FCC ELEMENT 3 EXAM REVIEW QUESTIONS WITH ALL CORRECT ANSWERS
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FCC ELEMENT 3
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FCC ELEMENT 3
FCC ELEMENT 3 EXAM REVIEW QUESTIONS WITH ALL CORRECT ANSWERS
3-52G4 What is the approximate DC input power to a Class AB RF power amplifier stage in an unmodulated carrier transmitter when the PEP output power is 500 watts? - Answer-1000 watts.
3-52G5 The class AB amplifier output is present f...
FCC ELEMENT 3 EXAM REVIEW
QUESTIONS WITH ALL CORRECT
ANSWERS
3-52G4 What is the approximate DC input power to a Class AB RF power amplifier
stage in an unmodulated carrier transmitter when the PEP output power is 500 watts? -
Answer-1000 watts.
3-52G5 The class AB amplifier output is present for what portion of the input cycle? -
Answer-More than 180 but less than 360 degrees.
3-52G6 What class of amplifier is characterized by conduction for 180 degrees of the
input wave? - Answer-Class B.
3-53G1 What is the modulation index in an FM phone signal having a maximum
frequency deviation of 3,000 Hz on either side of the carrier frequency when the
modulating frequency is 1,000 Hz? - Answer-3
3-53G2 What is the modulation index of a FM phone transmitter producing a maximum
carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency? -
Answer-3
3-53G3 What is the total bandwidth of a FM phone transmission having a 5 kHz
deviation and a 3 kHz modulating frequency? - Answer-16 kHz.
3-53G4 How does the modulation index of a phase-modulated emission vary with RF
carrier frequency? - Answer-It does not depend on the RF carrier frequency.
3-53G5 How can a single-sideband phone signal be generated? - Answer-By using a
balanced modulator followed by a filter.
3-53G6 What is a balanced modulator? - Answer-A modulator that produces a double
sideband, suppressed carrier signal.
3-54G1 What is an L-network? - Answer-A network consisting of an inductor and a
capacitor.
3-54G2 What is a pi-network? - Answer-. A network consisting of one inductor and two
capacitors or two inductors and one capacitor.
3-54G3 What is the resonant frequency in an electrical circuit? - Answer-The frequency
at which capacitive reactance equals inductive reactance.
,3-54G4 Which three network types are commonly used to match an amplifying device to
a transmission line? - Answer-L network, pi network and pi-L network.
3-54G5 What is a pi-L network? - Answer-A network consisting of two inductors and two
capacitors.
3-54G6 Which network provides the greatest harmonic suppression? - Answer-Pi-L
network.
3-55G1 What will occur when a non-linear amplifier is used with a single-sideband
phone transmitter? - Answer-. Distortion.
3-55G2 To produce a single-sideband suppressed carrier transmission it is necessary to
____ the carrier and to ____ the unwanted sideband. - Answer-Cancel, filter.
3-55G3 In a single-sideband phone signal, what determines the PEP-to-average power
ratio? - Answer-The speech characteristics.
3-55G4 What is the approximate ratio of peak envelope power to average power during
normal voice modulation peak in a single-sideband phone signal? - Answer-2.5 to 1.
3-55G5 What is the output peak envelope power from a transmitter as measured on an
oscilloscope showing 200 volts peak-to-peak across a 50-ohm load resistor? - Answer-
100 watts.
3-55G6 What would be the voltage across a 50-ohm dummy load dissipating 1,200
watts? - Answer-. 245 volts.
3-56G1 How can intermodulation interference between two transmitters in close
proximity often be reduced or eliminated? - Answer-By installing a terminated circulator
or ferrite isolator in the feed line to the transmitter and duplexer.
3-56G2 How can parasitic oscillations be eliminated in a power amplifier? - Answer-By
neutralization.
3-56G3 What is the name of the condition that occurs when the signals of two
transmitters in close proximity mix together in one or both of their final amplifiers, and
unwanted signals at the sum and difference frequencies of the original transmissions
are generated? - Answer-Intermodulation interference.
3-56G4 What term describes a wide-bandwidth communications system in which the RF
carrier varies according to some pre-determined sequence? - Answer-Spread-spectrum
communication.
