SUBELEMENT E4 AMATEUR PRACTICES [5 Exam Questions - 5 Groups] Amateur Practices1.

SUBELEMENT E4

AMATEUR PRACTICES

[5 Exam Questions - 5 Groups]

Amateur Practices 1

E4A Test equipment: analog and digital instruments; spectrum and network analyzers, antenna analyzers; oscilloscopes; testing transistors; RF measurements E4B Measurement technique and limitations: instrument accuracy and performance limitations; probes; techniques to minimize errors; measurement of "Q"; instrument calibration E4C Receiver performance characteristics, phase noise, capture effect, noise floor, image rejection, MDS, signal-to-noise-ratio; selectivity E4D Receiver performance characteristics, blocking dynamic range, intermodulation and cross-modulation interference; 3rd order intercept; desensitization; preselection E4E Noise suppression: system noise; electrical appliance noise; line noise; locating noise sources; DSP noise reduction; noise blankers

Amateur Practices 2

Oscilloscope

3Amateur Practices

Spectrum Analyzer

The Scoop on Scopes

 E4A01 How does a spectrum analyzer

differ from an oscilloscope?

A. A spectrum analyzer measures ionospheric reflection; an oscilloscope displays electrical signalsB. A spectrum analyzer displays the peak amplitude of signals; an oscilloscope displays the average amplitude of signalsC. A spectrum analyzer displays signals in the frequency domain; an oscilloscope displays signals in the time domainD. A spectrum analyzer displays radio frequencies; an oscilloscope displays audio frequencies

Amateur Practices 4

 E4A01 How does a spectrum analyzer

differ from an oscilloscope?

A. A spectrum analyzer measures ionospheric reflection; an oscilloscope displays electrical signalsB. 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 domainD. A spectrum analyzer displays radio frequencies; an oscilloscope displays audio frequenciesAmateur Practices 5

 E4A02 Which of the following

parameters would a spectrum analyzer display on the horizontal axis?

A. SWRB. QC. TimeD. Frequency

6Amateur Practices

 E4A02 Which of the following

parameters would a spectrum analyzer display on the horizontal axis?

A. SWRB. QC. Time

D. Frequency

7Amateur Practices

 E4A03 Which of the following

parameters would a spectrum analyzer display on the vertical axis?

A. AmplitudeB. DurationC. SWRD. Q

8Amateur Practices

 E4A03 Which of the following

parameters would a spectrum analyzer display on the vertical axis?

A. AmplitudeB. DurationC. SWRD. Q

9Amateur Practices

 E4A04 Which of the following test

instruments is used to display spurious signals from a radio transmitter?

A. A spectrum analyzerB. A wattmeterC. A logic analyzerD. A time-domain reflectometer

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 E4A04 Which of the following test

instruments is used to display spurious signals from a radio transmitter?

A. A spectrum analyzerB. A wattmeterC. A logic analyzerD. A time-domain reflectometer

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 E4A05 Which of the following test

instruments is used to display intermodulation distortion products in an

SSB transmission?

A. A wattmeterB. A spectrum analyzerC. A logic analyzerD. A time-domain reflectometer

12Amateur Practices

 E4A05 Which of the following test

instruments is used to display intermodulation distortion products in an

SSB transmission?

A. A wattmeter

B. A spectrum analyzerC. A logic analyzerD. A time-domain reflectometer

13Amateur Practices

If two separate (non-harmonically related) audio tones are applied to the the microphone input of a SSB transmitter wewould expect to see only two signals in the RF output (Carrier ± tone 1 and the carrier ±tone2). In the illustration belowyou can see that there two smaller signals about 55dB bellow the two RF signals. These are intermodulation distortionproducts.

14Amateur Practices

 E4A06 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 duplexerB. Whether a crystal is operating on its fundamental or overtone frequencyC. The spectral output of a transmitterD. All of these choices are correct

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 E4A06 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 duplexerB. Whether a crystal is operating on its fundamental or overtone frequencyC. The spectral output of a transmitter

D. All of these choices are correct

16Amateur Practices

These are some common antenna analyzers. The one the far left is made by MFJ and is the most commonly used

by amateur radio operator.

