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

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1. - E0A01

What is the primary function of an external earth connection or ground rod?

Select	Answer
A	Reduce received noise
B	Lightning protection
C	Reduce RF current flow between pieces of equipment
D	Reduce RFI to telephones and home entertainment systems

2. - E1A07

What is the maximum power permitted on the 2200 meter band?

Select	Answer
A	50 watts PEP
B	1 watt EIRP (Equivalent isotropic radiated power)
C	100 watts PEP
D	5 watts EIRP (Equivalent isotropic radiated power)

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

4. - E1C01

What is the maximum bandwidth for a data emission on 60 meters?

Select	Answer
A	170 Hz
B	1.5 kHz
C	2.8 kHz
D	60 Hz

5. - E1D01

What is the definition of telemetry?

Select	Answer
A	One-way transmission of measurements at a distance from the measuring instrument
B	Two-way transmissions of data
C	Two-way transmissions in excess of 1000 feet
D	One-way transmission that initiates, modifies, or terminates the functions of a device at a distance

6. - E1E02

Who does Part 97 task with maintaining the pools of questions for all U.S. amateur license examinations?

Select	Answer
A	The VEs
B	The ARRL
C	The FCC
D	The VECs

7. - E1F06

Under what circumstances might the FCC issue a Special Temporary Authority (STA) to an amateur station?

Select	Answer
A	To provide temporary operation while awaiting normal licensing
B	To provide for experimental amateur communications
C	To provide additional spectrum for personal use
D	To allow regular operation on Land Mobile channels

8. - E2A05

What do the letters in a satellite's mode designator specify?

Select	Answer
A	The uplink and downlink frequency ranges
B	The polarization of uplink and downlink signals
C	Power limits for uplink and downlink transmissions
D	The location of the ground control station

9. - E2B09

What hardware, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM)?

Select	Answer
A	A special notch filter to remove synchronization pulses
B	A special IF converter
C	A special front end limiter
D	No other hardware is needed

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 once or twice
C	Send your full call sign and grid square
D	Send the call sign of the DX station three times, the words this is,then your call sign three times

11. - E2D07

What digital protocol is used by APRS?

Select	Answer
A	PACTOR
B	AMTOR
C	802.11
D	AX.25

12. - E2E04

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

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

13. - E3A12

What is the cause of auroral activity?

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

14. - E3B11

At what time of day can sporadic E propagation occur?

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

15. - E3C02

What is indicated by a rising A or K index?

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

16. - E4A07

Which of the following is an advantage of using an antenna analyzer compared to an SWR bridge to measure antenna SWR?

Select	Answer
A	Antenna analyzers do not need an external RF source
B	Antenna analyzers automatically tune your antenna for resonance
C	Antenna analyzers display a time-varying representation of the modulation envelope
D	All these choices are correct

17. - E4B03

Which S parameter is equivalent to forward gain?

Select	Answer
A	S22
B	S21
C	S12
D	S11

18. - E4C08

An SDR receiver is overloaded when input signals exceed what level?

Select	Answer
A	The reference voltage of the analog-to-digital converter
B	One-half the maximum sampling buffer size
C	One-half the maximum sample rate
D	The maximum count value of the analog-to-digital converter

19. - E4D02

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

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

20. - E4E07

Which of the following can cause shielded cables to radiate or receive interference?

Select	Answer
A	Common-mode currents on the shield and conductors
B	Tying all ground connections to a common point resulting in differential-mode currents in the shield
C	Low inductance ground connections at both ends of the shield
D	Use of braided shielding material

21. - E5A04

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

Select	Answer
A	Approximately equal to circuit resistance
B	High compared to the circuit resistance
C	Approximately equal to inductive reactance
D	Low compared to the circuit resistance

22. - E5B05

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

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

23. - E5C12

Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and a 19-picofarad capacitor at 21.200 MHz?

Select	Answer
A	Point 1
B	Point 7
C	Point 8
D	Point 3

24. - E5D11

What is the power factor of an RL circuit having a 60-degree phase angle between the voltage and the current?

Select	Answer
A	0.866
B	0.5
C	1.73
D	1.414

25. - E6A02

Which of the following semiconductor materials contains excess free electrons?

Select	Answer
A	Insulated gate
B	Bipolar
C	P-type
D	N-type

26. - E6B05

What characteristic of a PIN diode makes it useful as an RF switch?

Select	Answer
A	Low junction capacitance
B	Ability to dissipate large amounts of power
C	Reverse bias controls its forward voltage drop
D	Extremely high reverse breakdown voltage

27. - E6C04

Which of the following is an advantage of BiCMOS logic?

