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

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1. - E0A10

What toxic material may be present in some electronic components such as high voltage capacitors and transformers?

Select	Answer
A	Polyethylene
B	Polychlorinated biphenyls
C	Polytetrafluoroethylene
D	Polymorphic silicon

2. - E1A01

Which of the following carrier frequencies is illegal for LSB AFSK emissions on the 17 meter band RTTY and data segment of 18.068 to 18.110 MHz?

Select	Answer
A	18.110 MHz
B	18.100 MHz
C	18.068 MHz
D	18.107 MHz

3. - E1B05

What is the National Radio Quiet Zone?

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

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 43 dB below
B	At least 73 dB below
C	At least 63 dB below
D	At least 53 dB below

5. - E1D12

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

Select	Answer
A	A local repeater or linked repeater station
B	A space station, beacon station, or telecommand station
C	A message forwarding station or automatically controlled digital station
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 70%
B	Minimum passing score of 77%
C	Minimum passing score of 80%
D	Minimum passing score of 74%

7. - E1F04

Which of the following geographic descriptions approximately describes "Line A"?

Select	Answer
A	A line roughly parallel to and south of the border between the U.S. and Canada
B	A line roughly parallel to and north of the border between the U.S. and Mexico
C	A line roughly parallel to and west of the U.S. Atlantic coastline
D	A line roughly parallel to and east of the U.S. Pacific coastline

8. - E2A11

What type of antenna can be used to minimize the effects of spin modulation and Faraday rotation?

Select	Answer
A	A linearly polarized antenna
B	An isotropic antenna
C	A log-periodic dipole array
D	A circularly polarized antenna

9. - E2B03

How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?

Select	Answer
A	By scanning lines from left to right in one field and right to left in the next
B	By scanning each field from bottom to top
C	By scanning two fields simultaneously
D	By scanning odd numbered lines in one field and even numbered lines in the next

10. - E2C07

What is the Cabrillo format?

Select	Answer
A	A standard for submission of electronic contest logs
B	A method of exchanging information during a contest QSO
C	The most common set of contest rules
D	The rules of order for meetings between contest sponsors

11. - E2D11

Which of the following data are used by the APRS network to communicate station location?

Select	Answer
A	Radio direction finding spectrum analysis
B	Latitude and longitude
C	Polar coordinates
D	Time and frequency

12. - E2E09

Which of the following HF digital modes uses variable-length coding for bandwidth efficiency?

Select	Answer
A	MT63
B	PACTOR
C	RTTY
D	PSK31

13. - E3A12

What is the cause of auroral activity?

Select	Answer
A	The interaction in the F2 layer between the solar wind and the Van Allen belt
B	The interaction in the E layer of charged particles from the Sun with the Earth's magnetic field
C	Meteor showers concentrated in the extreme northern and southern latitudes
D	An extreme low-pressure area in the polar regions

14. - E3B10

Why is chordal hop propagation desirable?

Select	Answer
A	Atmospheric noise is lower in the direction of chordal hop propagation
B	The signal experiences less loss compared to multi-hop using Earth as a reflector
C	The MUF for chordal hop propagation is much lower than for normal skip propagation
D	Signals travel faster along ionospheric chords

15. - E3C07

Which of the following descriptors indicates the greatest solar flare intensity?

Select	Answer
A	Class X
B	Class M
C	Class A
D	Class B

16. - E4A11

How should an antenna analyzer be connected when measuring antenna resonance and feed point impedance?

Select	Answer
A	Connect the antenna feed line directly to the analyzer's connector
B	Connect the analyzer via a high-impedance transformer to the antenna
C	Loosely couple the analyzer near the antenna base
D	Loosely couple the antenna and a dummy load to the analyzer

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S12
B	S21
C	S11
D	S22

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

19. - E4D03

How can intermodulation interference between two repeaters occur?

Select	Answer
A	When the signals from the transmitters are reflected in phase from airplanes passing overhead
B	When the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmitters
C	When the repeaters are in close proximity and the signals cause feedback in the final amplifier of one or both transmitters
D	When the signals from the transmitters are reflected out of phase from airplanes passing overhead

20. - E4E04

How can conducted and radiated noise caused by an automobile alternator be suppressed?

Select	Answer
A	By installing filter capacitors in series with the DC power lead and a blocking capacitor in the field lead
B	By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads
C	By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead
D	By installing a noise suppression resistor and a blocking capacitor in both leads

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	Maximum
D	R/L

22. - E5B03

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

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

23. - E5C03

Which of the following represents an inductive reactance in polar coordinates?

Select	Answer
A	A negative magnitude
B	A negative phase angle
C	A positive magnitude
D	A positive 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	0.577
C	0.866
D	1.73

25. - E6A12

Why do many MOSFET devices have internally connected Zener diodes on the gates?

Select	Answer
A	To protect the substrate from excessive voltages
B	To reduce the chance of static damage to the gate
C	To provide a voltage reference for the correct amount of reverse-bias gate voltage
D	To keep the gate voltage within specifications and prevent the device from overheating

26. - E6B11

What is used to control the attenuation of RF signals by a PIN diode?