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 E4A07 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 resonanceB. Antenna analyzers do not need an external RF source C. Antenna analyzers display a time-varying representation of the modulation envelopeD. All of these choices are correct

18Amateur Practices

 E4A07 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 envelopeD. All of these choices are correct

19Amateur Practices

 E4A08 Which of the following instruments would be best for

measuring the SWR of a beam antenna?

A. A spectrum analyzerB. A Q meterC. An ohmmeterD. An antenna analyzer

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 E4A08 Which of the following instruments would be best for

measuring the SWR of a beam antenna?

A. A spectrum analyzerB. A Q meterC. An ohmmeter

D. An antenna analyzer

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 E4A09 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 programB. Multiply the ALC level on the transmitter during a normal transmission by the average power outputC. Use an RF voltmeter coupled to the transmitter output using appropriate isolation to prevent damage to the meterD. All of these choices are correct

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 E4A09 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 programB. Multiply the ALC level on the transmitter during a normal transmission by the average power outputC. Use an RF voltmeter coupled to the transmitter output using appropriate isolation to prevent damage to the meterD. All of these choices are correct

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 E4A10 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 approximately6 to 7 ohmsB. Measure base-to-emitter resistance with an ohmmeter; it should be approximately 0.6 to 0.7 ohmsC. Measure base-to-emitter voltage with a voltmeter; it should be approximately 6 to 7 voltsD. Measure base-to-emitter voltage with a voltmeter; it should be approximately0.6 to 0.7 volts

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 E4A10 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 approximately6 to 7 ohmsB. Measure base-to-emitter resistance with an ohmmeter; it should be approximately 0.6 to 0.7 ohmsC. Measure base-to-emitter voltage with a voltmeter; it should be approximately 6 to 7 volts

D. Measure base-to-emitter voltage with a voltmeter; it should be approximately0.6 to 0.7 volts

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 E4A11 Which of these instruments could be used for detailed analysis of

digital signals?

A. Dip meterB. OscilloscopeC. OhmmeterD. Q meter

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 E4A11 Which of these instruments could be used for detailed analysis of

digital signals?

A. Dip meter

B. OscilloscopeC. OhmmeterD. Q meter

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 E4A12 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 lossesB. Attenuate the transmitter output going to the spectrum analyzerC. Match the antenna to the loadD. All of these choices are correct

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 E4A12 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 analyzerC. Match the antenna to the loadD. All of these choices are correct

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E4B Measurement techniques

Instrument accuracy and performance limitations; probes; techniques to

minimize errors; measurement of Q; instrument calibration

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 E4B01 Which of the following factors

most affects the accuracy of a frequency counter?

A. Input attenuator accuracyB. Time base accuracyC. Decade divider accuracyD. Temperature coefficient of the logic

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 E4B01 Which of the following factors

most affects the accuracy of a frequency counter?

A. Input attenuator accuracy

B. Time base accuracyC. Decade divider accuracyD. Temperature coefficient of the logic

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E4B02 What is an advantage of using a bridge circuit to measure

impedance?

A. It provides an excellent match under all conditionsB. It is relatively immune to drift in the signal generator sourceC. The measurement is based on obtaining a signal null, which can be done very preciselyD. It can display results directly in Smith chart format

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E4B02 What is an advantage of using a bridge circuit to measure

impedance?

A. It provides an excellent match under all conditionsB. 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 preciselyD. It can display results directly in Smith chart format

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 E4B03 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 HzB. 14.652 kHzC. 146.52 HzD. 1.4652 MHz

35Amateur Practices

 E4B03 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 HzB. 14.652 kHz

C. 146.52 HzD. 1.4652 MHz

36Amateur Practices

146.520.000 * 1 = 146.52 1,000,000

 E4B04 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 HzB. 0.1 MHzC. 1.4652 HzD. 1.4652 kHz

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 E4B04 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 HzB. 0.1 MHzC. 1.4652 HzD. 1.4652 kHz

38Amateur Practices

146.520.000 * 0.1 = 14 . 652 1,000,000

 E4B05 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 HzB. 10 HzC. 146.52 kHzD. 1465.20 Hz

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 E4B05 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 HzB. 10 HzC. 146.52 kHz

D. 1465.20 Hz

40Amateur Practices

146.520.000 * 10 = 1,465.2 1,000,000

 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?

