Element 3 - GROL, test 5

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1 Element 3 - GROL, test 5 First name: Mr Last name: Spock Date: 7/23/ :50:28 PM IP: Score: 58 1 [EL3a-05] What is an ascending pass for a low-earth-orbit communications satellite? A pass from west to east. A pass from east to west. A pass from south to north. A pass from north to south. 2 [EL3a-20] 6:00 PM PST is equal to what time in UTC? [EL3a-35] Which of the following is a feature of an Instrument Landing System (ILS)? Localizer: shows aircraft deviation horizontally from center of runway. Altimeter: shows aircraft height above sea-level. VHF Communications: provide communications to aircraft. Distance Measuring Equipment: shows aircraft distance to VORTAC station. 4 [EL3b-05] How does the bandwidth of the transmitted signal affect selective fading? It is more pronounced at wide bandwidths. It is more pronounced at narrow bandwidths. It is equally pronounced at both narrow and wide bandwidths. The receiver bandwidth determines the selective fading effect. 5 [EL3b-20] The band of frequencies least susceptible to atmospheric noise and interference is: Page 1 of 15

2 khz khz MHz MHz. 6 [EL3b-35] Tropospheric scatter is a method of sky wave propagation for which of the following frequency bands? 300 khz to 3 MHz. 3 MHz to 30 MHz. 30 MHz to 300 MHz. 300 MHz to 3 GHz. 7 [EL3c-05] What is the most the actual transmitter frequency could differ from a reading of 156,520,000-Hertz on a frequency counter with a time base accuracy of +/- 1.0 ppm? Hz khz Hz MHz. 8 [EL3c-11] What two ways could a dip-meter be used in a radio 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. 9 [EL3c-20] How can intermodulation interference between two 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. 10 [EL3c-35] How can you determine if a line-noise interference problem is being generated within a building? Check the power-line voltage with a time-domain reflectometer. Page 2 of 15

3 Observe the AC wave form on an oscilloscope. Turn off the main circuit breaker and listen on a battery-operated radio. Observe the power-line voltage on a spectrum analyzer. 11 [EL3c-50] Neglecting line losses, the RMS voltage along an RF transmission line having no standing waves: Is equal to the impedance. Is one-half of the surge impedance. Is the product of the surge impedance times the line current. Varies sinusodially along the line. 12 [EL3c-65] Aviation services use predominantly microphones. Carbon. Dynamic. Condenser. Piezoelectric crystal. 13 [EL3d-05] What is resonance in an electrical circuit? The highest frequency that will pass current. The lowest frequency that will pass current. The frequency at which capacitive reactance equals inductive reactance. The frequency at which power factor is at a minimum. 14 [EL3d-13] What is the term for the phenomenon where most of an RF current flows along the surface of the conductor? Layer effect. Seeburg Effect. Skin effect. Resonance. 15 [EL3d-20] What is the term used to express the amount of electrical energy stored in an electrostatic field? Coulombs. Joules. Watts. Page 3 of 15

4 Volts. 16 [EL3d-28] What does the power factor equal in an R-L circuit having a 30 degree phase angle between the voltage and the current? [EL3d-35] What is the effective radiated power of a repeater with 100 watts transmitter power output, 4 db feedline loss, 3 db duplexer and circulator loss, and 7 db antenna gain? 631 watts, assuming the antenna gain is referenced to a half-wave dipole. 400 watts, assuming the antenna gain is referenced to a half-wave dipole. 25 watts, assuming the antenna gain is referenced to a half-wave dipole. 100 watts, assuming the antenna gain is referenced to a half-wave dipole. 18 [EL3d-43] What happens to the resistance of a photoconductive material when light shines on it? It increases. It becomes temperature dependent. It stays the same. It decreases. 19 [EL3d-50] What is the meaning of the term time constant of an RL circuit? The time required for the current in the circuit to build up to 36.8% of the maximum value. The time required for the voltage in the circuit to build up to 63.2% of the maximum value. The time required for the current in the circuit to build up to 63.2% of the maximum value. The time required for the voltage in the circuit to build up to 36.8% of the maximum value. 20 [EL3d-65] What is the time constant of a circuit having a 470-microfarad capacitor and a 470-kilohm resistor in series? 221 seconds. 221,000 seconds. 470 seconds. Page 4 of 15

