21. Calculate the required Q for the bandpass filter depicted in Figure 4-1 for 80 dB sideband suppression if the carrier frequency component of the IF is 455 kHz.
a. 1137.5
b. 56,875
c. 227,500
d. 113,750
Answer: b
22. Crystal filters:
a. have Q values as high as 50,000.
b. employ phasing capacitors to produce a rejection notch of undesired resonant frequencies.
c. are quite delicate in construction.
d. all of the above.
Answer: c
23. Which is not an advantage of ceramic filters over crystal filters?
a. more rugged in construction.
b. smaller in size.
b. the ripple amplitude.
c. the quality factor.
d. the roll-off rate of the skirt.
Answer: a
25. The variation in attenuation within the bandpass frequencies of a ceramic filter is called:
a. the shape factor.
b. the ripple amplitude.
c. the quality factor.
d. the roll-off rate of the skirt.
Answer: b
26. The first designed sharp filter used in SSB transmitters to produce SSB is the:
a. crystal filter.
b. ceramic filter.
c. mechanical filter.
d. tank circuit.
Answer: c
TEST ITEM FILE – Chapter 4
27. The filter consisting of resonant disks, driving rods, bias magnets and transducer coils is the:
a. crystal filter.
b. ceramic filter.
c. mechanical filter.
d. tank circuit.
Answer: c
Figure 4-2
28. In Figure 4-2, the filter Q required in the linear amplifier is approximately:
a. 20.
b. 10.
c. 15.
d. 100.
Answer: b
29. In Figure 4-2, the output signal of stage (b) is:
a. DSB-SC at 500 kHz.
b. DSB-SC at 10 MHz.
c. SSB at 500 kHz.
d. SSB at 10 MHz.
Answer: a
30. In Figure 4-2, the ouput signal of stage (d) is:
a. DSB-SC at 500 kHz.
b. DSB-SC at 10 MHz.
c. SSB at 500 kHz.
d. SSB at 10 MHz.
Answer: b
TEST ITEM FILE – Chapter 4
31. In Figure 4-2, the first mixer and filter are necessary to:
a. produce SSB at the final transmitter output frequency.
b. produce SSB using filters having adequately high Q values.
c. produce DSB-SC at the final transmitter output frequency.
d. produce DSB-SC using filters having adequately high Q values.
Answer: b
32. In Figure 4-2, the second mixer and filter are necessary to:
a. produce SSB at the final transmitter output frequency.
b. produce SSB using filters having adequately high Q values.
c. produce DSB-SC at the transmitter output frequency.
d. produce DSB-SC using filters having adequately high Q values.
Answer: a
Figure 4-3
TEST ITEM FILE – Chapter 4
33. In Figure 4-3, the purpose of Q1 and Q2 are to:
a. mix the carrier with the intelligence signal to produce DSB-SC.
b. amplify the carrier signal.
c. filter out one of the sidebands.
d. amplify the audio intelligence signals.
Answer: a
34. In Figure 4-3, the required push-pull action of Q1 and Q2 is furnished by:
a. the balance potentiometer, R2.
b. the transformer, T1.
c. the fact that one of them is a common gate amplifier and the other is a common source amplifier.
d. the 0.1 µf capacitor that connects their sources together.
Answer: b
35. In Figure 4-3, Q4 is needed:
a. to provide gain to the carrier output signal.
b. to act as an oscillator to produce a carrier signal.
c. to upset the balance of the balanced modulator in order to produce a carrier output signal.
d. to help filter out the undesired sideband.
Answer: c
36. In Figure 4-3, the 9 MHz crystal filter can produce either USB or LSB due to:
a. its bandwidth being wide enough to filter out both sidebands.
b. the 30 pf capacitors across its input and output terminals.
c. the IF amplifier transistor, Q3, having sufficiently high bandwith.
d. the carrier frequency being slightly altered to create either sideband at 9 MHz.
Answer: d
37. Which is not a general method used to generate SSB in transmitter design?
a. filter method
b. lattice method
c. amplitude-compandoring method d. phase method
Answer: b
38. Which is the most popular method used to generate SSB in transmitter design?
a. filter method
b. lattice method
c. amplitude-compandoring method d. phase method
TEST ITEM FILE – Chapter 4
39. The main disadvantage of the phase method in generating SSB is:
a. the complex method of mixing the carrier with the intelligence signal.
b the complex method used to amplify the resulting SSB signal.
c. the complex design of the 90 degree phase shifting network for the intelligence signal.
d. the complex design of the 90 degree phase shifting network for the carrier signal.
