1.The upper frequency limit of a medium-frequency signal would be A. 30 kHz. C.
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Question
1.The upper frequency limit of a medium-frequency signal would be
A. 30 kHz. C. 3 MHz. B. 300 kHz. D. 30 MHz.
2. Intelligence is removed from the high-frequency carrier in a receiver by a process known as A. detection. C. demodulation. B. filtering. D. modulation.
3. The noise generated by a transistor below 1 kHz is termed _______ noise. A. thermal C. shot B. transient time D. excess
4. The typical bandwidth of a television channel in the United States is A. 6 MHz. C. 10 MHz. B. 8 MHz. D. 12 MHz.
5. To transmit a 1000-Hz square wave exactly as it’s generated requires a(n) A. 1 MHz bandwidth. C. 100 MHz bandwith. B. 10 MHz bandwidth. D. infinite bandwidth.
6. When evaluating a signal, selecting a sampling rate that’s much lower than the signal’s frequency results in A. very low error. C. minimal bandwidth error. B. undersampling. D. a Fourier representation.
7. To obtain an indication of the value of noise that’s generated by a transistor, you should A. insert two diodes into a circuit to simulate the transistor’s junctions. B. calculate the noise using Friiss’s formula. C. use the manufacturer’s data sheets. D. calculate the noise as a function of resistor combinations.
8. The most predominant source of atmospheric noise is A. the stratosphere. C. the sun. B. isotope decay. D. lightning.
9. M-derived and constant-k are two types of A. LC filters. C. crystal oscillators. B. bandwidth classifications. D. oscilloscope operating modes. 10. A change of the intensity control setting of an oscilloscope can change a noise measurement by as much as A. 2 dB. C. 4 dB. B. 3 dB. D. 6 dB.
11. An amplifier has an impedance of 50 . Using a matched-impedance diode noise generator, it’s found that the DUT has doubled noise output power when the diode has a DC current of 12 mA. What is the noise ratio of the DUT? A. 10 C. 14 B. 12 D. 16 12. An amplifier has an impedance of 50 . Using a matched-impedance diode noise generator, it’s found that the DUT has doubled noise output power when the diode has a DC current of 12 mA. What is the noise factor of the DUT? A. 10.79 dB C. 14.18 dB B. 11.24 dB D. 16.212 dB
13. Metal film resistors are often chosen for communication-circuit applications because A. carbon resistors are much more expensive. B. the alternative, wire-wound resistors, create too much noise. C. it’s the only application where their extreme bulk isn’t a problem. D. of their low noise characteristics.
14. When an RLC circuit is resonant, the A. circuit resistance is equal to 2R. B. inductive reactance is equal to the resistance. C. inductive reactance is equal to the capacitive reactance. D. resistance is equal to the capacitive reactance.
15. A high inductor-to-capacitor value ratio will give you a A. low resonant frequency. C. narrowband response. B. stable low-pass filter. D. wide-bandwidth filter.
16. The crystal in a crystal oscillator is normally made of A. silicon. C. quartz. B. mica. D. germanium.
17. You can test a crystal with an RF signal generator, a frequency counter, and an RF voltmeter as you look for the crystal’s series A. resonant point. C. backfeed quotient. B. frequency shift. D. AC resonance point.
18. A tapped inductor is used in what type of oscillator? A. Hartley C. Clapp B. Colpitts D. Pierce
19. A parallel LC tank circuit with a 4-mH inductor has a resonant frequency of 2.2 kHz. The inductor has a winding resistance of 4 . What is the Q of this circuit? A. 10.18 C. 13.82 B. 12.62 D. 14.91
20. You can test a Clapp oscillator’s capacitor by A. submitting the capacitor to a short burst of AC voltage. B. placing a known good spare capacitor in series with the capacitor in the circuit. C. cooling the capacitor with an aerosol spray and looking for a frequency change. D. placing an inductor in parallel across the questionable capacitor.
Explanation / Answer
1.The range of MF frequency is 300kHZ to 3 MHz.
Hence, the upper limit is 3 MHz, Option C.
2. To recover original signal, intelligence is removed at the receiver and the process is demodulation.
Correct option C.
3. Option B , transit time noise
4. The spectrum in the USA occupies in the range of 54 MHz to 60 MHz.
The bandwidth is 60 MHz-54 MHz=6 MHz
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