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	30 to 300 MHz
B	300 kHz to 3 MHz
C	300 to 3000 MHz
D	3 to 30 MHz

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. - E1B10

What frequencies are authorized to an amateur station operating under RACES rules?

Select	Answer
A	Military Auxiliary Radio System (MARS) channels
B	All amateur service frequencies authorized to the control operator
C	Specific local government channels
D	Specific segments in the amateur service MF, HF, VHF and UHF bands

4. - E1C12

On what portion of the 630 meter band are phone emissions permitted?

Select	Answer
A	Only the top 3 kHz
B	None
C	The entire band
D	Only the bottom 3 kHz

5. - E1D05

What must be posted at the station location of a station being operated by telecommand on or within 50 km of the earth's surface?

Select	Answer
A	A photocopy of the station license
B	A label with the name, address, and telephone number of the station licensee
C	All these choices are correct
D	A label with the name, address, and telephone number of the control operator

6. - E1E05

What is the minimum passing score on all amateur operator license examinations?

Select	Answer
A	Minimum passing score of 74%
B	Minimum passing score of 70%
C	Minimum passing score of 77%
D	Minimum passing score of 80%

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 east of the U.S. Pacific coastline
D	A line roughly parallel to and west of the U.S. Atlantic coastline

8. - E2A04

What is meant by the term mode? as applied to an amateur radio satellite?

Select	Answer
A	Whether the satellite is in a polar or equatorial orbit
B	The satellite's uplink and downlink frequency bands
C	Whether the satellite is in a low earth or geostationary orbit
D	The satellite's orientation with respect to the Earth

9. - E2B07

What is the name of the signal component that carries color information in NTSC video?

Select	Answer
A	Chroma
B	Hue
C	Luminance
D	Spectral intensity

10. - E2C04

Which of the following frequencies are sometimes used for amateur radio mesh networks?

Select	Answer
A	Cable TV channels 41 through 43
B	HF frequencies where digital communications are permitted
C	The 60 meter band channel centered on 5373 kHz
D	Frequencies shared with various unlicensed wireless data services

11. - E2D10

How can an APRS station be used to help support a public service communications activity?

Select	Answer
A	APRS stations with General Personnel Scanners can automatically relay the participant numbers and time as they pass the check points
B	An APRS station with an emergency medical technician can automatically transmit medical data to the nearest hospital
C	All these choices are correct
D	An APRS station with a Global Positioning System unit can automatically transmit information to show a mobile station's position during the event

12. - E2E11

What is the difference between direct FSK and audio FSK?

Select	Answer
A	Direct FSK applies the data signal to the transmitter VFO, while AFSK transmits tones via phone
B	Direct FSK can transmit faster baud rates
C	Direct FSK occupies less bandwidth
D	Only direct FSK can be decoded by computer

13. - E3A09

Which of the following frequency ranges is most suited for meteor scatter communications?

Select	Answer
A	28 MHz - 148 MHz
B	1.8 MHz - 1.9 MHz
C	220 MHz - 450 MHz
D	10 MHz - 14 MHz

14. - E3B09

At what time of year is sporadic E propagation most likely to occur?

Select	Answer
A	Around the solstices, especially the summer solstice
B	Around the equinoxes, especially the spring equinox
C	Around the solstices, especially the winter solstice
D	Around the equinoxes, especially the fall equinox

15. - E3C15

What might be indicated by a sudden rise in radio background noise across a large portion of the HF spectrum?

Select	Answer
A	Long-path propagation is likely
B	Increased transequatorial propagation is likely
C	A temperature inversion has occurred
D	A solar flare has occurred

16. - E4A04

How is the compensation of an oscilloscope probe typically adjusted?

Select	Answer
A	A high frequency sine wave is displayed and the probe is adjusted for maximum amplitude
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 square wave is displayed and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible

17. - E4B07

What do the subscripts of S parameters represent?

Select	Answer
A	The relative time between measurements
B	Frequency order of the measurements
C	The port or ports at which measurements are made
D	Relative quality of the data

18. - E4C08

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

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

19. - E4D07

Which of the following reduces the likelihood of receiver desensitization?

Select	Answer
A	Raise the receiver IF frequency
B	Switch from fast AGC to slow AGC
C	Increase the receiver front end gain
D	Decrease the RF bandwidth of the receiver

20. - E4E06

What is one type of electrical interference that might be caused by a nearby personal computer?

Select	Answer
A	The appearance of unstable modulated or unmodulated signals at specific frequencies
B	A whining type noise that continually pulses off and on
C	A loud AC hum in the audio output of your station receiver
D	A clicking noise at intervals of a few seconds

21. - E5A16

What is the resonant frequency of an RLC circuit if R is 33 ohms, L is 50 microhenries and C is 10 picofarads?

Select	Answer
A	7.12 MHz
B	23.5 kHz
C	23.5 MHz
D	7.12 kHz

22. - E5B10

What is the relationship between the AC current through an inductor and the voltage across an inductor?

