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2012 Amateur Extra pool
131 / 700 questions need explanations
81.3% complete
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What is the purpose of C3 in the circuit shown in Figure E7-3?
  • It prevents self-oscillation (0% chose this)
  • It provides brute force filtering of the output (0% chose this)
  • It provides fixed bias for Q1 (0% chose this)
  • It clips the peaks of the ripple (0% chose this)
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When may an amateur station send a message to a business?
  • When the total money involved does not exceed $25 (0% chose this)
  • When the control operator is employed by the FCC or another government agency (0% chose this)
  • When transmitting international third-party communications (0% chose this)
  • When neither the amateur nor his or her employer has a pecuniary interest in the communications (0% chose this)
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Which of the following best describes one of the standards that must be met by an external RF power amplifier if it is to qualify for a grant of FCC certification?
  • It must produce full legal output when driven by not more than 5 watts of mean RF input power (0% chose this)
  • It must be capable of external RF switching between its input and output networks (0% chose this)
  • It must exhibit a gain of 0 dB or less over its full output range (0% chose this)
  • It must satisfy the FCC's spurious emission standards when operated at the lesser of 1500 watts, or its full output power (0% chose this)
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Which of the following types of signals can be relayed through a linear transponder?
  • FM and CW (0% chose this)
  • SSB and SSTV (0% chose this)
  • PSK and Packet (0% chose this)
  • All of these choices are correct (0% chose this)
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Why may the received signal from an amateur satellite exhibit a rapidly repeating fading effect?
  • Because the satellite is spinning (0% chose this)
  • Because of ionospheric absorption (0% chose this)
  • Because of the satellite's low orbital altitude (0% chose this)
  • Because of the Doppler Effect (0% chose this)
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How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?
  • By scanning two fields simultaneously (0% chose this)
  • By scanning each field from bottom to top (0% chose this)
  • By scanning lines from left to right in one field and right to left in the next (0% chose this)
  • By scanning odd numbered lines in one field and even numbered ones in the next (0% chose this)
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What is blanking in a video signal?
  • Synchronization of the horizontal and vertical sync pulses (0% chose this)
  • Turning off the scanning beam while it is traveling from right to left or from bottom to top (0% chose this)
  • Turning off the scanning beam at the conclusion of a transmission (0% chose this)
  • Transmitting a black and white test pattern (0% chose this)
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Which of the following is a common method of transmitting accompanying audio with amateur fast-scan television?
  • Frequency-modulated sub-carrier (0% chose this)
  • A separate VHF or UHF audio link (0% chose this)
  • Frequency modulation of the video carrier (0% chose this)
  • All of these choices are correct (0% chose this)
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What hardware, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM)?
  • A special IF converter (0% chose this)
  • A special front end limiter (0% chose this)
  • A special notch filter to remove synchronization pulses (0% chose this)
  • No other hardware is needed (0% chose this)
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What aspect of an amateur slow-scan television signal encodes the brightness of the picture?
  • Tone frequency (0% chose this)
  • Tone amplitude (0% chose this)
  • Sync amplitude (0% chose this)
  • Sync frequency (0% chose this)
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What special operating frequency restrictions are imposed on slow scan TV transmissions?
  • None; they are allowed on all amateur frequencies (0% chose this)
  • They are restricted to 7.245 MHz, 14.245 MHz, 21.345, MHz, and 28.945 MHz (0% chose this)
  • They are restricted to phone band segments and their bandwidth can be no greater than that of a voice signal of the same modulation type (0% chose this)
  • They are not permitted above 54 MHz (0% chose this)
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During a VHF/UHF contest, in which band segment would you expect to find the highest level of activity?
  • At the top of each band, usually in a segment reserved for contests (0% chose this)
  • In the middle of each band, usually on the national calling frequency (0% chose this)
  • In the weak signal segment of the band, with most of the activity near the calling frequency (0% chose this)
  • In the middle of the band, usually 25 kHz above the national calling frequency (0% chose this)
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How does the spread-spectrum technique of frequency hopping work?
  • If interference is detected by the receiver it will signal the transmitter to change frequencies (0% chose this)
  • If interference is detected by the receiver it will signal the transmitter to wait until the frequency is clear (0% chose this)
  • A pseudo-random binary bit stream is used to shift the phase of an RF carrier very rapidly in a particular sequence (0% chose this)
  • The frequency of the transmitted signal is changed very rapidly according to a particular sequence also used by the receiving station (0% chose this)
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Which of the following techniques is normally used by low Earth orbiting digital satellites to relay messages around the world?
  • Digipeating (0% chose this)
  • Store-and-forward (0% chose this)
  • Multi-satellite relaying (0% chose this)
  • Node hopping (0% chose this)
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How can an APRS station be used to help support a public service communications activity?
  • An APRS station with an emergency medical technician can automatically transmit medical data to the nearest hospital (0% chose this)
  • APRS stations with General Personnel Scanners can automatically relay the participant numbers and time as they pass the check points (0% chose this)
  • An APRS station with a GPS unit can automatically transmit information to show a mobile station's position during the event (0% chose this)
  • All of these choices are correct (0% chose this)
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What is indicated when one of the ellipses in an FSK crossed-ellipse display suddenly disappears?
