Self-Test Elektronika Telekomunikasi

Hal 107-108

12.    Linear power amplifiers are used to raise the power level of Low Level AM and SSB Signals.

13.    A MOSFET power amplifier is used to increase the power level of an FM signal.

14.    Linear power amplifier operate class A, B, and AB.

15.    A class A transistor power amplifier has an efficiency of 50 percent. The output power is 27W. The power dissipated in the transistor is 13.5 W.

16.    Class A amplifier conduct for 360 degrees of a sine wave input.

17.    True or false. With no input, a class B amplifier does not conduct. FALSE

18.    Class B RF power amplifiers normally used a(n) Broadband configuration.

19.    A class C amplifier conducts for approximatly 90 degrees to 150 degrees of the input signal.

20.    In a class C amplifier, collector current flows in the form of positive pulses.

21.    In a class C amplifier, a complete sinusoidal output signal is produced by a(n) Timed Circuit.

22.    The efficiency of a class C amplifier is in the range of 60 to 85 percent.

23.    The tuned circuit in the collector of a class C amplifier acts as a filter to eliminate Induced Voltage.

24.    A class C amplifier whose output tuned circuit resonates at some integer multiple of the input frequency is called a(n) Flywheel effect.

25.    Frequency multipliers with factors of 2, 3, 4, and 5 are cascaded. The input is 1.5MHz. The output is 120 MHz.

26.    A class C amplifier has DC supply voltage of 28 V and an average collector current of 1.8A. The power input is 50.4 W.

Hal. 150-151

53.  RF amplifier provide initial RF Amplifier and Mixer in a receiver but also add Related Tune Circuits.

54.  A low-noise transistor preferred at microwave frequencies is the FET made of Metal Semiconductor.

55.  Most of the gain and selectivity in a superhet is obtained in the IF amplifier.

56.  The selectivity in an IF amplifier is usually produced by using Ferrite-core transformers between stages.

57.  The bandwidth of a double-tuned transformer depends upon the degree of coupling between primary and secondary windings.

58.  In a double-tuned circuit, minimum bandwidth is obtained with under coupling, maximum bandwidth with critical coupling and peak output with over or optimum coupling.

59.  An IF amplifier that clips the positive and negative peaks of a signal is called a(n) limiter.

60.  Clipping occurs in an amplifier because the transistor is driven by a high-level signal into Single transistor stage.

61.  The gain of a bipolar class A amplifier can be varied by changing the positive peaks and negative peaks.

62.  The overall RF-IF gain of a receiver is approximately 89 dB.

63.  Using the amplitude of the incoming signal to control the gain of the receiver is known as AGC Voltage gen.

64.  AGC circuits vary the gain of the IF amplifier.

65.  The DC AGC Voltage is derived from a(n) AGC circuit connected to the demodulator or IF output.

66.  Reverse AGC is where a signal amplitude increase causes a(n) AGC Voltage in the IF amplifier collector current.

67.  Forward AGC uses a signal amplitude increase to positive voltage the collector current,which decreases the IF amplifier gain.

68.  The AGC of a differential amplifier is produced by controlling the current produced by the Constant Current Source transistor.

69.  In dual-gate MOSFET IF amplifier, the dc AGC Voltage is applied to the R1 to gate 2.

70.  Another name for AGC in an AM receiver is Dual Gate MOSFET.

71.  In an AM receiver, the AGC voltage is derived from the IF Signal.

72.  Large input signals cause the gain of a receiver to be reduced by the AGC.

73.  An AFC circuit corrects for frequency drift in the feedback control circuit.

74.  The AFC DC control voltage is derived from the output of the demodulator circuit in a receiver.

75.  A(n) Demodulator is used in an AFC circuit to vary the LO frequency.

76.  A circuit that blocks the audio until a signal is received is called a(n) squelch circuit.

77.  Two types of signals used to operate the squelch circuit are audiotone and audiosignal.

78.  In a CTCS system, a low-frequency frequency tone is used to trigger the squelch circuit.

79.  A BFO is required to receive CWCode and SSB Signals.