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Amateur Radio Question PoolsNew! View the differences between the 2008 Extra question pool and the previous pool. Amateur Extra (Eff. July 2008) Question PoolPrev 1 2 3 4 5 6 7 8 9 0 NextE6A01 In what application is gallium arsenide used as a semiconductor material in preference to germanium or silicon? In high-current rectifier circuits In high-power audio circuits At microwave frequencies At very low frequency RF circuits E6A02 What type of semiconductor material contains more free electrons than pure germanium or silicon crystals? N-type P-type Bipolar Insulated gate E6A03 What are the majority charge carriers in P-type semiconductor material? Free neutrons Free protons Holes Free electrons E6A04 What is the name given to an impurity atom that adds holes to a semiconductor crystal structure? Insulator impurity N-type impurity Acceptor impurity Donor impurity E6A05 What is the alpha of a bipolar junction transistor? The change of collector current with respect to base current The change of base current with respect to collector current The change of collector current with respect to emitter current The change of collector current with respect to gate current E6A06 What is meant by the beta of a bipolar junction transistor? The frequency at which the current gain is reduced to 1 The change in collector current with respect to base current The breakdown voltage of the base to collector junction The switching speed of the transistor E6A07 In Figure E6-1, what is the schematic symbol for a PNP transistor? 1 2 4 5 E6A08 What term indicates the frequency at which a transistor grounded base current gain has decreased to 0.7 of the gain obtainable at 1 kHz? Corner frequency Alpha rejection frequency Beta cutoff frequency Alpha cutoff frequency E6A09 What is a depletion-mode FET? An FET that exhibits a current flow between source and drain when no gate voltage is applied An FET that has no current flow between source and drain when no gate voltage is applied An FET without a channel so no current flows with zero gate voltage An FET without a channel so maximum gate current flows E6A10 In Figure E6-2, what is the schematic symbol for an N-channel dual-gate MOSFET? ((Was E6A09) 2 4 5 6 E6A11 In Figure E6-2, what is the schematic symbol for a P-channel junction FET? 1 2 3 6 E6A12 Why do many MOSFET devices have built-in gate-protective Zener diodes? To provide a voltage reference for the correct amount of reverse-bias gate voltage To protect the substrate from excessive voltages To keep the gate voltage within specifications and prevent the device from overheating To reduce the chance of the gate insulation being punctured by static discharges or excessive voltages E6A13 What do the initials CMOS stand for? Common mode oscillating system Complementary mica-oxide silicon Complementary metal-oxide semiconductor Complementary metal-oxide substrate E6A14 How does DC input impedance at the gate of a field-effect transistor compare with the DC input impedance of a bipolar transistor? They cannot be compared without first knowing the supply voltage An FET has low input impedance; a bipolar transistor has high input impedance An FET has high input impedance; a bipolar transistor has low input impedance The input impedance of FETs and bipolar transistors is the same E6A15 What two elements widely used in semiconductor devices exhibit both metallic and nonmetallic characteristics? Silicon and gold Silicon and germanium Galena and germanium Galena and bismuth E6A16 What type of semiconductor material contains fewer free electrons than pure germanium or silicon crystals? N-type P-type Superconductor-type Bipolar-type E6A17 What are the majority charge carriers in N-type semiconductor material? Holes Free electrons Free protons Free neutrons E6A18 What are the names of the three terminals of a field-effect transistor? Gate 1, gate 2, drain Emitter, base, collector Emitter, base 1, base 2 Gate, drain, source E6B01 What is the principal characteristic of a Zener diode? A constant current under conditions of varying voltage A constant voltage under conditions of varying current A negative resistance region An internal capacitance that varies with the applied voltage E6B02 What is the principal characteristic of a tunnel diode? A high forward resistance A very high PIV A negative resistance region A high forward current rating E6B03 What is an important characteristic of a Schottky Barrier diode as compared to an ordinary silicon diode when used as a power supply rectifier? Much higher reverse voltage breakdown Controlled reverse avalanche voltage Enhanced carrier retention time Less forward voltage drop E6B04 What special type of diode is capable of both amplification and oscillation? Point contact Zener Tunnel Junction E6B05 What type of semiconductor device varies its internal capacitance as the voltage applied to its terminals varies? Varactor diode Tunnel diode Silicon-controlled rectifier Zener diode E6B06 In Figure E6-3, what is the schematic symbol for a varactor diode? 