Electronics and Communication Engineering - Radio Receivers

Exercise : Radio Receivers - Section 2
36.
In a broadcast superheterodynes receiver having no RF amplifier, the loaded Q of the antenna coupling circuit is 100. If the intermediate frequency is 455 kHz. In receivers operating upto the limit of shortwave broadcasting the local oscillator often used is
Armstrong oscillator
Colpitts oscillator
Clapp oscillator
Ultra Audio oscillator
Answer: Option
Explanation:
No answer description is available. Let's discuss.

37.
RF amplifiers are used in radio receivers for
better sensitivity
improved signal-to-noise ratio
better coupling of receiver to the antenna
all of the above
Answer: Option
Explanation:
No answer description is available. Let's discuss.

38.
In an FM signal, the power
increases as the modulation index increases
reduces as the modulation index increase
increases as the modulation index decreases
remains constant when the modulation index increases
Answer: Option
Explanation:
No answer description is available. Let's discuss.

39.
An unmodulated voltage 10 V effective is applied to a dioxide detector in which load resistance is 4 x 10-5 ohms. A micrometer shows that the rectified DC current in this resistance is 30 A. The efficiency of detection is
34%
55.5%
68.8%
84.7%
Answer: Option
Explanation:
No answer description is available. Let's discuss.

40.
Selectivity varies with receiving frequency, frequency is raised.
Somewhat better when the receiving frequency is raised
Somewhat better at intermediate frequency
Somewhat worse when the receiving frequency is lowered
Somewhat worse when the receiving frequency is raised
Answer: Option
Explanation:
No answer description is available. Let's discuss.