A. 100 wattsB. 125 wattsC. 25 wattsD. 75 watts

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 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?

A. 100 wattsB. 125 wattsC. 25 watts

D. 75 watts

42Amateur Practices

100 watts-25 watts 75 watts

 E4B07 Which of the following is good

practice when using an oscilloscope probe?

A. Keep the signal ground connection of the probe as short as possibleB. Never use a high impedance probe to measure a low impedance circuitC. Never use a DC-coupled probe to measure an AC circuitD. All of these choices are correct

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 E4B07 Which of the following is good

practice when using an oscilloscope probe?

A. Keep the signal ground connection of the probe as short as possibleB. Never use a high impedance probe to measure a low impedance circuitC. Never use a DC-coupled probe to measure an AC circuitD. All of these choices are correct

44Amateur Practices

 E4B08 Which of the following is a

characteristic of a good DC voltmeter?

A. High reluctance inputB. Low reluctance inputC. High impedance inputD. Low impedance input

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 E4B08 Which of the following is a

characteristic of a good DC voltmeter?

A. High reluctance inputB. Low reluctance input

C. High impedance inputD. Low impedance input

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 E4B09 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 lineB. The transmitter is not properly neutralizedC. There is an impedance mismatch between the antenna and feed lineD. There is more power going into the antenna

47Amateur Practices

 E4B09 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 lineB. The transmitter is not properly neutralizedC. There is an impedance mismatch between the antenna and feed line

D. There is more power going into the antenna

48Amateur Practices

 E4B10 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 analyzerB. Modulate the transmitter with two non-harmonically related audio frequencies and observe the RF output with a spectrum analyzerC. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a peak reading wattmeterD. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a logic analyzer

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 E4B10 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 analyzerB. Modulate the transmitter with two non-harmonically related audio frequencies and observe the RF output with a spectrum analyzerC. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a peak reading wattmeterD. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a logic analyzer

50Amateur Practices

 E4B11 How should a portable antenna analyzer be connected when measuring

antenna resonance and feed point impedance?

A. Loosely couple the analyzer near the antenna baseB. Connect the analyzer via a high-impedance transformer to the antennaC. Connect the antenna and a dummy load to the analyzerD. Connect the antenna feed line directly to the analyzer's connector

51Amateur Practices

 E4B11 How should a portable antenna analyzer be connected when measuring

antenna resonance and feed point impedance?

A. Loosely couple the analyzer near the antenna baseB. Connect the analyzer via a high-impedance transformer to the antennaC. Connect the antenna and a dummy load to the analyzer

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

52Amateur Practices

Never connect an antenna analyzer to a transmitter or measure an antenna in close proximity to an active transmittingantenna. This could destroy the antenna analyzer.

 E4B12 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 voltmeterB. When used as a galvanometer, the reading in volts multiplied by the ohms/volt will determine the power drawn by the device under testC. When used as an ohmmeter, the reading in ohms divided by the ohms/volt will determine the voltage applied to the circuitD. When used as an ammeter, the full scale reading in amps divided by ohms/volt will determine the size of shunt needed

53Amateur Practices

 E4B12 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 voltmeterB. When used as a galvanometer, the reading in volts multiplied by the ohms/volt will determine the power drawn by the device under testC. When used as an ohmmeter, the reading in ohms divided by the ohms/volt will determine the voltage applied to the circuitD. When used as an ammeter, the full scale reading in amps divided by ohms/volt will determine the size of shunt needed

54Amateur Practices

 E4B13 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 possibleB. A high frequency sine wave is displayed and the probe is adjusted for maximum amplitudeC. A frequency standard is displayed and the probe is adjusted until the deflection time is accurateD. A DC voltage standard is displayed and the probe is adjusted until the displayed voltage is accurate

55Amateur Practices

 E4B13 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 possibleB. A high frequency sine wave is displayed and the probe is adjusted for maximum amplitudeC. A frequency standard is displayed and the probe is adjusted until the deflection time is accurateD. A DC voltage standard is displayed and the probe is adjusted until the displayed voltage is accurate 56Amateur Practices

 E4B13 How is the compensation of an oscilloscope probe typically adjusted?

