User Manual

-60-
QUIZ - FM RADIO SECTION
INSTRUCTIONS: Complete the following examination, check your answers carefully.
Answers: 1. C, 2. B, 3. A, 4. A, 5. A, 6. B, 7. C, 8. A, 9. D, 10. B
1. The FM broadcast band is . . .
r A) 550 - 1,600kHz.
r B) 10.7MHz.
r C) 88 - 108MHz.
r D) 98.7 - 118.7MHz.
2. The maximum audio frequency used for FM is ...
r A) 7.5kHz.
r B) 15kHz.
r C) 20kHz.
r D) 10.7MHz.
3. The frequency of the modulating signal
determines the . . .
r A) number of times the frequency of the
carrier changes per second.
r B) maximum deviation of the FM carrier.
r C) maximum frequency swing of the FM
carrier.
r D) amount of amplitude change of the FM
carrier.
4. The AFC circuit is used to ...
r A) automatically hold the local oscillator on
frequency.
r B) maintain constant gain in the receiver to
prevent such things as fading.
r C) prevent amplitude variations of the FM
carrier.
r D) automatically control the audio
frequencies in the receiver.
5. The ratio detector transformer is tuned to ...
r A) 10.7MHz.
r B) 88MHz.
r C) 455kHz.
r D) 10.9MHz.
6. The ratio detector is used because ...
r A) it is sensitive to noise.
r B) it is insensitive to noise.
r C) it provides amplification.
r D) it doesn’t need a filter.
7. The device most often used for changing the
local oscillator frequency with the AFC voltage is
a ...
r A) feedthrough capacitor.
r B) variable inductor.
r C) varactor.
r D) trimmer capacitor.
8. The capacitance of a varactor is determined by ...
r A) the voltage level.
r B) the amount of current in the circuit.
r C) the signal strength of the RF carrier.
r D) the amount of resistance in the circuit.
9. Limiting in FM receivers is the process of ...
r A) removing interfering FM stations.
r B) providing greater station selectivity.
r C) separating the FM stations from the AM
stations.
r D) removing noise from the FM carrier.
10. A detector circuit that does not require a limiter is
a ...
r A) slope detector.
r B) ratio detector.
r C) Travis detector.
r D)
Foster-Seeley detector.