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Amateur Radio - Extra > E4 - AMATEUR PRACTICES [5 Exam Questions - 5 Groups] > Flashcards

E4 - AMATEUR PRACTICES [5 Exam Questions - 5 Groups] Flashcards

1
Q

How does a spectrum analyzer differ from an oscilloscope?

A. A spectrum analyzer measures ionospheric reflection; an oscilloscope displays electrical signals

B. A spectrum analyzer displays the peak amplitude of signals; an oscilloscope displays the average amplitude of signals

C. A spectrum analyzer displays signals in the frequency domain; an oscilloscope displays signals in the time domain

D. A spectrum analyzer displays radio frequencies; an oscilloscope displays audio frequencies

A

C. A spectrum analyzer displays signals in the frequency domain; an oscilloscope displays signals in the time domain

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2
Q

Which of the following parameters would a spectrum analyzer display on the horizontal axis?

A. SWR

B. Q

C. Time

D. Frequency

A

D. Frequency

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3
Q

Which of the following parameters would a spectrum analyzer display on the vertical axis?

A. Amplitude

B. Duration

C. SWR

D. Q

A

A. Amplitude

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4
Q

Which of the following test instruments is used to display spurious signals from a radio transmitter?

A. A spectrum analyzer

B. A wattmeter

C. A logic analyzer

D. A time-domain reflectometer

A

A. A spectrum analyzer

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5
Q

Which of the following test instruments is used to display intermodulation distortion products in an SSB transmission?

A. A wattmeter

B. A spectrum analyzer

C. A logic analyzer

D. A time-domain reflectometer

A

B. A spectrum analyzer

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6
Q

Which of the following could be determined with a spectrum analyzer?

A. The degree of isolation between the input and output ports of a 2 meter duplexer

B. Whether a crystal is operating on its fundamental or overtone frequency

C. The spectral output of a transmitter

D. All of these choices are correct

A

D. All of these choices are correct

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7
Q

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

A. Antenna analyzers automatically tune your antenna for resonance

B. Antenna analyzers do not need an external RF source

C. Antenna analyzers display a time-varying representation of the modulation envelope

D. All of these choices are correct

A

B. Antenna analyzers do not need an external RF source

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8
Q

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

A. A spectrum analyzer

B. A Q meter

C. An ohmmeter

D. An antenna analyzer

A

D. An antenna analyzer

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9
Q

Which of the following describes a good method for measuring the intermodulation distortion of your own PSK signal?

A. Transmit into a dummy load, receive the signal on a second receiver, and feed the audio into the sound card of a computer running an appropriate PSK program

B. Multiply the ALC level on the transmitter during a normal transmission by the average power output

C. Use an RF voltmeter coupled to the transmitter output using appropriate isolation to prevent damage to the meter

D. All of these choices are correct

A

A. Transmit into a dummy load, receive the signal on a second receiver, and feed the audio into the sound card of a computer running an appropriate PSK program

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10
Q

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

A. Measure base-to-emitter resistance with an ohmmeter; it should be approximately

6 to 7 ohms

B. Measure base-to-emitter resistance with an ohmmeter; it should be approximately 0.6 to 0.7 ohms

C. Measure base-to-emitter voltage with a voltmeter; it should be approximately

A

(D)

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11
Q

Which of these instruments could be used for detailed analysis of digital signals?

A. Dip meter

B. Oscilloscope

C. Ohmmeter

D. Q meter

A

B. Oscilloscope

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12
Q

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

A. Use high quality double shielded coaxial cables to reduce signal losses

B. Attenuate the transmitter output going to the spectrum analyzer

C. Match the antenna to the load

D. All of these choices are correct

A

B. Attenuate the transmitter output going to the spectrum analyzer

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13
Q

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

A. Input attenuator accuracy

B. Time base accuracy

C. Decade divider accuracy

D. Temperature coefficient of the logic

A

B. Time base accuracy

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14
Q

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

A. It provides an excellent match under all conditions

B. It is relatively immune to drift in the signal generator source

C. The measurement is based on obtaining a signal null, which can be done very precisely

D. It can display results directly in Smith chart format

A

C. The measurement is based on obtaining a signal null, which can be done very precisely

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15
Q

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. 165.2 Hz

B. 14.652 kHz

C. 146.52 Hz

D. 1.4652 MHz

A

C. 146.52 Hz

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16
Q

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. 14.652 Hz

B. 0.1 MHz

C. 1.4652 Hz

D. 1.4652 kHz

A

A. 14.652 Hz

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17
Q

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. 146.52 Hz

B. 10 Hz

C. 146.52 kHz

D. 1465.20 Hz

A

D. 1465.20 Hz

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18
Q

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. 100 watts

B. 125 watts

C. 25 watts

D. 75 watts

A

D. 75 watts

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19
Q

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

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

B. Never use a high impedance probe to measure a low impedance circuit

C. Never use a DC-coupled probe to measure an AC circuit

D. All of these choices are correct

A

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

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20
Q

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

A. High reluctance input

B. Low reluctance input

C. High impedance input

D. Low impedance input

A

C. High impedance input

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21
Q

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. There is possibly a short to ground in the feed line