Answer: c 40. ACSSB is:
a. a method of compressing the audio before modulation and to expand it following demodulation.
b. an acronym for amplitude compandored single-sideband.
c. a new method of allowing narrow band voice communications with the performance of FM systems for the land-mobile communication industry.
d. all of the above.
Answer: d
41. The signal processor that increases all negative dBm power levels and at the same time decreases all positive dBm power levels is:
a. a signal expander.
b. a linear amplifier.
c. a signal compressor.
d. a phase-locked loop.
Answer: c
42. The signal processor that decreases all negative dBm power levels and at the same time increases all positive dBm power levels is:
a. a signal expander.
b. a linear amplifier.
c. a signal compressor.
d. a phase-locked loop.
Answer: a
43. Why is the carrier signal needed in an SSB receiver?
a. It is needed for the receiver to maintain its sensitivity and selectivity.
b. It is needed for the demodulator to be able to recreate the intelligence.
c. The carrier actually contains the intelligence signal.
d. Without a carrier, the signal strength of the received station is zero.
Answer: b
44. The standard SSB demodulator consists of:
a. an RF amplifier, nonlinear mixer, and IF amplifier stage.
b. a nonlinear diode and a low-pass filter.
c. a sharp bandpass filter and an audio amplifier stage.
d. a beat frequency oscillator, nonlinear mixer, and low-pass filter.
Answer: d
TEST ITEM FILE – Chapter 4
45. In an SSB receiver, if the BFO drifts slightly off of the carrier frequency:
a. the output intelligence is badly distorted.
b. the output intelligence amplitude is reduced.
c. the noise level increases.
d. harmonics are produced by mixing action of the nonlinear device.
Answer: a
Figure 4-4
46. In Figure 4-4, the purpose of stage (b) is:
a. to demodulate the 20 MHz USB signal.
b. to create a 1 MHz SSB IF signal.
c. to recreate the 100 Hz to 3 kHz intelligence signal.
d. to act as a product detector.
Answer: b
47. In Figure 4-4, what stages have tracking capacitors?
a. stages d and f b. stages d and e c. stages b and e d. stages a and c
Answer: d
48 In Figure 4-4, what frequency must the BFO be set at for optimum results?
a. 455 kHz b. 20 MHz c. 1 MHz d. 21 MHz Answer: c
49. In Figure 4-4, most of the selectivity and sensitivity are furnished by:
a. stage a.
b. stage b.
c. stage e.
d. stage d.
TEST ITEM FILE – Chapter 4
50. In Figure 4-4, the SSB demodulation is accomplished by:
a. stages b and c.
b. stages d and f.
c. stages d and e.
d. stages e and f.
Answer: d
51. In which stages of Figure 4-4 should an AGC control signal be applied?
a. stages a and d b. stages b and e c. stages c and f d. stages e and g Answer: a
52. In Figure 4-5, transistor Q1 functions:
a. to recreate the original intelligence signal from the original SSB signal.
b. as a product detector.
c. to mix the VFO output signal with the received RF signal in order to produce a 453.55 kHz IF signal.
d. as an RF amplifier stage of the received SSB signal.
Answer: c
Figure 4-5
TEST ITEM FILE – Chapter 4
53. In Figure 4-5, transistor Q2 acts as:
a. an IF amplifier stage.
b. a beat frequency oscillator.
c. a variable frequency oscillator.
d. a mixer stage.
Answer: a
54. In Figure 4-5, transistor Q3 acts as:
a. an IF amplifier stage.
b. a beat frequency oscillator.
c. a variable frequency oscillator.
d. a mixer stage.
Answer: c
55. In Figure 4-5, transistor Q4 functions as:
a. a product detector.
b. an RF mixer to create the IF frequency.
c. a variable frequency oscillator.
d. a beat frequency oscillator.
Answer: a
56. In Figure 4-5, transistor Q5 functions as:
a. a product detector.
b. an RF mixer to create the IF frequency.
c. a variable frequency oscillator.
d. a beat frequency oscillator.
Answer: d
57. In Figure 4-5, the purpose of switches S1A and S1B is to:
a. ensure that the USB or LSB mixer output signal remains in the middle of the IF bandwidth filter.
b. alter the BFO frequency slightly by selecting separate crystals.
c. alter the VFO frequency slightly by adding bias to the switching diode, D2.
d. all of the above.
Answer: d
TEST ITEM FILE – Chapter 4
58. The image shown in figure 4-6 is an example of:
a. double sideband output spectrum b. DSB-SC
c. Upper sideband with a suppressed lower sideband d. Lower sideband with a suppressed upper sideband e. SSB-FC
Answer: c
Figure 4-6