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Ham Extra 2016-2020 > E4 Amateur Practices > Flashcards

E4 Amateur Practices Flashcards

1
Q

E4A01 (C)

Which of the following parameter determines the bandwidth of a digital or computer-based oscilloscope?

A

C. Sampling rate

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2
Q

E4A02 (B)

Which of the following parameters would a spectrum analyzer display on the vertical and horizontal axes?

A

B. RF amplitude and frequency

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3
Q

E4A03 (B)
Which of the following test instrument is used to display spurious signals and/or intermodulation distortion products in an SSB transmitter?

A

B. A spectrum analyzer

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4
Q

E4A04 (A)

What determines the upper frequency limit for a computer soundcard-based oscilloscope program?

A

A. Analog-to-digital conversion speed of the soundcard

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5
Q

E4A05 (D)

What might be an advantage of a digital vs an analog oscilloscope?

A

A. Automatic amplitude and frequency numerical readout
B. Storage of traces for future reference
C. Manipulation of time base after trace capture
D. All of these choices are correct

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6
Q

E4A06 (A)

What is the effect of aliasing in a digital or computer-based oscilloscope?

A

A. False signals are displayed

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7
Q

E4A07 (B)

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

A

B. Antenna analyzers do not need an external RF source

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8
Q

E4A08 (D)

Which of the following instrument would be best for measuring the SWR of a beam antenna?

A

D. An antenna analyzer

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9
Q

E4A09 (B)
When using a computer’s soundcard input to digitize signals, what is the highest frequency signal that can be digitized without aliasing?

A

B. One-half the sample rate

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10
Q

E4A10 (D)

Which of the following displays multiple digital signal states simultaneously?

A

D. Logic analyzer

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11
Q

E4A11 (A)

Which of the following is good practice when using an oscilloscope probe?

A

A. Keep the signal ground connection of the probe as short as possible

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12
Q

E4A12 (B)
Which of the following procedures is an important precaution to follow when connecting a spectrum analyzer to a transmitter output?

A

B. Attenuate the transmitter output going to the spectrum analyzer

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13
Q

E4A13 (A)

How is the compensation of an oscilloscope probe typically adjusted?

A

A. A square wave is displayed and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible

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14
Q

E4A14 (D)

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

A

D. It divides a higher frequency signal so a low-frequency counter can display the input frequency

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15
Q

E4A15 (C)

What is an advantage of a period-measuring frequency counter over a direct-count type?

A

C. It provides improved resolution of low-frequency signals within a comparable time period

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16
Q

E4B01 (B)

Which of the following factors most affects the accuracy of a frequency counter?

A

B. Time base accuracy

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17
Q

E4B02 (C)

What is an advantage of using a bridge circuit to measure impedance?

A

C. It is very precise in obtaining a signal null

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18
Q

E4B03 (C)
If a frequency counter with a specified accuracy of +/- 1.0 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

A

C. 146.52 Hz

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19
Q

E4B04 (A)
If a frequency counter with a specified accuracy of +/- 0.1 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

A

A. 14.652 Hz

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20
Q

E4B05 (D)
If a frequency counter with a specified accuracy of +/- 10 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

A

D. 1465.20 Hz

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21
Q

E4B06 (D)
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?

A

D. 75 watts

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22
Q

E4B07 (A)

What do the subscripts of S parameters represent?

A

A. The port or ports at which measurements are made

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23
Q

E4B08 (C)

Which of the following is a characteristic of a good DC voltmeter?

A

C. High impedance input

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24
Q

E4B09 (D)
What is indicated if the current reading on an RF ammeter placed in series with the antenna feed line of a transmitter increases as the transmitter is tuned to resonance?

A

D. There is more power going into the antenna

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25
Q

E4B10 (B)

Which of the following describes a method to measure intermodulation distortion in an SSB transmitter?

A

B. Modulate the transmitter with two non-harmonically related audio frequencies and observe the RF output with a spectrum analyzer

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26
Q

E4B11 (D)

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

A

D. Connect the antenna feed line directly to the analyzer’s connector

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27
Q

E4B12 (A)

What is the significance of voltmeter sensitivity expressed in ohms per volt?

