Your chosen subject is: Communications EngineeringOnly 513 questions remaining in this category. Please answer the following 513 questions and then press the Submit button below! 1. (Apr 1997) If a voltage is equal to twice its original value, what is its corresponding change in dB? a) 3 dB b) 9 dB c) 10 dB d) 6 dB 2. What is the power saving when the carrier is suppressed in a regular AM signal modulated to an index of 100%? a) 33.3% b) 16.7% c) 100% d) 66.7 % 3. (Apr 1997) The most common unit of noise measurement in white noise testing.. a) dBw b) NPR c) dBm d) dBk 4. Determine the equivalent noise bandwidth for a single RC low-pass filter if R=20 kohms and C= 0.1 uF a) 250 Hz b) 200 Hz c) 125 Hz d) 500 Hz 5. What portion of the TV signal is used to synchronize the video information on the recording tape? a) the vertical deflection coil b) the vertical sync c) the horizontal sync d) the raster lines 6. What circuit is used to create vestigial transmission? a) Diplexer b) HPF c) LPF d) Duplexer 7. What do you call the combining circuit used in TV? a) Matrix b) Synthesizer c) Multiplier d) Adder 8. A decibel notation relative to a reference noise level. a) dBa b) dBpwp c) dBrn d) dBf 9. What is the major problem with a very-high-frequency oscillator? a) Low sensitivity b) Poor frequency stability c) No power stability d) Poor image rejection 10. What BC service must used directional antennas? a) International broadcasting b) TV BC c) FM BC d) AM BC 11. Where is telemetering used in BC stations? a) At the receiver b) Within the transmitter c) Remote position to transmitter d) At the studio 12. When do BC stations make equipment tests? a) experimental period b) night time c) day time d) Sunday only 13. What is the waveform of sweep voltage? a) Sawtooth b) Rectangular wave c) Spikes d) Square wave 14. (Nov 1997) Two resistor, 20 kohms and 50 kohms are at ambient temperature. Calculate for a bandwidth equal to 100 kHz, the thermal noise voltage for the two resistors connected in parallel. a) 4278 uV b) 0.4782 uV c) 4.78 uV d) 47.8 uV 15. What is the required accuracy of BC station meters? a) 10% b) 5% c) 2% d) 1% 16. It is the liberation of electrons by thermionic means, used as the principal source of electron emission in microwave vacuum tube devices. a) Edison Effect b) Miller Effect c) Bunching d) Secondary Effect 17. Keyed AGC is AGC that: a) Is used in color TV receivers so that the transmitted color has no effect on the AGC b) Is used in TV receivers so that transmitted picture brightness does not affect the AGC c) Works only with Morse code. Is activated when keyed by the transmitting signal 18. What percentage of the primary colors used in color TV are needed to produce the brightest white? a) 30% red, 59% green, 11% blue b) 33% red, 33% green, 33% blue c) 58% red, 20% green, 22% blue d) 50% red, 28% green, 22% blue 19. Where is a color burst found? a) Front porch b) Synch pulse c) Blanking pulse d) Back porch 20. The velocity at which energy is transported by a wave of nearly constant frequency. a) Phase velocity b) Average velocity c) Group velocity d) Linear velocity 21. It is the ___ that tunes the receiver to different stations. a) RF Amplifier b) IF Amplifier c) Detector d) Local Oscillator 22. (Nov 1997) The Tendency for the sound energy to spread. a) Refraction b) Rarefaction c) Reflection d) Diffraction 23. The value(s) associated with sine waves of voltages are: a) Instantaneous b) Average c) Maximum d) All of the above 24. (Nov 1996) ____ is the average rate of transmission of sound energy in a given direction through a cross sectional area of 1 sq. m.. at right angle to the direction. a) Pressure variation b) Loudness c) Sound intensity d) Sound pressure 25. (Apr 1997) Reference noise temperature. a) 250C b) 300C c) 290 K d) 700F 26. What is usually transmitted by facsimile? a) Bits b) Voice c) Pictures d) Video signal 27. What is the main difference between an AF amplifier and an RF amplifier? a) The selectivity b) The range of frequencies that they amplify c) The stability d) The amplification factor 28. In AM, increasing the amplitude of the modulating signal, the amount of power in the information part of the transmitted signal is _____ relative to the power used for the carrier. a) Decreased b) Constant c) Varying d) Increased 29. An unmodulated carrier is 300 VP-P. Calculate %m when its maximum p-p value reaches 400 V. a) 33.3% b) 66.67% c) 100% d) 83.3% 30. What information must be contained in a TV signal? a) All of these b) Sound c) Synchronizing signal d) Video 31. In a TV picture tube, what is the purpose of the large tube voltage? a) create huge magnetic field b) produce good quality of picture c) repels electrons away from tube d) attracts electrons towards face of tube 32. How many ground radials should a ?/4 vertical AM broadcast antenna use? a) 24 or more b) 5 20 c) 3 10 d) 1 33. The power in FM _____ as the modulation index increases. a) Remain constant b) Increases c) Fluctuates d) Decreases 34. How many electron beans actually leave the electron gun of a single-gun color CRT? a) 2 b) 3 c) 4 d) 1 35. The audible pitch refers to a) amplitude b) purity c) frequency d) harmonics 36. (Mar 1996) what is the purpose of a beat frequency oscillator (BFO)? a) Aids in the reception of weak voice-modulated signals b) Generates an output, whose frequency differs from that of the intermediate frequency by 1 kHz c) Generates a signal, whose frequency is the same as that of the intermediate frequency d) Generates a 1 kHz tone to Morse reception 37. It is the representation of a waveform in such a way that its amplitude is displayed as a function of frequency. a) OTDR b) Frequency Domain c) Time Domain d) Wave Shape 38. In communications systems, demodulation ______. a) Is opposite of modulation b) Is performed at the transmitting station c) Rectifies modulated signal d) Removes sidebands 39. A major disadvantage of the vacuum tube is its need for a _____ to give energy to the electrons. a) Voltage source b) Limiter c) Heater d) Line equalizer 40. (Nov 1998) What is the major cause of atmospheric or static noise? a) meteor showers b) sunspot c) thunderstorm d) airplanes 41. Which of the following is not a major component of a color TV receiver? a) color demodulator circuit b) sync analyzer c) color signal amplifier d) color reference oscillator 42. (Nov 1997) Operating method in which the transmission is made alternately in each direction of a telecommunication channel. a) Semi-duplex operation b) Duplex operation c) Simplex operation d) Half duplex operation 43. (Nov 1996) What is the maximum color TV bandwidth? a) 1.0 MHz b) 0.5 MHz c) 1.6 MHz d) 1.3 MHz 44. What is the process where some of the medium through which it impinges? a) reflection b) absorption c) diffraction d) refraction 45. What is the horizontal resolution of a broadcast TV receiver? a) 30 lines b) 339 lines c) 500 lines d) 428 lines 46. In what classes are SSB linear amplifiers operated? a) D b) B or C c) A or AB d) C or D 47. The power of thermal noise is ___ of resistance. a) dependent b) equal c) a function d) independent 48. What is the frequency swing of an FM broadcast transmitter when modulated 60%? a) 60 kHz b) 75 kHz c) 45 kHz d) 35 kHz 49. (Nov 1996) Which determines the number of sideband components in FM? a) Modulation frequency b) All of these c) Carrier frequency d) Modulation index 50. (Mar 1996) What is the main purpose of a communications system? a) For modulation b) None of these c) To provide an acceptable replica of the information at the designation d) To have a frequency assignment 51. What section of a TV receiver determines the bandwidth and produces the signal gain? a) RF Amplifier b) Local oscillator c) IF Amplifier d) Mixer 52. In a TV receiver, what is the horizontal sync frequency? a) 525 Hz b) 30 Hz c) 60 Hz d) 15,750 Hz 53. What is the greatest possible modulation value without distortion? a) 50% b) 100% c) 99.9% d) 66.67% 54. During 100% modulation, what percentage of the average output power is in the sidebands? a) 16.67% b) 100% c) 33.3% d) 66.67% 55. What causes audio signals to be distorted in a receiver? a) Interference b) Harmonics c) Amplitude d) Gain 56. In 1877, _____ invented a method of making a permanent record of sound with his invention of the phonograph. a) Bell b) Marconi c) Edison d) Morse 57. Any periodic function is represented by the sum of a number of sinusoidal variations of different amplitudes, frequencies, and phases. a) Nyquist Theorem b) Fouriers Theorem c) Hartleys Theorem d) Huygens Theorem 58. What is the seventh harmonic of 360 kHz? a) 1260 kHz b) 5040 kHz c) 2520 kHz d) 7000 kHz 59. (Nov 1998) Determine from the following radio frequency that falls under the Very High Frequency band of the radio spectrum. a) 235.5 MHz b) 144.50 GHz c) 450.00 MHz d) 345.00 MHz 60. Which of the following is not a type of log used in BC stations? a) Program b) Maintenance c) Operating d) Period 61. How many AM stations can be accommodated in a 150-kHz bandwidth if the highest modulating frequency is 10 kHz? a) 14 b) 10 c) 7 d) 15 62. What is the lowest number of sections required by communications receiver? a) 1 b) 3 c) 4 d) 2 63. What radio frequencies are most affected by lightning or static waves? a) VHF b) VLF c) SHF d) UHF 64. This noise increases with bias current level and is inversely proportional to the square of frequency. a) thermal noise b) burst noise c) flicker d) shot noise 65. (Apr 1998) Refers to an emission designation for facsimile. a) A3C and F3C b) R3E and A3E c) J3E and F4E d) A3J and A4E 66. The noise figure of a system is 12 and its input signal-to-noise ratio is 60. What is the output signal-to-noise ratio? a) 0.2 b) 5 c) 72 d) 720 67. When diode is used as a detector in the simple AM radio, what happens to the waveform of the carrier? a) It is filtered. b) It is rectified. c) It is amplified. d) It is modulated. 