Electronics and Communication Engineering - Radio Receivers

Exercise :: Radio Receivers - Section 1

26. 

In a superheterodyne receiver, the IF is 455 kHz. If it is tuned to 1200 kHz, the image frequency will be

A. 1655 kHz
B. 2110 kHz
C. 745 kHz
D. 910 kHz

Answer: Option B

Explanation:

A signal (image) can interfere with a superheterodyne receiver if fits the following equation.

Image = Signal +/- 2 x I.F.

Which says that a signal has the capacity to interfere with a superhet receiver if its frequency is equal to the signal frequency (1200 kHz in our question) plus or minus twice the IF (455 kHz in our question).

So one possible image is: 1200 + ( 2 x 455 ) = 2110 kHz (possible).

And the other: 1200 - ( 2 x 455 ) = 290 kHz (not likely).


27. 

The selectivity of most receivers is determined largely by

A. sensitivity
B. characteristics of IF section
C. antenna direction
D. all of the above

Answer: Option B

Explanation:

No answer description available for this question. Let us discuss.

28. 

In a superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency is

A. 750 kHz
B. 990 kHz
C. 1650 kHz
D. 2100 kHz

Answer: Option D

Explanation:

No answer description available for this question. Let us discuss.

29. 

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. The rejection ratio at 25 MHz will be

A. 1.116
B. 1.386
C. 2.116
D. 2.386

Answer: Option A

Explanation:

No answer description available for this question. Let us discuss.

30. 

As compared to tuned radio frequency receivers which of the following is the advantage of using superheterodyne receivers?

A. High gain and better sensitivity
B. Better selectivity at high frequencies
C. Stability
D. Noise suppression

Answer: Option A

Explanation:

No answer description available for this question. Let us discuss.