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1. What are the steps of troubleshooting in correct order?

a) Visual inspection, Check power supply, Check inputs & outputs
b) Check power supply, Visual inspection, Check inputs & outputs
c) Visual inspection, Check inputs & outputs, Check power supply
d) None of the above

2. In troubleshooting a stage in an electronic device, where is the best place to check the power supply?

a) At the output terminal of the voltage regulator IC
b) Directly at the terminals of the device using the power
c) At the power supply buss line
d) None of the above

3. What difference between radio stations allows receivers to separate them?

a) Each has a different amplitude
b) Each has a different phase
c) Each has a different frequency
d) None of the above

4. What is the relationship of the 2 KHz frequency component to the 1 KHz component in the figure above?

a) The 2 KHz signal is twice the amplitude of the 1 KHz signal
b) The 2 KHz is a distorted form of the 1 KHz signal
c) The 2 KHz signal is the 2nd harmonic of the 1 KHz signal
d) None of the above

5. What frequency is two octaves above 1 KHz?

a) 2 KHz
b) 3 KHz
c) 5 KHz
d) None of the above

6. The horizontal axis of a spectrum analyzer is labeled in what units?

a) Time - Seconds
b) Resistance - Ohms
c) Frequency - Hz
d) None of the above

7. Which of these could be classified as an internal noise source?

a) Atmospheric noise
b) Cosmic noise
c) Johnson noise
d) None of the above

8. Which of these measures would decrease shot noise?

a) Decrease the forward DC bias current
b) Increase the junction voltage drop
c) Increase the forward DC bias current
d) None of the above

9. What noise voltage will be generated across a 47K resistor at room temperature (24 degrees Celsius) if the circuit's bandwidth is 500 KHz? (k=1.38 x 10-23 J/K)

a) 40.5 uV
b) 19.6 uV
c) 20 uV
d) None of the above

10. An AM signal was measured on an oscilloscope. The readings were Vmax=400 V, and Vmin = 100V. What is the percent modulation?

a) 33.3%
b) 60 %
c) 75 %
d) None of the above

11. What bandwidth will be required to transmit a 5 KHz sine-wave tone on an AM carrier wave if the carrier frequency is 710 KHz?

a) 10 KHz
b) 5 KHz
c) 1 KHz
d) None of the above

12. What is the total bandwidth of the AM signal pictured above?

a) 2 KHz
b) 700 KHz
c) 10 KHz
d) None of the above

13. What bandwidth will be required to transmit a 2 KHz sine-wave tone on an AM carrier wave if the carrier frequency is 118 MHz?

a) 10 KHz
b) 4 KHz
c) 8 KHz
d) None of these

14. What is the total bandwidth of the AM signal pictured above?

a) 500 Hz
b) 1 KHz
c) 2 KHz
d) 4 KHz

15. A certain high-level transmitter produces 10 Watts of carrier power. How much power must the audio amplifier produce to 100% modulate this transmitter?

a) 2 Watts
b) 4 Watts
c) 8 Watts
d) 5 Watts
e) None of the above

16. The oscillator in a certain transmitter produces +6 dBm of output. The signal is subsequently amplified in the following stages:

Buffer: +10 dB
Modulator: +6 dB
Driver: +10 dB
Final: +14 dB
Antenna Coupler: -1 dB
What is the final output power of this transmitter in Watts?

a) 8 Watts
b) 32 Watts
c) 400 mW
d) None of these

17. What is the purpose of the zener diode in a power supply circuit for an oscillator?

a) To regulate the DC supply of the oscillator, preventing frequency drift
b) To lower the DC supply voltage for the oscillator
c) To eliminate RF currents on the power supply rail
d) None of the above

18. Why would a class C amplifier be an excellent choice for use as a modulator in a radio transmitter?

a) The class C amplifier generates very low levels of distortion
b) The class C amplifier can operate on very low supply voltages
c) The class C amplifier is very nonlinear -- a requirement for modulation
d) None of the above

19. Why would the power supply to an oscillator stage be regulated?

a) To provide maximum power output from the oscillator
b) To prevent the oscillator from producing a distorted sine wave
c) To prevent the oscillator from being "pulled" off frequency
d) None of the above

20. To isolate a transmitter's carrier oscillator from undesired load changes, what stage is often used?

a) A buffer amplifier
b) A class C amplifier
c) A power amplifier
d) None of the above

21. What type of oscillator is pictured above?

a) Colpitts
b) Hartley
c) Armstrong
d) Pierce
e) None of the above

22. A certain oscillator has an amplifier with a phase shift of 45 degrees. According to the Barkhausen criteria for oscillation, what phase shift in the FEEDBACK network would be necessary to cause oscillation?

a) 90 Degrees
b) -45 Degrees
c) 315 Degrees
d) (b) or (c)
e) None of the above

23. In order for an oscillator to start, the loop gain must be:

a) Greater than 1
b) Greater than or equal to 1
c) Less than 1
d) None of the above

24. Another name for the series-resonant frequency of a crystal is the:

a) Pole
b) Zero
c) Maximum
d) Minimum

25. A certain crystal has the following characteristics: Ls=1 H, Cs=.001 pF, Rs = 150 Ohms, Cm = 5 pF. At parallel-resonance, what is the approximate terminal impedance of the unit?

a) 30 + j125 Ohms
b) 30 - j150 Ohms
c) 150 Ohms (Equal to Rs)
d) Infinity (Open Circuit)

26. A certain crystal has the following characteristics: Ls=1 H, Cs=.001 pF, Rs = 150 Ohms, Cm = 5 pF. At series-resonance, what is the approximate terminal impedance of the unit?