5 470,000 seconds. 21 [EL3d-80] What is the impedance of a network composed of a microfarad capacitor in series with a 400- ohm resistor, at 500 khz? (Specify your answer in rectangular coordinates.) j j j j [EL3d-95] Given a power supply with a no load voltage of 200 volts and a regulation of 25 %, what is the full load voltage. 150 volts. 160 volts. 240 volts. 250 volts. 23 [EL3d-110] A power transformer has a 120 volt primary winding and a 24 volt secondary winding. What is its turns ratio (referenced secondary to primary)? 10 : 1. 1 : : 1. 1 : [EL3d-125] Assuming a power source to have a fixed value of internal impedance, maximum power will be transferred to the load when: The load impedance equals the internal impedance of the source. The load impedance is greater than the source impedance. The load impedance is less than the source impedance. The fixed values of internal impedance is not relative to the power source. 25 [EL3d-140] The average fully charged voltage of a lead-acid storage cell is: 1 volt. 1.2 volts volts. Page 5 of 15

6 2.06 volts. 26 [EL3d-155] What is the purpose of a shunt resistor used with an ammeter? A shunt resistor is not used with an ammeter. It is used to increase the ampere indicating range of the ammeter. It is used to decrease the ampere indicating range of the ammeter. It is used to increase the voltage indicating range of the voltmeter not the ammeter. 27 [EL3d-170] A 12 volt automotive battery with an internal resistance of 0.2 ohms is connected to a 2 ohm headlight lamp. What is the amount of current passing through the lamp? 1.2 amperes amperes. 6 amperes. None of these. 28 [EL3d-185] At 240 degrees, what is the amplitude of sine-wave having a peak value of 5 volts? -4.3 volts volts volts volts. 29 [EL3d-200] If a series circuit consist of an inductor with an inductive reactance of 57.7 ohms and a resistance of 100 ohms, the phase angle between voltage and current will be approximately: 30 degrees. 35 degrees. 55 degrees. 60 degrees. 30 [EL3e-05] What is the principal characteristic of a tunnel diode? A high forward resistance. A very high PIV(peak inverse voltage). A negative resistance region. A high forward current rating. Page 6 of 15

7 31 [EL3e-20] What is the meaning of the term beta with regard to bipolar transistors? The change of collector current with respect to base current. The change of base current with respect to emitter current. The change of collector current with respect to emitter current. The change in base current with respect to gate current. 32 [EL3e-35] What is the transistor called which is fabricated as two complementary SCRs in parallel with a common gate terminal? TRIAC. Bilateral SCR. Unijunction transistor. Field effect transistor. 33 [EL3e-50] What do the initials CMOS stand for? Common mode oscillating system. Complementary mica-oxide silicon. Complementary metal-oxide semiconductor. Complementary metal-oxide substrate. 34 [EL3e-65] What is the recommended power supply voltage for TTL series integrated circuits? volts volts volts volts. 35 [EL3e-80] Most bipolar junction transistors have a doped and base region compared to the emitter and collector regions.. Heavily, thin. Heavily, small. Lightly, thin. Lightly, small. 36 [EL3e-95] What semiconductor device controls current between source and drain due to a variable width channel controlled by a voltage applied between gate and source? Page 7 of 15

8 A bipolar transistor (BJT). A field-effect transistor (FET). A gate-controlled diode. A PNP transistor. 37 [EL3e-110] Which of the following is not an advantage of using pentodes. Usually requires no neutralization in high frequency circuits. Higher Mu than triodes or tetrodes. Higher secondary emission resulting in greater plate current. Better shielding between plate and control grid. 38 [EL3e-125] An R-S flip-flop is capable of doing all of the following except:. Accept data input into R-S inputs with CLK initiated. Accept data input into PRE and CLR inputs without CLK being initiated. Refuse to accept synchronous data if asynchronous data is being input at same time. Operate in toggle mode with R-S inputs held constant and CLK initiated. 39 [EL3e-140] Which of the following op-amp circuits is operated open-loop? Comparator. Non-inverting amp. Inverting amp. Active filter. 40 [EL3f-01] What is a linear electronic voltage regulator? A regulator that has a ramp voltage as its output. A regulator in which the pass transistor switches from the "off" state to the "on" state. A regulator in which the control device is switched on or off, with the duty cycle proportional to the line or load conditions. A regulator in which the conduction of a control element is varied in direct proportion to the line voltage or load current. 41 [EL3f-05] What type of linear voltage regulator is used in applications where the load on the unregulated voltage source must be kept constant? A constant current source. Page 8 of 15

