Amateur Extra Class Exam Question Pool- Subelement E-4

Subelement E-1           Subelement E-2          Subelement E-3          Subbelement E-4          Subelement E-5
Subelement E-6           Subelement E-7          Subelement E-8          Subbelement E-9          Subelement E-0

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

 

 

E4A -  Test equipment: analog and digital instruments; spectrum and network analyzers, antenna analyzers; oscilloscopes; RF measurements; computer aided measurements

 

 

E4A01 

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

A. Input capacitance

B. Input impedance

C. Sampling rate

D. Sample resolution

~~

 

E4A02 

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

A. RF amplitude and time

B. RF amplitude and frequency

C. SWR and frequency

D. SWR and time

~~

 

E4A03 

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

A. A wattmeter

B. A spectrum analyzer

C. A logic analyzer

D. A time-domain reflectometer

~~

 

E4A04 

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

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

B. Amount of memory on the soundcard

C. Q of the interface of the interface circuit

D. All of these choices are correct

~~

 

E4A05 

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

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

~~

 

E4A06 

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

A. False signals are displayed

B. All signals will have a DC offset

C. Calibration of the vertical scale is no longer valid

D. False triggering occurs

~~

 

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 envelope

D. All of these choices are correct

~~

 

E4A08 

Which of the following instrument 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

~~

 

E4A09 

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

A. The same as the sample rate

B. One-half the sample rate

C. One-tenth the sample rate

D. It depends on how the data is stored internally

~~

 

E4A10 

Which of the following displays multiple digital signal states simultaneously?

A. Network analyzer

B. Bit error rate tester

C. Modulation monitor

D. Logic analyzer

~~

 

E4A11 

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

~~

 

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 analyzer

C. Match the antenna to the load

D. All of these choices are correct

~~

 

E4A13 

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

~~

 

E4A14 

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

A. It amplifies low level signals for more accurate counting

B. It multiplies a higher frequency signal so a low-frequency counter can display the operating frequency

C. It prevents oscillation in a low-frequency counter circuit

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

~~

 

E4A15 

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

A. It can run on battery power for remote measurements

B. It does not require an expensive high-precision time base

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

D. It can directly measure the modulation index of an FM transmitter

~~

 

 

 

 

 

 

 

 

E4B -  Measurement technique and limitations: instrument accuracy and performance limitations; probes; techniques to minimize errors; measurement of "Q"; instrument calibration; S parameters; vector network analyzers

 

 

E4B01 

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

~~

 

E4B02 

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. It is very precise in obtaining a signal null

D. It can display results directly in Smith chart format

~~

 

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 Hz

B. 14.652 kHz

C. 146.52 Hz

D. 1.4652 MHz

~~

 

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 Hz

B. 0.1 MHz

C. 1.4652 Hz

D. 1.4652 kHz

~~

 

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 Hz

B. 10 Hz

C. 146.52 kHz

D. 1465.20 Hz

~~

 

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 watts

B. 125 watts

C. 25 watts

D. 75 watts

~~

 

E4B07 

What do the subscripts of S parameters represent?

A. The port or ports at which measurements are made

B. The relative time between measurements

C. Relative quality of the data

D. Frequency order of the measurements

~~

 

E4B08 

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

~~

 

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 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

~~

 

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 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

~~

 

E4B11 

How should an 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. Loosely couple the antenna and a dummy load to the analyzer

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

~~

 

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 indicate the input impedance of the voltmeter

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

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

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

~~

 

E4B13 

Which S parameter is equivalent to forward gain?

A. S11

B. S12

C. S21

D. S22

~~

 

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 results

C. Cross modulation occurs

D. Intermodulation distortion occurs

~~

 

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 ratio

B. The frequency shift

C. The bandwidth of the circuit's frequency response

D. The resonant frequency of the circuit

~~

 

E4B16 

Which S parameter represents return loss or SWR?

