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Amateur Radio Question PoolsNew! View the differences between the 2008 Extra question pool and the previous pool. Amateur Extra Class Question PoolPrev 1 2 3 4 5 6 7 8 9 0 NextE4A01 How does a spectrum analyzer differ from a conventional time-domain oscilloscope? A spectrum analyzer measures ionospheric reflection; an oscilloscope displays electrical signals A spectrum analyzer displays signals in the time domain; an oscilloscope displays signals in the frequency domain A spectrum analyzer displays signals in the frequency domain; an oscilloscope displays signals in the time domain A spectrum analyzer displays radio frequencies; an oscilloscope displays audio frequencies E4A02 What parameter does the horizontal axis of a spectrum analyzer display? Amplitude Voltage Resonance Frequency E4A03 What parameter does the vertical axis of a spectrum analyzer display? Amplitude Duration Frequency Time E4A04 Which test instrument is used to display spurious signals from a radio transmitter? A spectrum analyzer A wattmeter A logic analyzer A time-domain reflectometer E4A05 Which test instrument is used to display intermodulation distortion products in an SSB transmission? A wattmeter A spectrum analyzer A logic analyzer A time-domain reflectometer E4A06 Which of the following is NOT something that could be determined with a spectrum analyzer? The degree of isolation between the input and output ports of a 2meter duplexer Whether a crystal is operating on its fundamental or overtone frequency The speed at which a transceiver switches from transmit to receive when being used for packet radio The spectral output of a transmitter E4A07 What is an advantage of using a spectrum analyzer to observe the output from a VHF transmitter? There are no advantages; an inexpensive oscilloscope can display the same information It displays all frequency components of the transmitted signal It displays a time-varying representation of the modulation envelope It costs much less than any other instrumentation useful for such measurements E4A08 What advantage does a logic probe have over a voltmeter for monitoring the status of a logic circuit? It has many more leads to connect to the circuit than a voltmeter It can be used to test analog and digital circuits It can read logic circuit voltage more accurately than a voltmeter It is smaller and shows a simplified readout E4A09 Which test instrument is used to directly indicate high and low digital voltage states? An ohmmeter An electroscope A logic probe A Wheatstone bridge E4A10 What can a logic probe indicate about a digital logic circuit? A short-circuit fault An open-circuit fault The resistance between logic modules The high and low logic states E4A11 Which of the following test instruments can be used to indicate pulse conditions in a digital logic circuit? A logic probe An ohmmeter An electroscope A Wheatstone bridge E4A12 Which of the following procedures should you follow when connecting a spectrum analyzer to a transmitter output? Use high quality coaxial lines Attenuate the transmitter output going to the spectrum analyzer Use a signal divider Match the antenna to the load E4B01 What is a frequency standard? A frequency chosen by a net control operator for net operations A device used to produce a highly accurate reference frequency A device for accurately measuring frequency to within 1 Hz A device used to generate wide-band random frequencies E4B02 What factors limit the accuracy, frequency response and stability of a frequency counter? Phase comparator slew rate, speed of the logic and time base stability Time base accuracy, speed of the logic and time base stability Time base accuracy, temperature coefficient of the logic and timebase reactance Number of digits in the readout, external frequency reference and temperature coefficient of the logic E4B03 How can the accuracy of a frequency counter be improved? By using slower digital logic By improving the accuracy of the frequency response By increasing the accuracy of the time base By using faster digital logic E4B04 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? 165.2 Hz 14.652 kHz 146.52 Hz 1.4652 MHz E4B05 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? 14.652 Hz 0.1 MHz 1.4652 Hz 1.4652 kHz E4B06 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? 146.52 Hz 10 Hz 146.52 kHz 1465.20 Hz E4B07 If a frequency counter with a specified accuracy of +/- 1.0 ppm reads 432,100,000 Hz, what is the most the actual frequency being measured could differ from the reading? 43.21 MHz 10 Hz 1.0 MHz 432.1 Hz E4B08 If a frequency counter with a specified accuracy of +/- 0.1 ppm reads 432,100,000 Hz, what is the most the actual frequency being measured could differ from the reading? 43.21 Hz 0.1 MHz 432.1 Hz 0.2 MHz E4B09 If a frequency counter with a specified accuracy of +/- 10 ppm reads 432,100,000 Hz, what is the most the actual frequency being measured could differ from the reading? 