9 A series regulator. A shunt current source. A shunt regulator. 42 [EL3f-16] What class of amplifier is distinguished by the bias being set well beyond cutoff? Class A. Class B. Class C. Class AB. 43 [EL3f-20] What is an L-network? A network consisting entirely of four inductors. A network consisting of an inductor and a capacitor. A network used to generate a leading phase angle. A network used to generate a lagging phase angle. 44 [EL3f-31] What is a constant-k filter? A filter that uses Boltzmann's constant. A filter whose velocity factor is constant over a wide range of frequencies. A filter whose product of the series- and shunt-element impedances is a constant for all frequencies. A filter whose input impedance varies widely over the design bandwidth. 45 [EL3f-35] What are the distinguishing features of a Chebyshev filter? It has a maximally flat response over its passband. It allows ripple in the passband. It only requires inductors. A filter whose product of the series- and shunt-element impedances is a constant for all frequencies. 46 [EL3f-46] What is meant by the term: modulation? The squelching of a signal until a critical signal-to-noise ratio is reached. Carrier rejection through phase nulling. A linear amplification mode. Page 9 of 15

10 A mixing process whereby information is imposed upon a carrier. 47 [EL3f-50] How can a single-sideband phone signal be generated? By driving a product detector with a DSB signal. By using a reactance modulator followed by a mixer. By using a loop modulator followed by a mixer. By using a balanced modulator followed by a filter. 48 [EL3f-61] What is a frequency discriminator? A circuit for detecting FM signals. A circuit for filtering two closely adjacent signals. An automatic bandswitching circuit. An FM generator. 49 [EL3f-65] What occurs in a receiver when an excessive amount of signal energy reaches the mixer circuit? Spurious mixer products are generated. Mixer blanking occurs. Automatic limiting occurs. A beat frequency is generated. 50 [EL3f-76] How many output changes are obtained for every two trigger pulses applied to the input of a bistable T flip-flop circuit? No output level changes. One output level change. Two output level changes. Four output level changes. 51 [EL3f-80] What is an astable multivibrator? A circuit that alternates between two stable states. A circuit that alternates between a stable state and an unstable state. A circuit set to block either a 0 pulse or a 1 pulse and pass the other. A circuit that alternates between two unstable states. 52 Page 10 of 15

11 52 [EL3f-91] In a negative-logic circuit, what level is used to represent a logic 0? A low level. A positive-transition level. A negative-transition level. A high level. 53 [EL3f-95] What does the accuracy of a frequency counter depend on? The internal crystal reference. A voltage-regulated power supply with an unvarying output. Accuracy of the AC input frequency to the power supply. Proper balancing of the power-supply diodes. 54 [EL3f-106] 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. 55 [EL3f-110] What occurs during CW reception if too narrow a filter bandwidth is used in the IF stage of a receiver? Undesired signals will reach the audio stage. Output-offset overshoot. Cross-modulation distortion. Filter ringing. 56 [EL3f-125] What is a noninverting op-amp circuit? An operational amplifier circuit connected such that the input and output signals are 180 degrees out of phase. An operational amplifier circuit connected such that the input and output signals are in phase. An operational amplifier circuit connected such that the input and output signals are 90 degrees out of phase. An operational amplifier circuit connected such that the input impedance is held at zero while the output impedance is high. 57 [EL3g-05] What is emission A3F? Page 11 of 15

12 RTTY. Television. SSB. Modulated CW. 58 [EL3g-09] How can an FM-phone signal be produced? By modulating the supply voltage to a class-b amplifier. By modulating the supply voltage to a class-c amplifier. By using a reactance modulator on an oscillator. By using a balanced modulator on an oscillator. 59 [EL3g-20] What is the modulation index of an FM-phone transmitter producing an instantaneous carrier deviation of 6 khz when modulated with a 2 khz modulating frequency? /3. 60 [EL3g-35] What is the period of a wave? The time required to complete one cycle. The number of degrees in one cycle. The number of zero crossings in one cycle. The amplitude of the wave. 61 [EL3g-50] What is RMS voltage of a 165-volt peak pure sine wave? 233-V AC. 330-V AC V AC. 117-V AC. 62 [EL3g-65] What is one advantage of using the ASCII code, with its larger character set, instead of the Baudot code? ASCII includes built-in error-correction features. Page 12 of 15