  • Selective fading has occurred (0% chose this)
  • One of the signal filters has saturated (0% chose this)
  • The receiver has drifted 5 kHz from the desired receive frequency (0% chose this)
  • The mark and space signal have been inverted (0% chose this)
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Which of the following is a good technique for making meteor-scatter contacts?
  • 15 second timed transmission sequences with stations alternating based on location (0% chose this)
  • Use of high speed CW or digital modes (0% chose this)
  • Short transmission with rapidly repeated call signs and signal reports (0% chose this)
  • All of these choices are correct (0% chose this)
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Which amateur bands typically support long-path propagation?
  • 160 to 40 meters (0% chose this)
  • 30 to 10 meters (0% chose this)
  • 160 to 10 meters (0% chose this)
  • 6 meters to 2 meters (0% chose this)
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Which of the following effects does Aurora activity have on radio communications?
  • SSB signals are raspy (0% chose this)
  • Signals propagating through the Aurora are fluttery (0% chose this)
  • CW signals appear to be modulated by white noise (0% chose this)
  • All of these choices are correct (0% chose this)
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Which of the following test instruments is used to display intermodulation distortion products in an SSB transmission?
  • A wattmeter (0% chose this)
  • A spectrum analyzer (0% chose this)
  • A logic analyzer (0% chose this)
  • A time-domain reflectometer (0% chose this)
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Which of the following could be determined with a spectrum analyzer?
  • The degree of isolation between the input and output ports of a 2 meter duplexer (0% chose this)
  • Whether a crystal is operating on its fundamental or overtone frequency (0% chose this)
  • The spectral output of a transmitter (0% chose this)
  • All of these choices are correct (0% chose this)
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Which of the following describes a good method for measuring the intermodulation distortion of your own PSK signal?
  • Transmit into a dummy load, receive the signal on a second receiver, and feed the audio into the sound card of a computer running an appropriate PSK program (0% chose this)
  • Multiply the ALC level on the transmitter during a normal transmission by the average power output (0% chose this)
  • Use an RF voltmeter coupled to the transmitter output using appropriate isolation to prevent damage to the meter (0% chose this)
  • All of these choices are correct (0% chose this)
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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?
  • There is possibly a short to ground in the feed line (0% chose this)
  • The transmitter is not properly neutralized (0% chose this)
  • There is an impedance mismatch between the antenna and feed line (0% chose this)
  • There is more power going into the antenna (0% chose this)
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What is the definition of the noise figure of a receiver?
  • The ratio of atmospheric noise to phase noise (0% chose this)
  • The noise bandwidth in Hertz compared to the theoretical bandwidth of a resistive network (0% chose this)
  • The ratio of thermal noise to atmospheric noise (0% chose this)
  • The ratio in dB of the noise generated by the receiver compared to the theoretical minimum noise (0% chose this)
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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 large increase in background noise (0% chose this)
  • A reduction in apparent signal strength (0% chose this)
  • The desired signal can no longer be heard (0% chose this)
  • The off-frequency unwanted signal is heard in addition to the desired signal (0% chose this)
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What is the purpose of the preselector in a communications receiver?
  • To store often-used frequencies (0% chose this)
  • To provide a range of AGC time constants (0% chose this)
  • To increase rejection of unwanted signals (0% chose this)
  • To allow selection of the optimum RF amplifier device (0% chose this)
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What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?
  • Desensitization (0% chose this)
  • Quieting (0% chose this)
  • Cross-modulation interference (0% chose this)
  • Squelch gain rollback (0% chose this)
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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 (0% chose this)
  • By installing a noise suppression resistor and a blocking capacitor in both leads (0% chose this)
  • 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 (0% chose this)
  • By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads (0% chose this)
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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?
  • The broadcast station is transmitting an over-modulated signal (0% chose this)
  • Nearby corroded metal joints are mixing and re-radiating the broadcast signals (0% chose this)
  • You are receiving sky wave signals from a distant station (0% chose this)
  • Your station receiver IF amplifier stage is defective (0% chose this)
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What is one disadvantage of using some types of automatic DSP notch-filters when attempting to copy CW signals?
  • The DSP filter can remove the desired signal at the same time as it removes interfering signals (0% chose this)
  • Any nearby signal passing through the DSP system will overwhelm the desired signal (0% chose this)
  • Received CW signals will appear to be modulated at the DSP clock frequency (0% chose this)
  • Ringing in the DSP filter will completely remove the spaces between the CW characters (0% chose this)
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What do the two numbers represent that are used to define a point on a graph using rectangular coordinates?
  • The magnitude and phase of the point (0% chose this)
  • The sine and cosine values (0% chose this)
  • The coordinate values along the horizontal and vertical axes (0% chose this)
  • The tangent and cotangent values (0% chose this)
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What coordinate system is often used to display the resistive, inductive, and/or capacitive reactance components of an impedance?