68. What distinguishes one electromagnetic wave form another? a) Phase b) Frequency c) Amplitude d) Energy 69. What is the advantage of using a high IF? a) improve S/N ratio b) better image rejection c) better quality of music d) high gain 70. (Nov 1998) In radio regulation. The first symbol in the designation of radio emission is _____. a) Bandwidth b) Type of modulation of the main carrier c) Type of information to be transmitted d) Nature of signal(s) 71. A suppressed-carrier synchronous detector requires: a) The presence of a reinserted carrier that has a frequency close to the original carrier. b) The presence of a reinserted carrier of exactly the same frequency and phase as the original. c) A BFO that is at the exact frequency difference between the original carrier and modulating frequency. d) A BFO that is near the frequency difference between the original carrier and modulating frequency. 72. (Nov 1996) Which of the following filters block FM radio band for TV channels (2 to 13)? a) High-pass filter b) Band-pass filter c) Low-pass filter d) Band-reject filter 73. Most of the communications receiver is in the form of ___type. a) Single-ended b) Super heterodyne c) High-level d) TRF 74. What does AFC mean? a) All Filipino Conference b) Audio Frequency Camera c) Automatic Frequency Control d) Anti Firing Countermeasure 75. In FM, what produces the sidebands? a) Modulating signal b) RF signal c) Carrier signal d) Carrier and its harmonics 76. What is the amount of power lost in a device due to its presence in the path of energy flow? a) Gain b) Insertion loss c) Phase shift d) Wave attenuation 77. A device used for abating the noise accompanying the flow of gas through a pipe. a) Acoustic Filter b) Helmholtz Resonator c) Muffler d) Acoustic Chamber 78. (Nov 1997) Atmospheric noise is less severe at frequencies above a) audio level b) 1 GHz c) 30 MHz d) 10 GHz 79. How many watts are represented by 40 dBw? a) 40 W b) 1000 W c) 40000 W d) 10000 W 80. The input power to a 50-O receiver is 200 pW. Determine the receiver gain required to produce 3 dBm at the detector. a) 40 dB b) 20 dB c) 70 dB d) 7 dB 81. It refers to the sending, receiving and processing of information by electronic means. a) Broadcasting b) Telephony c) Telemetry d) Communications 82. What is the allowable bandwidth of commercial AM radio in the United States? a) 10 MHz b) 15 kHz c) 30 kHz d) 10 kHz 83. For an FM transmitter, the initial carrier frequency is 8 MHz with a frequency deviation of 1 kHz. If the total frequency multiplication of the transmitter is 12, determine the final; frequency deviation. a) 8 MHz b) 12 kHz c) 120 kHz d) 1 kHz 84. The circuit that performs the suppression of the carrier signal. a) LPF b) Carrier synthesizer c) Pre-emphasis d) Balanced modulator 85. Which of the following services use crystal local oscillators? a) AM b) Aircraft c) Shortwave listener d) FM 86. Which type of microphone has a high Z output? a) Ribbon b) Crystal c) Dynamic d) Carbon 87. What determines the rate of frequency swing for an FM broadcast transmitter? a) Carrier frequency b) Modulation frequency c) Modulation amplitude d) Carrier amplitude 88. (Nov 1997) A good example of a pilot tone system used in commercial frequency modulation stations. a) Frequency modulation b) Stereo multiplexing c) FDM d) Time division 89. How many mixers are in an SSB receiver? a) 2 b) 1 c) 4 d) 3 90. (Nov 1998) Which of the following is referred to as a radio emission without sidebands? a) Data b) Analog c) Carrier d) Voice 91. The modulation index of an AM wave is changes from 0 to 1. The transmitter power is? a) Increased by 50% b) Halved c) Doubled d) Unchanged 92. What produces the dark spots on fax receiving paper? a) Burning due to electric current flow between helix wire and blade b) Excessive heat c) High current d) Low impedance 93. Determine the open-circuit noise voltage in 1Hz of bandwidth at 290 K for a diode biased at 1 mA. a) 654 pV b) 465 pV c) 56 pV d) 65 pV 94. What electrical device inside a communication receiver selects one station and rejects all others? a) Local Oscillator b) Tuner c) Detector d) AGC 95. A method of generating SSB signal; that utilizes only one balanced modulator circuit. a) Third method b) Weaver method c) Filter method d) Phase-Shift method 96. What is the interference due to single tone or complex periodic waveforms? a) Insertion b) Harmonic Distortion c) Inter-modulation Distortion d) Tone interference 97. What is another term meaning downward modulation? a) Distortion Modulation b) Harmonic Modulation c) Negative Carrier Shift d) Positive Carrier Shift 98. _____ frequencies are exact multiples of the fundamental frequency. a) Modulation b) Distortion c) Radio d) Harmonic 99. (Apr 1997) Sound intensity level is_____. a) 10 log I / I ref b) 30 log I / ref c) 20 log I / ref d) 10 log I / ref / I 100. A 2-kW RF carrier is sinusoidally modulated 100% . Haw much power is in one sideband? a) 2000 W b) 250 W c) 500 W d) 125 W 101. Complex number, equal to the ratio of a complex pressure amplitude to the complex amplitude of the volume velocity a) Acoustic Impendance b) Acoustic Pressure c) Acoustic Intensity d) Air Elasticity 102. A double conversion receiver uses a first IF of 10.7 MHz and a second of 455 kHz, both with high tracking. If a signal is received at 50 MHz, what signal/s will go into the second mixer? a) 110.7 MHz b) 10.7 MHz c) All of the above d) 39.3 MHz 103. What is a hybrid transmitter? a) Part semiconductor, part vacuum tube b) \part metal, part liquid c) Combination of metal and plastic d) Multiple transmitter 104. Which of the following is not commonly used in the LO? a) Colpitts b) Hartley c) Crystal d) Armstrong 105. What factor determines the modulation index of an FM transmission? a) Carrier phase b) Modulating signal frequency c) Carrier frequency d) Carrier amplitude 106. Pilot carrier transmission, means a) Only one sideband is transmitted b) One sideband and carrier are transmitted c) Two sidebands as well as a trace of carrier are transmitted d) Only two sidebands are transmitted 107. What is the frequency for the pilot subcarrier for commercial stereo FM? a) 67.5 kHz b) 38 kHz c) 19 kHz d) 20 kHz 108. (Nov 1997) Noise caused by the thermal agitation of electrons in resistance. a) Johnsons Noise b) ALL of these c) White Noise d) Thermal Noise 109. What is the aspect ratio in commercial TV receivers? a) 2:3 b) 4:3 c) 3:4 d) 16:9 110. What is the meaning of kinescope? a) Color CRT b) Wide screen CRT c) Enhanced CRT d) TV picture tube 111. What is the coupling used in Stoneman transmission bridge? a) Inductive b) A combination of the above c) Resistive d) Capacitive 112. He was the one who developed the mathematical solution to a complex repetitive waveform. a) Y. Uda b) J. Fourier c) Carson d) P.H Smith 113. Which of the following is not normally tested in a transmitter? a) Amplitude b) Modulation c) Frequency d) Power 114. In what type of transmitters is balanced modulators used? a) F3E b) A3E c) PM d) SSB 115. Does the video transmitter at a TV BC station employ FM or AM? a) AM b) both AM and FM c) FM d) PM 116. (Nov 1998) In modulation technique, which of the following is referred to audible pitch? a) Harmonic b) Amplitude c) Width d) Frequency 117. What is the main feature of DSB transmission? a) Carrier is suppressed b) Narrow bandwidth c) High reliability d) High voltage 118. Connecting a headset directly across the tuner in a simple AM radio receiver: a) Produces sound in the headset. b) Will not work until a battery is added. c) Will burn out the tuner. d) Will not produce sound in the headset. 119. What constitutes the input to an AM transmitter? a) RF oscillator and/or audio amplifier b) Buffer and IF amplifier c) Mixer and amplifier d) Mixer and local oscillator 120. The rms antenna current of a radio transmitter is 10 A when unmodulated, rising to 12 A when the carrier is sinusoidally modulated. What is the modulation factor? a) 0.83 b) 1 c) 0.67 d) 0..94 121. (Mar 1996) One-hundred twenty bars of pressure variation is equal to a) 120 dBSPL b) 115.56 dBSPL c) 57.78 dBSPL d) 41.58 dBSPL 122. An adjustable resonant cavity calibrated if frequency and which undergoes some power absorption at resonance. a) Frequency Meter b) Ferrite isolator c) Cavity Resonator d) Auto Coupler 123. What type of second detector is used for AM? a) PLL b) Lattice c) Ratio d) Diode 124. A receiver has a dynamic range of 81 dB. It has 0.55 nW sensitivity. What is the maximum allowable input signal? a) 5.01 W b) 0.0692 W c) 5.01 uW d) 15 uW 125. What type of device can be used in balanced modulators? a) RF, IF b) AF, RF c) AF, PF d) AF, IF 126. (Nov 1998) Which band does channel 14 of the television channel belongs? a) EHF band b) Low VHF band c) High VHF band d) UHF band 127. An earth station receiver has a signal of 4 x 10-12 W across 50 O input. What is the signal level in microvolts? a) 328 b) 1000 c) 1.6 d) 14.14 128. What does VOX mean? a) Very onward circuit b) Voice onward transmission c) Voice-operated transmission d) Very oxford transmitter 129. (Apr 1997) What is the local oscillator frequency range in commercial AM broadcast if IF is equal to 455 kHz? a) 0 to 1600kHz b) 0 to 455 kHz c) 955 to 2055 kHz d) 540 to 1600 kHz 130. (Nov 1996) What is the type of emission used by the standard AM radio broadcast? a) A b) D c) F d) C 131. What class of bias should produce least harmonics? a) Class B b) Class D c) Class C d) Class A 132. A super heterodyne is tuned to 2738 kHz. The IF is 475 kHz. What is the image frequency? a) 4385 kHz b) 3688 kHz c) 4.5 kHz d) 3.09 MHz 133. Which of the following is not a major difference between FM and AM receivers? a) AGC b) IF frequency c) deemphasis d) Limiter 134. What is the circuit that changes