Select	Answer
A	A sub-harmonic pump signal
B	Forward DC bias current
C	Reverse voltage larger than the RF signal
D	Capacitance of an RF coupling capacitor

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 allow the comparator to be used with AC input signals
D	To cause the output to change states continually

28. - E6D04

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

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

29. - E6E03

Which of the following materials is likely to provide the highest frequency of operation when used in MMICs?

Select	Answer
A	Silicon dioxide
B	Silicon
C	Silicon nitride
D	Gallium nitride

30. - E6F06

Which of these materials is most commonly used to create photoconductive devices?

Select	Answer
A	An ordinary metal
B	A heavy metal
C	A liquid semiconductor
D	A crystalline semiconductor

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 switches momentarily to the opposite binary state and then returns to its original state after a set time
C	It stores one bit of data in either a 0 or 1 state
D	It maintains a constant output voltage, regardless of variations in the input voltage

32. - E7B05

What can be done to prevent unwanted oscillations in an RF power amplifier?

Select	Answer
A	Install parasitic suppressors and/or neutralize the stage
B	Tune both the input and output for maximum power
C	Use a phase inverter in the output filter
D	Tune the stage for maximum SWR

33. - E7C03

What advantage does a series-L Pi-L-network have over a series-L Pi-network for impedance matching between the final amplifier of a vacuum-tube transmitter and an antenna?

Select	Answer
A	Higher efficiency
B	Greater harmonic suppression
C	Greater transformation range
D	Does not require a capacitor

34. - E7D08

What type of circuit is shown in Figure E7-2?

Select	Answer
A	Monostable multivibrator
B	Grounded emitter amplifier
C	Switching voltage regulator
D	Linear voltage regulator

35. - E7E03

What is a frequency discriminator stage in a FM receiver?

Select	Answer
A	A circuit for detecting FM signals
B	An automatic band-switching circuit
C	An FM generator circuit
D	A circuit for filtering two closely adjacent signals

36. - E7F13

What is the function of taps in a digital signal processing filter?

Select	Answer
A	To reduce excess signal pressure levels
B	Provide access for debugging software
C	Select the point at which baseband signals are generated
D	Provide incremental signal delays for filter algorithms

37. - E7G02

What is ringing in a filter?

Select	Answer
A	An echo caused by a long time delay
B	Partial cancellation of the signal over a range of frequencies
C	Undesired oscillations added to the desired signal
D	A reduction in high frequency response

38. - E7H10

What information is contained in the lookup table of a direct digital synthesizer (DDS)?

Select	Answer
A	The phase relationship between a voltage-controlled oscillator and the output waveform
B	The phase relationship between a reference oscillator and the output waveform
C	Frequently used receiver and transmitter frequencies
D	Amplitude values that represent the desired waveform

39. - E8A03

What type of wave does a Fourier analysis show to be made up of sine waves of a given fundamental frequency plus all its harmonics?

Select	Answer
A	A sawtooth wave
B	A cosine wave
C	A sine wave
D	A square wave

40. - E8B11

What is digital time division multiplexing?

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

41. - E8C11

What is the relationship between symbol rate and baud?

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

42. - E8D01

Why are received spread spectrum signals resistant to interference?

Select	Answer
A	The receiver is always equipped with a digital blanker
B	If interference is detected by the receiver it will signal the transmitter to change frequencies
C	Signals not using the spread spectrum algorithm are suppressed in the receiver
D	The high power used by a spread spectrum transmitter keeps its signal from being easily overpowered

43. - E9A01

What is an isotropic antenna?

Select	Answer
A	A theoretical, omnidirectional antenna used as a reference for antenna gain
B	A horizontally polarized antenna used to compare Yagi antennas
C	A grounded antenna used to measure Earth conductivity
D	A spacecraft antenna used to direct signals toward Earth

44. - E9B02

In the antenna radiation pattern shown in Figure E9-1, what is the front-to-back ratio?

Select	Answer
A	14 dB
B	24 dB
C	18 dB
D	36 dB

45. - E9C10

Which of the following describes a Zepp antenna?

Select	Answer
A	A vertical array capable of quickly changing the direction of maximum radiation by changing phasing lines
B	A dipole constructed from zip cord
C	An omni-directional antenna commonly used for satellite communications
D	An end-fed dipole antenna

46. - E9D01

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

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

47. - E9E09

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

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

48. - E9F09

What is the approximate physical length of a foam polyethylene dielectric coaxial transmission line that is electrically 1/4 wavelength long at 7.2 MHz?

Select	Answer
A	5.2 meters
B	10.4 meters
C	8.3 meters
D	6.9 meters

49. - E9G04

What are the two families of circles and arcs that make up a Smith chart?

Select	Answer
A	Voltage and impedance
B	Resistance and reactance
C	Resistance and voltage
D	Reactance and voltage

50. - E9H03

What is Receiving Directivity Factor (RDF)?

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

Figure E7-2

Figure E9-1