10 MHz 10 Hz 4321 Hz 432.1 Hz E4B10 If a 100 Hz signal is fed to the horizontal input of an oscilloscope and a 150 Hz signal is fed to the vertical input, what type of Lissajous figure will be displayed on the screen? A looping pattern with 100 loops horizontally and 150 loops vertically A rectangular pattern 100 mm wide and 150 mm high A looping pattern with 3 loops horizontally and 2 loops vertically An oval pattern 100 mm wide and 150 mm high E4B11 What is a dip-meter? A field-strength meter An SWR meter A device consisting of a variable frequency LC oscillator and an indicator showing the metered feedback current A marker generator E4B12 What does a dip-meter do? It accurately indicates signal strength It measures frequency accurately It measures transmitter output power accurately It gives an indication of the resonant frequency of a nearby circuit E4B13 How does a dip-meter function? Reflected waves at a specific frequency desensitize a detector coil Power coupled from an oscillator causes a decrease in metered current Power from a transmitter cancels feedback current Harmonics from an oscillator cause an increase in resonant circuit Q E4B14 What two ways could a dip-meter be used in an amateur station? To measure resonant frequency of antenna traps and to measure percentage of modulation To measure antenna resonance and to measure percentage of modulation To measure antenna resonance and to measure antenna impedance To measure resonant frequency of antenna traps and to measure a tuned circuit resonant frequency E4B15 For best accuracy, how tightly should a dip-meter be coupled with the LC circuit being checked? As loosely as possible As tightly as possible First loosely, then tightly With a jumper wire between the meter and the circuit to be checked E4B16 What factors limit the accuracy, frequency response and stability of an oscilloscope? Accuracy and linearity of the time base and the linearity and bandwidth of the deflection amplifiers Tube face voltage increments and deflection amplifier voltage Accuracy and linearity of the time base and tube face voltage increments Deflection amplifier output impedance and tube face frequency increments E4B17 What happens in a dip-meter when it is too tightly coupled with a tuned circuit being checked? Harmonics are generated A less accurate reading results Cross modulation occurs Intermodulation distortion occurs E4B18 What factors limit the accuracy, frequency response and stability of a D'Arsonval-type meter? Calibration, coil impedance and meter size Calibration, mechanical tolerance and coil impedance Coil impedance, electromagnetic voltage and movement mass Calibration, series resistance and electromagnet current E4B19 How can the frequency response of an oscilloscope be improved? By using a triggered sweep and a crystal oscillator as the time base By using a crystal oscillator as the time base and increasing the vertical sweep rate By increasing the vertical sweep rate and the horizontal amplifier frequency response By increasing the horizontal sweep rate and the vertical amplifier frequency response E4C01 What is the effect of excessive phase noise in the local oscillator section of a receiver? It limits the receiver ability to receive strong signals It reduces the receiver sensitivity It decreases the receiver third-order intermodulation distortion dynamic range It allows strong signals on nearby frequencies to interfere with reception of weak signals E4C02 What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency? Desensitization Quieting Cross-modulation interference Squelch gain rollback E4C03 Which of the following can cause receiver desensitization? Audio gain adjusted too low Strong adjacent-channel signals Audio bias adjusted too high Squelch gain adjusted too low E4C04 Which of the following is one way receiver desensitization can be reduced? Improve the shielding between the receiver and the transmitter causing the problem Increase the transmitter audio gain Decrease the receiver squelch level Increase the receiver bandwidth E4C05 What is the FM capture effect? All signals on a frequency are demodulated by an FM receiver All signals on a frequency are demodulated by an AM receiver The strongest signal received is the only demodulated signal The weakest signal received is the only demodulated signal E4C06 What is the term for the blocking of one FM phone signal by another, stronger FM phone signal? Desensitization Cross-modulation interference Capture effect Frequency discrimination E4C07 What is meant by the noise floor of a receiver? The weakest signal that can be detected under noisy atmospheric conditions The amount of phase noise generated by the receiver local oscillator The minimum level of noise that will overload the receiver RF amplifier stage The weakest signal that can be detected above the receiver internal noise E4C08 What is the blocking dynamic range for a receiver that has an 8-dB noise figure and an IF bandwidth of 500 Hz when the blocking level (1-dB compression point) is -20 dBm? -119 dBm 119 dB 146 dB -146 dBm E4C09 What is meant by the dynamic range of a communications receiver? The number of kHz between the lowest and the highest frequency to which the receiver can be tuned The maximum possible undistorted audio output of the receiver,referenced to one milliwatt The ratio between the minimum discernible signal and the largest tolerable signal without causing audible distortion products The difference between the lowest-frequency signal and the highest frequency signal detectable without moving the frequency control E4C10 What type of problems are caused by poor dynamic range in a communications receiver? Cross modulation of the desired signal and desensitization from strong adjacent signals Oscillator instability requiring frequent retuning, and loss of ability to recover the opposite sideband, should it be transmitted Cross modulation of the desired signal and insufficient audio power to operate