FCC ELEMENT 3 EXAM TEST BANK
600 QUESTIONS WITH CORRECT
ANSWERS
What is the total bandwidth of a FM phone transmission having a 5 kHz deviation and a
3 kHz modulating frequency?
A. 3 kHz.
B. 8 kHz.
C. 5 kHz.
D. 16 kHz. - Answer-D. 16 kHz.
How does the modulation index of a phase-modulated emission vary with RF carrier
frequency?
A. It does not depend on the RF carrier frequency.
B. Modulation index increases as the RF carrier frequency increases.
C. It varies with the square root of the RF carrier frequency.
D. It decreases as the RF carrier frequency increases. - Answer-A. It does not depend
on the RF carrier frequency.
How can a single-sideband phone signal be generated?
A. By driving a product detector with a DSB signal.
B. By using a reactance modulator followed by a mixer.
C. By using a loop modulator followed by a mixer.
D. By using a balanced modulator followed by a filter. - Answer-D. By using a balanced
modulator followed by a filter.
What is a balanced modulator?
A. An FM modulator that produces a balanced deviation.
B. A modulator that produces a double sideband, suppressed carrier signal.
C. A modulator that produces a single sideband, suppressed carrier signal.
D. A modulator that produces a full carrier signal. - Answer-B. A modulator that
produces a double sideband, suppressed carrier signal.
What is an L-network?
A. A low power Wi-Fi RF network connection.
B. A network consisting of an inductor and a capacitor.
C. A "lossy" network.
D. A network formed by joining two low pass filters. - Answer-B. A network consisting of
an inductor and a capacitor.
What is a pi-network?
,A. A network consisting of a capacitor, resistor and inductor.
B. The Phase inversion stage.
C. An enhanced token ring network.
D. A network consisting of one inductor and two capacitors or two inductors and one
capacitor. - Answer-D. A network consisting of one inductor and two capacitors or two
inductors and one capacitor.
What is the resonant frequency in an electrical circuit?
A. The frequency at which capacitive reactance equals inductive reactance.
B. The highest frequency that will pass current.
C. The lowest frequency that will pass current.
D. The frequency at which power factor is at a minimum. - Answer-A. The frequency at
which capacitive reactance equals inductive reactance.
Which three network types are commonly used to match an amplifying device to a
transmission line?
A. Pi-C network, pi network and T network.
B. T network, M network and Z network.
C. L network, pi network and pi-L network.
D. L network, pi network and C network. - Answer-C. L network, pi network and pi-L
network.
What is a pi-L network?
A. A Phase Inverter Load network.
B. A network consisting of two inductors and two capacitors.
C. A network with only three discrete parts.
D. A matching network in which all components are isolated from ground. - Answer-B. A
network consisting of two inductors and two capacitors.
Which network provides the greatest harmonic suppression?
A. L network.
B. Pi network.
C. Pi-L network.
D. Inverse L network. - Answer-C. Pi-L network.
What will occur when a non-linear amplifier is used with a single-sideband phone
transmitter?
A. Reduced amplifier efficiency.
B. Increased intelligibility.
C. Sideband inversion.
D. Distortion. - Answer-D. Distortion.
To produce a single-sideband suppressed carrier transmission it is necessary to ____
the carrier and to ____ the unwanted sideband.
A. Filter, filter.
B. Cancel, filter.
,C. Filter, cancel.
D. Cancel, cancel. - Answer-B. Cancel, filter.
In a single-sideband phone signal, what determines the PEP-to-average power ratio?
A. The frequency of the modulating signal.
B. The degree of carrier suppression.
C. The speech characteristics.
D. The amplifier power. - Answer-C. The speech characteristics.
What is the approximate ratio of peak envelope power to average power during normal
voice modulation peak in a single-sideband phone signal?
A. 2.5 to 1.
B. 1 to 1.
C. 25 to 1.
D. 100 to 1. - Answer-A. 2.5 to 1.
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?
A. 1,000 watts.
B. 100 watts.
C. 200 watts.
D. 400 watts. - Answer-B. 100 watts.
What would be the voltage across a 50-ohm dummy load dissipating 1,200 watts?