  • Maidenhead grid (0% chose this)
  • Faraday grid (0% chose this)
  • Elliptical coordinates (0% chose this)
  • Rectangular coordinates (0% chose this)
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What type of energy is stored in an electromagnetic or electrostatic field?
  • Electromechanical energy (0% chose this)
  • Potential energy (0% chose this)
  • Thermodynamic energy (0% chose this)
  • Kinetic energy (0% chose this)
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What happens to reactive power in an AC circuit that has both ideal inductors and ideal capacitors?
  • It is dissipated as heat in the circuit (0% chose this)
  • It is repeatedly exchanged between the associated magnetic and electric fields, but is not dissipated (0% chose this)
  • It is dissipated as kinetic energy in the circuit (0% chose this)
  • It is dissipated in the formation of inductive and capacitive fields (0% chose this)
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In Figure E6-2, what is the schematic symbol for an N-channel dual-gate MOSFET?
  • 2 (0% chose this)
  • 4 (0% chose this)
  • 5 (0% chose this)
  • 6 (0% chose this)
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Why do many MOSFET devices have internally connected Zener diodes on the gates?
  • To provide a voltage reference for the correct amount of reverse-bias gate voltage (0% chose this)
  • To protect the substrate from excessive voltages (0% chose this)
  • To keep the gate voltage within specifications and prevent the device from overheating (0% chose this)
  • To reduce the chance of the gate insulation being punctured by static discharges or excessive voltages (0% chose this)
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What is the failure mechanism when a junction diode fails due to excessive current?
  • Excessive inverse voltage (0% chose this)
  • Excessive junction temperature (0% chose this)
  • Insufficient forward voltage (0% chose this)
  • Charge carrier depletion (0% chose this)
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Which of the following describes a type of semiconductor diode?
  • Metal-semiconductor junction (0% chose this)
  • Electrolytic rectifier (0% chose this)
  • CMOS-field effect (0% chose this)
  • Thermionic emission diode (0% chose this)
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In Figure E6-3, what is the schematic symbol for a light-emitting diode?
  • 1 (0% chose this)
  • 5 (0% chose this)
  • 6 (0% chose this)
  • 7 (0% chose this)
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What is the recommended power supply voltage for TTL series integrated circuits?
  • 12 volts (0% chose this)
  • 1.5 volts (0% chose this)
  • 5 volts (0% chose this)
  • 13.6 volts (0% chose this)
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What logic state do the inputs of a TTL device assume if they are left open?
  • A logic-high state (0% chose this)
  • A logic-low state (0% chose this)
  • The device becomes randomized and will not provide consistent high or low-logic states (0% chose this)
  • Open inputs on a TTL device are ignored (0% chose this)
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Which of the following describes tri-state logic?
  • Logic devices with 0, 1, and high impedance output states (0% chose this)
  • Logic devices that utilize ternary math (0% chose this)
  • Low power logic devices designed to operate at 3 volts (0% chose this)
  • Proprietary logic devices manufactured by Tri-State Devices (0% chose this)
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Which of the following is an advantage of CMOS logic devices over TTL devices?
  • Differential output capability (0% chose this)
  • Lower distortion (0% chose this)
  • Immune to damage from static discharge (0% chose this)
  • Lower power consumption (0% chose this)
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In Figure E6-5, what is the schematic symbol for a NAND gate?
  • 1 (0% chose this)
  • 2 (0% chose this)
  • 3 (0% chose this)
  • 4 (0% chose this)
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What is a crystal lattice filter?
  • A power supply filter made with interlaced quartz crystals (0% chose this)
  • An audio filter made with four quartz crystals that resonate at 1-kHz intervals (0% chose this)
  • A filter with wide bandwidth and shallow skirts made using quartz crystals (0% chose this)
  • A filter with narrow bandwidth and steep skirts made using quartz crystals (0% chose this)
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Which of the following factors has the greatest effect in helping determine the bandwidth and response shape of a crystal ladder filter?
  • The relative frequencies of the individual crystals (0% chose this)
  • The DC voltage applied to the quartz crystal (0% chose this)
  • The gain of the RF stage preceding the filter (0% chose this)
  • The amplitude of the signals passing through the filter (0% chose this)
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What characteristics of the MMIC make it a popular choice for VHF through microwave circuits?
  • The ability to retrieve information from a single signal even in the presence of other strong signals. (0% chose this)
  • Plate current that is controlled by a control grid (0% chose this)
  • Nearly infinite gain, very high input impedance, and very low output impedance (0% chose this)
  • Controlled gain, low noise figure, and constant input and output impedance over the specified frequency range (0% chose this)
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How is power-supply voltage normally furnished to the most common type of monolithic microwave integrated circuit (MMIC)?
  • Through a resistor and/or RF choke connected to the amplifier output lead (0% chose this)
  • MMICs require no operating bias (0% chose this)
  • Through a capacitor and RF choke connected to the amplifier input lead (0% chose this)
  • Directly to the bias-voltage (VCC IN) lead (0% chose this)
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What is photoconductivity?
