SelfTest
Halaman 107-108
12. Linear
power amplifiers are used to raise the power level of Low Level AM and SSB
Signals.
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
SelfTest
Halaman 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.
Tidak ada komentar:
Posting Komentar