AMS 380 Unit 2 Practice Test
3-31D1 What frequency synthesizer circuit uses a phase A
comparator, look-up table, digital-to-analog converter,
and a low-pass antialias filter?
A. A direct digital synthesizer.
B. Phase-locked-loop synthesizer.
C. A diode-switching matrix synthesizer.
D. A hybrid synthesizer.
3-31D2 A circuit that compares the output of a voltage- B
controlled oscillator (VCO) to a frequency standard and
produces an error voltage that is then used to adjust the
capacitance of a varactor diode used to control
frequency in that same VCO is called what?
A. Doubly balanced mixer.
B. Phase-locked loop.
C. Differential voltage amplifier.
D. Variable frequency oscillator.
3-31D3 RF input to a mixer is 200 MHz and the local A
oscillator frequency is 150 MHz. What output would you
expect to see at the IF output prior to any filtering?
A. 50, 150, 200 and 350 MHz.
B. 50 MHz.
C. 350 MHz.
D. 50 and 350 MHz.
3-31D4 What spectral impurity components might be C
generated by a phase-locked-loop synthesizer?
A. Spurs at discrete frequencies.
B. Random spurs which gradually drift up in frequency.
C. Broadband noise.
D. Digital conversion noise.
3-31D5 In a direct digital synthesizer, what are the B
unwanted components on its output?
A. Broadband noise.
B. Spurs at discrete frequencies.
C. Digital conversion noise.
D. Nyquist limit noise pulses.
3-31D6 What is the definition of a phase-locked loop D
(PLL) circuit?
A. A servo loop consisting of a ratio detector, reactance
modulator, and voltage-controlled oscillator.
B. A circuit also known as a monostable multivibrator.
C. A circuit consisting of a precision push-pull amplifier
with a differential input.
D. A servo loop consisting of a phase detector, a low-
pass filter and voltage-controlled oscillator.
3-41F1 What is the limiting condition for sensitivity in a A
communications receiver?
A. The noise floor of the receiver.
B. The power supply output ripple.
C. The two-tone intermodulation distortion.
D. The input impedance to the detector.
3-41F2 What is the definition of the term "receiver B
desensitizing"?
A. A burst of noise when the squelch is set too low.
B. A reduction in receiver sensitivity because of a strong
signal on a nearby frequency.
C. A burst of noise when the squelch is set too high.
D. A reduction in receiver sensitivity when the AF gain
control is turned down.
3-41F3 What is the term used to refer to a reduction in A
receiver sensitivity caused by unwanted high-level
adjacent channel signals?
A. Desensitizing.
B. Intermodulation distortion.
C. Quieting.
D. Overloading.
, AMS 380 Unit 2 Practice Test
3-41F4 What is meant by the term noise figure of a C
communications receiver?
A. The level of noise entering the receiver from the
antenna.
B. The relative strength of a received signal 3 kHz
removed from the carrier frequency.
C. The level of noise generated in the front end and
succeeding stages of a receiver.
D. The ability of a receiver to reject unwanted signals at
frequencies close to the desired one.
3-41F5 Which stage of a receiver primarily establishes B
its noise figure?
A. The audio stage.
B. The RF stage.
C. The IF strip.
D. The local oscillator.
3-41F6 What is the term for the ratio between the largest D
tolerable receiver input signal and the minimum
discernible signal?
A. Intermodulation distortion.
B. Noise floor.
C. Noise figure.
D. Dynamic range.
3-42F1 How can selectivity be achieved in the front-end D
circuitry of a communications receiver?
A. By using an audio filter.
B. By using an additional RF amplifier stage.
C. By using an additional IF amplifier stage.
D. By using a preselector.
3-42F2 What is the primary purpose of an RF amplifier in C
a receiver?
A. To provide most of the receiver gain.
B. To vary the receiver image rejection by utilizing the
AGC.
C. To improve the receiver's noise figure.
D. To develop the AGC voltage.
3-42F3 How much gain should be used in the RF A
amplifier stage of a receiver?
A. Sufficient gain to allow weak signals to overcome
noise generated in the first mixer stage.
B. As much gain as possible short of self oscillation.
C. Sufficient gain to keep weak signals below the noise
of the first mixer stage.
D. It depends on the amplification factor of the first IF
stage.
3-42F4 Too much gain in a VHF receiver front end could D
result in this:
A. Local signals become weaker.
B. Difficult to match receiver impedances.
C. Dramatic increase in receiver current.
D. Susceptibility of intermodulation interference from
nearby transmitters.
3-42F5 What is the advantage of a GaAsFET C
preamplifier in a modern VHF radio receiver?
A. Increased selectivity and flat gain.
B. Low gain but high selectivity.
C. High gain and low noise floor.
D. High gain with high noise floor.
3-42F6 In what stage of a VHF receiver would a low B
noise amplifier be most advantageous?
