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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?

SelectAnswer
AOnly with a carbon monoxide detector
BAny ordinary smoke detector can be used
CBy the odor
DBy the yellowish appearance of the gas

2. - E1A02

When using a transceiver that displays the carrier frequency of phone signals, which of the following displayed frequencies represents the lowest frequency at which a properly adjusted LSB emission will be totally within the band?

SelectAnswer
AThe exact lower band edge
B3 kHz above the lower band edge
C300 Hz above the lower band edge
D1 kHz above the lower band edge

3. - E1B02

Which of the following is an acceptable bandwidth for Digital Radio Mondiale (DRM) based voice or SSTV digital transmissions made on the HF amateur bands?

SelectAnswer
A15 kHz
B10 kHz
C3 kHz
D20 kHz

4. - E1C11

Which of the following operating arrangements allows an FCC-licensed U.S. citizen to operate in many European countries, and alien amateurs from many European countries to operate in the U.S.?

SelectAnswer
AIARP agreement
BITU reciprocal license
CCEPT agreement
DAll these choices are correct

5. - E1D01

What is the definition of telemetry?

SelectAnswer
ATwo-way transmissions in excess of 1000 feet
BOne-way transmission that initiates, modifies, or terminates the functions of a device at a distance
COne-way transmission of measurements at a distance from the measuring instrument
DTwo-way transmissions of data

6. - E1E02

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

SelectAnswer
AThe ARRL
BThe VECs
CThe FCC
DThe VEs

7. - E1F03

Under what circumstances may a dealer sell an external RF power amplifier capable of operation below 144 MHz if it has not been granted FCC certification?

SelectAnswer
AIt was imported from a manufacturer in another country and was certificated by that country's government
BThe equipment dealer assembled it from a kit
CIt was purchased in used condition from an amateur operator and is sold to another amateur operator for use at that operator's station
DIt was imported from a manufacturer in a country that does not require certification of RF power amplifiers

8. - E2A10

What type of satellite appears to stay in one position in the sky?

SelectAnswer
AGeomagnetic
BGeostationary
CLEO
DHEO

9. - E2B01

How many times per second is a new frame transmitted in a fast-scan (NTSC) television system?

SelectAnswer
A60
B120
C90
D30

10. - E2C11

How should you generally identify your station when attempting to contact a DX station during a contest or in a pileup?

SelectAnswer
ASend your full call sign once or twice
BSend the call sign of the DX station three times, the words this is,then your call sign three times
CSend only the last two letters of your call sign until you make contact
DSend your full call sign and grid square

11. - E2D10

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

SelectAnswer
AAPRS stations with General Personnel Scanners can automatically relay the participant numbers and time as they pass the check points
BAn APRS station with an emergency medical technician can automatically transmit medical data to the nearest hospital
CAll these choices are correct
DAn APRS station with a Global Positioning System unit can automatically transmit information to show a mobile station's position during the event

12. - E2E10

Which of these digital modes has the narrowest bandwidth?

SelectAnswer
A170 Hz shift, 45-baud RTTY
B300-baud packet
CMFSK16
DPSK31

13. - E3A06

What might help to restore contact when DX signals become too weak to copy across an entire HF band a few hours after sunset?

SelectAnswer
AWait 90 minutes or so for the signal degradation to pass
BSwitch to a lower frequency HF band
CSwitch to a higher frequency HF band
DWait 24 hours before attempting another communication on the band

14. - E3B03

What is the best time of day for transequatorial propagation?

SelectAnswer
AMorning
BNoon
CLate at night
DAfternoon or early evening

15. - E3C09

How does the intensity of an X3 flare compare to that of an X2 flare?

SelectAnswer
A10 percent greater
B50 percent greater
CTwice as great
DFour times as great

16. - E4A06

What is the effect of aliasing on a digital oscilloscope caused by setting the time base too slow?