A

A. The full scale reading of the voltmeter multiplied by its ohms per volt rating will indicate the input impedance of the voltmeter

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28
Q

E4B13 (C)

Which S parameter is equivalent to forward gain?

A

C. S21

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29
Q

E4B14 (B)

What happens if a dip meter is too tightly coupled to a tuned circuit being checked?

A

B. A less accurate reading results

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30
Q

E4B15 (C)

Which of the following can be used as a relative measurement of the Q for a series-tuned circuit?

A

C. The bandwidth of the circuit’s frequency response

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31
Q

E4B16 (A)

Which S parameter represents return loss or SWR?

A

A. S11

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32
Q

E4B17 (B)

What three test loads are used to calibrate a standard RF vector network analyzer?

A

B. Short circuit, open circuit, and 50 ohms

33
Q

E4C01 (D)

What is an effect of excessive phase noise in the local oscillator section of a receiver?

A

D. It can cause strong signals on nearby frequencies to interfere with reception of weak signals

34
Q

E4C02 (A)

Which of the following portions of a receiver can be effective in eliminating image signal interference?

A

A. A front-end filter or pre-selector

35
Q

E4C03 (C)

What is the term for the blocking of one FM phone signal by another, stronger FM phone signal?

A

C. Capture effect

36
Q

E4C04 (D)

How is the noise figure of a receiver defined?

A

D. The ratio in dB of the noise generated by the receiver to the theoretical minimum noise

37
Q

E4C05 (B)

What does a value of -174 dBm/Hz represent with regard to the noise floor of a receiver?

A

B. The theoretical noise at the input of a perfect receiver at room temperature

38
Q

E4C06 (D)
A CW receiver with the AGC off has an equivalent input noise power density of -174 dBm/Hz. What would be the level of an unmodulated carrier input to this receiver that would yield an audio output SNR of 0 dB in a 400 Hz noise bandwidth?

A

D. -148 dBm

39
Q

E4C07 (B)

What does the MDS of a receiver represent?

A

B. The minimum discernible signal

40
Q

E4C08 (C)

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

A

C. The maximum count value of the analog-to-digital converter

41
Q

E4C09 (C)
Which of the following choices is a good reason for selecting a high frequency for the design of the IF in a conventional HF or VHF communications receiver?

A

C. Easier for front-end circuitry to eliminate image responses

42
Q

E4C10 (B)

Which of the following is a desirable amount of selectivity for an amateur RTTY HF receiver?

43
Q

E4C11 (B)

Which of the following is a desirable amount of selectivity for an amateur SSB phone receiver?

A

B. 2.4 kHz

44
Q

E4C12 (D)

What is an undesirable effect of using too wide a filter bandwidth in the IF section of a receiver?

A

D. Undesired signals may be heard

45
Q

E4C13 (C)

How does a narrow-band roofing filter affect receiver performance?

A

C. It improves dynamic range by attenuating strong signals near the receive frequency

46
Q

E4C14 (D)
What transmit frequency might generate an image response signal in a receiver tuned to 14.300 MHz and which uses a 455 kHz IF frequency?

A

D. 15.210 MHz

47
Q

E4C15 (D)

What is usually the primary source of noise that is heard from an HF receiver with an antenna connected?

A

D. Atmospheric noise

48
Q

E4C16 (A)

Which of the following is caused by missing codes in an SDR receiver’s analog-to-digital converter?

A

A. Distortion

49
Q

E4C17 (D)

Which of the following has the largest effect on an SDR receiver’s linearity?

A

D. Analog-to-digital converter sample width in bits

50
Q

E4D01 (A)

What is meant by the blocking dynamic range of a receiver?

A

A. The difference in dB between the noise floor and the level of an incoming signal which will cause 1 dB of gain compression

51
Q

E4D02 (A)

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

A

A. Cross-modulation of the desired signal and desensitization from strong adjacent signals

52
Q

E4D03 (B)

How can intermodulation interference between two repeaters occur?

A

B. When the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmitters

53
Q

E4D04 (B)
Which of the following may reduce or eliminate intermodulation interference in a repeater caused by another transmitter operating in close proximity?

A

B. A properly terminated circulator at the output of the transmitter

54
Q

E4D05 (A)
What transmitter frequencies would cause an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz?