  • The conversion of photon energy to electromotive energy (0% chose this)
  • The increased conductivity of an illuminated semiconductor (0% chose this)
  • The conversion of electromotive energy to photon energy (0% chose this)
  • The decreased conductivity of an illuminated semiconductor (0% chose this)
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Which of these materials is affected the most by photoconductivity?
  • A crystalline semiconductor (0% chose this)
  • An ordinary metal (0% chose this)
  • A heavy metal (0% chose this)
  • A liquid semiconductor (0% chose this)
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What absorbs the energy from light falling on a photovoltaic cell?
  • Protons (0% chose this)
  • Photons (0% chose this)
  • Electrons (0% chose this)
  • Holes (0% chose this)
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How can an RF power amplifier be neutralized?
  • By increasing the driving power (0% chose this)
  • By reducing the driving power (0% chose this)
  • By feeding a 180-degree out-of-phase portion of the output back to the input (0% chose this)
  • By feeding an in-phase component of the output back to the input (0% chose this)
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In Figure E7-1, what is the purpose of R1 and R2?
  • Load resistors (0% chose this)
  • Fixed bias (0% chose this)
  • Self bias (0% chose this)
  • Feedback (0% chose this)
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In Figure E7-1, what is the purpose of R3?
  • Fixed bias (0% chose this)
  • Emitter bypass (0% chose this)
  • Output load resistor (0% chose this)
  • Self bias (0% chose this)
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What type of circuit is shown in Figure E7-1?
  • Switching voltage regulator (0% chose this)
  • Linear voltage regulator (0% chose this)
  • Common emitter amplifier (0% chose this)
  • Emitter follower amplifier (0% chose this)
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In Figure E7-2, what is the purpose of C2?
  • Output coupling (0% chose this)
  • Emitter bypass (0% chose this)
  • Input coupling (0% chose this)
  • Hum filtering (0% chose this)
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Why are third-order intermodulation distortion products of particular concern in linear power amplifiers?
  • Because they are relatively close in frequency to the desired signal (0% chose this)
  • Because they are relatively far in frequency from the desired signal (0% chose this)
  • Because they invert the sidebands causing distortion (0% chose this)
  • Because they maintain the sidebands, thus causing multiple duplicate signals (0% chose this)
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What advantage does a Pi-L-network have over a Pi-network for impedance matching between the final amplifier of a vacuum-tube transmitter and an antenna?
  • Greater harmonic suppression (0% chose this)
  • Higher efficiency (0% chose this)
  • Lower losses (0% chose this)
  • Greater transformation range (0% chose this)
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What is one advantage of a Pi matching network over an L matching network consisting of a single inductor and a single capacitor?
  • The Q of Pi networks can be varied depending on the component values chosen (0% chose this)
  • L networks cannot perform impedance transformation (0% chose this)
  • Pi networks have fewer components (0% chose this)
  • Pi networks are designed for balanced input and output (0% chose this)
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Which of these modes is most affected by non-linear phase response in a receiver IF filter?
  • Meteor Scatter (0% chose this)
  • Single-Sideband voice (0% chose this)
  • Digital (0% chose this)
  • Video (0% chose this)
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What is one characteristic of a switching electronic voltage regulator?
  • The resistance of a control element is varied in direct proportion to the line voltage or load current (0% chose this)
  • It is generally less efficient than a linear regulator (0% chose this)
  • The control device's duty cycle is controlled to produce a constant average output voltage (0% chose this)
  • It gives a ramp voltage at its output (0% chose this)
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Which of the following types of linear voltage regulator usually make the most efficient use of the primary power source?
  • A series current source (0% chose this)
  • A series regulator (0% chose this)
  • A shunt regulator (0% chose this)
  • A shunt current source (0% chose this)
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What is the purpose of Q1 in the circuit shown in Figure E7-3?
  • It provides negative feedback to improve regulation (0% chose this)
  • It provides a constant load for the voltage source (0% chose this)
  • It increases the current-handling capability of the regulator (0% chose this)
  • It provides D1 with current (0% chose this)
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What type of circuit is shown in Figure E7-3?
  • Switching voltage regulator (0% chose this)
  • Grounded emitter amplifier (0% chose this)
  • Linear voltage regulator (0% chose this)
  • Emitter follower (0% chose this)
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What is the purpose of C1 in the circuit shown in Figure E7-3?
  • It resonates at the ripple frequency (0% chose this)
  • It provides fixed bias for Q1 (0% chose this)
  • It decouples the output (0% chose this)
  • It filters the supply voltage (0% chose this)
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Which of the following conditions apply when transmitting spread spectrum emission?
  • A station transmitting SS emission must not cause harmful interference to other stations employing other authorized emissions (0% chose this)
  • The transmitting station must be in an area regulated by the FCC or in a country that permits SS emissions (0% chose this)
  • The transmission must not be used to obscure the meaning of any communication (0% chose this)
  • All of these choices are correct (0% chose this)
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What is the purpose of R1 in the circuit shown in Figure E7-3?