the speaker Oscillator instability and severe audio distortion of all but the strongest received signals E4C11 If you measured the MDS of a receiver, what would you be measuring? The meter display sensitivity (MDS), or the responsiveness of the receiver S-meter to all signals The minimum discernible signal (MDS), or the weakest signal that the receiver can detect The minimum distorting signal (MDS), or the strongest signal the receiver can detect without overloading The maximum detectable spectrum (MDS), or the lowest to highest frequency range of the receiver E4C12 How does intermodulation interference between two repeater transmitters usually occur? When the signals from the transmitters are reflected out of phase from airplanes passing overhead When they are in close proximity and the signals mix in one or both of their final amplifiers When they are in close proximity and the signals cause feedback in one or both of their final amplifiers When the signals from the transmitters are reflected in phase from airplanes passing overhead E4C13 How can intermodulation interference between two repeater transmitters in close proximity often be reduced or eliminated? By using a Class C final amplifier with high driving power By installing a terminated circulator or ferrite isolator in the feed line to the transmitter and duplexer By installing a band-pass filter in the antenna feed line By installing a low-pass filter in the antenna feed line E4C14 If a receiver tuned to 146.70 MHz receives an intermodulation-product signal whenever a nearby transmitter transmits on 146.52 MHz, what are the two most likely frequencies for the other interfering signal? 146.34 MHz and 146.61 MHz 146.88 MHz and 146.34 MHz 146.10 MHz and 147.30 MHz 73.35 MHz and 239.40 MHz E4C15 If the signals of two transmitters mix together in one or both of their final amplifiers and unwanted signals at the sum and difference frequencies of the original signals are generated, what is this called? Amplifier desensitization Neutralization Adjacent channel interference Intermodulation interference E4C16 What is cross-modulation interference? Interference between two transmitters of different modulation type Interference caused by audio rectification in the receiver preamp Harmonic distortion of the transmitted signal Modulation from an unwanted signal is heard in addition to the desired signal E4C17 What causes intermodulation in an electronic circuit? Too little gain Lack of neutralization Nonlinear circuits or devices Positive feedback E4C18 What two factors determine the sensitivity of a receiver? Dynamic range and third-order intercept Cost and availability Intermodulation distortion and dynamic range Bandwidth and noise figure E4C19 What is the limiting condition for sensitivity in a communications receiver? The noise floor of the receiver The power-supply output ripple The two-tone intermodulation distortion The input impedance to the detector E4C20 Selectivity can be achieved in the front-end circuitry of a communications receiver by using what means? An audio filter An additional RF amplifier stage A preselector An additional IF amplifier stage E4C21 What degree of selectivity is desirable in the IF circuitry of an amateur RTTY receiver? 100 Hz 300 Hz 6000 Hz 2400 Hz E4C22 What degree of selectivity is desirable in the IF circuitry of a single sideband phone receiver? 1 kHz 2.4 kHz 4.2 kHz 4.8 kHz E4C23 What is an undesirable effect of using too wide a filter bandwidth in the IF section of a receiver? Output-offset overshoot Filter ringing Thermal-noise distortion Undesired signals will reach the audio stage E4C24 How should the filter bandwidth of a receiver IF section compare with the bandwidth of a received signal? It should be slightly greater than the received-signal bandwidth It should be approximately half the received-signal bandwidth It should be approximately twice the received-signal bandwidth It should be approximately four times the received-signal bandwidth E4C25 What degree of selectivity is desirable in the IF section of an FM phone receiver? 1 kHz 2.4 kHz 4.2 kHz 15 kHz E4C26 In a receiver, if the third-order intermodulation products have a power of-70 dBm when using two test tones at -30 dBm, what is the third-order intercept point? -20 dBm -10 dBm 0 dBm +10 dBm E4C27 In a receiver, if the second-order intermodulation products have a power of-70 dBm when using two test tones at -30 dBm, what is the second-order intercept point? -20 dBm -10 dBm 0 dBm +10 dBm E4D01 What is one of the most significant problems associated with reception in HF transceivers? Ignition noise Doppler shift Radar interference Mechanical vibrations E4D02 What is the proper procedure for suppressing electrical noise in a mobile transceiver? Follow the vehicle manufacturer's recommended procedures Insulate all plane sheet metal surfaces from each other Apply antistatic spray liberally to all non-metallic surfaces Install filter capacitors in series with all DC wiring E4D03 Where should ferrite beads be installed to suppress ignition noise in a mobile transceiver? In the resistive high-voltage cable Between the starter solenoid and the starter motor In the primary and secondary ignition leads In the antenna lead to the transceiver E4D04 How can alternator whine be minimized? By connecting the radio's power leads to the battery by the longest possible path By connecting the radio's power leads to the battery by the shortest possible path By installing a