B. The transmitter is not properly neutralized

C. There is an impedance mismatch between the antenna and feed line

D. There is more power going into the antenna

A

D. There is more power going into the antenna

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22
Q

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

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

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

C. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a peak reading wattmeter

D. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a logic analyzer

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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23
Q

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

A. Loosely couple the analyzer near the antenna base

B. Connect the analyzer via a high-impedance transformer to the antenna

C. Connect the antenna and a dummy load to the analyzer

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

A

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

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24
Q

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

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

B. When used as a galvanometer, the reading in volts multiplied by the ohms/volt will determine the power drawn by the device under test

C. When used as an ohmmeter, the reading in ohms divided by the ohms/volt will determine the voltage applied to the circuit

D. When used as an ammeter, the full scale reading in amps divided by ohms/volt will determine the size of shunt needed

A

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

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25
Q

How is the compensation of an oscilloscope probe typically adjusted?

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

B. A high frequency sine wave is displayed and the probe is adjusted for maximum amplitude

C. A frequency standard is displayed and the probe is adjusted until the deflection time is accurate

D. A DC voltage standard is displayed and the probe is adjusted until the displayed voltage is accurate

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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26
Q

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

A. Harmonics are generated

B. A less accurate reading results

C. Cross modulation occurs

D. Intermodulation distortion occurs

A

B. A less accurate reading results

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27
Q

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

A. The inductance to capacitance ratio

B. The frequency shift

C. The bandwidth of the circuit’s frequency response

D. The resonant frequency of the circuit

A

C. The bandwidth of the circuit’s frequency response

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28
Q

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

A. It limits the receiver’s ability to receive strong signals

B. It reduces receiver sensitivity

C. It decreases receiver third-order intermodulation distortion dynamic range

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

A

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

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29
Q

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

A. A front-end filter or pre-selector

B. A narrow IF filter

C. A notch filter

D. A properly adjusted product detector

A

A. A front-end filter or pre-selector

30
Q

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

A. Desensitization

B. Cross-modulation interference

C. Capture effect

D. Frequency discrimination

A

C. Capture effect

31
Q

What is the definition of the noise figure of a receiver?

A. The ratio of atmospheric noise to phase noise

B. The noise bandwidth in Hertz compared to the theoretical bandwidth of a resistive network

C. The ratio of thermal noise to atmospheric noise

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

A

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

32
Q

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

A. The minimum detectable signal as a function of receive frequency

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

C. The noise figure of a 1 Hz bandwidth receiver

D. The galactic noise contribution to minimum detectable signal

A

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

33
Q

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. 174 dBm

B. -164 dBm

C. -155 dBm

D. -148 dBm

A

D. -148 dBm

34
Q

What does the MDS of a receiver represent?

A. The meter display sensitivity

B. The minimum discernible signal

C. The multiplex distortion stability

D. The maximum detectable spectrum

A

B. The minimum discernible signal

35
Q

How might lowering the noise figure affect receiver performance?

A. It would reduce the signal to noise ratio

B. It would improve weak signal sensitivity

C. It would reduce bandwidth

D. It would increase bandwidth

A

B. It would improve weak signal sensitivity

36
Q

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. Fewer components in the receiver

B. Reduced drift

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

D. Improved receiver noise figure

A

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

37
Q

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

A. 100 Hz

B. 300 Hz

C. 6000 Hz

D. 2400 Hz

A

B. 300 Hz

38
Q

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

A. 1 kHz

B. 2.4 kHz

C. 4.2 kHz

D. 4.8 kHz

A

B. 2.4 kHz

39
Q

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

A. Output-offset overshoot

B. Filter ringing

C. Thermal-noise distortion

D. Undesired signals may be heard

A

D. Undesired signals may be heard

40
Q

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

A. It improves sensitivity by reducing front end noise

B. It improves intelligibility by using low Q circuitry to reduce ringing

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

D. All of these choices are correct

A

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

41
Q

On which of the following frequencies might a signal be transmitting which is generating a spurious image signal in a receiver tuned to 14.300 MHz and which uses a 455 kHz IF frequency?

A. 13.845 MHz

B. 14.755 MHz

C. 14.445 MHz

D. 15.210 MHz

A

D. 15.210 MHz

42
Q

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

A. Detector noise

B. Induction motor noise

C. Receiver front-end noise

D. Atmospheric noise

A

D. Atmospheric noise

43
Q

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

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

B. The minimum difference in dB between the levels of two FM signals which will cause one signal to block the other

C. The difference in dB between the noise floor and the third order intercept point

D. The minimum difference in dB between two signals which produce third order intermodulation products greater than the noise floor

A

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

44
Q

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

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

B. Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sideband

C. Cross-modulation of the desired signal and insufficient audio power to operate the speaker

D. Oscillator instability and severe audio distortion of all but the strongest received signals

A

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

45
Q

How can intermodulation interference between two repeaters occur?

