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

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1. - E0A07

How may dangerous levels of carbon monoxide from an emergency generator be detected?

Select	Answer
A	By the odor
B	Any ordinary smoke detector can be used
C	Only with a carbon monoxide detector
D	By the yellowish appearance of the gas

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	14.070 MHz
B	14.349 MHz
C	14.100 MHz
D	14.149 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	File an FAA NOTAM (Notice to Airmen) with the repeater system's ERP, call sign, and six-character grid locator
B	Cease operation or make changes to the repeater to mitigate the interference
C	Reduce the repeater antenna HAAT (Height Above Average Terrain)
D	All these choices are correct

4. - E1C14

How long must an operator wait after filing a notification with the Utilities Technology Council (UTC) before operating on the 2200 meter or 630 meter band?

Select	Answer
A	Operators may not operate until a test signal has been transmitted in coordination with the local power company
B	Operators must not operate until approval is received
C	Operators may operate after 30 days, providing they have not been told that their station is within 1 km of PLC systems using those frequencies
D	Operations may commence immediately, and may continue unless interference is reported by the UTC

5. - E1D01

What is the definition of telemetry?

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

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

7. - E1F01

On what frequencies are spread spectrum transmissions permitted?

Select	Answer
A	Only on amateur frequencies above 144 MHz
B	Only on amateur frequencies above 222 MHz
C	Only on amateur frequencies above 50 MHz
D	Only on amateur frequencies above 420 MHz

8. - E2A03

How is the signal inverted by an inverting linear transponder?

Select	Answer
A	The signal is passed through a non-linear filter
B	The signal is detected and remodulated on the reverse sideband
C	The signal is reduced to I and Q components and the Q component is filtered out
D	The signal is passed through a mixer and the difference rather than the sum is transmitted

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. - E2C08

Which of the following contacts may be confirmed through the U.S. QSL bureau system?

Select	Answer
A	Contacts between a U.S. station and a non-U.S. station
B	Special event contacts between stations in the U.S.
C	Repeater contacts between U.S. club members
D	Contacts using tactical call signs

11. - E2D03

Which of the following digital modes is especially useful for EME communications?

Select	Answer
A	JT65
B	Olivia
C	MSK144
D	PACTOR III

12. - E2E09

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

Select	Answer
A	PACTOR
B	PSK31
C	MT63
D	RTTY

13. - E3A03

When scheduling EME contacts, which of these conditions will generally result in the least path loss?

Select	Answer
A	When the MUF is above 30 MHz
B	When the moon is at perigee
C	When the moon is full
D	When the moon is at apogee

14. - E3B01

What is transequatorial propagation?

Select	Answer
A	Propagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator
B	Propagation between points at the same latitude
C	Propagation between points located on the magnetic equator
D	Propagation between a point on the equator and its antipodal point

15. - E3C05

What orientation of Bz (B sub z) increases the likelihood that incoming particles from the sun will cause disturbed conditions?

Select	Answer
A	Westward
B	Northward
C	Southward
D	Eastward

16. - E4A05

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

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

17. - E4B06

How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?

Select	Answer
A	125 watts
B	100 watts
C	25 watts
D	75 watts

18. - E4C10

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

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

19. - E4D11

Why are odd-order intermodulation products, created within a receiver, of particular interest compared to other products?

Select	Answer
A	Odd-order products are an indication of poor image rejection
B	Odd-order products of two signals in the band of interest are also likely to be within the band
C	Odd-order products overload the IF filters
D	Odd-order intermodulation produces three products for every input signal within the band of interest

20. - E4E08

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

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

21. - E5A12

What is the half-power bandwidth of a resonant circuit that has a resonant frequency of 3.7 MHz and a Q of 118?

Select	Answer
A	436.6 kHz
B	15.7 kHz
C	218.3 kHz
D	31.4 kHz

22. - E5B03

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

Select	Answer
A	Take the reciprocal of the magnitude and change the sign of the angle
B	Take the square root of the magnitude and add 180 degrees to the angle
C	Take the reciprocal of the angle and change the sign of the magnitude
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 positive magnitude
B	A negative magnitude
C	A positive phase angle
D	A negative phase angle

24. - E5D10

How can the true power be determined in an AC circuit where the voltage and current are out of phase?

Select	Answer
A	By multiplying the reactive power by the power factor
B	By dividing the apparent power by the power factor
C	By multiplying the apparent power by the power factor
D	By dividing the reactive power by the power factor

25. - E6A07

Which of the following indicates that a silicon NPN junction transistor is biased on?