8 6 2 1 E6B07 What is a common use of a hot-carrier diode? As balanced mixers in FM generation As a variable capacitance in an automatic frequency control circuit As a constant voltage reference in a power supply As a VHF / UHF mixer or detector E6B08 What limits the maximum forward current rating in a junction diode? Peak inverse voltage Junction temperature Forward voltage Back EMF E6B09 Which of the following describes a type of semiconductor diode? Metal-semiconductor junction Electrolytic rectifier CMOS-field effect Thermionic emission diode E6B10 What is a common use for point contact diodes? As a constant current source As a constant voltage source As an RF detector As a high voltage rectifier E6B11 In Figure E6-3, what is the schematic symbol for a light-emitting diode? 1 5 6 7 E6B12 How are junction diodes rated? Maximum forward current and capacitance Maximum reverse current and PIV Maximum reverse current and capacitance Maximum forward current and PIV E6B13 What is one common use for PIN diodes? As a constant current source As a constant voltage source As an RF switch As a high voltage rectifier E6B14 What type of bias is required for an LED to produce luminescence? Reverse bias Forward bias Zero bias Inductive bias E6C01 What is the recommended power supply voltage for TTL series integrated circuits? 12 volts 1.5 volts 5 volts 13.6 volts E6C02 What logic state do the inputs of a TTL device assume if they are left open? A logic-high state A logic-low state The device becomes randomized and will not provide consistent high or low-logic states Open inputs on a TTL device are ignored E6C03 What level of input voltage is a logic "high" in a TTL device operating with a positive 5-volt power supply? 2.0 to 5.5 volts 1.5 to 3.0 volts 1.0 to 1.5 volts -5.0 to -2.0 volts E6C04 What level of input voltage is a logic "low" in a TTL device operating with a positive 5-volt power-supply? -2.0 to -5.5 volts 2.0 to 5.5 volts 0.0 to 0.8 volts -0.8 to 0.4 volts E6C05 Which of the following is an advantage of CMOS logic devices over TTL devices? Differential output capability Lower distortion Immune to damage from static discharge Lower power consumption E6C06 Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply? Larger bypass capacitors are used in CMOS circuit design The input switching threshold is about two times the power supply voltage The input switching threshold is about one-half the power supply voltage Input signals are stronger E6C07 In Figure E6-5, what is the schematic symbol for an AND gate? 1 2 3 4 E6C08 In Figure E6-5, what is the schematic symbol for a NAND gate? 1 2 3 4 E6C09 In Figure E6-5, what is the schematic symbol for an OR gate? 2 3 4 6 E6C10 In Figure E6-5, what is the schematic symbol for a NOR gate? 1 2 3 4 E6C11 In Figure E6-5, what is the schematic symbol for the NOT operation (inverter)? 2 4 5 6 E6D01 How is the electron beam deflected in a vidicon? By varying the beam voltage By varying the bias voltage on the beam forming grids inside the tube By varying the beam current By varying electromagnetic fields E6D02 What is cathode ray tube (CRT) persistence? The time it takes for an image to appear after the electron beam is turned on The relative brightness of the display under varying conditions of ambient light The ability of the display to remain in focus under varying conditions The length of time the image remains on the screen after the beam is turned off E6D03 If a cathode ray tube (CRT) is designed to operate with an anode voltage of 25,000 volts, what will happen if the anode voltage is increased to 35,000 volts? The image size will decrease The image size will increase The image will become larger and brighter There will be no apparent change E6D04 Exceeding what design rating can cause a cathode ray tube (CRT) to generate X-rays? The heater voltage The anode voltage The operating temperature The operating frequency E6D05 Which of the following is true of a charge-coupled device (CCD)? Its phase shift changes rapidly with frequency It is a CMOS analog-to-digital converter It samples an analog signal and passes it in stages from the input to the output It is used in a battery charger circuit E6D06 What function does a charge-coupled device (CCD) serve in a modern video camera? It stores photogenerated charges as signals corresponding to pixels It generates the horizontal pulses needed for electron beam scanning It focuses the light used to produce a pattern of electrical charges corresponding to the image It combines audio and video information to produce a composite RF signal E6D07 What is a liquid-crystal display (LCD)? A modern replacement for a quartz crystal oscillator which displays