A. IF stage.
B. Front end RF stage.
C. Audio stage.
D. Power supply.
, AMS 380 Unit 2 Practice Test
3-43F1 Why is the Colpitts oscillator circuit commonly C
used in a VFO (variable frequency oscillator)?
A. It can be phase locked.
B. It can be remotely tuned.
C. It is stable.
D. It has little or no effect on the crystal's stability.
3-43F2 What is the oscillator stage called in a frequency A
synthesizer?
A. VCO. C. Phase detector.
B. Divider. D. Reference standard.
3-43F3 What are three major oscillator circuits found in D
radio equipment?
A. Taft, Pierce, and negative feedback.
B. Colpitts, Hartley, and Taft.
C. Taft, Hartley, and Pierce.
D. Colpitts, Hartley, and Pierce.
3-43F4 Which type of oscillator circuit is commonly used A
in a VFO (variable frequency oscillator)?
A. Colpitts. C. Hartley.
B. Pierce. D. Negative feedback.
3-43F5 What condition must exist for a circuit to D
oscillate? It must:
A. Have a gain of less than 1.
B. Be neutralized.
C. Have sufficient negative feedback.
D. Have sufficient positive feedback.
3-43F6 In Figure 3F15, which block diagram symbol B
(labeled 1 through 4) is used to represent a local
oscillator?
A. 1 C. 3
B. 2 D. 4
3-44F1 What is the image frequency if the normal B
channel is 151.000 MHz, the IF is operating at 11.000
MHz, and the LO is at 140.000 MHz?
A. 131.000 MHz.
B. 129.000 MHz.
C. 162.000 MHz.
D. 150.000 MHz.
3-44F2 What is the mixing process in a radio receiver? D
A. The elimination of noise in a wideband receiver by
phase comparison.
B. The elimination of noise in a wideband receiver by
phase differentiation.
C. Distortion caused by auroral propagation.
D. The combination of two signals to produce sum and
difference frequencies.
3-44F3 In what radio stage is the image frequency A
normally rejected?
A. RF.
B. IF.
C. LO.
D. Detector.
3-44F4 What are the principal frequencies that appear at C
the output of a mixer circuit?
A. Two and four times the original frequency.
B. The sum, difference and square root of the input
frequencies.
C. The original frequencies and the sum and difference
frequencies.
D. 1.414 and 0.707 times the input frequency.
3-31D1 What frequency synthesizer circuit uses a phase A
comparator, look-up table, digital-to-analog converter,
and a low-pass antialias filter?
A. A direct digital synthesizer.
B. Phase-locked-loop synthesizer.
C. A diode-switching matrix synthesizer.
D. A hybrid synthesizer.
3-31D2 A circuit that compares the output of a voltage- B
controlled oscillator (VCO) to a frequency standard and
produces an error voltage that is then used to adjust the
capacitance of a varactor diode used to control
frequency in that same VCO is called what?
A. Doubly balanced mixer.
B. Phase-locked loop.
C. Differential voltage amplifier.
D. Variable frequency oscillator.
3-31D3 RF input to a mixer is 200 MHz and the local A
oscillator frequency is 150 MHz. What output would you
expect to see at the IF output prior to any filtering?
A. 50, 150, 200 and 350 MHz.
B. 50 MHz.
C. 350 MHz.
D. 50 and 350 MHz.
3-31D4 What spectral impurity components might be C
generated by a phase-locked-loop synthesizer?
A. Spurs at discrete frequencies.
B. Random spurs which gradually drift up in frequency.
C. Broadband noise.
D. Digital conversion noise.
3-31D5 In a direct digital synthesizer, what are the B
unwanted components on its output?
A. Broadband noise.
B. Spurs at discrete frequencies.
C. Digital conversion noise.
D. Nyquist limit noise pulses.
3-31D6 What is the definition of a phase-locked loop D
(PLL) circuit?
A. A servo loop consisting of a ratio detector, reactance
modulator, and voltage-controlled oscillator.
B. A circuit also known as a monostable multivibrator.
C. A circuit consisting of a precision push-pull amplifier
with a differential input.
D. A servo loop consisting of a phase detector, a low-
pass filter and voltage-controlled oscillator.
3-41F1 What is the limiting condition for sensitivity in a A
communications receiver?
A. The noise floor of the receiver.
B. The power supply output ripple.
C. The two-tone intermodulation distortion.
D. The input impedance to the detector.
3-41F2 What is the definition of the term "receiver B
desensitizing"?
A. A burst of noise when the squelch is set too low.
B. A reduction in receiver sensitivity because of a strong
signal on a nearby frequency.
C. A burst of noise when the squelch is set too high.
D. A reduction in receiver sensitivity when the AF gain
control is turned down.