modulated RF to AF? a) Demodulator b) Synthesizer c) Modem d) Modulator 135. What is the standard intermediate frequency for FM radio? a) 455 kHz b) 10.7 kHz c) 112 kHz d) 4..5 kHz 136. The process of impressing information signals to a high frequency carrier is called _____. a) modulation b) scrambling c) multiplexing d) detection 137. Which of the following is not contained in TV tuner? a) Duplexer b) VHF oscillator c) VHF mixer d) VHF RF amplifier 138. The local FM stereo rock station is at 96.5 MHz. What must be the local oscillator frequency? a) 107.2 MHz b) 112.5 MHz c) 93.9 MHz d) 105.9 MHz 139. Which of the following FM detectors is not used in mobile? a) Quadrature b) Ratio c) Discriminator d) Balanced Detector 140. What does aspect ratio mean? a) Ratio of the screen height to its width b) Ratio of the screen width to its height c) Ratio of the screen diagonal to its height d) Ratio of the screen diagonal to its width 141. If two signals are in quadrature, what is their phase relation? a) 0 b) 90 c) 45 d) 180 142. Which of the following must not be included? a) galactic noise b) cosmic noise c) solar noise d) atmospheric noise 143. In free-space, the phase velocity of a TEM wave is _____ the group velocity. a) Less than b) None of the above c) Greater than d) Equal to 144. Receiver ___ is a gauge of the receivers capacity to receive weak signals. a) Gain Factor b) Selectivity c) Sensitivity d) Dynamic Range 145. What type of circuit reduces even-order harmonics? a) Demodulator b) Armstrong circuit c) Push-Pull d) Class A 146. If the second-harmonic amplitude is 2V and the fundamental is 10V, then the second-harmonic distortion is ___. a) 2 b) 40% c) 4 d) 20% 147. What is a device such as the microphone and the headset sometimes called? a) Transmission Medium b) Reproducer c) Converter d) Receiver 148. An FM signal has a frequency deviation of 2000 Hz caused by modulating signal of 500 Hz. What is the modulation index? a) 2 b) 4 c) 5 d) 8 149. (Apr 1998) Best describes as an amplifier used in radio telephony. a) Class C b) Class A c) Magnifier d) Class B 150. What frequencies are considered to be in the AF range? a) 300 Hz 3000 kHz b) 50 Hz 50 kHz c) 15 Hz 10 kHz d) 20 Hz 20 kHz 151. What is meant by amplitude modulation? a) The carrier sign is varied b) The carrier frequency is varied c) The carrier phase is varied d) The carrier amplitude is varied 152. What is the device designed to display the signal state of many lines simultaneously? a) OTDR b) Spectrum analyzer c) Oscilloscope d) Logic analyzer 153. (Nov 1996) Which stands for dB relative level? a) dBa b) dBr c) dBm d) dBm 154. What is the function of an FM limiter? a) to remove amplitude variation b) to provide image rejection c) to eliminate interference d) to increase stability 155. A 1500-kHz carrier and 2 kHz intelligence signal are combined in anon-liner device. What component is present at the output? a) all of the above b) 1500 kHz c) 1492 kHz d) 1502 kHz 156. A ______ is a resonant circuit tuned to reject an undesired signal by reducing the gain at the trap frequency. a) HPF b) LPF c) Wave trap d) LC tank 157. Find the noise voltage for a 1-kohms resistor at 170C tuned by an LC circuit with a BW of 1 MHz. a) 15 uV b) 15.01 uV c) 5.01 uV d) 50 uV 158. Determine the open-circuit noise voltage in 1 Hz of bandwidth at 290 K for a 26 ohms resistor. a) 45 pV b) 65 pV c) 145 pV d) 645 pV 159. A device which can perform the function of both a transmitter and a receiver. a) Repeater b) Buffer c) Relay d) Transceiver 160. Which of the following limits the performance of a communication system? a) Accessibility b) Reliability c) Cost d) Bandwidth 161. What is the circuit that automatically holds the level or strength of a signal at a predetermined level used to compensate for variations due to fading? a) AGC b) Discriminator c) AFC d) Limiter 162. Where is the single-button microphone used most? a) Paging system b) Broadcast Studio c) Intercom d) Telephone 163. (Mar 1996) Which of the following pulse modulation systems is analog? a) Delta b) Differential PCM c) PWM d) PCM 164. What is the channel width of an AM BC station? a) 5 kHz b) 50 kHz c) 10 kHz d) 20 kHz 165. The type of device noise, which is important at high frequencies, is ___ noise. a) shot b) Johnson c) flicker d) Transit-time 166. What is the meaning of the acronym WDM? a) Wap distributed mode b) Wavelength division multiplexing c) Wireless data monitoring d) Wide distribution media 167. The maximum swing of the sound carrier in TV system is ______. a) 15 kHz b) 10 kHz c) 25 kHz d) 75 kHz 168. (Nov 1997) Extra-terrestrial noise is observable at frequencies from a) 0 to 20 kHz b) Above 2 GHz c) 8 to 1.43 GHz d) 5 to 8 GHz 169. (Apr 1998) With which emission type is the capture-effect most pronounced? a) SSB b) CW c) FM d) AM 170. (Apr 1998) A form of single sideband emission where the degree of carrier suppression enables the carrier to be reconstituted and be used for demodulation. a) Full carrier single sideband emission b) Double sideband emission c) Reduced carrier single sideband emission d) Half carrier single sideband emission 171. The purpose of the balances modulator circuits is to eliminate the _____. a) Sidebands b) Distortion c) Noise d) Carrier 172. The total transmitted power for an AM signal is 1200 W at 100% modulation. What is the power for each sideband? a) 1200 W b) 1000 W c) 100 W d) 200 W 173. (Apr 1997) Which transmit only sideband? a) H3E b) 11BE c) A3E d) 3AJ 174. What is the sound carrier for channel 10? a) 193.25 MHz b) 192 MHz c) 196.83 MHz d) 197.75 MHz 175. For an AM signal modulated to a depth of 100% by a pure tone, the power is _____ the power of unmodulated carrier. a) 3 / 2 times b) Same as c) twice as d) less than 176. What method can be used to invert speech? a) Frequency multiplier b) Inverter c) AGC d) Frequency translation 177. Which produces greater interference, overmodulated positive or negative peaks? a) Positive b) Negative c) neither d) either 178. What is another name for AF volume control? a) AMC b) ARC c) AFC d) Gain 179. What is the percent modulation of an AM wave that has a power content of 12 kW in each sideband when modulated by a single tone? a) 66% b) 75% c) 82% d) 30% 180. How many horizontal lines are used to develop a TV raster? a) 615 b) 525 c) 750 d) 15750 181. (Nov 1997) In the designation of bandwidth and emission, what letter in the symbol represents a double-sideband of modulation? a) H b) C c) B d) A 182. A relatively rigid extended surface surrounding an acoustic source. a) Screen b) Dash Board c) Panel Board d) Baffle 183. What is the highest video frequency set by the FCC for commercial TV? a) 5.5 MHz b) 6 MHz c) 4.2 MHz d) 15 kHz 184. What do you call a heterodyne frequency changer? a) Mixer b) Frequency synthesizer c) Frequency translator d) Modulator 185. The value of a resistor creating thermal noise is halved. The noise power generated is a) doubled b) halved c) unchanged d) quadrupled 186. What does ANSI mean? a) American non stop information b) American national standards institute c) Auxiliary non station identifier d) Auxiliary net system interconnection 187. A radio transmitter is rated as having a frequency accuracy of 0.2 parts per million. What is the maximum frequency error at 150 MHz? a) 150 Hz b) 20 Hz c) 7.5 Hz d) 30 Hz 188. Quantization noise is produced in a) All pulse modulation system b) All modulation system c) PCM d) FSK 189. What is the amount of carrier swing necessary to produce an 80% modulation for the audio portion of the TV band? a) 20 kHz b) 40 kHz c) 25 kHz d) 50 kHz 190. (Nov 1997) Which of the following falls under the high frequency band of the radio spectrum? a) 150.50 MHz b) 2.4555 MHz c) 8.2345 MHz d) 35.535 MHz 191. (Mar 1996) What is the primary advantage of DSBSC in AM? a) No transmitter power is wasted in the carrier b) All of these c) It is simpler to transmit and receive than the standard AM d) Reduce bandwidth over standard AM 192. A subcarrier has a (n) _____ frequency than the main carrier. a) Higher b) Lower c) Equal d) Good 193. How often must remote control instrumentals be calibrated? a) Monthly b) Daily c) Yearly d) Weekly 194. In SSB transmission, which sideband can be eliminated? a) Upper only b) Depends upon the use c) Either d) Lower only 195. What percent of the radiated power is in the sidebands with 50% sinusoidal modulation (AM)? a) 20% b) 16.67% c) 11% d) 33% 196. (Apr 1998) If a transmitter supplies 8 kW to the antenna when it is unmodulated, determine the total radiated power when modulated at 30%. a) 20 kW b) 5 kW c) 8..36 kW d) 15 kW 197. The SI unit of magnetic field intensity is a) Volt/meter b) Ampere c) Ampere/square meter d) Ampere/meter 198. What is the picture carrier frequency for channel 7? a) 175.25 MHz b) 179.75 MHz c) 174 MHz d) 178.83 MHz 199. (Nov 1997) What is the effect in over modulated amplitude modulated radio broadcasting transmission? a) Higher audio signal b) Interference to adjacent channel c) Increase noise d) Higher fidelity 200. (Nov 1997) Modulation in which the modulated wave is always present. a) Log-periodic modulation b) Continues modulation c) Front-end d) Carrier modulation 201. The color phasor has what phase for the I signal? a) 90 b) 57 c) 180 d) 37 202. Amplitude distortion results from _____ amplification. a) Nonlinear b) Direct c) Indirect d) Linear 203. A mirror that reflects one color but passes all other are called ____. a) Convex b) Dichroic c) Concave d) Monochroic 204. A function y = f(t) is even if it has perfect symmetry about the _____. a) x-axis b) w-axis c) z-axis d) y-axis 205. An amplifier with NF= 6 dB has (S/N), of 25 dB. What is the output S/N? a) 6 dB b) 25 dB c) 19 dB d) 31 dB 206. What stage in an AM transmitter creates its own sine wave? a) Amplifier b) Oscillator c) Modulator d) Buffer 