57Amateur Practices

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

E4B14 What happens if a dip meter is too tightly coupled to a tuned circuit

being checked?

A. Harmonics are generatedB. A less accurate reading resultsC. Cross modulation occursD. Intermodulation distortion occurs

58Amateur Practices

E4B14 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 resultsC. Cross modulation occursD. Intermodulation distortion occurs

59Amateur Practices

 E4B15 Which of the following can be

used as a relative measurement of the Q for a series-tuned circuit?

A. The inductance to capacitance ratioB. The frequency shiftC. The bandwidth of the circuit's frequency responseD. The resonant frequency of the circuit

60Amateur Practices

 E4B15 Which of the following can be

used as a relative measurement of the Q for a series-tuned circuit?

A. The inductance to capacitance ratioB. The frequency shift

C. The bandwidth of the circuit's frequency responseD. The resonant frequency of the circuit

61Amateur Practices

 E4C Receiver performance

characteristics

phase noise; capture effect; noise floor; image rejection; MDS; signal-to-noise-

ratio; selectivity

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 E4C01 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 signalsB. It reduces receiver sensitivityC. It decreases receiver third-order intermodulation distortion dynamic rangeD. It can cause strong signals on nearby frequencies to interfere with reception of weak signals

63Amateur Practices

 E4C01 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 signalsB. It reduces receiver sensitivityC. 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

64Amateur Practices

 E4C02 Which of the following portions

of a receiver can be effective in eliminating image signal interference?

A. A front-end filter or pre-selectorB. A narrow IF filterC. A notch filterD. A properly adjusted product detector

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 E4C02 Which of the following portions

of a receiver can be effective in eliminating image signal interference?

A. A front-end filter or pre-selectorB. A narrow IF filterC. A notch filterD. A properly adjusted product detector

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 E4C03 What is the term for the

blocking of one FM phone signal by another, stronger FM phone signal?

A. DesensitizationB. Cross-modulation interferenceC. Capture effectD. Frequency discrimination

67Amateur Practices

 E4C03 What is the term for the

blocking of one FM phone signal by another, stronger FM phone signal?

A. DesensitizationB. Cross-modulation interference

C. Capture effectD. Frequency discrimination

68Amateur Practices

 E4C04 What is the definition of the

noise figure of a receiver?

A. The ratio of atmospheric noise to phase noiseB. The noise bandwidth in Hertz compared to the theoretical bandwidth of a resistive networkC. The ratio of thermal noise to atmospheric noiseD. The ratio in dB of the noise generated by the receiver compared to the theoretical minimum noise

69Amateur Practices

 E4C04 What is the definition of the

noise figure of a receiver?

A. The ratio of atmospheric noise to phase noiseB. The noise bandwidth in Hertz compared to the theoretical bandwidth of a resistive networkC. 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

70Amateur Practices

The noise figure is a way of describing the amount of noise generated in a receiver, amp, transmission line, antenna system, or other component. The noise figure of a component or system is defined as the signal-to-noise ratio at the input divided by the signal-to-noise ratio at the output, with the input noise equal to the noise available from a matched resistance at a temperature of T0=290 Kelvin.

 E4C05 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 frequencyB. The theoretical noise at the input of a perfect receiver at room temperatureC. The noise figure of a 1 Hz bandwidth receiverD. The galactic noise contribution to minimum detectable signal

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 E4C05 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 temperatureC. The noise figure of a 1 Hz bandwidth receiverD. The galactic noise contribution to minimum detectable signal

72Amateur Practices

This noise floor will be higher as the receiver bandwidth is increased. A receiver with a 10 KHz bandwidth will have 10,000 times more noise or an additional 40dB of noise bringing the noise floor up to – 174dBm + 40 dB or -134 dBm.

 E4C06 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 dBmB. -164 dBmC. -155 dBmD. -148 dBm

73Amateur Practices

 E4C06 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 dBmB. -164 dBmC. -155 dBm

D. -148 dBm

74Amateur Practices

This noise floor will be higher as the receiver bandwidth is increased. A receiver with a 400 KHz bandwidth will have 4 00 times more noise or an additional 26 dB of noise bringing the noise floor up to – 174dBm + 26 dB or -148 dBm.dB= 10(log bw2/bw1) or dB= 10(log 400/1) dB= 10 (2.602) or dB=26 Therefore the new noise floor will be -174 +26 or -148dBm

 E4C07 What does the MDS of a

receiver represent?