  • It provides a constant load to the voltage source (0% chose this)
  • It couples hum to D1 (0% chose this)
  • It supplies current to D1 (0% chose this)
  • It bypasses hum around D1 (0% chose this)
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What is the purpose of R2 in the circuit shown in Figure E7-3?
  • It provides fixed bias for Q1 (0% chose this)
  • It provides fixed bias for D1 (0% chose this)
  • It decouples hum from D1 (0% chose this)
  • It provides a constant minimum load for Q1 (0% chose this)
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What is the purpose of a "step-start" circuit in a high-voltage power supply?
  • To provide a dual-voltage output for reduced power applications (0% chose this)
  • To compensate for variations of the incoming line voltage (0% chose this)
  • To allow for remote control of the power supply (0% chose this)
  • To allow the filter capacitors to charge gradually (0% chose this)
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When several electrolytic filter capacitors are connected in series to increase the operating voltage of a power supply filter circuit, why should resistors be connected across each capacitor?
  • To equalize, as much as possible, the voltage drop across each capacitor (0% chose this)
  • To provide a safety bleeder to discharge the capacitors when the supply is off (0% chose this)
  • To provide a minimum load current to reduce voltage excursions at light loads (0% chose this)
  • All of these choices are correct (0% chose this)
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Which of the following can be used to generate FM phone emissions?
  • A balanced modulator on the audio amplifier (0% chose this)
  • A reactance modulator on the oscillator (0% chose this)
  • A reactance modulator on the final amplifier (0% chose this)
  • A balanced modulator on the oscillator (0% chose this)
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How does an analog phase modulator function?
  • By varying the tuning of a microphone preamplifier to produce PM signals (0% chose this)
  • By varying the tuning of an amplifier tank circuit to produce AM signals (0% chose this)
  • By varying the tuning of an amplifier tank circuit to produce PM signals (0% chose this)
  • By varying the tuning of a microphone preamplifier to produce AM signals (0% chose this)
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What is one way a single-sideband phone signal can be generated?
  • By using a balanced modulator followed by a filter (0% chose this)
  • By using a reactance modulator followed by a mixer (0% chose this)
  • By using a loop modulator followed by a mixer (0% chose this)
  • By driving a product detector with a DSB signal (0% chose this)
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Why is de-emphasis commonly used in FM communications receivers?
  • For compatibility with transmitters using phase modulation (0% chose this)
  • To reduce impulse noise reception (0% chose this)
  • For higher efficiency (0% chose this)
  • To remove third-order distortion products (0% chose this)
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What are the principal frequencies that appear at the output of a mixer circuit?
  • Two and four times the original frequency (0% chose this)
  • The sum, difference and square root of the input frequencies (0% chose this)
  • The two input frequencies along with their sum and difference frequencies (0% chose this)
  • 1.414 and 0.707 times the input frequency (0% chose this)
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What occurs when an excessive amount of signal energy reaches a mixer circuit?
  • Spurious mixer products are generated (0% chose this)
  • Mixer blanking occurs (0% chose this)
  • Automatic limiting occurs (0% chose this)
  • A beat frequency is generated (0% chose this)
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Which of the following types of detector is well suited for demodulating SSB signals?
  • Discriminator (0% chose this)
  • Phase detector (0% chose this)
  • Product detector (0% chose this)
  • Phase comparator (0% chose this)
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What is the purpose of a frequency counter?
  • To provide a digital representation of the frequency of a signal (0% chose this)
  • To generate a series of reference signals at known frequency intervals (0% chose this)
  • To display all frequency components of a transmitted signal (0% chose this)
  • To provide a signal source at a very accurate frequency (0% chose this)
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What is an advantage of a period-measuring frequency counter over a direct-count type?
  • It can run on battery power for remote measurements (0% chose this)
  • It does not require an expensive high-precision time base (0% chose this)
  • It provides improved resolution of low-frequency signals within a comparable time period (0% chose this)
  • It can directly measure the modulation index of an FM transmitter (0% chose this)
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What primarily determines the gain and frequency characteristics of an op-amp RC active filter?
  • The values of capacitors and resistors built into the op-amp (0% chose this)
  • The values of capacitors and resistors external to the op-amp (0% chose this)
  • The input voltage and frequency of the op-amp's DC power supply (0% chose this)
  • The output voltage and smoothness of the op-amp's DC power supply (0% chose this)
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What is the typical input impedance of an integrated circuit op-amp?
  • 100 ohms (0% chose this)
  • 1000 ohms (0% chose this)
  • Very low (0% chose this)
  • Very high (0% chose this)
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What condition must exist for a circuit to oscillate?
  • It must have at least two stages (0% chose this)
  • It must be neutralized (0% chose this)
  • It must have positive feedback with a gain greater than 1 (0% chose this)
  • It must have negative feedback sufficient to cancel the input signal (0% chose this)
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What type of frequency synthesizer circuit uses a phase accumulator, lookup table, digital to analog converter and a low-pass anti-alias filter?