SelectAnswer
AA false, jittery low-frequency version of the signal is displayed
BExcessive blanking occurs, which prevents display of the signal
CCalibration of the vertical scale is no longer valid
DAll signals will have a DC offset

17. - E4B11

Which of the following can be measured with a vector network analyzer?

SelectAnswer
AReflection coefficient
BAll these choices are correct
COutput impedance
DInput impedance

18. - E4C10

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

SelectAnswer
AReceive bandwidth can be set to match the modulation bandwidth, maximizing signal-to-noise ratio and minimizing interference
BMultiple frequencies can be received simultaneously if desired
CThe noise figure of the RF amplifier can be adjusted to match the modulation type, thus increasing receiver sensitivity
DReceiver power consumption can be reduced when wider bandwidth is not required

19. - E4D03

How can intermodulation interference between two repeaters occur?

SelectAnswer
AWhen the repeaters are in close proximity and the signals cause feedback in the final amplifier of one or both transmitters
BWhen the signals from the transmitters are reflected in phase from airplanes passing overhead
CWhen the signals from the transmitters are reflected out of phase from airplanes passing overhead
DWhen the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmitters

20. - E4E08

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

SelectAnswer
AReturn current
BReactive current only
CCommon-mode current
DDifferential-mode current

21. - E5A03

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

SelectAnswer
AHigh, as compared to the circuit resistance
BApproximately equal to circuit resistance
CApproximately equal to capacitive reactance
DApproximately equal to inductive reactance

22. - E5B07

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 500 ohms, R is 1 kilohm, and XL is 250 ohms?

SelectAnswer
A68.2 degrees with the voltage leading the current
B14.0 degrees with the voltage lagging the current
C14.0 degrees with the voltage leading the current
D68.2 degrees with the voltage lagging the current

23. - E5C05

What is the name of the diagram used to show the phase relationship between impedances at a given frequency?

SelectAnswer
ANear field diagram
BPhasor diagram
CFar field diagram
DVenn diagram

24. - E5D13

How many watts are consumed in a circuit consisting of a 100-ohm resistor in series with a 100-ohm inductive reactance drawing 1 ampere?

SelectAnswer
A100 watts
B70.7 watts
C141.4 watts
D200 watts

25. - E6A06

What is the beta of a bipolar junction transistor?

SelectAnswer
AThe switching speed
BThe breakdown voltage of the base to collector junction
CThe change in collector current with respect to base current
DThe frequency at which the current gain is reduced to 0.707

26. - E6B06

Which of the following is a common use of a Schottky diode?

SelectAnswer
AAs a rectifier in high current power supplies
BAs a constant voltage reference in a power supply
CAs a VHF/UHF mixer or detector
DAs a variable capacitance in an automatic frequency control circuit

27. - E6C05

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

SelectAnswer
ALower power consumption
BImmune to damage from static discharge
CDifferential output capability
DLower distortion

28. - E6D07

What is current in the primary winding of a transformer called if no load is attached to the secondary?

SelectAnswer
AExcitation current
BDirect current
CMagnetizing current
DStabilizing current

29. - E6E05

Which of the following noise figure values is typical of a low-noise UHF preamplifier?

SelectAnswer
A-10 dB
B2 dB
C44 dBm
D-20 dBm

30. - E6F10

What is the most common type of photovoltaic cell used for electrical power generation?

SelectAnswer
ACopper oxide
BSilicon
CCadmium Sulfide
DSelenium

31. - E7A04

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

SelectAnswer
A8
B4
C1
D2

32. - E7B06

Which of the following amplifier types reduces even-order harmonics?

SelectAnswer
AClass AB
BPush-push
CClass C
DPush-pull

33. - E7C06

What are the distinguishing features of an elliptical filter?

SelectAnswer
AExtremely flat response over its pass band with gradually rounded stop band corners
BExtremely sharp cutoff with one or more notches in the stop band
CGradual passband rolloff with minimal stop band ripple
DGradual passband rolloff with extreme stop band ripple

34. - E7D01

How does a linear electronic voltage regulator work?