A. The meter display sensitivity B. The minimum discernible signalC. The multiplex distortion stabilityD. The maximum detectable spectrum

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 E4C07 What does the MDS of a

receiver represent?

A. The meter display sensitivity

B. The minimum discernible signalC. The multiplex distortion stabilityD. The maximum detectable spectrum

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 E4C08 How might lowering the noise

figure affect receiver performance?

A. It would reduce the signal to noise ratio B. It would improve weak signal sensitivityC. It would reduce bandwidthD. It would increase bandwidth

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 E4C08 How might lowering the noise

figure affect receiver performance?

A. It would reduce the signal to noise ratio

B. It would improve weak signal sensitivityC. It would reduce bandwidthD. It would increase bandwidth

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 E4C09 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 receiverB. Reduced driftC. Easier for front-end circuitry to eliminate image responsesD. Improved receiver noise figure

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 E4C09 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 receiverB. Reduced drift

C. Easier for front-end circuitry to eliminate image responsesD. Improved receiver noise figure

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 E4C10 Which of the following is a

desirable amount of selectivity for an amateur RTTY HF receiver?

A. 100 HzB. 300 HzC. 6000 HzD. 2400 Hz

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 E4C10 Which of the following is a

desirable amount of selectivity for an amateur RTTY HF receiver?

A. 100 Hz

B. 300 HzC. 6000 HzD. 2400 Hz

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 E4C11 Which of the following is a

desirable amount of selectivity for an amateur SSB phone receiver?

A. 1 kHzB. 2.4 kHzC. 4.2 kHzD. 4.8 kHz

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 E4C11 Which of the following is a

desirable amount of selectivity for an amateur SSB phone receiver?

A. 1 kHz

B. 2.4 kHzC. 4.2 kHzD. 4.8 kHz

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E4C12 What is an undesirable effect of using too wide a filter bandwidth in the IF section of a

receiver?

A. Output-offset overshootB. Filter ringingC. Thermal-noise distortionD. Undesired signals may be heard

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E4C12 What is an undesirable effect of using too wide a filter bandwidth in the IF section of a

receiver?

A. Output-offset overshootB. Filter ringingC. Thermal-noise distortion

D. Undesired signals may be heard

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 E4C13 How does a narrow-band

roofing filter affect receiver performance?

A. It improves sensitivity by reducing front end noiseB. It improves intelligibility by using low Q circuitry to reduce ringingC. It improves dynamic range by attenuating strong signals near the receive frequencyD. All of these choices are correct

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 E4C13 How does a narrow-band

roofing filter affect receiver performance?

A. It improves sensitivity by reducing front end noiseB. It improves intelligibility by using low Q circuitry to reduce ringing

C. It improves dynamic range by attenuating strong signals near the receive frequencyD. All of these choices are correct

88Amateur Practices

 E4C14 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 MHzB. 14.755 MHzC. 14.445 MHzD. 15.210 MHz

89Amateur Practices

 E4C14 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 MHzB. 14.755 MHzC. 14.445 MHz

D. 15.210 MHz

90Amateur Practices

When a local oscillator signal is mixed with an incoming signal in generates the sum and the difference of the two signals. If we assume High side mix (the LO is higher than the tuned frequency then the LO will be the tuned frequency + 455KHz. A signal 455 KHz above the LO would also generate a 455 KHz IF spurious or image signal. So taking the receive frequency of 14.300 MHz and 2 times the IF frequency of 0.455 MHz (14.300 – (2x.455) we get 15.210 MHz.

14,300 14,300 - 455 + 45513,845 VFO 14,755 2nd harmonic - 455 + 45513,390 15,210 3rd harmonic

 E4C15 What is the primary source of

noise that can be heard from an HF receiver with an antenna connected?

A. Detector noiseB. Induction motor noiseC. Receiver front-end noiseD. Atmospheric noise

91Amateur Practices

 E4C15 What is the primary source of

noise that can be heard from an HF receiver with an antenna connected?