A

A. 146.34 MHz and 146.61 MHz

55
Q

E4D06 (D)

What is the term for unwanted signals generated by the mixing of two or more signals?

A

D. Intermodulation interference

56
Q

E4D07 (D)
Which describes the most significant effect of an off-frequency signal when it is causing cross-modulation interference to a desired signal?

A

D. The off-frequency unwanted signal is heard in addition to the desired signal

57
Q

E4D08 (C)

What causes intermodulation in an electronic circuit?

A

C. To increase rejection of unwanted signals

58
Q

E4D10 (C)

What does a third-order intercept level of 40 dBm mean with respect to receiver performance?

A

C. A pair of 40 dBm signals will theoretically generate a third-order intermodulation product with the same level as the input signals

59
Q

E4D11 (A)
Why are third-order intermodulation products created within a receiver of particular interest compared to other products?

A

A. The third-order product of two signals which are in the band of interest is also likely to be within the band

60
Q

E4D12 (A)

What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?

A

A. Desensitization

61
Q

E4D13 (B)

Which of the following can cause receiver desensitization?

A

B. Strong adjacent channel signals

62
Q

E4D14 (A)

Which of the following is a way to reduce the likelihood of receiver desensitization?

A

A. Decrease the RF bandwidth of the receiver

63
Q

E4E01 (A)

Which of the following types of receiver noise can often be reduced by use of a receiver noise blanker?

A

A. Ignition noise

64
Q

E4E02 (D)

Which of the following types of receiver noise can often be reduced with a DSP noise filter?

A

A. Broadband white noise
B. Ignition noise
C. Power line noise
D. All of these choices are correct

65
Q

E4E03 (B)

Which of the following signals might a receiver noise blanker be able to remove from desired signals?

A

B. Signals which appear across a wide bandwidth

66
Q

E4E04 (D)

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

A

D. By connecting the radio’s power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads

67
Q

E4E05 (B)

How can noise from an electric motor be suppressed?

A

B. By installing a brute-force AC-line filter in series with the motor leads

68
Q

E4E06 (B)

What is a major cause of atmospheric static?

A

B. Thunderstorms

69
Q

E4E07 (C)

How can you determine if line noise interference is being generated within your home?

A

C. By turning off the AC power line main circuit breaker and listening on a battery operated radio

70
Q

E4E08 (A)

What type of signal is picked up by electrical wiring near a radio antenna?

A

A. A common-mode signal at the frequency of the radio transmitter

71
Q

E4E09 (C)

What undesirable effect can occur when using an IF noise blanker?

A

C. Nearby signals may appear to be excessively wide even if they meet emission standards

72
Q

E4E10 (D)

What is a common characteristic of interference caused by a touch controlled electrical device?

A

A. The interfering signal sounds like AC hum on an AM receiver or a carrier modulated by 60 Hz hum on a SSB or CW receiver
B. The interfering signal may drift slowly across the HF spectrum
C. The interfering signal can be several kHz in width and usually repeats at regular intervals across a HF band
D. All of these choices are correct

73
Q

E4E11 (B)
Which is the most likely cause if you are hearing combinations of local AM broadcast signals within one or more of the MF or HF ham bands?

A

B. Nearby corroded metal joints are mixing and re-radiating the broadcast signals

74
Q

E4E12 (A)

What is one disadvantage of using some types of automatic DSP notch-filters when attempting to copy CW signals?

A

A. A DSP filter can remove the desired signal at the same time as it removes interfering signals

75
Q

E4E13 (D)

What might be the cause of a loud roaring or buzzing AC line interference that comes and goes at intervals?

A

A. Arcing contacts in a thermostatically controlled device
B. A defective doorbell or doorbell transformer inside a nearby residence
C. A malfunctioning illuminated advertising display
D. All of these choices are correct

76
Q

E4E14 (C)

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

A

C. The appearance of unstable modulated or unmodulated signals at specific frequencies

77
Q

E4E15 (B)

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

A

B. Common mode currents on the shield and conductors

78
Q

E4E16 (B)

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

A

B. Common-mode current

Ham Extra 2016-2020 (10 decks)

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