Select	Answer
A	Voltage and current are 180 degrees out of phase
B	Voltage and current are in phase
C	Current leads voltage by 90 degrees
D	Voltage leads current by 90 degrees

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 5
B	Point 2
C	Point 6
D	Point 4

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 apparent power by the power factor
B	By multiplying the reactive power by the power factor
C	By dividing the reactive power by the power factor
D	By dividing the apparent 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 voltage of approximately 0.6 to 0.7 volts
C	Base-to-emitter voltage of approximately 6 to 7 volts
D	Base-to-emitter resistance of approximately 6 to 7 ohms

26. - E6B10

In Figure E6-2, what is the schematic symbol for a light-emitting diode?

Select	Answer
A	6
B	5
C	1
D	7

27. - E6C05

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

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

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

29. - E6E02

Which of the following device packages is a through-hole type?

Select	Answer
A	SOT
B	DIP
C	PLCC
D	Ball grid array

30. - E6F03

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

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

31. - E7A02

What is the function of a decade counter?

Select	Answer
A	It decodes a decimal number for display on a seven-segment LED display
B	It produces 10 output pulses for every input pulse
C	It produces one output pulse for every 10 input pulses
D	It decodes a binary number for display on a seven-segment LED display

32. - E7B04

Where on the load line of a Class A common emitter amplifier would bias normally be set?

Select	Answer
A	Where the load line intersects the voltage axis
B	At a point where the load line intersects the zero bias current curve
C	Approximately halfway between saturation and cutoff
D	At a point where the bias resistor equals the load resistor

33. - E7C12

What is one advantage of a Pi-matching network over an L-matching network consisting of a single inductor and a single capacitor?

Select	Answer
A	Pi-networks are more stable
B	L-networks cannot perform impedance transformation
C	Pi-networks provide balanced input and output
D	The Q of Pi-networks can be controlled

34. - E7D01

How does a linear electronic voltage regulator work?

Select	Answer
A	It eliminates the need for a pass transistor
B	The control element duty cycle is proportional to the line or load conditions
C	It has a ramp voltage as its output
D	The conduction of a control element is varied to maintain a constant output voltage

35. - E7E02

What is the function of a reactance modulator?

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

36. - E7F01

What is meant by direct digital conversion as applied to software defined radios?

Select	Answer
A	Software is converted from source code to object code during operation of the receiver
B	Incoming RF is digitized by an analog-to-digital converter without being mixed with a local oscillator signal
C	Incoming RF is converted to a control voltage for a voltage controlled oscillator
D	A switching mixer is used to generate I and Q signals directly from the RF input

37. - E7G08

How does the gain of an ideal operational amplifier vary with frequency?

Select	Answer
A	It decreases logarithmically with increasing frequency
B	It does not vary with frequency
C	It increases linearly with increasing frequency
D	It decreases linearly with increasing frequency

38. - E7H11

What are the major spectral impurity components of direct digital synthesizers?

Select	Answer
A	Digital conversion noise
B	Nyquist limit noise
C	Broadband noise
D	Spurious signals at discrete frequencies

39. - E8A04

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

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

40. - E8B01

What is the modulation index of an FM signal?

Select	Answer
A	The ratio of modulating signal amplitude to frequency deviation
B	The type of modulation used by the transmitter
C	The ratio of frequency deviation to modulating signal frequency
D	The bandwidth of the transmitted signal divided by the modulating signal frequency

41. - E8C08

How does ARQ accomplish error correction?

Select	Answer
A	Special binary codes provide automatic correction
B	If errors are detected, a retransmission is requested
C	If errors are detected, redundant data is substituted
D	Special polynomial codes provide automatic correction

42. - E8D05

What is the most common method of reducing key clicks?

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

43. - E9A01

What is an isotropic antenna?

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

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	18 dB
C	24 dB
D	36 dB

45. - E9C07

What is the approximate feed point impedance at the center of a two-wire folded dipole antenna?

Select	Answer
A	300 ohms
B	50 ohms
C	72 ohms
D	450 ohms

46. - E9D06

What happens to the SWR bandwidth when one or more loading coils are used to resonate an electrically short antenna?

Select	Answer
A	It is unchanged if the loading coil is located at the feed point
B	It is increased
C	It is unchanged if the loading coil is located at a voltage maximum point
D	It is decreased

47. - E9E08

What is a use for a Wilkinson divider?

Select	Answer
A	It is used to feed high-impedance antennas from a low-impedance source
B	It is used to feed low-impedance loads from a high-impedance source
C	It is used to divide power equally between two 50-ohm loads while maintaining 50-ohm input impedance
D	It divides the operating frequency of a transmitter signal so it can be used on a lower frequency band

48. - E9F03

Why is the physical length of a coaxial cable transmission line shorter than its electrical length?

Select	Answer
A	Skin effect is less pronounced in the coaxial cable
B	The characteristic impedance is higher in a parallel feed line
C	Electrical signals move more slowly in a coaxial cable than in air
D	The surge impedance is higher in a parallel feed line

49. - E9G11

How are the wavelength scales on a Smith chart calibrated?

Select	Answer
A	In fractions of antenna electrical frequency
B	In fractions of transmission line electrical frequency
C	In fractions of antenna electrical wavelength
D	In fractions of transmission line electrical wavelength

50. - E9H10

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

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

Figure E5-1

Figure E6-2

Figure E9-1