13 ASCII characters contain fewer information bits than Baudot characters. It is possible to transmit upper and lower case text. The larger character set allows store-and-forward control characters to be added to a message. 63 [EL3g-80] What is amplitude compandored single sideband? Reception of single sideband with a conventional CW receiver. Reception of single sideband with a conventional FM receiver. Single sideband incorporating speech compression at the transmitter and speech expansion at the receiver. Single sideband incorporating speech expansion at the transmitter and speech compression at the receiver. 64 [EL3g-95] What is the seventh harmonic of 2182 khz when the transmitter is connected to a half-wave Hertz antenna? 2182 khz MHz khz MHz. 65 [EL3g-110] What is the main underlying operating principle of an aircraft's Distance Measuring Equipment (DME)? A measurable amount of time is required to send and receive a radio signal through the earth's atmosphere. The difference between the peak values of two DC voltages may be used to determine an aircraft's distance to another aircraft. A measurable frequency compression of an AC signal may be used to determine an aircraft's altitude above the earth. A phase inversion between two AC voltages may be used to determine an aircraft's distance to the exit ramp of an airport's runway. 66 [EL3g-125] Choose the only correct statement about an aircraft's Automatic Direction Finding (ADF) equipment. An aircraft's ADF transmission exhibits primarily a line-of-sight range to the ground-based target station and will not follow the curvature of the earth. Only a single omnidirectional sense antenna is required to receive an NDB transmission and process the signal to calculate the aircraft's bearing to the selected ground station. All frequencies in the ADF's operating range except the commercial standard broadcast stations (550 khz to 1660 khz) can be utilized as a navigational Non Directional Beacon (NDB) signal. An aircraft's ADF antennas can receive transmissions that are over the earth's horizon (sometimes several hundred miles away) since these signals will follow the curvature of the earth. 67 [EL3h-05] What is a trap antenna? An antenna for rejecting interfering signals. A highly sensitive antenna with maximum gain in all directions. Page 13 of 15

14 An antenna capable of being used on more than one band because of the presence of parallel LC networks. An antenna with a large capture area. 68 [EL3h-20] What is included in the total resistance of an antenna system? Radiation resistance plus space impedance. Radiation resistance plus transmission resistance. Transmission line resistance plus radiation resistance. Radiation resistance plus ohmic resistance. 69 [EL3h-35] In a half-wave antenna, where are the current nodes? At the ends. At the center. Three-quarters of the way from the feed point toward the end. One-half of the way from the feed point toward the end. 70 [EL3h-50] How much gain does a 1/2-wavelength dipole have over an isotropic radiator? About 1.5 db. About 2.1 db. About 3.0 db. About 6.0 db. 71 [EL3h-65] Why does an antenna system for earth operation (for communications through a satellite) need to have rotators for both azimuth and elevation control? In order to point the antenna above the horizon to avoid terrestrial interference. Satellite antennas require two rotators because they are so large and heavy. In order to track the satellite as it orbits the earth. The elevation rotator points the antenna at the satellite and the azimuth rotator changes the antenna polarization. 72 [EL3h-80] What ferrite rod device prevents the formation of reflected waves on a waveguide transmission line? Reflector. Isolator. Wave-trap. SWR refractor. Page 14 of 15

15 73 [EL3h-95] What allows microwaves to pass in only one direction? RF emitter. Ferrite isolator. Capacitor. Varactor-triac. 74 [EL3h-110] The resonant frequency of a Hertz antenna can be lowered by: Lowering the frequency of the transmitter. Placing a condenser in series with the antenna. Placing a resistor in series with the antenna. Placing an inductance in series with the antenna. 75 [EL3h-125] What type of antenna radiates the 1090 MHz "squitter" signals from an aircraft's Mode S transponder installation of the Air Traffic Control Radar Beacon System (ATCRBS)? An L-band monopole blade-type omnidirectional antenna. An electronically steerable phased-array antenna radiating an omnidirectional pattern. A folded dipole antenna. An internally mounted, mechanically rotatable loop antenna. 76 [EL3h-140] Concerning shunt-fed 1/4 wavelength Marconi antenna: DC resistance of the antenna to ground is zero. RF resistance from antenna feed point to ground is zero. Harmonic radiation is zero under all conditions. It must be grounded at both feed and far ends. Print Copywrite (c) 2004, Technical Services Limited Page 15 of 15

1. What is the unit of electromotive force? (a) volt (b) ampere (c) watt (d) ohm. 2. The resonant frequency of a tuned (LRC) circuit is given by

1. What is the unit of electromotive force? (a) volt (b) ampere (c) watt (d) ohm. 2. The resonant frequency of a tuned (LRC) circuit is given by Department of Examinations, Sri Lanka EXAMINATION FOR THE AMATEUR RADIO OPERATORS CERTIFICATE OF PROFICIENCY ISSUED BY THE DIRECTOR GENERAL OF TELECOMMUNICATIONS, SRI LANKA 2004 (NOVICE CLASS) Basic Electricity,