3-41F3 What is the term used to refer to a reduction in A
receiver sensitivity caused by unwanted high-level
adjacent channel signals?
A. Desensitizing.
B. Intermodulation distortion.
C. Quieting.
D. Overloading.
, AMS 380 Unit 2 Practice Test
3-41F4 What is meant by the term noise figure of a C
communications receiver?
A. The level of noise entering the receiver from the
antenna.
B. The relative strength of a received signal 3 kHz
removed from the carrier frequency.
C. The level of noise generated in the front end and
succeeding stages of a receiver.
D. The ability of a receiver to reject unwanted signals at
frequencies close to the desired one.
3-41F5 Which stage of a receiver primarily establishes B
its noise figure?
A. The audio stage.
B. The RF stage.
C. The IF strip.
D. The local oscillator.
3-41F6 What is the term for the ratio between the largest D
tolerable receiver input signal and the minimum
discernible signal?
A. Intermodulation distortion.
B. Noise floor.
C. Noise figure.
D. Dynamic range.
3-42F1 How can selectivity be achieved in the front-end D
circuitry of a communications receiver?
A. By using an audio filter.
B. By using an additional RF amplifier stage.
C. By using an additional IF amplifier stage.
D. By using a preselector.
3-42F2 What is the primary purpose of an RF amplifier in C
a receiver?
A. To provide most of the receiver gain.
B. To vary the receiver image rejection by utilizing the
AGC.
C. To improve the receiver's noise figure.
D. To develop the AGC voltage.
3-42F3 How much gain should be used in the RF A
amplifier stage of a receiver?
A. Sufficient gain to allow weak signals to overcome
noise generated in the first mixer stage.
B. As much gain as possible short of self oscillation.
C. Sufficient gain to keep weak signals below the noise
of the first mixer stage.
D. It depends on the amplification factor of the first IF
stage.
3-42F4 Too much gain in a VHF receiver front end could D
result in this:
A. Local signals become weaker.
B. Difficult to match receiver impedances.
C. Dramatic increase in receiver current.
D. Susceptibility of intermodulation interference from
nearby transmitters.
3-42F5 What is the advantage of a GaAsFET C
preamplifier in a modern VHF radio receiver?
A. Increased selectivity and flat gain.
B. Low gain but high selectivity.
C. High gain and low noise floor.
D. High gain with high noise floor.
3-42F6 In what stage of a VHF receiver would a low B
noise amplifier be most advantageous?
A. IF stage.
B. Front end RF stage.
C. Audio stage.
D. Power supply.
, AMS 380 Unit 2 Practice Test
3-43F1 Why is the Colpitts oscillator circuit commonly C
used in a VFO (variable frequency oscillator)?
A. It can be phase locked.
B. It can be remotely tuned.
C. It is stable.
D. It has little or no effect on the crystal's stability.
3-43F2 What is the oscillator stage called in a frequency A
synthesizer?
A. VCO. C. Phase detector.
B. Divider. D. Reference standard.
3-43F3 What are three major oscillator circuits found in D
radio equipment?
A. Taft, Pierce, and negative feedback.
B. Colpitts, Hartley, and Taft.
C. Taft, Hartley, and Pierce.
D. Colpitts, Hartley, and Pierce.
3-43F4 Which type of oscillator circuit is commonly used A
in a VFO (variable frequency oscillator)?
A. Colpitts. C. Hartley.
B. Pierce. D. Negative feedback.
3-43F5 What condition must exist for a circuit to D
oscillate? It must:
A. Have a gain of less than 1.
B. Be neutralized.
C. Have sufficient negative feedback.
D. Have sufficient positive feedback.
3-43F6 In Figure 3F15, which block diagram symbol B
(labeled 1 through 4) is used to represent a local
oscillator?
A. 1 C. 3
B. 2 D. 4
3-44F1 What is the image frequency if the normal B
channel is 151.000 MHz, the IF is operating at 11.000
MHz, and the LO is at 140.000 MHz?
A. 131.000 MHz.
B. 129.000 MHz.
C. 162.000 MHz.
D. 150.000 MHz.
3-44F2 What is the mixing process in a radio receiver? D
A. The elimination of noise in a wideband receiver by
phase comparison.
B. The elimination of noise in a wideband receiver by
phase differentiation.
C. Distortion caused by auroral propagation.
D. The combination of two signals to produce sum and
difference frequencies.
3-44F3 In what radio stage is the image frequency A
normally rejected?
A. RF.
B. IF.
C. LO.
D. Detector.
3-44F4 What are the principal frequencies that appear at C
the output of a mixer circuit?
A. Two and four times the original frequency.
B. The sum, difference and square root of the input
frequencies.
C. The original frequencies and the sum and difference
frequencies.
D. 1.414 and 0.707 times the input frequency.
