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
1655 kHz
2110 kHz
745 kHz
910 kHz
Answer: Option
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
sensitivity
characteristics of IF section
antenna direction
all of the above
Answer: Option
Explanation:
No answer description is available. Let's discuss.

28.
In a superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency is
750 kHz
990 kHz
1650 kHz
2100 kHz
Answer: Option
Explanation:
No answer description is available. Let's 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
1.116
1.386
2.116
2.386
Answer: Option
Explanation:
No answer description is available. Let's discuss.

30.
As compared to tuned radio frequency receivers which of the following is the advantage of using superheterodyne receivers?
High gain and better sensitivity
Better selectivity at high frequencies
Stability
Noise suppression
Answer: Option
Explanation:
No answer description is available. Let's discuss.