207. (Nov 1998) In amplitude modulation technique the unmodulated carrier is referred as having _____. a) over modulated b) 0% modulation c) 100% modulation d) 50% modulated 208. What is the approximate efficiency of a class B linear RF AM amplifier? a) 90% b) 50% c) 12% d) 35% 209. Which is better, an NF of 20 or 10 dB? a) 10 dB b) Neither c) Either d) 20 dB 210. (Mar 1996) In the phase shift method, how many circuits must be balanced? a) 4 b) 1 c) None of these d) 2 211. A 100-V carrier is amplitude modulated by a 1-kHz sine wave. What is the side-frequency amplitude when m=0.75? a) 100 V b) 37.5 V c) 18.75 V d) 75 V 212. The major difference between FM and PM a) All of the above b) Lies in the poorer audio response of phase modulation index c) Is too great to make the two system compatible d) Lies in the different definition of modulation index 213. Which subcarrier leads by 90 in TV system? a) R b) Y c) Q d) I 214. In an FM receiver, the circuit that keeps the receiver tuned exactly to the desired station is ___. a) Limiter b) AGC c) Discriminator d) AFC 215. (Apr 1998) What is the period of a wave? a) The number of degrees in tone cycle b) The time required to complete one cycle c) The number of zero crossing in one cycle d) The amplitude of the wave 216. A radio receiver is called ___ if the local oscillator frequency is made equal to the wanted RF signal frequency. a) Up-conversion b) homodyne c) Single-conversion d) TRF 217. How guardbands are allocated in commercial FM stations? a) 15 kHz modulation b) 75 kHz deviation c) 25 kHz on either side of the transmitting signal d) 50 kHz on each side of the carrier 218. Any waveform that is not symmetrical in area about the time axis has a (n) _____ component. a) DC b) FC c) RC d) AC 219. What type of field does a Faraday shield stop? a) Common b) Magnetostatic c) Array d) Electrostatic 220. In a low-level modulation system, the type of amplifier that follows the modulated stage should be a _____. a) Harmonic generator b) Any of the above c) Class C amplifier d) Linear amplifier 221. What is the name of the operation that uses an antenna changeover switch? a) Crossover b) Duplex c) Switching d) Simplex 222. What is the letter-number designation for an FM facsimile? a) C3C b) A3E c) F3E d) F3C 223. What is the power in each sideband for an AM signal with 80%modulation and a total power of 2500 W? a) 250 W b) 303 W c) 400 W d) 500 W 224. (Apr 1998) Type of modulation used in TV broadcast visual transmitter. a) SSBFC b) Pulse modulation c) Vestigial sideband d) DSBFC 225. When the modulating frequency is halved, the modulation index is doubled and the modulating voltage remains constant. The type of modulation is a) PM b) FM c) AM d) PCM 226. Compute the noise figure of a receiving system with a noise temperature of 2000C. a) 24 dB b) 2.4 dB c) 42 dB d) 4.2 dB 227. What formula determines sideband power in AM emissions? a) Pc(m2/5) b) Pc(m2/4) c) Pc(m2/3) d) Pc(m2/2) 228. (Nov 1996) The maximum power suggested by the KBP on 919 1312 kHz AM broadcast station I Metro Manila is a) 15 kW b) 5 kW c) 20 kW d) 10 kW 229. Which came first, the invention of the telephone or the invention of the phonograph? a) neither b) either c) phonograph d) telephone 230. In TV system. A picture signals are transmitted by a) PCM b) AM c) PM d) FM 231. (Apr 1998) In television broadband vivid strong color are often referred as ____. a) hue b) luminance c) chrominance d) saturation 232. A mixer is tuned to 2000 kHz and the local oscillator is on 1300 kHz. What frequency would cause an image? a) 600 kHz b) 1100 kHz c) 3300 kHz d) 700 kHz 233. What kind of system relays has remote readings? a) Data gathering b) Broadcasting c) Telemetering d) Telecast 234. What is an application for vestigial sideband transmission? a) FDM b) AM Broadcast c) Telephony d) TV Broadcast 235. (Nov 1996) Noise from random acoustic or electric noise that has equal per cycle over a specified total frequency band. a) Thermal noise b) Gaussian noise c) All of these d) White noise 236. What is the ratio of maximum deviation allowed to the modulating frequency being used called? a) Percent Modulation b) Deviation ratio c) Modulation Sideband d) Modulation Index 237. What determine the bandwidth of a transmitted AM signal? a) The maximum modulation amplitude b) The lowest frequency component of the intelligence c) The highest frequency component of the modulating signal d) The lowest modulation amplitude 238. High-frequency distortion occurs when the _____ harmonic components of a digital square wave are lost. a) High frequency b) Low frequency c) Sub d) Cut-off frequency 239. What type of wave trap is connected in series with a line? a) Parallel b) Series c) Synchronous d) Asynchronous 240. An AM transmission of 1000 W is fully modulated. Calculate the power transmitted as a SSB signal. a) 1000 W b) 167 W c) 333 W d) 667 W 241. Which of the following is not a type of external noise? a) Pink Noise b) Solar Noise c) Galactic Noise d) Atmospheric Noise 242. In a 5-kW AM transmitter high-level modulation is used. What is the value of the audio signal power needed for 100 percent modulation? a) 50 kW b) 2.5 kW c) 15 kW d) 5 kW 243. Which of the following is not an advantage of vestigial sideband transmission? a) Reduces power requirements b) Reduces transmission bandwidth c) Easy to detect the carrier d) Simple receiver circuitry 244. What is the BFO in SSB receiver called? a) Backward Oscillator b) Frequency Oscillator c) Local Oscillator d) Carrier Oscillator 245. Which of the following is not a requirement for a color TV signal? a) compatibility with B/W receivers b) within 6 MHz bandwidth c) good raster reproduction d) simulate a width variety of colors 246. The rms antenna current for an AM transmitter increases by 15% over the unmodulated value when sinusoidal modulation is applied. Find the daepth of modulation. a) 0..8 b) 0.6 c) .05 d) 0..75 247. What is the maximum power that ca be contained in the sideband without distortion? a) 66.67% b) 25% c) 50% d) 16.67% 248. What circuit accompanies a mixer? a) IF Amplifier b) Detector c) LO d) RF Amplifier 249. For an FM signal a) The carrier frequency cannot disappear b) The total number of sidebands depends on the modulation frequency the carrier frequency c) The amplitude of any sideband depends on the modulation index d) The carrier frequency disappears when the modulation index is large 250. (Apr 1997) Unit of noise power of psophometer a) dBmo b) dBm c) dBa d) pWp 251. (Nov 1996) Both frequency and phase modulation utilizes _____ modulation. a) angle b) Digital c) Phase d) AM and Fm 252. (Nov 1996) What is the equivalent output of a circuit in dBm , if it has an output of 10 watts? a) 10 dBm b) 40 dBm c) 20 dBm d) 30 dBm 253. (Nov 1998) The third symbol radio emission which represent telephone transmission including sound broadcasting. a) C b) W c) E d) F 254. The term angular velocity as applied to electronic system refers to the number of: a) Degrees subtracted from the radians b) Degrees averaged together c) Radian per second a voltage vector rotates d) None of these 255. Which is not true about modulation a) Transmission over longer distances b) More practical antenna c) Multiple transmission d) Narrower bandwidth 256. (Apr 1997) Tendency of sound energy to spread. a) Reflection b) Rarefaction c) Diffraction d) Refraction 257. Which of the following is not an advantage of FM over AM? a) Better noise immunity is provided b) Less modulating power is required c) The transmitted power is mote useful d) Lower bandwidth is required 258. What will the normal AM receiver detect from an unmodulated RF AC wave? a) Nothing b) noise c) AF signal d) Carrier 259. What is an advantage of series modulation? a) High gain and selectivity b) Capable of generating high power c) Low noise and interference d) Capable of modulating very high frequencies 260. (Apr 1998) What is a frequency discriminator? a) An automatic bandswitching circuit b) An FM generator c) A circuit for detecting FM signals d) A circuit for filtering two closely adjacent signal 261. What is the required time constant for an FM broadcast preemphasis and deemphasis network? a) 100 s b) 75 s c) 50 s d) 25 s 262. Where is a degaussing coil in a TV set? a) at the tuner b) around the IF amp c) inside the CRT d) around the tube face 263. What type of microphone has the lowest power output? a) Dynamic b) Carbon c) Ribbon d) Condenser 264. The device that prevents aural RF from entering the video transmitter and vice versa is called____. a) duplexer b) tuner c) coupler d) diplexer 265. A duplexer is used to a) Connect a receiver and a transmitter to the same antenna b) Feed more than one transmitter from a single antenna c) Connect two t6ransmitter to the same antenna d) Feed more than one receiver from a single antenna 266. What is the result of overmodulation of an FM emission? a) Excessive bandwidth distortion b) Lower frequency c) Higher power d) distortion 267. (Apr 1997) What particular circuit gets rids of FM noise? a) Phase Shifter b) Limiter c) LPF d) HPF 268. (Apr 1997) Lowest frequency produced by musical instrument. a) Midrange b) Period c) Fundamental d) Harmonic 269. What TV signal are amplified by the video IF amplifier? a) Sound carriers b) Sound the picture carriers c) Sync pulse d) Color burst 270. What is the small amount of the signal applied to the input port that leaks through to the output port? a) Insertion loss b) Feedthrough loss c) Reflection loss d) Regenerative loss 271. What is gained by operating an oscillator on some subharmonic of the transmission frequency? a) High sensitivity b) Frequency stability c) Good selectivity d) Frequency sensitivity 272. Which of the following is not an application of PLL? a) AM Discriminator b) FSK decoder c) FM demodulators d) Frequency Synthesizers 273. A