SelectAnswer
AIt eliminates the need for a pass transistor
BThe conduction of a control element is varied to maintain a constant output voltage
CIt has a ramp voltage as its output
DThe control element duty cycle is proportional to the line or load conditions

35. - E7E11

Which type of detector circuit is used for demodulating SSB signals?

SelectAnswer
AProduct detector
BPhase detector
CPhase comparator
DDiscriminator

36. - E7F14

Which of the following would allow a digital signal processing filter to create a sharper filter response?

SelectAnswer
AHigher data rate
BMore taps
CComplex phasor representations
DDouble-precision math routines

37. - E7G04

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

SelectAnswer
AThe difference between the output voltage of the op-amp and the input voltage required in the immediately following stage
BThe potential between the amplifier input terminals of the op-amp in an open loop condition
CThe output voltage of the op-amp minus its input voltage
DThe differential input voltage needed to bring the open loop output voltage to zero

38. - E7H08

Which of the following components can be used to reduce thermal drift in crystal oscillators?

SelectAnswer
AWirewound resistors
BNP0 capacitors
CToroidal inductors
DNon-inductive resistors

39. - E8A08

Why would a direct or flash conversion analog-to-digital converter be useful for a software defined radio?

SelectAnswer
AVery high speed allows digitizing high frequencies
BAll these choices are correct
CImmunity to out-of-sequence coding reduces spurious responses
DVery low power consumption decreases frequency drift

40. - E8B05

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus-or-minus 5 kHz when the maximum modulation frequency is 3 kHz?

SelectAnswer
A0.6
B0.167
C60
D1.67

41. - E8C03

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

SelectAnswer
ATo improve carrier suppression
BTo minimize bandwidth
CTo simplify modulation
DAll these choices are correct

42. - E8D05

What is the most common method of reducing key clicks?

SelectAnswer
ALow-pass filters at the transmitter output
BIncrease keying waveform rise and fall times
CHigh-pass filters at the transmitter output
DReduce keying waveform rise and fall times

43. - E9A03

What is the radiation resistance of an antenna?

SelectAnswer
AThe combined losses of the antenna elements and feed line
BThe specific impedance of the antenna
CThe value of a resistance that would dissipate the same amount of power as that radiated from an antenna
DThe resistance in the atmosphere that an antenna must overcome to be able to radiate a signal

44. - E9B07

How does the total amount of radiation emitted by a directional gain antenna compare with the total amount of radiation emitted from a theoretical isotropic antenna, assuming each is driven by the same amount of power?

SelectAnswer
AThey are the same
BThe total amount of radiation from the directional antenna is stronger by its front-to-back ratio
CThe radiation from the isotropic antenna is 2.15 dB stronger than that from the directional antenna
DThe total amount of radiation from the directional antenna is increased by the gain of the antenna

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?

SelectAnswer
AA figure-8 end-fire along the axis of the array
BCardioid
CA figure-8 broadside to the axis of the array
DOmni-directional

46. - E9D06

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

SelectAnswer
AIt is unchanged if the loading coil is located at a voltage maximum point
BIt is increased
CIt is decreased
DIt is unchanged if the loading coil is located at the feed point

47. - E9E07

What parameter describes the interactions at the load end of a mismatched transmission line?

SelectAnswer
ACharacteristic impedance
BReflection coefficient
CDielectric constant
DVelocity factor

48. - E9F04

What impedance does a 1/2-wavelength transmission line present to a generator when the line is shorted at the far end?

SelectAnswer
AVery low impedance
BThe same as the output impedance of the generator
CThe same as the characteristic impedance of the line
DVery high impedance

49. - E9G09

What third family of circles is often added to a Smith chart during the process of solving problems?

SelectAnswer
AAntenna-length circles
BCoaxial-length circles
CRadiation-pattern circles
DStanding wave ratio circles

50. - E9H11

What feature of a cardioid pattern antenna makes it useful for direction finding?

SelectAnswer
AHigh radiation angle
BA very sharp single null
CBroadband response
DA very sharp peak