A. S11

B. S12

C. S21

D. S22

~~

 

E4B17 

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

A. 50 ohms, 75 ohms, and 90 ohms

B. Short circuit, open circuit, and 50 ohms

C. Short circuit, open circuit, and resonant circuit

D. 50 ohms through 1/8 wavelength, 1/4 wavelength, and 1/2 wavelength of coaxial cable

~~

 

 

 

 

 

 

 

 

E4C -  Receiver performance characteristics, phase noise, noise floor, image rejection, MDS, signal-to-noise-ratio; selectivity; effects of SDR receiver non-linearity

 

 

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 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

~~

 

E4C02 

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

~~

 

E4C03 

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

~~

 

E4C04 

How is the noise figure of a receiver defined?

A. The ratio of atmospheric noise to phase noise

B. The ratio of the noise bandwidth in Hertz 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 to the theoretical minimum noise

~~

 

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 temperature

C. The noise figure of a 1 Hz bandwidth receiver

D. The galactic noise contribution to minimum detectable signal

~~

 

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 dBm

B. -164 dBm

C. -155 dBm

D. -148 dBm

~~

 

E4C07 

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

~~

 

E4C08 

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

A. One-half the maximum sample rate

B. One-half the maximum sampling buffer size

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

D. The reference voltage of the analog-to-digital converter

~~

 

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 receiver

B. Reduced drift

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

D. Improved receiver noise figure

~~

 

E4C10 

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

~~

 

E4C11 

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

~~

 

E4C12 

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

~~

 

E4C13 

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

~~

 

E4C14 

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. 13.845 MHz

B. 14.755 MHz

C. 14.445 MHz

D. 15.210 MHz

~~

 

E4C15 

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

A. Detector noise

B. Induction motor noise

C. Receiver front-end noise

D. Atmospheric noise

~~

 

E4C16 

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

A. Distortion

B. Overload

C. Loss of sensitivity

D. Excess output level

~~

 

E4C17 

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

A. CPU register width in bits

B. Anti-aliasing input filter bandwidth

C. RAM speed used for data storage

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

~~

 

 

 

 

 

 

 

E4D -  Receiver performance characteristics: blocking dynamic range; intermodulation and cross-modulation interference; 3rd order intercept; desensitization; preselector

 

 

 

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 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

~~

 

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 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

~~

 

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 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

~~

 

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 transmitter

C. A Class C final amplifier

D. A Class D final amplifier

~~

 

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 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

~~

 

E4D06 

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

~~

 

E4D07 

Which 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

~~

 

E4D08 

What causes intermodulation in an electronic circuit?

A. Too little gain

B. Lack of neutralization

C. Nonlinear circuits or devices

D. Positive feedback

~~

 

E4D09 

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

~~

 

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 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

~~

 

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 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

~~

 

E4D12 

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

~~

 

E4D13 

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

~~

 

E4D14 

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

~~

 

 

 

 

 

 

 

 

E4E -  Noise suppression: system noise; electrical appliance noise; line noise; locating noise sources; DSP noise reduction; noise blankers; grounding for signals

 

 

E4E01 

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

~~

 

E4E02 

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

~~

 

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 bandwidth

C. Signals which appear at one IF but not another

D. Signals which have a sharply peaked frequency distribution

~~

 

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 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

~~

 

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 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

~~

 

E4E06 

What is a major cause of atmospheric static?

A. Solar radio frequency emissions

B. Thunderstorms

C. Geomagnetic storms

D. Meteor showers

~~

 

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 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

~~

 

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 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

~~

 

E4E09 

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

~~

 

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 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

~~

 

E4E11 

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. 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

~~

 

E4E12 

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

A. A 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

~~

 

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 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

~~

 

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 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

~~

 

E4E15 

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

A. Low inductance ground connections at both ends of the shield

B. Common mode currents on the shield and conductors

C. Use of braided shielding material

D. Tying all ground connections to a common point resulting in differential mode currents in the shield

~~

 

E4E16 

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

A. Differential-mode current

B. Common-mode current

C. Reactive current only

D. Return current

~~

Subelement E-1           Subelement E-2          Subelement E-3          Subbelement E-4          Subelement E-5
Subelement E-6           Subelement E-7          Subelement E-8          Subbelement E-9          Subelement E-0
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