A. Detector noiseB. Induction motor noiseC. Receiver front-end noise

D. Atmospheric noise

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E4D Receiver performance characteristics

blocking dynamic range; intermodulation and cross-modulation

interference; 3rd order intercept; desensitization; preselection

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 E4D01 What is meant by the blocking

dynamic range of a receiver?

A. The difference in dB between the noise floor and the level of an incoming signal which will cause 1 dB of gain compressionB. The minimum difference in dB between the levels of two FM signals which will cause one signal to block the otherC. The difference in dB between the noise floor and the third order intercept pointD. The minimum difference in dB between two signals which produce third order intermodulation products greater than the noise floor

94Amateur Practices

 E4D01 What is meant by the blocking

dynamic range of a receiver?

A. The difference in dB between the noise floor and the level of an incoming signal which will cause 1 dB of gain compressionB. The minimum difference in dB between the levels of two FM signals which will cause one signal to block the otherC. The difference in dB between the noise floor and the third order intercept pointD. The minimum difference in dB between two signals which produce third order intermodulation products greater than the noise floor

95Amateur Practices

 E4D02 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 signalsB. Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sidebandC. Cross-modulation of the desired signal and insufficient audio power to operate the speakerD. Oscillator instability and severe audio distortion of all but the strongest received signals

96Amateur Practices

 E4D02 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 signalsB. Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sidebandC. Cross-modulation of the desired signal and insufficient audio power to operate the speakerD. Oscillator instability and severe audio distortion of all but the strongest received signals

97Amateur Practices

 E4D03 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 transmittersB. When the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmittersC. When the signals from the transmitters are reflected out of phase from airplanes passing overheadD. When the signals from the transmitters are reflected in phase from airplanes passing overhead

98Amateur Practices

 E4D03 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 transmittersC. When the signals from the transmitters are reflected out of phase from airplanes passing overheadD. When the signals from the transmitters are reflected in phase from airplanes passing overhead 99Amateur Practices

 E4D04 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 transmitterC. A Class C final amplifierD. A Class D final amplifier

100Amateur Practices

 E4D04 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 transmitterC. A Class C final amplifierD. A Class D final amplifier

101Amateur Practices

 E4D05 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 MHzB. 146.88 MHz and 146.34 MHzC. 146.10 MHz and 147.30 MHzD. 173.35 MHz and 139.40 MHz

102Amateur Practices

 E4D05 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 MHzB. 146.88 MHz and 146.34 MHzC. 146.10 MHz and 147.30 MHzD. 173.35 MHz and 139.40 MHz

103Amateur Practices

 E4D06 What is the term for unwanted signals generated by the mixing of two

or more signals?

A. Amplifier desensitizationB. NeutralizationC. Adjacent channel interferenceD. Intermodulation interference

104Amateur Practices

 E4D06 What is the term for unwanted signals generated by the mixing of two

or more signals?

A. Amplifier desensitizationB. NeutralizationC. Adjacent channel interference

D. Intermodulation interference

105Amateur Practices

 E4D07 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 noiseB. A reduction in apparent signal strength C. The desired signal can no longer be heardD. The off-frequency unwanted signal is heard in addition to the desired signal

106Amateur Practices

 E4D07 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 noiseB. 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

107Amateur Practices

 E4D08 What causes intermodulation in

an electronic circuit?

A. Too little gainB. Lack of neutralizationC. Nonlinear circuits or devicesD. Positive feedback

108Amateur Practices

 E4D08 What causes intermodulation in

an electronic circuit?

A. Too little gainB. Lack of neutralization

C. Nonlinear circuits or devicesD. Positive feedback

109Amateur Practices

 E4D09 What is the purpose of the

preselector in a communications receiver?

A. To store often-used frequenciesB. To provide a range of AGC time constantsC. To increase rejection of unwanted signals D. To allow selection of the optimum RF amplifier device

110Amateur Practices

 E4D09 What is the purpose of the

preselector in a communications receiver?