  • A direct digital synthesizer (0% chose this)
  • A hybrid synthesizer (0% chose this)
  • A phase locked loop synthesizer (0% chose this)
  • A diode-switching matrix synthesizer (0% chose this)
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What information is contained in the lookup table of a direct digital frequency synthesizer?
  • The phase relationship between a reference oscillator and the output waveform (0% chose this)
  • The amplitude values that represent a sine-wave output (0% chose this)
  • The phase relationship between a voltage-controlled oscillator and the output waveform (0% chose this)
  • The synthesizer frequency limits and frequency values stored in the radio memories (0% chose this)
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What is the capture range of a phase-locked loop circuit?
  • The frequency range over which the circuit can lock (0% chose this)
  • The voltage range over which the circuit can lock (0% chose this)
  • The input impedance range over which the circuit can lock (0% chose this)
  • The range of time it takes the circuit to lock (0% chose this)
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Which of these functions can be performed by a phase-locked loop?
  • Wide-band AF and RF power amplification (0% chose this)
  • Comparison of two digital input signals, digital pulse counter (0% chose this)
  • Photovoltaic conversion, optical coupling (0% chose this)
  • Frequency synthesis, FM demodulation (0% chose this)
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Why is a phase-locked loop often used as part of a variable frequency synthesizer for receivers and transmitters?
  • It generates FM sidebands (0% chose this)
  • It eliminates the need for a voltage controlled oscillator (0% chose this)
  • It makes it possible for a VFO to have the same degree of frequency stability as a crystal oscillator (0% chose this)
  • It can be used to generate or demodulate SSB signals by quadrature phase synchronization (0% chose this)
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What is the approximate ratio of PEP-to-average power in a typical single-sideband phone signal?
  • 2.5 to 1 (0% chose this)
  • 25 to 1 (0% chose this)
  • 1 to 1 (0% chose this)
  • 100 to 1 (0% chose this)
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What is the period of a wave?
  • The time required to complete one cycle (0% chose this)
  • The number of degrees in one cycle (0% chose this)
  • The number of zero crossings in one cycle (0% chose this)
  • The amplitude of the wave (0% chose this)
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What type of waveform is produced by human speech?
  • Sinusoidal (0% chose this)
  • Logarithmic (0% chose this)
  • Irregular (0% chose this)
  • Trapezoidal (0% chose this)
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Which of the following is a distinguishing characteristic of a pulse waveform?
  • Regular sinusoidal oscillations (0% chose this)
  • Narrow bursts of energy separated by periods of no signal (0% chose this)
  • A series of tones that vary between two frequencies (0% chose this)
  • A signal that contains three or more discrete tones (0% chose this)
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What type of information can be conveyed using digital waveforms?
  • Human speech (0% chose this)
  • Video signals (0% chose this)
  • Data (0% chose this)
  • All of these choices are correct (0% chose this)
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What is an advantage of using digital signals instead of analog signals to convey the same information?
  • Less complex circuitry is required for digital signal generation and detection (0% chose this)
  • Digital signals always occupy a narrower bandwidth (0% chose this)
  • Digital signals can be regenerated multiple times without error (0% chose this)
  • All of these choices are correct (0% chose this)
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What is the term for the ratio between the frequency deviation of an RF carrier wave, and the modulating frequency of its corresponding FM-phone signal?
  • FM compressibility (0% chose this)
  • Quieting index (0% chose this)
  • Percentage of modulation (0% chose this)
  • Modulation index (0% chose this)
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How does the modulation index of a phase-modulated emission vary with RF carrier frequency (the modulated frequency)?
  • It increases as the RF carrier frequency increases (0% chose this)
  • It decreases as the RF carrier frequency increases (0% chose this)
  • It varies with the square root of the RF carrier frequency (0% chose this)
  • It does not depend on the RF carrier frequency (0% chose this)
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What parameter does the modulating signal vary in a pulse-position modulation system?
  • The number of pulses per second (0% chose this)
  • The amplitude of the pulses (0% chose this)
  • The duration of the pulses (0% chose this)
  • The time at which each pulse occurs (0% chose this)
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Which of these methods can be used to combine several separate analog information streams into a single analog radio frequency signal?
  • Frequency shift keying (0% chose this)
  • A diversity combiner (0% chose this)
  • Frequency division multiplexing (0% chose this)
  • Pulse compression (0% chose this)
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What technique is used to minimize the bandwidth requirements of a PSK31 signal?
  • Zero-sum character encoding (0% chose this)
  • Reed-Solomon character encoding (0% chose this)
  • Use of sinusoidal data pulses (0% chose this)
  • Use of trapezoidal data pulses (0% chose this)
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Which of these techniques causes a digital signal to appear as wide-band noise to a conventional receiver?
  • Spread-spectrum (0% chose this)
  • Independent sideband (0% chose this)
  • Regenerative detection (0% chose this)
  • Exponential addition (0% chose this)
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What spread-spectrum communications technique alters the center frequency of a conventional carrier many times per second in accordance with a pseudo-random list of channels?