A. When the repeaters are in close proximity and the signals cause feedback in the final amplifier of one or both transmitters

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

C. When the signals from the transmitters are reflected out of phase from airplanes passing overhead

D. When the signals from the transmitters are reflected in phase from airplanes passing overhead

A

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

46
Q

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

A. A band-pass filter in the feed line between the transmitter and receiver

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

C. A Class C final amplifier

D. A Class D final amplifier

A

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

47
Q

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. 146.34 MHz and 146.61 MHz

B. 146.88 MHz and 146.34 MHz

C. 146.10 MHz and 147.30 MHz

D. 173.35 MHz and 139.40 MHz

A

A. 146.34 MHz and 146.61 MHz

48
Q

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

A. Amplifier desensitization

B. Neutralization

C. Adjacent channel interference

D. Intermodulation interference

A

D. Intermodulation interference

49
Q

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

A. A large increase in background noise

B. A reduction in apparent signal strength

C. The desired signal can no longer be heard

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

A

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

50
Q

What causes intermodulation in an electronic circuit?

A. Too little gain

B. Lack of neutralization

C. Nonlinear circuits or devices

D. Positive feedback

A

C. Nonlinear circuits or devices

51
Q

What is the purpose of the preselector in a communications receiver?

A. To store often-used frequencies

B. To provide a range of AGC time constants

C. To increase rejection of unwanted signals

D. To allow selection of the optimum RF amplifier device

A

C. To increase rejection of unwanted signals

52
Q

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

A. Signals less than 40 dBm will not generate audible third-order intermodulation products

B. The receiver can tolerate signals up to 40 dB above the noise floor without producing third-order intermodulation products

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

D. A pair of 1 mW input signals will produce a third-order intermodulation product which is 40 dB stronger than the input signal

A

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

53
Q

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

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

B. The third-order intercept is much higher than other orders

C. Third-order products are an indication of poor image rejection

D. Third-order intermodulation produces three products for every input signal within the band of interest

A

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

54
Q

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

A. Desensitization

B. Quieting

C. Cross-modulation interference

D. Squelch gain rollback

A

A. Desensitization

55
Q

Which of the following can cause receiver desensitization?

A. Audio gain adjusted too low

B. Strong adjacent-channel signals

C. Audio bias adjusted too high

D. Squelch gain misadjusted

A

B. Strong adjacent-channel signals

56
Q

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

A. Decrease the RF bandwidth of the receiver

B. Raise the receiver IF frequency

C. Increase the receiver front end gain

D. Switch from fast AGC to slow AGC

A

A. Decrease the RF bandwidth of the receiver

57
Q

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

A. Ignition noise

B. Broadband white noise

C. Heterodyne interference

D. All of these choices are correct

A

A. Ignition noise

58
Q

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

A. Broadband white noise

B. Ignition noise

C. Power line noise

D. All of these choices are correct

A

D. All of these choices are correct

59
Q

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

A. Signals which are constant at all IF levels

B. Signals which appear across a wide bandwidth

C. Signals which appear at one IF but not another

D. Signals which have a sharply peaked frequency distribution

A

B. Signals which appear across a wide bandwidth

60
Q

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

A. By installing filter capacitors in series with the DC power lead and by installing a blocking capacitor in the field lead

B. By installing a noise suppression resistor and a blocking capacitor in both leads

C. By installing a high-pass filter in series with the radio’s power lead and a low-pass filter in parallel with the field lead

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

A

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

61
Q

How can noise from an electric motor be suppressed?

A. By installing a high pass filter in series with the motor’s power leads

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

C. By installing a bypass capacitor in series with the motor leads

D. By using a ground-fault current interrupter in the circuit used to power the motor

A

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

62
Q

What is a major cause of atmospheric static?

A. Solar radio frequency emissions

B. Thunderstorms

C. Geomagnetic storms

D. Meteor showers

A

B. Thunderstorms

63
Q

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

A. By checking the power line voltage with a time domain reflectometer

B. By observing the AC power line waveform with an oscilloscope

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

D. By observing the AC power line voltage with a spectrum analyzer

A

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

64
Q

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

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

B. An electrical-sparking signal

C. A differential-mode signal at the AC power line frequency

D. Harmonics of the AC power line frequency

A

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

65
Q

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

A. Received audio in the speech range might have an echo effect

B. The audio frequency bandwidth of the received signal might be compressed

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

D. FM signals can no longer be demodulated

A

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

66
Q

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

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

A

D. All of these choices are correct

67
Q

Which of the following 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. The broadcast station is transmitting an over-modulated signal

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

C. You are receiving sky wave signals from a distant station

D. Your station receiver IF amplifier stage is defective

A

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

68
Q

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

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

B. Any nearby signal passing through the DSP system will overwhelm the desired signal

C. Received CW signals will appear to be modulated at the DSP clock frequency

D. Ringing in the DSP filter will completely remove the spaces between the CW characters

A

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

69
Q

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

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

A

D. All of these choices are correct

70
Q

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

A. A loud AC hum in the audio output of your station receiver

B. A clicking noise at intervals of a few seconds

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

D. A whining type noise that continually pulses off and on

A

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

Amateur Radio - Extra (10 decks)

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