carrier wave is amplitude modulated by two sine waves of different frequencies with modulation indices of 0.3 and 0.4. What is the overall modulation index? a) 0.2 b) 0.7 c) 0.5 d) 0.1 274. Which of the following is not associated with transistors? a) shot noise b) transit-time c) jitter d) flicker noise 275. The bandwidth in _____ depends on the number of significant sidebands. a) Delta Modulation b) FCM c) Frequency Modulation d) QAM 276. What is reduced by rounding off square-wave emissions? a) energy b) Amplitude c) Phase d) Bandwidth 277. Calculate the modulating frequency that causes an FM signal to have a bandwidth of 50 kHz when its frequency deviation is 15 kHz. a) 20 kHz b) 40 kHz c) 50 kHz d) 10 kHz 278. What major principle prevents the TV viewer from observing flicker? a) scanning b) light reflections c) persistence of the picture tube and human eye d) drowsiness 279. In a transmitted AM wave, state where the information is contained? a) Sidebands b) Modulating signal c) Carrier d) Envelope 280. (Mar 1996) After the IF stages have been aligned, the next state to align in FM receiver is a) local oscillator b) limiter stage c) Mixer stage d) RF Amplifier 281. (Apr 1997) The random and unpredictable electric signal from natural causes, both internal and external to the system is known as ___. a) attenuation b) noise c) distortion d) interference 282. Is the information used to represent a TV picture transmitted at the same time? a) None of the above b) No c) Sometimes d) Yes 283. What broadcast station use vertical antennas on flat ground? a) AM b) TV c) Shortwave d) FM 284. (Apr 1997) What is the reference frequency of CCITT psophometric noise measurement? a) 1000 Hz b) 1500 Hz c) 800 Hz d) 3400 Hz 285. (Apr 1998) Quantity that do not change when a beam of light enters one medium to another. a) Frequency b) Wavelength c) Speed d) Direction 286. Which of the following do not require a tuner? a) Communications Satellite Receiver b) CB receiver c) TV receiver d) None of these 287. What is the power saving in J3E system at 100% modulation? a) 100% b) 66.67% c) 33.3% d) 83.3% 288. How much time is allocated for horizontal retrace? a) 63.5 s b) 7.5 s c) 76 s d) 10.2 s 289. What is the noise figure of an ideal amplifier? a) unity b) zero c) infinity d) 100 290. With _____, the modulation envelope is an expression of the amplitude and frequency of the modulation signal. a) PM b) AM c) FM d) PCM 291. (Apr 1997) The sound power level of a jet plane flying at a height of 1 km is 160 dB (ref = 10-12 W). What is the maximum sound pressure level on the ground directly below the plane assuming that the aircraft radiates sound equality in all directions? a) 79.1 dB b) 59.1 dB c) 89.1 dB d) 69.1 dB 292. (Apr 1997) The final amplifier of either FM or AM transmitter operates as a) Class C b) Class D c) Class A d) Class B 293. What is the magnitude of the frequency component at seven times the fundamental frequency for a square wave amplitude 1 V? a) 0.2 b) 0.7 c) 0.14 d) 0.18 294. It is the ability of a radio receiver to receive weak signal. a) sensitivity b) stability c) fidelity d) selectivity 295. How often should BC stations be identified? a) every ten minutes b) at least once an hour c) every thirty minutes d) at least once a day 296. What part of a super heterodyne is responsible for the band pass of the receiver? a) RF Amplifier b) IF Amplifier c) Detector d) LO 297. (Apr 1997) channels 2, 4 and 5 are known as a) high band VHF b) low band VHF c) low band UHF d) mid band UHF 298. (April 1997) Industrial noise frequency is between ___. a) 0 to 10 kHz b) 200 to 3000 MHz c) 15 to 160 MHz d) 20 GH 299. What is the wavelength for a frequency of 1 million hertz? a) 3 km b) 30 km c) 30 m d) 300 m 300. What holds the horizontal oscillator on frequency? a) AFC b) ECL c) ALC d) AGC 301. What devise is used to determine phase difference between two broadcast antennas? a) FSM b) Frequency monitor c) Phase monitor d) OTDR 302. (Apr 1998) How does a SSB transmitter output power normally expressed? a) Average power b) In term of peak envelope power c) Peak power d) In term of peak-to-peak power 303. The super heterodyne circuit uses local oscillator to ___ with the RF signal of the station and convert the carrier to the intermediate frequency. a) beat b) heterodyne c) mix d) all of the above 304. What is the percent modulation of a signal in the FM broadcast band at 92 MHz with 20 kHz frequency deviation? a) 72% b) 60% c) 27% d) 12% 305. When the loop in a PLL is locked, what is the difference in frequency detected by the phase detector? a) 450 b) 1800 c) 900 d) 00 306. What does the acronym VIR mean? a) Video Interval Recording b) Video Interface Relay c) Vertical Interface Relay d) Vertical Interval Reference 307. The pre-emphasis network in Europe has a time constant of ___.. a) 150 us b) 75 us c) 100 us d) 300 us 308. A system uses a deviation of 100 kHz and a modulating frequency of 15 kHz. What is the approximate bandwidth? a) 215 kHz b) 200 kHz c) 230 kHz d) 115 kHz 309. (Nov 1998) What is the first symbol of radio signal emission having an amplitude modulated main carrier, double sideband? a) C b) A c) H d) B 310. Noise is most problematic at the___. a) transmitter b) source c) communication channel d) receiver 311. What characteristic of the sound wave determines its pitch? a) harmonics b) amplitude c) frequency d) phase 312. Another name for burst noise a) popcorn noise b) pink noise c) flicker d) shot noise 313. What is the S/N at the output of an amplifier whose NF=10 dB and the input S/N=25 dB? a) 25 dB b) 15 dB c) 10 dB d) 35 dB 314. An AM signal displayed on an oscilloscope has a maximum span of 5 V and a minimum of 1 V. What is the modulation index? a) 20% b) 80% c) 120% d) 67% 315. What are the le7tter-number designations of carrier and one SB? a) H3E b) A3E c) J3E d) F3E 316. What is the noise current for a diode with a forward bias of 1 mA over a 1 MHz bandwidth? a) 9.15 nA b) 179 nA c) 17.9 nA d) 91.5 uA 317. Two 4? speakers connected in series have a total impedance of ____. a) 2? b) 4? c) 6? d) 8? 318. In FM for a given frequency deviation, the modulation index varies _____ with the modulating frequency. a) Inversely b) Independently c) Directly d) Equally 319. (Nov 1998) Refers to the first symbol in an emission designation with an amplitude modulated main carrier represented by letter A. a) Independent sideband b) Double sideband full carrier c) Double sideband d) Single sideband suppressed carrier 320. What is the most common application of carbon microphone? a) TV transmitter b) FM radio c) Am radio d) telephone 321. What is the signal, usually of random character, which is always present in a communications system? a) sideband b) spur c) interference d) noise 322. It is the interference of a signal from one channel into another channel. a) Spur b) Crosstalk c) Inter-modulation distortion d) Sideband splatter 323. Basically, what would be added to a TRF to produce a super heterodyne? a) All of the above b) Mixer stage c) IF stage d) Local Oscillator 324. Most household radio receiver uses ___ detector. a) asynchronous b) synchronous c) phase d) envelope 325. What is the maximum power output of a CB A3E emission? a) 4 W b) 3 kW c) 10 kW d) 10 W 326. What would be produce by weak blue, weak green, and weak red signals on a color CRT? a) Weak white b) White c) Black d) Gray 327. What stage in a super heterodyne is aligned first? a) RF Amplifier b) Mixer c) Second Detector d) IF Amplifier 328. For an unmodulated carrier of 1000V and a modulated peak value of 1800 V, what is the modulation index? a) 0..8 b) 0.9 c) 0.5 d) 0.7 329. The total power content of an AM signal is 600 W. What is the percentage modulation if each sideband contains 100 W? a) 33.3% b) 66.7% c) 83.3% d) 100% 330. For an FM signal in the 88-108-MHz broadcast band with a frequency deviation of 15 kHz, determine the percent modulation. a) 20% b) 80% c) 40% d) 60% 331. (Nov 1997) Background noise is the same as the following except a) gaussian noise b) white noise c) thermal noise d) impulse noise 332. What id the purpose of a conversion frequency oscillator? a) To provide good selectivity b) To increase stability c) To produce the IF d) To provide a conversion frequency 333. (Mar 1996) Cross modulation on a receiver is eliminated at the a) Mixer stage b) RF stage c) Detector stage d) IF stage 334. What determines the purity of received colors? a) Y and I amplitudes b) Y amplitudes c) Q and Y amplitudes d) Q and I amplitudes 335. An indirect method of generating FM is a) Reactance transistor modulator b) Armstrong modulator c) Varactor diode modulator d) Reactance tube modulator 336. In single-gun color CRT, what electron beam travels straight through the tube? a) red b) blue c) yellow d) green 337. When an operator wishes to indicate that he has received all of the last transmission, he will transmit the word _____. a) Over b) Ok c) Out d) Roger 338. (Apr 1997) Modulation means a) varying of information b) varying of some parameters of a carrier such as its amplitude to transmit information c) utilization of a single transmission channels to carry multiple signals d) transmit pulse in DC form on a copper wire 339. An FM signal with modulation index m is applied to a frequency tripler. The modulation index at the output is _____. a) 0 b) m c) m / 2 d) 3m 340. (Apr 1997) 100% modulation inn AM means a corresponding increase in total power by _____. a) 25% b) 50% c) 75% d) 100% 341. What is the main function of a balanced modulator? a) Limit noise picked by a receiver b) Suppress carrier signal in order to create a SSB or DSB c) Produce 100% modulation d) Produce balanced modulation of a carrier wave 342. What service uses HF CW communications? a) Telephony b) Police c) Satellite System d) Broadcasting 343. The all-encompassing noise