Select	Answer
A	Its simplicity results in much less expensive devices than standard CMOS
B	All these choices are correct
C	It is immune to electrostatic damage
D	It has the high input impedance of CMOS and the low output impedance of bipolar transistors

28. - E6D03

Which of the following is an aspect of the piezoelectric effect?

Select	Answer
A	Mechanical deformation of material by the application of a magnetic field
B	Increased conductivity in the presence of light
C	Generation of electrical energy in the presence of light
D	Mechanical deformation of material by the application of a voltage

29. - E6E09

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

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

30. - E6F03

What is the most common configuration of an optoisolator or optocoupler?

Select	Answer
A	A frequency modulated helium-neon laser
B	An amplitude modulated helium-neon laser
C	An LED and a phototransistor
D	A lens and a photomultiplier

31. - E7A11

What type of logic defines "1" as a high voltage?

Select	Answer
A	Assertive Logic
B	Negative logic
C	Reverse Logic
D	Positive Logic

32. - E7B15

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

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

33. - E7C01

How are the capacitors and inductors of a low-pass filter Pi-network arranged between the network's input and output?

Select	Answer
A	A capacitor is connected between the input and ground, another capacitor is connected between the output and ground, and an inductor is connected between input and output
B	Two inductors are in series between the input and output, and a capacitor is connected between the two inductors and ground
C	An inductor is connected between the input and ground, another inductor is connected between the output and ground, and a capacitor is connected between the input and output
D	Two capacitors are in series between the input and output, and an inductor is connected between the two capacitors and ground

34. - E7D15

What is the purpose of a step-start circuit in a high-voltage power supply?

Select	Answer
A	To allow the filter capacitors to charge gradually
B	To provide a dual-voltage output for reduced power applications
C	To allow for remote control of the power supply
D	To compensate for variations of the incoming line voltage

35. - E7E08

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

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

36. - E7F09

Why is an anti-aliasing digital filter required in a digital decimator?

Select	Answer
A	It notches out the sampling frequency to avoid sampling errors
B	It removes low-frequency signal components to eliminate the need for DC restoration
C	It peaks the response of the decimator, improving bandwidth
D	It removes high-frequency signal components that would otherwise be reproduced as lower frequency components

37. - E7G04

What is meant by the "op-amp input offset voltage"?

Select	Answer
A	The difference between the output voltage of the op-amp and the input voltage required in the immediately following stage
B	The potential between the amplifier input terminals of the op-amp in an open loop condition
C	The differential input voltage needed to bring the open loop output voltage to zero
D	The output voltage of the op-amp minus its input voltage

38. - E7H03

How is positive feedback supplied in a Hartley oscillator?

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

39. - E8A04

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

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

40. - E8B02

How does the modulation index of a phase-modulated emission vary with RF carrier frequency?

Select	Answer
A	It does not depend on the RF carrier frequency
B	It decreases as the RF carrier frequency increases
C	It varies with the square root of the RF carrier frequency
D	It increases as the RF carrier frequency increases

41. - E8C03

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

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

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

43. - E9A04

Which of the following factors affect the feed point impedance of an antenna?

Select	Answer
A	Transmission line length
B	The settings of an antenna tuner at the transmitter
C	The input power level
D	Antenna height

44. - E9B01

In the antenna radiation pattern shown in Figure E9-1, what is the beamwidth?

Select	Answer
A	50 degrees
B	30 degrees
C	25 degrees
D	75 degrees

45. - E9C13

How does the radiation pattern of a horizontally polarized 3-element beam antenna vary with increasing height above ground?

Select	Answer
A	The takeoff angle of the lowest elevation lobe decreases
B	The horizontal beamwidth increases
C	The horizontal beamwidth decreases
D	The takeoff angle of the lowest elevation lobe increases

46. - E9D08

What happens as the Q of an antenna increases?

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

47. - E9E06

Which of these feed line impedances would be suitable for constructing a quarter-wave Q-section for matching a 100-ohm loop to 50-ohm feed line?

Select	Answer
A	62 ohms
B	75 ohms
C	450 ohms
D	50 ohms

48. - E9F12

What impedance does a 1/4-wavelength transmission line present to a generator when the line is open at the far end?

Select	Answer
A	Very low impedance
B	The same as the input impedance to the generator
C	The same as the characteristic impedance of the line
D	Very high impedance

49. - E9G01

Which of the following can be calculated using a Smith chart?

Select	Answer
A	Antenna radiation pattern
B	Radiation resistance
C	Radio propagation
D	Impedance along transmission lines

50. - E9H08

What is the function of a sense antenna?

Select	Answer
A	It provides diversity reception that cancels multipath signals
B	It allows DF antennas to receive signals at different vertical angles
C	It increases the sensitivity of a DF antenna array
D	It modifies the pattern of a DF antenna array to provide a null in one direction

Figure E5-1

Figure E9-1