its fundamental frequency A display that uses a crystalline liquid to change the way light is refracted A frequency-determining unit for a transmitter or receiver A display that uses a glowing liquid to remain brightly lit in dim light E6D08 What material property determines the inductance of a toroidal inductor with a 10-turn winding? Core load current Core resistance Core reactivity Core permeability E6D09 What is the usable frequency range of inductors that use toroidal cores, assuming a correct selection of core material for the frequency being used? From a few kHz to no more than 30 MHz From less than 20 Hz to approximately 300 MHz From approximately 1000 Hz to no more than 3000 kHz From about 100 kHz to at least 1000 GHz E6D10 What is one important reason for using powdered-iron toroids rather than ferrite toroids in an inductor? Powdered-iron toroids generally have greater initial permeabilities Powdered-iron toroids generally have better temperature stability Powdered-iron toroids generally require fewer turns to produce a given inductance value Powdered-iron toroids have the highest power handling capacity E6D11 What devices are commonly used as VHF and UHF parasitic suppressors at the input and output terminals of transistorized HF amplifiers? Electrolytic capacitors Butterworth filters Ferrite beads Steel-core toroids E6D12 What is a primary advantage of using a toroidal core instead of a solenoidal core in an inductor? Toroidal cores contain most of the magnetic field within the core material Toroidal cores make it easier to couple the magnetic energy into other components Toroidal cores exhibit greater hysteresis Toroidal cores have lower Q characteristics E6D13 How many turns will be required to produce a 1-mH inductor using a ferrite toroidal core that has an inductance index (A L) value of 523 millihenrys/1000 turns? 2 turns 4 turns 43 turns 229 turns E6D14 How many turns will be required to produce a 5-microhenry inductor using a powdered-iron toroidal core that has an inductance index (A L) value of 40 microhenrys/100 turns? 35 turns 13 turns 79 turns 141 turns E6D15 What type of CRT deflection is better when high-frequency waves are to be displayed on the screen? Electromagnetic Tubular Radar Electrostatic E6D16 Which is NOT true of a charge-coupled device (CCD)? It uses a combination of analog and digital circuitry It can be used to make an audio delay line It is commonly used as an analog-to-digital converter It samples and stores analog signals E6D17 What is the principle advantage of liquid-crystal display (LCD) devices over other types of display devices? They consume less power They can display changes instantly They are visible in all light conditions They can be easily interchanged with other display devices E6D18 What is one reason for using ferrite toroids rather than powdered-iron toroids in an inductor? Ferrite toroids generally have lower initial permeabilities Ferrite toroids generally have better temperature stability Ferrite toroids generally require fewer turns to produce a given inductance value Ferrite toroids are easier to use with surface mount technology E6E01 Which of these filter bandwidths would be a good choice for use in a SSB radiotelephone transmitter? 6 kHz at -6 dB 2.4 kHz at -6 dB 500 Hz at -6 dB 15 kHz at -6 dB E6E02 Which of these filter bandwidths would be a good choice for use with standard double-sideband AM transmissions? 1 kHz at -6 dB 500 Hz at -6 dB 6 kHz at -6 dB 15 kHz at -6 dB E6E03 What is a crystal lattice filter? A power supply filter made with interlaced quartz crystals An audio filter made with four quartz crystals that resonate at 1-kHz intervals A filter with wide bandwidth and shallow skirts made using quartz crystals A filter with narrow bandwidth and steep skirts made using quartz crystals E6E04 What technique is used to construct low-cost, high-performance crystal ladder filters? Obtain a small quantity of custom-made crystals Choose a crystal with the desired bandwidth and operating frequency to match a desired center frequency Measure crystal bandwidth to ensure at least 20% coupling Measure crystal frequencies and carefully select units with a frequency variation of less than 10% of the desired filter bandwidth E6E05 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 The DC voltage applied to the quartz crystal The gain of the RF stage preceding the filter The amplitude of the signals passing through the filter E6E06 What is the one aspect of the piezoelectric effect? Physical deformation of a crystal by the application of a voltage Mechanical deformation of a crystal by the application of a magnetic field The generation of electrical energy by the application of light Reversed conduction states when a P-N junction is exposed to light E6E07 What is the characteristic impedance of circuits in which almost all MMICs are designed to work? 