associated with a give environment, being usually composite of sounds from many sources near and far. a) Relative Noise b) Ambient Noise c) Average Noise d) Nominal Room 344. (Apr 1998) Which of the following refers to a double side band full carrier? a) F3 b) A3E c) A3J d) R3A 345. What are the two emission designations of a TV transmission? a) J3E, C3F b) A3E, ISB c) B8e, C3F d) F3E, C3F 346. It is the representation of a complex waveform in such a way that the sinusoidal components are displayed as a function of time. a) Wave Representation b) Frequency Domain c) Time Domain d) TDR 347. What are the frequency limits of the AM BC band? a) 535 1605 kHz b) 500 1600 kHz c) 88 108 MHz d) 300 3000 kHz 348. In Phase Modulation (PM), the modulation index represents ______. a) The maximum phase shift b) The total number of sidebands c) The ratio of the modulation amplifier to the carrier amplitude d) The maximum frequency deviation 349. A DSB-SC system must suppress the carrier by 50 dB from its original value of 10 W. To what value must the carrier be reduced? a) 0.1 W b) 0.0001 W c) 0.01W d) 0.001 W 350. (Nov 1998) A third symbol emission which represent television. (0 correct answers) a) A b) D c) F d) C 351. An 88-MHz carrier is modulated by an audio tone that caused a frequency deviation of 15 kHz. What is the carrier swing of this FM signal? a) 15 kHz b) 60 kHz c) 45 kHz d) 30 kHz 352. Normally, for how long must logs be kept for the FCC? a) 1 year b) 1 week c) 1 month d) 2 years 353. What is the reason for using pre-emphasis? a) increase selectivity b) to increase noise figure c) reduce noise reception d) reduce S/N ratio 354. A type of device noise whose intensity decreases with frequency. a) popcorn noise b) thermal noise c) shot noise d) flicker 355. (Mar 1996) The _____ filter attenuates signals but passes frequencies below and above the band. a) High pass b) Band stop c) Low pass d) Band pass 356. The antenna current of an AM transmitter is 6.2 A when unmodulated and rises to 6.7 A when modulated. What is the %m? a) 42.8% b) 57.9% c) 67% d) 51% 357. Treble sound corresponds to a) Mid- frequencies b) High frequencies c) Low frequencies d) Radio frequencies 358. What is an NO RY? a) Normally open relay b) Non organic relay c) Normally ready d) Non operational relay 359. What determines the maximum number of vertical picture element? a) Number of pixel b) Number of fields per second c) Number of lines on the screen d) Number of frames per second 360. When did the first transatlantic radio communications take place? a) 1901 b) 1888 c) 1876 d) 1942 361. Where is ISB primarily used? a) Telephone and Telegraph Communications b) Radar c) FM Broadcast d) Telemetry 362. It describe the acoustic energy flowing per unit area and per unit time. a) Acoustic Intensity b) Sound Absorption c) Sound Reflection d) Acoustic Pressure 363. How many oscillators does black and white TV receiver contain? a) 3 b) 1 c) 4 d) 2 364. Which of the following items need not be checked with receivers? a) Squelch b) Sensitivity c) Distortion d) Gain 365. In an AM transmitter, after the modulation stage, _____ amplifier cannot be used. a) Class B b) Class A c) Class C d) Linear 366. (Mar1996) The equivalent noise temperature of the amplifier is 25 K. What is the noise figure? a) 1..86 b) 1.086 c) 0.1086 d) 10.86 367. (Nov 1998) The extremely high frequency (EHF) band is in the radio spectrum range of _____. a) 3 to 30 MHz b) 30 to 300 GHz c) 3 to 30 GHz d) 30 to 300 kHz 368. (Nov 1997) An antenna that can only receive a television signal? a) Isotropic antenna b) Yagi antenna c) Reference Anenna d) TVRO 369. What is the disadvantage slope detection of FM? a) low noise reduction b) complexity c) no noise discrimination d) high level of noise 370. (Nov 1998) Frequencies above _____ kHz, are referred to as the radio frequencies. a) 2 b) 20 c) 10 d) 100 371. For _____ percent modulation in AM, the modulation envelope has a peak value double the unmodulated carrier level. a) 83.3 b) 100 c) 50 d) 66.67 372. What happens to noise when you increase the bandwidth of an amplifier? a) Remain constant b) it decreases c) fluctuates d) it increases 373. (Apr 1998) Term in communication which is referred, to send out in all direction. a) Transmit b) Broadcast c) Media d) Announce 374. What form of energy is contained in a sound? a) elastic b) kinetic c) electromagnetic d) acoustic 375. To make the headset reproduce the original modulating signal, the metal disk mask: a) Have a source of energy from a battery. b) Move in step with the frequency of the received carrier. c) Move in step with the changes in amplitude of the received carrier. d) Vibrate fast enough to keep up with the high frequency radio wave. 376. What is the power requirement for international BC stations? a) 50 kW b) 15 W c) 5 kW d) 100 W 377. (Apr 1998) What is emission C3F? a) Modulated CW b) Television c) Facsimile d) RTTY 378. What information other than the sound has to be transmitted in TV transmission? a) synchronizing signals b) visual signal c) all of the above d) blanking pulses 379. (Nov 1997) Nominal voice channel a) 20 to 20 kHz b) 4 kHz c) 3 to 3 kHz d) 16 to 16 kHz 380. What is the following is not a product of overmodulation? a) Image b) Spurious signal c) Splatter d) Buckshot 381. What kind of crystal is used in oscillators? a) Salt b) Carborundum c) Quartz d) Galena 382. What is the relative permittivity of air? a) 1.26 x 10-6 b) 20 c) 8..853 x 10-12 d) 1 383. What is the deviation ratio for commercial FM? a) 10 b) 1 c) 5 d) 2 384. What produces splatter in an AM transmission? a) overmodulation b) Clipping c) Flickering d) Harmonics 385. What is the carrier power transmitted on a 75-O antenna if mf=2 and Vc (unmodulated) is 2 kVpk? a) 1.29 kW b) 10 kW c) 9 kW d) 12.9 kW 386. What is the shape of a trapezoidal pattern at 100% modulation? a) Square b) Triangle c) Circle d) Rectangle 387. Who is in overall control of a TV production? a) producer b) actor c) manager d) director 388. What is the purpose of AFC in an FM receiver? a) to stabilize the gain b) to increase the sensitivity c) to provide good selectivity d) to help maintain a steady local oscillator frequency 389. What AF range is required of the aural transmitter of a TV BC station? a) 20 Hz 2 kHz b) 20 Hz 20 kHz c) 50 Hz 15,000 Hz d) 5 50 kHz 390. In FM, what determines bandwidth? a) Carrier frequency b) Modulation phase c) Modulation index d) Carrier power 391. Which of the following is not a continuous wave modulation? a) PCM b) FM c) PM d) AM 392. (Nov 1996) A loudspeaker cabinet has an internal volume of 5,184 in (84,950 cm). If has a port area on the on the baffle of 50 in (323cm) and the thickness of 0.75 in (19mm). What is the Helmholtz resonance, in hertz, of this loudspeaker enclosure? a) 250 Hz b) 245 Hz c) 240 Hz d) 255 Hz 393. To what feature of the modulating tone is FM deviation proportional? a) Amplitude b) Frequency c) Harmonics d) Phase 394. If a broadcast station is transmitting but not modulating, what is heard in a receiver tuned to its frequency? a) Audio only b) Nothing c) Hiss d) Carrier only 395. (Mar 1996) In an FM receiver, which circuit removes amplitude variations? a) Mixer b) Discriminator c) Exciter d) Limiter 396. What pattern of modulation must used when neutralizing an operating transmitter? a) 100% or over b) 10 % c) 80% d) 50% 397. What is a radio carrier? a) A higher frequency signal b) A lower frequency signal c) A lower amplitude signal d) A higher amplitude signal 398. What device can be used to make a modulated envelope visible? a) Calibrator b) Spectrum Analyzer c) Synthesizer d) Oscilloscope 399. What happens in standard AM transmission when no modulating signal is being transmitted? a) There is no signal. b) There are no sidebands. c) There are several sidebands. d) There are two carriers 400. (Nov 1996) Which symbol indicates that only one sideband is transmitted? a) A3E b) H3E c) C3F d) B8E 401. Calculate the thermal noise delivered to a system with a bandwidth of 1 Hz operating at 170C. a) 4 x 10-12 W b) 2.1 x 10-14 W c) 4 x 10-21 W d) 1.2 x 10-14 W 402. When voltages are out-of-phase, the total voltage can be found by adding: a) Vectorially b) Arithmetically c) Peak values d) Average values 403. The three kind of demodulators for AM are: a) frequency, phase and amplitude b) a and c but not b c) simple, suppressed carrier, and single sideband d) simple, medium, and complex 404. What is the frequency of the VCR control signal? a) 30 Hz b) 15750 Hz c) 60 Hz d) 15625 Hz 405. (Apr 1998) An instrument for recording waveforms of audio frequency. a) Radioscope b) Phonoscope c) Audioscope d) Oscilloscope 406. Which stages in a broadcast transmitter are normally class C? a) modulated amplifier b) AF amplifier c) buffer amplifier d) oscillator 407. (Nov 1997) A method of expressing the amplitude of complex non-periodic signals such as speech. a) Pitch b) Wavelength c) Frequency d) Volume 408. (Nov 1997) An AM transmitter is rated 100 W at 100% modulation. How much power is required for the carrier? a) 33.33 W b) 66.66 W c) 83.33 W d) 100 W 409. A type of microphone which has a permanent magnet a) ribbon b) carbon c) crystal d) electret 410. What happens to the spectrum of a repetitive pulse as the pulse width decreases? a) More harmonics of the same phase b) Remain constant c) Less harmonics of the same phase d) decreases 411. How many times more bandwidth does the UHF band have than VHF band? a) 1 b) 1000 c) 100 d) 10 412. What is the major advantage of FM over AM? a) Simple circuits b) High frequency c) Less noise d) No interference 413. (Apr 1997) _____ used to measure speech volume. a) Volume meter b) Audio frequency meter c) Volume unit meter d) Speech meter 414. The term wolfe number refers to the front-end circuit of a VHF TV super heterodyne receiver? a) X-rays b) 