15

What is one way to prevent thermal runaway in a bipolar transistor amplifier?

Select	Answer
A	Select transistors with high beta
B	Neutralization
C	All these choices are correct
D	Use a resistor in series with the emitter

33. - E7C05

Which filter type is described as having ripple in the passband and a sharp cutoff?

Select	Answer
A	A passive op-amp filter
B	A Butterworth filter
C	An active LC filter
D	A Chebyshev filter

34. - E7D11

What is the function of the pass transistor in a linear voltage regulator circuit?

Select	Answer
A	Maintains nearly constant output voltage over a wide range of load current
B	Provides a stable input impedance over a wide range of source voltage
C	Maintains nearly constant output impedance over a wide range of load current
D	Permits a wide range of output voltage settings

35. - E7E10

How does a diode envelope detector function?

Select	Answer
A	By mixing signals with noise in the transition region of the diode
B	By sensing the change of reactance in the diode with respect to frequency
C	By breakdown of the Zener voltage
D	By rectification and filtering of RF signals

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	Mixing products are converted to voltages and subtracted by adder circuits
C	Signals are combined in quadrature phase relationship
D	Varying quartz crystal characteristics emulated in digital form

37. - E7G11

What absolute voltage gain can be expected from the circuit in Figure E7-3 when R1 is 3300 ohms and RF is 47 kilohms?

Select	Answer
A	14
B	7
C	28
D	0.07

38. - E7H03

How is positive feedback supplied in a Hartley oscillator?

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

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	Vector analysis
B	Numerical analysis
C	Fourier analysis
D	Differential 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	1000
B	3
C	0.3
D	3000

41. - E8C11

What is the relationship between symbol rate and baud?

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

42. - E8D05

What is the most common method of reducing key clicks?

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

43. - E9A10

Which of the following improves the efficiency of a ground-mounted quarter-wave vertical antenna?

Select	Answer
A	Installing a radial system
B	All these choices are correct
C	Isolating the coax shield from ground
D	Shortening the radiating element

44. - E9B05

What type of antenna pattern is shown in Figure E9-2?

Select	Answer
A	Polarization
B	Elevation
C	Radiation resistance
D	Azimuth

45. - E9C08

What is a folded dipole antenna?

Select	Answer
A	A type of ground-plane antenna
B	A dipole configured to provide forward gain
C	A dipole one-quarter wavelength long
D	A half-wave dipole with an additional parallel wire connecting its two ends

46. - E9D08

What happens as the Q of an antenna increases?

Select	Answer
A	SWR bandwidth decreases
B	Gain is reduced
C	SWR bandwidth increases
D	More common-mode current is present on the feed line

47. - E9E10

Which of these choices is an effective way to match an antenna with a 100-ohm feed point impedance to a 50-ohm coaxial cable feed line?

Select	Answer
A	Insert a 1/4-wavelength piece of 75-ohm coaxial cable transmission line in series between the antenna terminals and the 50-ohm feed cable
B	Connect a 1/4-wavelength open stub of 300-ohm twinlead in parallel with the coaxial feed line where it connects to the antenna
C	Connect a 1/2 wavelength shorted stub of 75-ohm cable in parallel with the 50-ohm cable where it attaches to the antenna
D	Insert a 1/2 wavelength piece of 300-ohm twinlead in series between the antenna terminals and the 50-ohm feed cable

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	3.5 meters
C	5.3 meters
D	4.3 meters

49. - E9G08

What is the process of normalization with regard to a Smith chart?

Select	Answer
A	Reassigning prime center with regard to the reactance axis
B	Reassigning impedance values with regard to the prime center
C	Reassigning resistance values with regard to the reactance axis
D	Reassigning reactance values with regard to the resistance axis

50. - E9H10

How can the output voltage of a multiple-turn receiving loop antenna be increased?

Select	Answer
A	By utilizing high impedance wire for the coupling loop
B	By reducing the permeability of the loop shield
C	By winding adjacent turns in opposing directions
D	By increasing the number of turns and/or the area

Figure E5-1

Figure E7-3

Figure E9-2