A. 245 volts.
B. 692 volts.
C. 346 volts.
D. 173 volts. - Answer-A. 245 volts.
How can intermodulation interference between two transmitters in close proximity often
be reduced or eliminated?
A. By using a Class C final amplifier with high driving power.
B. By installing a terminated circulator or ferrite isolator in the feed line to the transmitter
and duplexer.
C. By installing a band-pass filter in the antenna feed line.
D. By installing a low-pass filter in the antenna feed line. - Answer-B. By installing a
terminated circulator or ferrite isolator in the feed line to the transmitter and duplexer.
How can parasitic oscillations be eliminated in a power amplifier?
A. By tuning for maximum SWR.
B. By tuning for maximum power output.
C. By neutralization.
D. By tuning the output. - Answer-C. By neutralization.
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?
A. Amplifier desensitization.
B. Neutralization.
C. Adjacent channel interference.
D. Intermodulation interference. - Answer-D. Intermodulation interference.
What term describes a wide-bandwidth communications system in which the RF carrier
varies according to some pre-determined sequence?
A. Spread-spectrum communication.
B. AMTOR.
C. SITOR.
D. Time-domain frequency modulation. - Answer-A. Spread-spectrum communication.
How can even-order harmonics be reduced or prevented in transmitter amplifier design?
A. By using a push-push amplifier.
B. By operating class C.
C. By using a push-pull amplifier.
D. By operating class AB. - Answer-C. By using a push-pull amplifier.
What is the modulation type that can be a frequency hopping of one carrier or multiple
simultaneous carriers?
A. SSB.
B. FM.
C. OFSK.
D. Spread spectrum. - Answer-D. Spread spectrum.
The deviation ratio is the:
A. Audio modulating frequency to the center carrier frequency.
B. Maximum carrier frequency deviation to the highest audio modulating frequency.
C. Carrier center frequency to the audio modulating frequency.
D. Highest audio modulating frequency to the average audio modulating frequency. -
Answer-B. Maximum carrier frequency deviation to the highest audio modulating
frequency.
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?
A. 60
B. 0.16
C. 0.6
D. 1.66 - Answer-D. 1.66
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?
A. 2.14
B. 0.214
600 QUESTIONS WITH CORRECT
ANSWERS
What is the total bandwidth of a FM phone transmission having a 5 kHz deviation and a
3 kHz modulating frequency?
A. 3 kHz.
B. 8 kHz.
C. 5 kHz.
D. 16 kHz. - Answer-D. 16 kHz.
How does the modulation index of a phase-modulated emission vary with RF carrier
frequency?
A. It does not depend on the RF carrier frequency.
B. Modulation index increases as the RF carrier frequency increases.
C. It varies with the square root of the RF carrier frequency.
D. It decreases as the RF carrier frequency increases. - Answer-A. It does not depend
on the RF carrier frequency.
How can a single-sideband phone signal be generated?
A. By driving a product detector with a DSB signal.
B. By using a reactance modulator followed by a mixer.
C. By using a loop modulator followed by a mixer.
D. By using a balanced modulator followed by a filter. - Answer-D. By using a balanced
modulator followed by a filter.
What is a balanced modulator?
A. An FM modulator that produces a balanced deviation.
B. A modulator that produces a double sideband, suppressed carrier signal.
C. A modulator that produces a single sideband, suppressed carrier signal.
D. A modulator that produces a full carrier signal. - Answer-B. A modulator that
produces a double sideband, suppressed carrier signal.
What is an L-network?
A. A low power Wi-Fi RF network connection.
B. A network consisting of an inductor and a capacitor.
C. A "lossy" network.
D. A network formed by joining two low pass filters. - Answer-B. A network consisting of
an inductor and a capacitor.
What is a pi-network?
,A. A network consisting of a capacitor, resistor and inductor.
B. The Phase inversion stage.
C. An enhanced token ring network.
D. A network consisting of one inductor and two capacitors or two inductors and one
capacitor. - Answer-D. A network consisting of one inductor and two capacitors or two
inductors and one capacitor.
What is the resonant frequency in an electrical circuit?
A. The frequency at which capacitive reactance equals inductive reactance.
B. The highest frequency that will pass current.
C. The lowest frequency that will pass current.
D. The frequency at which power factor is at a minimum. - Answer-A. The frequency at
which capacitive reactance equals inductive reactance.