a) 30 + j125 Ohms
b) 30 - j150 Ohms
c) 150 Ohms (Equal to Rs)
d) Infinity (Open Circuit)

27. A certain crystal has the following characteristics: Ls=1 H, Cs=.001 pF, Rs = 150 Ohms, Cm = 5 pF. What is the parallel-resonant frequency of the unit?

a) 5.032921 MHz
b) 4.986123 MHz
c) 5.033424 MHz
d) None of the above

28. A certain crystal has the following characteristics: Ls=1 H, Cs=.001 pF, Rs = 150 Ohms, Cm = 5 pF. What is the series-resonant frequency of the unit?

a) 5.032921 MHz
b) 4.986123 MHz
c) 5.033424 MHz
d) None of the above

29. A certain superhet receiver has a preselector bandwidth that averages 100 KHz, and an IF bandwidth of 10 KHz. What will the receiver's total bandwidth be?

a) 10 KHz
b) 110 KHz
c) 210 KHz
d) 150 KHz
e) None of these

30. The ability of the preselector and local oscillator stages to keep a constant difference of F(if) in a superhet receiver is referred to as:

a) AGC
b) Detection
c) Alignment
d) Tracking

31. What is the function of the preselector in a superhet receiver?

a) Boosts the gain of the IF amplifier
b) Used to produce the AGC control signal
c) Eliminates the image frequency
d) None of these

32. The DC bias for the RF and IF stages in a superheterodyne receiver is derived partly from:

a) The audio power amplifier
b) The 2nd IF amplifier
c) The local oscillator
d) The AM detector
e) None of these

33. The purpose of the frequency converter section of a superhet receiver is to:

a) Keep the output level at the speaker constant, regardless of input signal level changes
b) Eliminate the image response
c) Prevent local oscillator frequency drift
d) None of these

34. In a superhet receiver, the difference between the preselector and local oscillator frequencies should always be:

a) The IF frequency
b) The carrier frequency
c) One-half the local oscillator frequency
d) None of these

35. What frequency should be at TP "B" above if N=1, R=10, F1=1 MHz? Note: F1 is the crystal reference oscillator frequency.

a) 1 MHz
b) 100 KHz
c) 10 KHz
d) None of the above

36. Which part of a PLL converts voltage changes into frequency changes?

a) Phase Detector
b) Low Pass Filter
c) VCO
d) None of the above

37. How can a technician determine that a PLL is in lock?

a) Check that Vcontrol = Vcc/2
b) Check that Fvco = Fref
c) Check that Fvco = Fref / 2
d) None of the above

38. Given that N=1593, R=1024, and F1 = 10.240 MHz, what will the output frequency Fout of the PLL synthesizer above be?

a) 10.240 MHz
b) 4.9152 MHz
c) 15.930 MHz
d) None of the above

39. An FM transmitter is producing 45 KHz of deviation; the information signal is 5 KHz, 10 Vpk. What will happen to the deviation if the information signal is changed to 5 Vpk?

a) The deviation will become 37 KHz
b) The deviation will become 22.5 KHz
c) The deviation will become 75 KHz
d) None of the above

40. How many significant PAIRS of sidebands will be produced by an FM transmitter that is producing 2 KHz of deviation with a 1 KHz deviation rate (information frequency)?

a) 2
b) 1
c) 3
d) 4

41. What is the total bandwidth allocated for an FM broadcast station in the USA (Including guard bands)?

a) 200 KHz
b) 150 KHz
c) 75 KHz
d) None of the above

42. An FM transmitter is operating on 49.860 MHz. Fm = 5 KHz and the deviation is 5 KHz. The unmodulated carrier voltage is 1V. If the output of this transmitter is viewed on a spectrum analyzer, what voltage will be visible at the frequency 49.865 MHz?

a) 440 mV
b) 1000 mV
c) 880 mV
d) None of the above

43. A 5 MHz crystal oscillator is being driven so that it has 1000 Hz of deviation. This signal is fed into an X3 frequency multiplier. What is the resultant output frequency and deviation?

a) Fout=3 MHz, Deviation=2 KHz
b) Fout=5 MHz, Deviation=3 KHz
c) Fout=15 MHz, Deviation=1 KHz
d) None of the above

44. Which class of amplifier is generally preferred for power amplification in FM transmitters?

a) A
b) B
c) C
d) None of the above

45. A 7 MHz crystal oscillator is being driven so that it has 1100 Hz of deviation. This signal is fed into an X5 frequency multiplier. What is the resultant output frequency and deviation?

a) Fout=35 MHz, Deviation=5.5 KHz
b) Fout=21 MHz, Deviation=3.3 KHz
c) Fout=15 MHz, Deviation=1 KHz
d) None of the above

46. What type of FM transmitter is pictured above?

a) Armstrong WBFM
b) PLL
c) Crosby Frequency-Locked-Loop
d) None of the above

47. An FM detector can be ideally viewed as a/an:

a) Frequency to voltage converter
b) Voltage to frequency converter
c) Amplitude to current converter
d) None of the above

48. Which of these FM detectors rely on a closed loop that "follows" the instantaneous frequency changes of the incoming carrier signal?

a) Quadrature
b) Foster-Seeley
c) Ratio
d) PLL
e) None of these

49. Why is FM reception generally free from interference in the form of static?

a) FM Receivers are not sensitive to amplitude variations
b) FM receivers have a very high IF frequency
c) FM receivers use class C amplifiers to reject noise
d) None of the above

50. What stage in an FM receiver rejects amplitude disturbances?

a) Detector
b) Limiter
c) Mixer
d) Preselector

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