A. To store often-used frequenciesB. 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

111Amateur Practices

 E4D10 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 productsB. The receiver can tolerate signals up to 40 dB above the noise floor without producing third-order intermodulation productsC. A pair of 40 dBm signals will theoretically generate a third-order intermodulation product with the same level as the input signalsD. A pair of 1 mW input signals will produce a third-order intermodulation product which is 40 dB stronger than the input signal

112Amateur Practices

 E4D10 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 productsB. 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 signalsD. A pair of 1 mW input signals will produce a third-order intermodulation product which is 40 dB stronger than the input signal

113Amateur Practices

 E4D11 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 bandB. The third-order intercept is much higher than other ordersC. Third-order products are an indication of poor image rejectionD. Third-order intermodulation produces three products for every input signal within the band of interest

114Amateur Practices

 E4D11 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 bandB. The third-order intercept is much higher than other ordersC. Third-order products are an indication of poor image rejectionD. Third-order intermodulation produces three products for every input signal within the band of interest

115Amateur Practices

 E4D12 What is the term for the

reduction in receiver sensitivity caused by a strong signal near the received

frequency?

A. DesensitizationB. QuietingC. Cross-modulation interferenceD. Squelch gain rollback

116Amateur Practices

 E4D12 What is the term for the

reduction in receiver sensitivity caused by a strong signal near the received

frequency?

A. DesensitizationB. QuietingC. Cross-modulation interferenceD. Squelch gain rollback

117Amateur Practices

 E4D13 Which of the following can

cause receiver desensitization?

A. Audio gain adjusted too lowB. Strong adjacent-channel signalsC. Audio bias adjusted too highD. Squelch gain misadjusted

118Amateur Practices

 E4D13 Which of the following can

cause receiver desensitization?

A. Audio gain adjusted too low

B. Strong adjacent-channel signalsC. Audio bias adjusted too highD. Squelch gain misadjusted

119Amateur Practices

 E4D14 Which of the following is a way

to reduce the likelihood of receiver desensitization?

A. Decrease the RF bandwidth of the receiverB. Raise the receiver IF frequency C. Increase the receiver front end gainD. Switch from fast AGC to slow AGC

120Amateur Practices

 E4D14 Which of the following is a way

to reduce the likelihood of receiver desensitization?

A. Decrease the RF bandwidth of the receiverB. Raise the receiver IF frequency C. Increase the receiver front end gainD. Switch from fast AGC to slow AGC

121Amateur Practices

E4E Noise suppression

system noise; electrical appliance noise; line noise; locating noise sources; DSP

noise reduction; noise blankers 

122Amateur Practices

 E4E01 Which of the following types of receiver noise can often be reduced by

use of a receiver noise blanker?

A. Ignition noiseB. Broadband white noiseC. Heterodyne interferenceD. All of these choices are correct

123Amateur Practices

 E4E01 Which of the following types of receiver noise can often be reduced by

use of a receiver noise blanker?

A. Ignition noiseB. Broadband white noiseC. Heterodyne interferenceD. All of these choices are correct

124Amateur Practices

 E4E02 Which of the following types of receiver noise can often be reduced with

a DSP noise filter?

A. Broadband white noiseB. Ignition noiseC. Power line noiseD. All of these choices are correct

125Amateur Practices

 E4E02 Which of the following types of receiver noise can often be reduced with

a DSP noise filter?

A. Broadband white noiseB. Ignition noiseC. Power line noise

D. All of these choices are correct

126Amateur Practices

 E4E03 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 levelsB. Signals which appear across a wide bandwidthC. Signals which appear at one IF but not anotherD. Signals which have a sharply peaked frequency distribution

127Amateur Practices

 E4E03 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 bandwidthC. Signals which appear at one IF but not anotherD. Signals which have a sharply peaked frequency distribution

128Amateur Practices

 E4E04 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 leadB. By installing a noise suppression resistor and a blocking capacitor in both leadsC. By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field leadD. By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads

129Amateur Practices

 E4E04 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 leadB. By installing a noise suppression resistor and a blocking capacitor in both leadsC. By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field leadD. By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads

130Amateur Practices

 E4E05 How can noise from an electric

motor be suppressed?

A. By installing a high pass filter in series with the motor’s power leadsB. By installing a brute-force AC-line filter in series with the motor leadsC. By installing a bypass capacitor in series with the motor leadsD. By using a ground-fault current interrupter in the circuit used to power the motor

131Amateur Practices

 E4E05 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 leadsC. By installing a bypass capacitor in series with the motor leadsD. By using a ground-fault current interrupter in the circuit used to power the motor

132Amateur Practices

 E4E06 What is a major cause of

atmospheric static?