high-pass filter in series with the radio's DC power lead to the vehicle's electrical system By installing filter capacitors in series with the DC power lead E4D05 How can conducted and radiated noise caused by an automobile alternator be suppressed? By installing filter capacitors in series with the DC power lead and by installing a blocking capacitor in the field lead By connecting the radio to the battery by the longest possible path and installing a blocking capacitor in both leads 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 By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in the alternator leads E4D06 How can noise from an electric motor be suppressed? Install a ferrite bead on the AC line used to power the motor Install a brute-force, AC-line filter in series with the motor leads Install a bypass capacitor in series with the motor leads Use a ground-fault current interrupter in the circuit used to power the motor E4D07 What is a major cause of atmospheric static? Sunspots Thunderstorms Airplanes Meteor showers E4D08 How can it be determined if line-noise interference is being generated within your home? By checking the power-line voltage with a time-domain reflectometer By observing the AC power line waveform with an oscilloscope By turning off the AC power line main circuit breaker and listening on a battery-operated radio By observing the AC power line voltage with a spectrum analyzer E4D09 What type of signal is picked up by electrical wiring near a radio transmitter? A common-mode signal at the frequency of the radio transmitter An electrical-sparking signal A differential-mode signal at the AC power line frequency Harmonics of the AC power line frequency E4D10 Which of the following types of equipment would be least useful in locating power line noise? An AM receiver with a directional antenna An FM receiver with a directional antenna A hand-held RF sniffer An ultrasonic transducer, amplifier and parabolic reflector E4E01 What circuit construction technique uses lead less components mounted between circuit board pads? Raised mounting Integrated circuit mounting Hybrid device mounting Surface mounting E4E02 What is the main drawback of a wire-loop antenna for direction finding? It has a bidirectional pattern broadside to the loop It is non-rotatable It receives equally well in all directions It is practical for use only on VHF bands E4E03 What pattern is desirable for a direction-finding antenna? One which is non-cardioid One with good front-to-back and front-to-side ratio One with good top-to-bottom and side-to-side ratio One with shallow nulls E4E04 What is the triangulation method of direction finding? The geometric angle of ground waves and sky waves from the signal source are used to locate the source A fixed receiving station plots three beam headings from the signal source on a map Beam antenna headings from several receiving stations are used to plot the signal source on a map A fixed receiving station uses three different antennas to plot the location of the signal source E4E05 Why is an RF attenuator desirable in a receiver used for direction finding? It narrows the bandwidth of the received signal It eliminates the effects of isotropic radiation It reduces loss of received signals caused by antenna pattern nulls It prevents receiver overload from extremely strong signals E4E06 What is a sense antenna? A vertical antenna added to a loop antenna to produce a cardioid reception pattern A horizontal antenna added to a loop antenna to produce a cardioid reception pattern A vertical antenna added to an Adcock antenna to produce omnidirectional reception pattern A horizontal antenna added to an Adcock antenna to produce an omnidirectional reception pattern E4E07 What is a loop antenna? A large circularly-polarized antenna A small coil of wire tightly wound around a toroidal ferrite core Several turns of wire wound in the shape of a large open coil Any antenna coupled to a feed line through an inductive loop of wire E4E08 How can the output voltage of a loop antenna be increased? By reducing the permeability of the loop shield By increasing the number of wire turns in the loop and reducing the area of the loop structure By reducing either the number of wire turns in the loop or the area of the loop structure By increasing either the number of wire turns in the loop or the area of the loop structure E4E09 Why is an antenna with a cardioid pattern desirable for a direction finding system? The broad-side responses of the cardioid pattern can be aimed at the desired station The deep null of the cardioid pattern can pinpoint the direction of the desired station The sharp peak response of the cardioid pattern can pinpoint the direction of the desired station The high-radiation angle of the cardioid pattern is useful for short-distance direction finding E4E10 What type of terrain can cause errors in direction finding? Homogeneous terrain Smooth grassy terrain Varied terrain Terrain with no buildings or mountains E4E11 What is the amateur station activity known as fox hunting? Attempting to locate a hidden transmitter by using receivers and direction-finding techniques Attempting to locate a hidden receiver by using receivers and direction-finding techniques Assisting government agents with tracking transmitter collars worn by foxes Assembling stations using generators and portable antennas to test emergency communications skills |
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