  • Frequency hopping (0% chose this)
  • Direct sequence (0% chose this)
  • Time-domain frequency modulation (0% chose this)
  • Frequency compandored spread-spectrum (0% chose this)
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Which of the following is the easiest voltage amplitude parameter to measure when viewing a pure sine wave signal on an analog oscilloscope?
  • Peak-to-peak voltage (0% chose this)
  • RMS voltage (0% chose this)
  • Average voltage (0% chose this)
  • DC voltage (0% chose this)
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What is the advantage of using a peak-reading wattmeter to monitor the output of a SSB phone transmitter?
  • It is easier to determine the correct tuning of the output circuit (0% chose this)
  • It gives a more accurate display of the PEP output when modulation is present (0% chose this)
  • It makes it easier to detect high SWR on the feed line (0% chose this)
  • It can determine if any flat-topping is present during modulation peaks (0% chose this)
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What is an electromagnetic wave?
  • Alternating currents in the core of an electromagnet (0% chose this)
  • A wave consisting of two electric fields at right angles to each other (0% chose this)
  • A wave consisting of an electric field and a magnetic field oscillating at right angles to each other (0% chose this)
  • A wave consisting of two magnetic fields at right angles to each other (0% chose this)
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Which of the following best describes electromagnetic waves traveling in free space?
  • Electric and magnetic fields become aligned as they travel (0% chose this)
  • The energy propagates through a medium with a high refractive index (0% chose this)
  • The waves are reflected by the ionosphere and return to their source (0% chose this)
  • Changing electric and magnetic fields propagate the energy (0% chose this)
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Why would one need to know the feed point impedance of an antenna?
  • To match impedances in order to minimize standing wave ratio on the transmission line (0% chose this)
  • To measure the near-field radiation density from a transmitting antenna (0% chose this)
  • To calculate the front-to-side ratio of the antenna (0% chose this)
  • To calculate the front-to-back ratio of the antenna (0% chose this)
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What is meant by antenna gain?
  • The ratio relating the radiated signal strength of an antenna in the direction of maximum radiation to that of a reference antenna (0% chose this)
  • The ratio of the signal in the forward direction to that in the opposite direction (0% chose this)
  • The ratio of the amount of power radiated by an antenna compared to the transmitter output power (0% chose this)
  • The final amplifier gain minus the transmission-line losses, including any phasing lines present (0% chose this)
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How is antenna efficiency calculated?
  • (radiation resistance / transmission resistance) x 100% (0% chose this)
  • (radiation resistance / total resistance) x 100% (0% chose this)
  • (total resistance / radiation resistance) x 100% (0% chose this)
  • (effective radiated power / transmitter output) x 100% (0% chose this)
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Which of the following choices is a way to improve the efficiency of a ground-mounted quarter-wave vertical antenna?
  • Install a good radial system (0% chose this)
  • Isolate the coax shield from ground (0% chose this)
  • Shorten the radiating element (0% chose this)
  • Reduce the diameter of the radiating element (0% chose this)
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What may occur when a directional antenna is operated at different frequencies within the band for which it was designed?
  • Feed point impedance may become negative (0% chose this)
  • The E-field and H-field patterns may reverse (0% chose this)
  • Element spacing limits could be exceeded (0% chose this)
  • The gain may change depending on frequency (0% chose this)
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How can the approximate beamwidth in a given plane of a directional antenna be determined?
  • Note the two points where the signal strength of the antenna is 3 dB less than maximum and compute the angular difference (0% chose this)
  • Measure the ratio of the signal strengths of the radiated power lobes from the front and rear of the antenna (0% chose this)
  • Draw two imaginary lines through the ends of the elements and measure the angle between the lines (0% chose this)
  • Measure the ratio of the signal strengths of the radiated power lobes from the front and side of the antenna (0% chose this)
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What type of computer program technique is commonly used for modeling antennas?
  • Graphical analysis (0% chose this)
  • Method of Moments (0% chose this)
  • Mutual impedance analysis (0% chose this)
  • Calculus differentiation with respect to physical properties (0% chose this)
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What is the principle of a Method of Moments analysis?
  • A wire is modeled as a series of segments, each having a uniform value of current (0% chose this)
  • A wire is modeled as a single sine-wave current generator (0% chose this)
  • A wire is modeled as a series of points, each having a distinct location in space (0% chose this)
  • A wire is modeled as a series of segments, each having a distinct value of voltage across it (0% chose this)
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What type of information can be obtained by submitting the details of a proposed new antenna to a modeling program?
  • SWR vs. frequency charts (0% chose this)
  • Polar plots of the far-field elevation and azimuth patterns (0% chose this)
  • Antenna gain (0% chose this)
  • All of these choices are correct (0% chose this)
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What type of antenna pattern over real ground is shown in Figure E9-2?
  • Elevation (0% chose this)
  • Azimuth (0% chose this)
  • Radiation resistance (0% chose this)
  • Polarization (0% chose this)
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What is the main effect of placing a vertical antenna over an imperfect ground?
  • It causes increased SWR (0% chose this)
  • It changes the impedance angle of the matching network (0% chose this)
  • It reduces low-angle radiation (0% chose this)
  • It reduces losses in the radiating portion of the antenna (0% chose this)
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How can linearly polarized Yagi antennas be used to produce circular polarization?
