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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. Which of these describes the process of modulation?

a) Recovering information from a carrier wave
b) Placing information onto a carrier wave
c) Controlling the frequency of a carrier wave
d) None of the above

4. What frequency is two octaves above 1 KHz?

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

5. The signal shown above is fed into a bandpass filter with a center frequency of 1 KHz. What will the output of the bandpass filter look like on an oscilloscope?

a) A 1 KHz square wave
b) A 1 KHz sine wave
c) A 2 KHz triangle wave
d) None of the above

6. What is the frequency of the 3rd harmonic for the signal above?

a) 1 KHz
b) 2 KHz
c) 3 KHz
d) None of these

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. Noise can best be defined as:

a) Any undesired signal within a system
b) Pulses appearing at the output of a system
c) Distortion at the output of a system
d) None of the above

9. 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

10. New frequencies that are generated during the process of modulation are known as:

a) Harmonics
b) Fundamentals
c) Sidebands
d) None of the above

11. A certain AM transmitter produces 16W of power into a 50 Ohm load with no modulation. What total power will be produced at 50% modulation?

a) 17 W
b) 18 W
c) 20 W
d) None of the above

12. What is the information frequency in the AM signal pictured above?

a) 1 KHz
b) 2 KHz
c) 4 KHz
d) 5 KHz

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

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

14. An AM transmitter is operating on a carrier frequency (Fc) of 10.000 MHz, with 5000 volts of carrier (Vc). The transmitter is operating at 70% modulation. What is the voltage in the upper side band?

a) 3500 V
b) 2750 V
c) 2000 V
d) 1750 V

15. 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

16. 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

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. What is the function of an RF bypass capacitor?

a) To couple signal from one stage to the next
b) To couple RF energy into the antenna
c) To force RF energy to go to ground
d) None of the above

19. The oscillator in a certain transmitter produces 1 mW of output. The signal is subsequently amplified in the following stages:

Buffer: +10 dB
Modulator: +6 dB
Driver: +10 dB
Final: +13 dB

What is the final output power of this transmitter in Watts?

a) 8 Watts
b) 4 Watts
c) 400 mW
d) None of these

20. What is the purpose of a buffer amplifier?

a) To provide a large voltage gain
b) To isolate the oscillator from the next stage
c) To reduce distortion of the carrier sine wave
d) None of the above

21. 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

22. What type of oscillator is pictured above?

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

23. What type of oscillator is pictured above?

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

24. Another name for the parallel-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. 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

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. 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)

29. Why can't TRF receivers be constructed for high-frequency (above 1-2 MHz) use?

a) Insufficent "Q" is available from discrete LC components at these frequencies
b) Transistors and ICs have insufficient gain at these frequencies
c) Detector circuits produce excessive distortion at these frequencies
d) None of the above

30. Which of the following specifies the most sensitive receiver? All the units have the same bandwidth. Hint: Convert all into absolute power units.

a) 1 uV into 75 Ohms for better than 10 dB S/N ratio
b) 0.5 uV into 50 Ohms for better than 10 dB S/N ratio
c) -120 dBm for better than 10 dB S/N ratio
d) -110 dBm for better than 10 dB S/N ratio

31. A mixer is producing the following frequency outputs: 710 KHz, 455 KHz, 1165 KHz, 1875 KHz. What are the two most likely frequencies being applied?

a) 710 KHz, 1165 KHz
b) 1875 KHz, 1165 KHz
c) 1000 KHz, 875 KHz
d) 262.5 KHz, 300 KHz
e) None of these

32. The DC component from the AM detector is used for what purpose?

a) To reduce distortion in the audio amplifier
b) To prevent frequency drift in the local oscillator
c) To control the gain of the RF and IF stages (AGC)
d) None of the above

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. 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

36. When no input signal is being applied to a PLL, what state will it be in?

a) Lock
b) Capture
c) Free-Run
d) None of the above

37. When the REFERENCE and VCO frequencies are equal, what state is a PLL in?

a) Free-Running
b) Capture
c) Lock
d) None of the above

38. Which portion of a PLL is primarily responsible for determining the capture range?

a) VCO
b) Phase Detector
c) Low-Pass Filter
d) Reference Divider

39. A certain FM transmitter is operating on 29.600 MHz; the unmodulated carrier voltage Vc = 50 V. How much bandwidth will this transmitter occupy if Fm = 1 KHz and the deviation is 2 KHz? (Use a Bessel table, not Carson's rule).

a) 2 KHz
b) 8 KHz
c) 16 KHz
d) 32 KHz
e) None of the above

40. 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 49.860 MHz?

a) 440 mV
b) 770 mV
c) 880 mV
d) None of the above

41. An FM transmitter is operating on 49.860 MHz. Fm = 5 KHz and the deviation is 5 KHz. The unmodulated carrier voltage is 1V. The information voltage is 3Vpk. What MINIMUM information voltage will cause the 49.860 frequency component (as viewed on a spectrum analyzer) to become ZERO?

a) 3.24 Vpk
b) 5.00 Vpk
c) 7.20 Vpk
d) None of the above

42. A certain FM transmitter is operating on 29.600 MHz; the unmodulated carrier power is 50 Watts. The maximum permitted deviation is 5 KHz. What power will be delivered to the antenna at 50% modulation?

a) 25 Watts
b) 75 Watts
c) 50 Watts
d) 100 Watts

43. 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

44. What type of FM transmitter is pictured above?

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

45. 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

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. What stage in an FM receiver rejects amplitude disturbances?

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

48. What is the name of the amplifier that operates at a constant frequency in an FM superheterodyne receiver?

a) The audio amplifier
b) The RF amplifier
c) The IF amplifier
d) None of these

49. Why is a 10.7 MHz (rather than 455 KHz) IF used in an FM broadcast receiver?

a) More gain is required to receive FM signals
b) Using a higher frequency IF reduces noise
c) FM broadcasts use much more bandwidth than AM broadcasts
d) None of the above

50. 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

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