Select	Answer
A	Base-to-emitter resistance of approximately 0.6 to 0.7 ohms
B	Base-to-emitter resistance of approximately 6 to 7 ohms
C	Base-to-emitter voltage of approximately 6 to 7 volts
D	Base-to-emitter voltage of approximately 0.6 to 0.7 volts

26. - E6B01

What is the most useful characteristic of a Zener diode?

Select	Answer
A	An internal capacitance that varies with the applied voltage
B	A negative resistance region
C	A constant voltage drop under conditions of varying current
D	A constant current drop under conditions of varying voltage

27. - E6C01

What is the function of hysteresis in a comparator?

Select	Answer
A	To cause the output to change states continually
B	To increase the sensitivity
C	To prevent input noise from causing unstable output signals
D	To allow the comparator to be used with AC input signals

28. - E6D02

What is the equivalent circuit of a quartz crystal?

Select	Answer
A	Motional inductance and loss resistance in series, paralleled with motional capacitance and a capacitor representing electrode and stray capacitance
B	Motional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in parallel
C	Motional capacitance, motional inductance, loss resistance, and a capacitor representing electrode and stray capacitance all in series
D	Motional capacitance, motional inductance, and loss resistance in series, all in parallel with a shunt capacitor representing electrode and stray capacitance

29. - E6E01

Why is gallium arsenide (GaAs) useful for semiconductor devices operating at UHF and higher frequencies?

Select	Answer
A	Lower junction voltage drop
B	Higher noise figures
C	Lower transconductance
D	Higher electron mobility

30. - E6F09

What is the efficiency of a photovoltaic cell?

Select	Answer
A	The relative fraction of light that is converted to current
B	The open-circuit voltage divided by the short-circuit current under full illumination
C	Cost per kilowatt-hour generated
D	The output RF power divided by the input DC power

31. - E7A04

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

Select	Answer
A	2
B	1
C	4
D	8

32. - E7B07

Which of the following is a likely result when a Class C amplifier is used to amplify a single-sideband phone signal?

Select	Answer
A	Increased overall intelligibility
B	Reduced intermodulation products
C	Signal inversion
D	Signal distortion and excessive bandwidth

33. - E7C06

What are the distinguishing features of an elliptical filter?

Select	Answer
A	Gradual passband rolloff with extreme stop band ripple
B	Gradual passband rolloff with minimal stop band ripple
C	Extremely flat response over its pass band with gradually rounded stop band corners
D	Extremely sharp cutoff with one or more notches in the stop band

34. - E7D04

Which of the following types of linear voltage regulator usually make the most efficient use of the primary power source?

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

35. - E7E02

What is the function of a reactance modulator?

Select	Answer
A	To produce PM signals by using an electrically variable resistance
B	To produce PM or FM signals by using an electrically variable inductance or capacitance
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. - 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	Provide incremental signal delays for filter algorithms
D	Select the point at which baseband signals are generated

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. - E7H07

How can an oscillator's microphonic responses be reduced?

Select	Answer
A	Mechanically isolate the oscillator circuitry from its enclosure
B	Increase the bias voltage
C	Use NP0 capacitors
D	Reduce noise on the oscillator's power supply

39. - E8A09

How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?

Select	Answer
A	8
B	256 divided by the gain of the input amplifier
C	8 multiplied by the gain of the input amplifier
D	256

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	3
B	0.3
C	1000
D	3000

41. - E8C04

What technique minimizes the bandwidth of a PSK31 signal?

Select	Answer
A	Reed-Solomon character encoding
B	Use of sinusoidal data pulses
C	Use of trapezoidal data pulses
D	Zero-sum character encoding

42. - E8D05

What is the most common method of reducing key clicks?

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

43. - E9A02

What is the effective radiated power relative to a dipole of a repeater station with 150 watts transmitter power output, 2 dB feed line loss, 2.2 dB duplexer loss, and 7 dBd antenna gain?

Select	Answer
A	286 watts
B	420 watts
C	78.7 watts
D	1977 watts

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. - E9C02

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/4 wavelength apart and fed 90 degrees out of phase?

Select	Answer
A	A figure-8 end-fire along the axis of the array
B	Cardioid
C	A figure-8 broadside to the axis of the array
D	Omni-directional

46. - E9D03

Where should a high Q loading coil be placed to minimize losses in a shortened vertical antenna?

Select	Answer
A	Near the center of the vertical radiator
B	As close to the transmitter as possible
C	As low as possible on the vertical radiator
D	At a voltage node

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	50 ohms
B	450 ohms
C	62 ohms
D	75 ohms

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

49. - E9G02

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

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

50. - E9H08

What is the function of a sense antenna?

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

Figure E9-2