50 ohms 300 ohms 450 ohms 10 ohms E6E08 What is the typical noise figure of a monolithic microwave integrated circuit (MMIC) amplifier? Less than 1 dB Approximately 3.5 to 6 dB Approximately 8 to 10 dB More than 20 dB E6E09 What type of amplifier device consists of a small pill-type package with an input lead, an output lead and 2 ground leads? A junction field-effect transistor (JFET) An operational amplifier integrated circuit (OAIC) An indium arsenide integrated circuit (IAIC) A monolithic microwave integrated circuit (MMIC) E6E10 What typical construction technique is used when building an amplifier for the microwave bands containing a monolithic microwave integrated circuit (MMIC)? Ground-plane "ugly" construction Microstrip construction Point-to-point construction Wave-soldering construction E6E11 How is the operating bias voltage normally supplied to the most common type of monolithic microwave integrated circuit (MMIC)? Through a resistor and/or RF choke connected to the amplifier output lead MMICs require no operating bias Through a capacitor and RF choke connected to the amplifier input lead Directly to the bias-voltage (VCC IN) lead E6E12 What supply voltage do monolithic microwave integrated circuits (MMIC) amplifiers typically require? 1 volt DC 12 volts DC 20 volts DC 120 volts DC E6E13 What is the most common package for inexpensive monolithic microwave integrated circuit (MMIC) amplifiers? Beryllium oxide packages Glass packages Plastic packages Ceramic packages E6F01 What is photoconductivity? The conversion of photon energy to electromotive energy The increased conductivity of an illuminated semiconductor The conversion of electromotive energy to photon energy The decreased conductivity of an illuminated semiconductor E6F02 What happens to the conductivity of a photoconductive material when light shines on it? It increases It decreases It stays the same It becomes unstable E6F03 What is the most common configuration for an optocoupler? A lens and a photomultiplier A frequency modulated helium-neon laser An amplitude modulated helium-neon laser An LED and a phototransistor E6F04 Which of the following is an optoisolator? An LED and a phototransistor A P-N junction that develops an excess positive charge when exposed to light An LED and a capacitor A P-N junction that develops an excess negative charge when exposed to light E6F05 What is an optical shaft encoder? An array of neon or LED indicators whose light transmission path is controlled by a rotating wheel An array of optocouplers whose light transmission path is controlled by a rotating wheel An array of neon or LED indicators mounted on a rotating wheel in a coded pattern An array of optocouplers mounted on a rotating wheel in a coded pattern E6F06 What characteristic of a crystalline solid will photoconductivity change? The capacitance The inductance The specific gravity The resistance E6F07 Which material will exhibit the greatest photoconductive effect when illuminated by visible light? Potassium nitrate Lead sulfide Cadmium sulfide Sodium chloride E6F08 Which material will exhibit the greatest photoconductive effect when illuminated by infrared light? Potassium nitrate Lead sulfide Cadmium sulfide Sodium chloride E6F09 Which of the following materials is affected the most by photoconductivity? A crystalline semiconductor An ordinary metal A heavy metal A liquid semiconductor E6F10 What characteristic of optoisolators is often used in power supplies? They have low impedance between the light source and the phototransistor They have very high impedance between the light source and the phototransistor They have low impedance between the light source and the LED They have very high impedance between the light source and the LED E6F11 What characteristic of optoisolators makes them suitable for use with a triac to form the solid-state equivalent of a mechanical relay for a 120 V AC household circuit? Optoisolators provide a low impedance link between a control circuit and a power circuit Optoisolators provide impedance matching between the control circuit and power circuit Optoisolators provide a very high degree of electrical isolation between a control circuit and a power circuit Optoisolators eliminate (isolate) the effects of reflected light in the control circuit E6F12 Which of the following types of photovoltaic cell has the highest efficiency? Silicon Silver iodide Selenium Gallium arsenide E6F13 What is the most common type of photovoltaic cell used for electrical power generation? Selenium Silicon Cadmium Sulfide Copper oxide E6F14 B) What of the following is the approximate open-circuit voltage produced by a fully-illuminated silicon photovoltaic cell? 0.1 V 0.5 V 1.5 V 12 V E6F15 What absorbs the energy from light falling on a photovoltaic cell? Protons Photons Electrons Holes |
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