Which three network types are commonly used to match an amplifying device to a
transmission line?
A. Pi-C network, pi network and T network.
B. T network, M network and Z network.
C. L network, pi network and pi-L network.
D. L network, pi network and C network. - Answer-C. L network, pi network and pi-L
network.
What is a pi-L network?
A. A Phase Inverter Load network.
B. A network consisting of two inductors and two capacitors.
C. A network with only three discrete parts.
D. A matching network in which all components are isolated from ground. - Answer-B. A
network consisting of two inductors and two capacitors.
Which network provides the greatest harmonic suppression?
A. L network.
B. Pi network.
C. Pi-L network.
D. Inverse L network. - Answer-C. Pi-L network.
What will occur when a non-linear amplifier is used with a single-sideband phone
transmitter?
A. Reduced amplifier efficiency.
B. Increased intelligibility.
C. Sideband inversion.
D. Distortion. - Answer-D. Distortion.
To produce a single-sideband suppressed carrier transmission it is necessary to ____
the carrier and to ____ the unwanted sideband.
A. Filter, filter.
B. Cancel, filter.
,C. Filter, cancel.
D. Cancel, cancel. - Answer-B. Cancel, filter.
In a single-sideband phone signal, what determines the PEP-to-average power ratio?
A. The frequency of the modulating signal.
B. The degree of carrier suppression.
C. The speech characteristics.
D. The amplifier power. - Answer-C. The speech characteristics.
What is the approximate ratio of peak envelope power to average power during normal
voice modulation peak in a single-sideband phone signal?
A. 2.5 to 1.
B. 1 to 1.
C. 25 to 1.
D. 100 to 1. - Answer-A. 2.5 to 1.
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?
A. 1,000 watts.
B. 100 watts.
C. 200 watts.
D. 400 watts. - Answer-B. 100 watts.
What would be the voltage across a 50-ohm dummy load dissipating 1,200 watts?
A. 245 volts.
B. 692 volts.
C. 346 volts.
D. 173 volts. - Answer-A. 245 volts.
How can intermodulation interference between two transmitters in close proximity often
be reduced or eliminated?
A. By using a Class C final amplifier with high driving power.
B. By installing a terminated circulator or ferrite isolator in the feed line to the transmitter
and duplexer.
C. By installing a band-pass filter in the antenna feed line.
D. By installing a low-pass filter in the antenna feed line. - Answer-B. By installing a
terminated circulator or ferrite isolator in the feed line to the transmitter and duplexer.
How can parasitic oscillations be eliminated in a power amplifier?
A. By tuning for maximum SWR.
B. By tuning for maximum power output.
C. By neutralization.
D. By tuning the output. - Answer-C. By neutralization.
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?
A. Amplifier desensitization.
B. Neutralization.
C. Adjacent channel interference.
D. Intermodulation interference. - Answer-D. Intermodulation interference.
What term describes a wide-bandwidth communications system in which the RF carrier
varies according to some pre-determined sequence?
A. Spread-spectrum communication.
B. AMTOR.
C. SITOR.
D. Time-domain frequency modulation. - Answer-A. Spread-spectrum communication.
How can even-order harmonics be reduced or prevented in transmitter amplifier design?
A. By using a push-push amplifier.
B. By operating class C.
C. By using a push-pull amplifier.
D. By operating class AB. - Answer-C. By using a push-pull amplifier.
What is the modulation type that can be a frequency hopping of one carrier or multiple
simultaneous carriers?
A. SSB.
B. FM.
C. OFSK.
D. Spread spectrum. - Answer-D. Spread spectrum.
The deviation ratio is the:
A. Audio modulating frequency to the center carrier frequency.
B. Maximum carrier frequency deviation to the highest audio modulating frequency.
C. Carrier center frequency to the audio modulating frequency.
D. Highest audio modulating frequency to the average audio modulating frequency. -
Answer-B. Maximum carrier frequency deviation to the highest audio modulating
frequency.
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?
A. 60
B. 0.16
C. 0.6
D. 1.66 - Answer-D. 1.66
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?
A. 2.14
B. 0.214