  • Stack two Yagis, fed 90 degrees out of phase, to form an array with the respective elements in parallel planes (0% chose this)
  • Stack two Yagis, fed in phase, to form an array with the respective elements in parallel planes (0% chose this)
  • Arrange two Yagis perpendicular to each other with the driven elements at the same point on the boom and fed 90 degrees out of phase (0% chose this)
  • Arrange two Yagis collinear to each other, with the driven elements fed 180 degrees out of phase (0% chose this)
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Where should a high-Q loading coil be placed to minimize losses in a shortened vertical antenna?
  • Near the center of the vertical radiator (0% chose this)
  • As low as possible on the vertical radiator (0% chose this)
  • As close to the transmitter as possible (0% chose this)
  • At a voltage node (0% chose this)
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What is a disadvantage of using a multiband trapped antenna?
  • It might radiate harmonics (0% chose this)
  • It radiates the harmonics and fundamental equally well (0% chose this)
  • It is too sharply directional at lower frequencies (0% chose this)
  • It must be neutralized (0% chose this)
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What is one advantage of using a trapped antenna?
  • It has high directivity in the higher-frequency bands (0% chose this)
  • It has high gain (0% chose this)
  • It minimizes harmonic radiation (0% chose this)
  • It may be used for multiband operation (0% chose this)
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Which of these matching systems is an effective method of connecting a 50-ohm coaxial cable feed line to a grounded tower so it can be used as a vertical antenna?
  • Double-bazooka match (0% chose this)
  • Hairpin match (0% chose this)
  • Gamma match (0% chose this)
  • All of these choices are correct (0% chose this)
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What is the purpose of a Wilkinson divider?
  • It divides the operating frequency of a transmitter signal so it can be used on a lower frequency band (0% chose this)
  • It is used to feed high-impedance antennas from a low-impedance source (0% chose this)
  • It divides power equally among multiple loads while preventing changes in one load from disturbing power flow to the others (0% chose this)
  • It is used to feed low-impedance loads from a high-impedance source (0% chose this)
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What is the typical velocity factor for a coaxial cable with solid polyethylene dielectric?
  • 2.70 (0% chose this)
  • 0.66 (0% chose this)
  • 0.30 (0% chose this)
  • 0.10 (0% chose this)
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How does ladder line compare to small-diameter coaxial cable such as RG-58 at 50 MHz?
  • Lower loss (0% chose this)
  • Higher SWR (0% chose this)
  • Smaller reflection coefficient (0% chose this)
  • Lower velocity factor (0% chose this)
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What impedance does a 1/2-wavelength transmission line present to a generator when the line is open at the far end?
  • Very high impedance (0% chose this)
  • Very low impedance (0% chose this)
  • The same as the characteristic impedance of the line (0% chose this)
  • The same as the output impedance of the generator (0% chose this)
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What type of chart is shown in Figure E9-3?
  • Smith chart (0% chose this)
  • Free-space radiation directivity chart (0% chose this)
  • Elevation angle radiation pattern chart (0% chose this)
  • Azimuth angle radiation pattern chart (0% chose this)
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On the Smith chart shown in Figure E9-3, what is the only straight line shown?
  • The reactance axis (0% chose this)
  • The current axis (0% chose this)
  • The voltage axis (0% chose this)
  • The resistance axis (0% chose this)
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What do the arcs on a Smith chart represent?
  • Frequency (0% chose this)
  • SWR (0% chose this)
  • Points with constant resistance (0% chose this)
  • Points with constant reactance (0% chose this)
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How are the wavelength scales on a Smith chart calibrated?
  • In fractions of transmission line electrical frequency (0% chose this)
  • In fractions of transmission line electrical wavelength (0% chose this)
  • In fractions of antenna electrical wavelength (0% chose this)
  • In fractions of antenna electrical frequency (0% chose this)
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What term describes station output, including the transmitter, antenna and everything in between, when considering transmitter power and system gains and losses?
  • Power factor (0% chose this)
  • Half-power bandwidth (0% chose this)
  • Effective radiated power (0% chose this)
  • Apparent power (0% chose this)
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Why is it advisable to use an RF attenuator on a receiver being used for direction finding?
  • It narrows the bandwidth of the received signal to improve signal to noise ratio (0% chose this)
  • It compensates for the effects of an isotropic antenna, thereby improving directivity (0% chose this)
  • It reduces loss of received signals caused by antenna pattern nulls, thereby increasing sensitivity (0% chose this)
  • It prevents receiver overload which could make it difficult to determine peaks or nulls (0% chose this)
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How can the output voltage of a multi-turn receiving loop antenna be increased?
  • By reducing the permeability of the loop shield (0% chose this)
  • By increasing the number of wire turns in the loop and reducing the area of the loop structure (0% chose this)
  • By winding adjacent turns in opposing directions (0% chose this)
  • By increasing either the number of wire turns in the loop or the area of the loop structure or both (0% chose this)
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