A. Solar radio frequency emissionsB. ThunderstormsC. Geomagnetic stormsD. Meteor showers

133Amateur Practices

 E4E06 What is a major cause of

atmospheric static?

A. Solar radio frequency emissions

B. ThunderstormsC. Geomagnetic stormsD. Meteor showers

134Amateur Practices

 E4E07 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 reflectometerB. By observing the AC power line waveform with an oscilloscopeC. By turning off the AC power line main circuit breaker and listening on a battery operated radioD. By observing the AC power line voltage with a spectrum analyzer

135Amateur Practices

 E4E07 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 reflectometerB. 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 radioD. By observing the AC power line voltage with a spectrum analyzer

136Amateur Practices

The principal aim of any data-transmission system is to send data from one location to another, whether within a single boxor enclosure, between boxes within an enclosure, between enclosures within a building or defined area, or betweenbuildings. Figure 1 illustrates an RS-485 signaling situation in which the buildings are supplied from different powercircuits.

137Amateur Practices

 E4E08 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 transmitterB. An electrical-sparking signalC. A differential-mode signal at the AC power line frequencyD. Harmonics of the AC power line frequency

138Amateur Practices

 E4E08 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 transmitterB. An electrical-sparking signalC. A differential-mode signal at the AC power line frequencyD. Harmonics of the AC power line frequency

139Amateur Practices

 E4E09 What undesirable effect can occur when using an IF noise blanker?

A. Received audio in the speech range might have an echo effectB. The audio frequency bandwidth of the received signal might be compressedC. Nearby signals may appear to be excessively wide even if they meet emission standardsD. FM signals can no longer be demodulated

140Amateur Practices

 E4E09 What undesirable effect can occur when using an IF noise blanker?

A. Received audio in the speech range might have an echo effectB. 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 standardsD. FM signals can no longer be demodulated

141Amateur Practices

 E4E10 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 receiverB. The interfering signal may drift slowly across the HF spectrumC. The interfering signal can be several kHz in width and usually repeats at regular intervals across a HF bandD. All of these choices are correct

142Amateur Practices

 E4E10 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 receiverB. The interfering signal may drift slowly across the HF spectrumC. 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

143Amateur Practices

E4E11 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 signalB. Nearby corroded metal joints are mixing and re-radiating the broadcast signalsC. You are receiving sky wave signals from a distant station D. Your station receiver IF amplifier stage is defective

144Amateur Practices

E4E11 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 signalsC. You are receiving sky wave signals from a distant station D. Your station receiver IF amplifier stage is defective

145Amateur Practices

 E4E12 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 signalsB. Any nearby signal passing through the DSP system will overwhelm the desired signalC. Received CW signals will appear to be modulated at the DSP clock frequencyD. Ringing in the DSP filter will completely remove the spaces between the CW characters

146Amateur Practices

 E4E12 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 signalsB. Any nearby signal passing through the DSP system will overwhelm the desired signalC. Received CW signals will appear to be modulated at the DSP clock frequencyD. Ringing in the DSP filter will completely remove the spaces between the CW characters

147Amateur Practices

E4E13 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 deviceB. A defective doorbell or doorbell transformer inside a nearby residenceC. A malfunctioning illuminated advertising displayD. All of these choices are correct

148Amateur Practices

E4E13 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 deviceB. A defective doorbell or doorbell transformer inside a nearby residenceC. A malfunctioning illuminated advertising display

D. All of these choices are correct

149Amateur Practices

E4E14 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 receiverB. A clicking noise at intervals of a few secondsC. The appearance of unstable modulated or unmodulated signals at specific frequenciesD. A whining type noise that continually pulses off and on

150Amateur Practices

E4E14 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 receiverB. A clicking noise at intervals of a few seconds

C. The appearance of unstable modulated or unmodulated signals at specific frequenciesD. A whining type noise that continually pulses off and on

151Amateur Practices

End ofSUBELEMENT E4

AMATEUR PRACTICES

Amateur Practices 152