11-year sunspot cycle c) 27-year solar cycle d) Ultraviolet Radiation 415. (Nov 1998) What connects the front-end circuit of a VHF TV super heterodyne receiver? a) Local oscillator, mixer and RF amplifier b) RF amplifier, Band pass filter and mixer c) Mixer, RF amplifier and AFC d) Local oscillator, AGC and antenna 416. (Nov 1997) The third symbol in the designation of radio emission under the IYU rules refers to a) nature of signal(s)modulating the main carrier b) type of information to be transmitted c) bandwidth d) type of modulation of the main carrier 417. (Nov 1996) Speaker is a device that ____. a) none of these b) convert current variations into sound waves c) convert sound waves into current and voltage d) convert electrical energy to mechanical energy 418. (Apr 1998) Considered as the main source of an internal noise. a) Temperature change b) Thermal agitation c) Device imperfection d) Flicker 419. The signal which is superimposed on a high-frequency sine wave is called _____. a) Information b) Sideband c) Carrier d) Square wave 420. FM has a major disadvantage of _____. a) High voltage b) Greater coverage c) Low efficiency d) Greater bandwidth 421. The range of frequencies represented in a signal. a) Guardband b) Bandwidth c) Crisp d) Beamwidth 422. (Nov 1997) The first symbol in the designation of radio emission under the ITU rules refers to a) nature of signal(s) modulating the main carrier b) type of information to be transmitted c) type of modulation of the main carrier d) bandwidth 423. The entire range of _____ of electromagnetic radiation is called the frequency spectrum. a) Phases b) Frequencies c) Amplitudes d) Energies 424. (Mar 1996) Three audio waves with 100, 200 and 300 volts amplitude respectively, simultaneously modulate a 450 volts carrier. What is the total percent of modulation of the Am wave? a) 115.5% b) 50% c) 69% d) 83% 425. What is the blanking level for negative transmission? a) 75% b) 66.6% c) 12.5% d) 50% 426. Sound is a wave motion of varying air____. a) Pressure b) Density c) Resistance d) Viscosity 427. How many cathodes are there in a shadow-mask tube? a) 1 b) 3 c) 4 d) 2 428. What is the color subcarrier for channel 5? a) 76 MHz b) 80.83 MHz c) 76.25 MHz d) 81.75 MHz 429. (Nov 1996)Multiplexing in a time division multiplexer occurs based upon a) The priority assigned to a connected device b) The position of a frame within a group of frames c) The positioning of data within a frame d) The activity of a connected device 430. (Apr 1998) A carrier signal has _____. a) Frequency range 20-20000 Hz b) The information c) A varying amplitude d) Constant peak amplitude 431. What sweep frequency could be used on a scope to stop an envelope pattern of 600-Hz modulation? a) 150 Hz b) 600 Hz c) 1200 Hz d) 300 Hz 432. Name a periodic waveform that consists of only odd harmonics. a) Square wave b) Cosine wave c) Spikes d) Sine wave 433. Is SSB, voice compression is better in the AF or Rf section? a) SB b) Intermediate c) RF d) AF 434. A microwave antenna at an earth station has Tant=25 K. If the receiver has Tr=290 K (3 dB NF), then the resultant equivalent system noise temperature is ___. a) 290 K b) 25 K c) 300 K d) 315 K 435. A modulation technique commonly used for low-cost digitization of voice signals. a) F3 b) A0 c) A5C d) A3 436. For a 75-MHz FM carrier modulated by 5-kHZ audio tone that causes a frequency deviation of 15 kHz, determine the FM signal bandwidth. a) 200 kHz b) 100 kHz c) 40 kHz d) 80 kHz 437. What is the source of wheel static? a) Brakes b) Oscillations c) Piston d) Wheel 438. In AM, maximum desirable output of a transmitter is obtained when its modulation is _____%. a) 100 b) less than 100 c) greater than 100 d) 50 439. (Nov 1997) A single sideband emission in which the degree of carrier suppression enables the carrier to be reconstituted and to be used for demodulation. a) Full carrier single band emission b) Standard single sideband emission c) Reduce carrier single sideband emission d) Half carrier single sideband emission 440. The big breakthrough in electric communications came with the invention of the _____ in 1844. a) Transistor b) Phonograph c) Telephone d) Telegraph 441. The circuit used for producing a double sideband suppressed carrier type of AM signal is called _____. a) Mixer b) AGC c) PLL d) Balances modulator 442. For an IF frequency of 455 kHz, what must be the LO frequency when receiving a 580 kHz transmission? a) 3.51 MHz b) 1.035 MHz c) 1035 MHz d) 351 kHz 443. When a carrier is frequency-modulated, what is developed on both sides carrier? a) Envelope b) Noise c) sidebands d) Carrier 444. (Mar 1996) Power is always _____. a) All of these b) A definite amount of energy c) The rate at which energy is used d) Expressed in watts 445. Amplitude limiting in the IF section eliminates _____ interference from the FM signal. a) AM b) Broadband c) PM d) FM 446. A type of information signal which is made up of rapid and unpredictable variations in amplitude and frequency. a) speech b) pulses c) bits d) digital 447. The audio is reconstructed from the radio wave by: a) The action of a filter capacitor connected across the headset b) The action of the headset c) None of the above. d) Having the audio removed from the carrier 448. The modulated carrier power in FM a) Is independent of modulating signal power b) Increases with modulating signal power c) Decreases with modulating signal power d) All of the above 449. (Nov 1996) The unit of pitch. a) Decibel b) Mel c) Phon d) Sone 450. (Apr 1997) If you have an available number of power amplifiers with a gain of 100 each, how many such amplifiers do you need to cascade to give an overall gain of 60 dB? a) 2 b) 3 c) 4 d) 5 451. (Mar 1996) A car horn outdoors, produces a sound intensity level of 90 dB at ft away. At this distance, what is the sound power in watt? a) 1.2 W b) 0.12 W c) 12 W d) 0.012 W 452. (Nov 1998) What do you call the service area of a standard AM broadcast where fading is allowed but no objectionable co-channel interference? a) Experimental b) Secondary c) Primary d) Tertiary 453. What might cause a 120-MHz aircraft transmission to be received on an FM broadcast band receiver with a 10.7-MHz IF? a) 97.2 MHz b) 99.3 MHz c) 96.3 MHz d) 98.6 MHz 454. (Nov 1996) The output of a balanced modulator is _____. a) LSB b) Carrier c) USB d) LSB and USB 455. Determine the noise power delivered to a receiver input at 300 K and noise bandwidth of 20 kHz. a) 131dBm b) -130.8 dBm c) -120 dBm d) -25 dBm 456. If a 7-A carrier is modulated 100% by a sinusoidal tone, how much does the antenna current increase? a) 66.7% b) 33.3% c) 22.5% d) 44.8% 457. What is the main disadvantage of a single-tube transmitted? a) Low gain b) High attenuation c) Frequency instability d) High resistivity 458. (Mar 1996) In AM, the carrier carries _____ intelligence. a) Difference b) Same c) No d) Distorted 459. A system has 150 kHz of bandwidth available for a 10-kHz modulating signal. What is the approximate deviation? a) 75 kHz b) 65 kHz c) 70 kHz d) 100 kHz 460. What source of noise is related to system temperature? a) shot noise b) thermal noise c) pink noise d) burst noise 461. What was the first BC PM system called? a) Armstrong b) Fourier c) Wienbridge d) Weaver 462. Modulating two waves of the same frequency but with _____. a) 45 b) 180 c) 90 d) 360 463. Which of the following is not an advantage of SSB over AM? a) Less spectrum b) None of these c) Power saving d) Simple receiver circuit 464. What is the main problem in receiving a suppressed carrier transmission or a single sideband transmission? a) The selectivity of the receiver must be good. b) There must be three detectors. c) The gain of the amplifier must be high d) The receiver needs to reinsert the missing carrier. 465. Who hears high audio frequency best? a) all of the above b) old people c) young people d) 40 years old 466. What determines the selectivity of a receiver? a) the bandwidth of the tuned circuits b) the gain of the amplifier c) the power handling capability d) the frequency stability 467. The information carrying capacity of a signal is _____ to its bandwidth. a) Inversely proportional b) Directly proportional c) Not related d) Equal 468. (Mar 1996) What is the difference between phase and frequency modulation? a) Lies in poorer audio response of phase modulation b) Lies in the different definitions of the modulation index c) Is purely theoretical because they are the same in practice d) Os too great to make two systems compatible 469. (Mar 1996) The letter-number designation B8E is a form of modulation also known as _____. a) Pilot-carrier system b) Vestigial sideband transmission c) Lincompex d) Independent sideband emission 470. In what way would a program may be received at BC stations? a) Radio Relay b) All of the above c) Telephone Lines d) Satellite 471. What does an FM detector do? a) to convert phase changes to frequency changes b) to increase the frequency change c) to convert frequency changes to amplitude changes d) to extract amplitude variations 472. What is the major requirement of the oscillators used in an SSB receiver? a) Goof feedback b) High frequency c) stability d) Selectivity 473. (Nov 1997) A large speaker having diameter (15 cm. and above) a) Coaxial speaker b) Triaxial speaker c) Tweeter d) Woofer 474. The typical output voltage from a magnetic microphone is a) 5 mV b) 10 mV c) 1 mV d) 50 mV 475. What is the major advantage of a super heterodyne receiver? a) good image rejection b) excellent selectivity and sensitivity c) high amplification factor d) inexpensive 476. Compute the modulation index of an FM signal with a carrier swing of 10 kHz when the modulating signal is 5 kHz. a) 4 b) 2 c) 0.5 d) 1 477. Determine the power saving in percent when the carrier is suppressed in an AM signal modulated to 80% a) 75.8% b) 