,3-56G5 How can even-order harmonics be reduced or prevented in transmitter amplifier
design? - Answer-By using a push-pull amplifier.
3-56G6 What is the modulation type that can be a frequency hopping of one carrier or
multiple simultaneous carriers? - Answer-Spread spectrum.
3-57H1 The deviation ratio is the: - Answer-Maximum carrier frequency deviation to the
highest audio modulating frequency.
3-57H2 What is the deviation ratio for an FM phone signal having a maximum frequency
deviation of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz? -
Answer-1.66
3-57H3 What is the deviation ratio of an FM-phone signal having a maximum frequency
swing of plus or minus 7.5 kHz and accepting a maximum modulation rate of 3.5 kHz? -
Answer-2.14
3-57H4 How can an FM-phone signal be produced in a transmitter? - Answer-By
feeding the audio directly to the oscillator.
3-57H5 What is meant by the term modulation index? - Answer-The ratio between the
deviation of a frequency modulated signal and the modulating frequency.
3-57H6 In an FM-phone signal, what is the term for the maximum deviation from the
carrier frequency divided by the maximum audio modulating frequency? - Answer-
Deviation ratio.
3-58H1 In Figure 3H17, the block labeled 4 would indicate that this schematic is most
likely a/an: - Answer-SSB radio transmitter.
3-58H2 In Figure 3H17, which block diagram symbol (labeled 1 through 4) represents
where audio intelligence is inserted? - Answer-2
3-58H3 What kind of input signal could be used to test the amplitude linearity of a
single-sideband phone transmitter while viewing the output on an oscilloscope? -
Answer-A two-tone audio-frequency sine wave.
3-58H4 What does a two-tone test illustrate on an oscilloscope? - Answer-Linearity of a
SSB transmitter.
3-58H5 How can a double-sideband phone signal be produced? - Answer-By
modulating the supply voltage to a class C amplifier.
3-58H6 What type of signals are used to conduct an SSB two-tone test? - Answer-Two
non-harmonically related audio signals that are within the modulation band pass of the
transmitter.
, 3-59H1 What is an important factor in pulse-code modulation using time-division
multiplex? - Answer-Synchronization of transmit and receive clock pulse rates.
3-59H2 In a pulse-width modulation system, what parameter does the modulating signal
vary? - Answer-Pulse duration.
3-59H3 What is the name of the type of modulation in which the modulating signal
varies the duration of the transmitted pulse? - Answer-Pulse-width modulation.
3-59H4 Which of the following best describes a pulse modulation system? - Answer-The
peak transmitter power is normally much greater than the average power.
3-59H5 In a pulse-position modulation system, what parameter does the modulating
signal vary? - Answer-The time at which each pulse occurs.
3-59H6 What is one way that voice is transmitted in a pulse-width modulation system? -
Answer-A standard pulse is varied in duration by an amount depending on the voice
waveform at that instant.
3-60I1 When a lead-acid storage battery is being charged, a harmful effect to humans
is: - Answer-Emission of hydrogen gas.
3-60I2 A battery with a terminal voltage of 12.5 volts is to be trickle-charged at a 0.5 A
rate. What resistance should be connected in series with the battery to charge it from a
110-V DC line? - Answer-195 ohms.
3-60I3 What capacity in amperes does a storage battery need to be in order to operate
a 50 watt transmitter for 6 hours? Assume a continuous transmitter load of 70% of the
key-locked demand of 40 A, and an emergency light load of 1.5 A. - Answer-177
ampere-hours.
3-60I4 What is the total voltage when 12 Nickel-Cadmium batteries are connected in
series? - Answer-15 volts.
3-60I5 The average fully-charged voltage of a lead-acid storage cell is: - Answer-2.06
volts.
3-60I6 A nickel-cadmium cell has an operating voltage of about: - Answer-1.25 volts.
3-61I1 When an emergency transmitter uses 325 watts and a receiver uses 50 watts,
how many hours can a 12.6 volt, 55 ampere-hour battery supply full power to both
units? - Answer-1.8 hours.
3-61I2 What current will flow in a 6 volt storage battery with an internal resistance of
0.01 ohms, when a 3-watt, 6-volt lamp is connected? - Answer-0.4995 amps.
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