66.7% c) 80% d) 100% 478. What is the letter symbol for the luminance signal? a) Q b) Y c) R d) I 479. Which of the following is an advantage of PM over FM? a) Requires a complex circuitry b) A need for several modulators c) Requires a simpler transmitter d) One amplifier is required 480. (Apr 1998) The signal to noise ratio that is required for a satisfactory television reception. a) 20 dB b) 10 dB c) 40 dB d) 30 dB 481. The PM signal produces by an FM circuit is called a) Indirect FM b) Indirect PM c) Direct PM d) Direct FM 482. A diode detector: a) Converts AC into pulsating DC. b) Detects the modulating signal. c) Does all of the above. d) Allows current to flow in one direction only. 483. (Nov 1998) What is meant by the term deviation ratio? a) The ratio of the highest audio modulating frequency to the average audio modulating frequency b) The ratio of the carrier center frequency to the audio modulating frequency c) The ratio of the maximum carrier frequency deviation to the highest audio modulation frequency d) The ratio of the audio modulating frequency to the center carrier frequency 484. (Mar 1996) The signal in a channel is measured to be 23 dB while noise in the same channel is measured to be 9 dB. The signal to noise ratio therefore is ____. a) 23/9 b) 9/23 c) 14-dB d) 32-dB 485. What type of coupling discriminates against harmonic transmission a) Inductive b) Capacitive c) Direct d) Transformer 486. He was the one who developed the wireless telegraph. a) Marconi b) Armstrong c) Edison d) Bell 487. What is the oldest and simplest form of multiplexing? a) Time-division multiplexing b) Hybrid-division multiplexing c) Space-division multiplexing d) Frequency-division multiplexing 488. The parameter of a high-frequency carrier that may be varied by a low-frequency intelligence signal is _____. a) Phase b) All of the above c) Frequency d) Amplitude 489. What is an ideal pulse? a) A low duty cycle b) A perfect square wave with zero rise time c) A high amplitude d) A very short duration 490. To provide two or more voice circuits with the same carrier, what system must be used? a) ISB emission b) Vestigial sideband system c) Pilot carrier system d) Lincomplex 491. (Apr 1998) Term for transmission of printed picture by radio. a) ACSSB b) Television c) Facsimile d) Xerography 492. What other term is essentially synonymous with beating? a) Filtering b) Scrambling c) Suppressing d) Heterodyning 493. Which of the following is used in microwave ovens? a) BWO b) Magnetron c) Klystron d) TWT 494. (Nov 1996) The wavelength of light has no role in a) Resolving power b) Diffraction c) Polarization d) Interference 495. A SSB transmitter drives 121 V peak into a 50-O antenna. What is the PEP? a) 146W b) 292 W c) 73 W d) 121 W 496. (Apr 1998) The final power amplifier in an FM y=transmitter usually operates class _____. a) AB b) C c) A d) B 497. (Mar 1996) If the percentage of modulation of an AM amplifier is 88% and the modulation signal is 1 volt, the carrier has an amplitude of _____. a) 0.12 volt b) 0.88 volt c) 1.88 volts d) 1.14 volts 498. In Frequency Modulation ______. a) The amplitude of the carrier according to the amplitude of the modulating signal b) The frequency of carrier varies according to the phase of the modulating signal c) The frequency of carrier varies according to the amplitude of the modulating signal d) The frequency of carrier varies according to the frequency of the modulating signal 499. Which is not a method of generating single sideband signal? a) Filter b) Weaver c) Phase-shift d) Balanced modulator 500. If the 500-Hz modulation of a 1-MHz carrier has 3rd harmonic distortion, what is the emission bandwidth? a) 1 MHz b) 1 kHz c) 3 kHz d) 1500 Hz 501. What is the bandwidth of a narrowband FM signal generates by a 2 kHz audio signal a 110-MHz FM carrier? a) 4 kHz b) 1 kHz c) 2 kHz d) 5 kHz 502. (Nov 1996) Which frequency band is the standard AM radio broadcast? a) VHF b) HF c) UHF d) MF 503. An SSB contains 30 kW. The power content of the carrier is _____ kW. a) 10 b) 0 c) 20 d) 30 504. What determines the station that will be selected by a tuner? a) The sensitivity of the tuner b) The bandwidth of the amplifier c) The resonant frequency of the tuner d) The selectivity of the IF 505. What is the frequency of the color burst? a) 3.58 MHz b) 60 Hz c) 6 MHz d) 30 Hz 506. What factor(s) determine the modulation index of an FM signal? a) Amplitude of the carrier b) A and b are true c) Frequency deviation d) Frequency of the modulation signal 507. The noise power generated by a resistor depends upon a) none of the above b) its resistance value c) both a and b d) its operating temperature 508. (Nov 1996) When was the UHF channels (14-83) of television were added? a) 1852 b) 1952 c) 1947 d) 1904 509. If an FM transmitter has two doublers and one tripler, what is the carrier swing when the oscillator deviates 2 kHz? a) 24 kHz b) 48 kHz c) 36 kHz d) 2 kHz 510. What is the result if a balanced modulator is not perfectly balanced? a) SB filtered b) Carrier transmitted c) Low sideband transmitted d) Both sideband transmitted 511. FM system is superior to AM because a) It has wider bandwidth b) It eliminates most of amplitude variation noise c) It is at VHR band d) It produces more rock music 512. (Mar 1996) Atmospheric condition is controlled by a) Temperature b) All of these c) Pressure d) Humidity 513. What does ALC mean? a) All Local Circuits b) Automatic Link Circuit c) Asynchronous Link Control d) Automatic Level Control Your chosen subject is: Electronics EngineeringOnly 851 questions remaining in this category. Please answer the following 851 questions and then press the Submit button below! 1. The minimum negative VGK to force the plate current to be zero in vacuum tubes. a) Cutoff bias b) 0 V c) Threshold voltage d) Pinch off voltage 2. What is the most positive voltage out of a negative clamper whose input is 10 peak - to - peak sinusoidal voltages? a) 5V b) 10V c) 3V d) 0V 3. Which of the following does not have a base terminal? a) UJT b) SCR c) Pnp d) Npn 4. Tetrodes and pentodes are usually rated by their ___________. a) b) rp c) gm d) voltage gain 5. Given that the lower cutoff frequency is 10 Hz and the higher cutoff frequency is 1 kHz. Calculate the center frequency f0. a) 100 Hz b) 1 kHz c) 1.5 kHz d) 1005 Hz 6. Filter that exhibits an extremely fast roll-off rate. Filter that is characterized by a relatively flat passband and slow roll-off rate. a) Butterworth b) Chebyshev c) Notch d) Elliptic 7. What FET terminal corresponds to Emitter of BJT? a) Source b) Drain c) Anode d) Gate 8. It is the biasing of the BJT at room temperature with no voltage applied. a) Zero bias b) Unbias c) Base bias d) VDB 9. Material usually used as gate of MOS for IC. a) Gold b) Platinum c) Poly-silicon d) Mono-crystalline silicon 10. A circuit whose output is the continuous summation of a signal over a period of time. a) Integrator b) Differentiator c) Schmitt trigger d) Level detector 11. To limit the current during starting, a __________ is inserted with the armature circuit. a) Resistor in parallel b) Inductor in parallel c) Capacitor in series d) Resistor in series 12. This happens when a free electron returns to the valence shell. (0 correct answers) a) Recombination b) Hole c) Ionization d) Lifetime 13. When the ohmmeter is connected with its positive terminal to the base of an npn transistor and its negative terminal to the emitter, what is the most probable value that will be displayed? a) 10k ? b) 100k ? c) 1k ? d) 0? 14. What is the residual magnetism? a) The flux density, which exist in the iron core when the magnetic field intensity is at its maximum value. b) The external magnetic field when the current is flowing through the exciting coil. c) The flux density, which exist in the iron core when the magnetic field intensity reduced to zero. d) The flux density when the magnetic core is saturated. 15. Kind of AC-motor, light load high speed or high speed or high load low speed. a) Universal motor b) Squirrel cage motor c) Split case motor d) Synchronous motor 16. Which of the following is a good practice in replacing capacitors in voltage multipliers? a) Reversing the capacitor polarity b) Using a smaller value capacitor but with higher voltage rating c) The replacement capacitors must have the same or higher voltage ratings than the originals d) Using a smaller value capacitor but with lower voltage rating 17. Common - base (CB) amplifier has ___________ compared to common - emitter (CE) and common - collector (CC) amplifier. a) A larger current gain b) A higher input resistance c) A larger voltage gain d) A lower input resistance 18. Which of the following is not a popular biasing technique for vacuum tubes? a) VDB b) Self bias c) Grid-leak bias d) Fixed bias 19. Which is a common use for point contact diode? a) As an RF detector b) As a constant voltage source c) As a high voltage rectifier d) As a constant current source 20. An FET can act as an excellent buffer amplifier because __________. a) It has a low input impedance and a high output impedance b) Smaller size, longer life, and lower efficiency c) It has a very high voltage gain and a low noise level d) It has a high input impedance and a low output impedance 21. Type of clipper that has an output when the diode is forward biased. a) Rectifier b) Series clipper c) Forward clipper d) Positive clipper 22. In order to have the best efficiency and stability, where on the loadline should a solid state power amplifier be operated? a) Just power below the saturation point b) At 1.414 times the saturation point c) Just above the saturation point d) At the saturation point 23. A 33 k ? resistor connected in series with a parallel combination made up of a 56 k ? resistor and a 7.8 k ? resistor. What is the total combined resistance of these t