One of the main functions of the RF amplifier in a superheterodyne receiver is to

Solution (By Examveda Team)

Superheterodyne Receiver:
A superheterodyne receiver is a type of radio receiver that uses a mixer to convert a radio signal of a certain frequency range into a fixed intermediate frequency (IF). This IF signal is then amplified and further processed to extract the audio or other information contained in the original radio signal.

RF Amplifier:
The radio frequency (RF) amplifier is the first stage in a superheterodyne receiver. It amplifies the weak received RF signal before it reaches the mixer. This amplification is crucial for good receiver sensitivity and selectivity.

Option A: Provide improved tracking
Incorrect. Tracking refers to the ability of the receiver to maintain the correct intermediate frequency (IF) over a range of input frequencies. The RF amplifier does not directly contribute to tracking; that's primarily determined by the mixer and IF stages.

Option B: Permit better adjacent-channel rejection
Incorrect. While a strong RF amplifier can contribute to *overall* selectivity (the ability to reject unwanted signals), it doesn't directly improve *adjacent channel* rejection as much as other components. Adjacent channel rejection is mainly achieved through high-Q tuned circuits (high quality factor) in the IF stage. A strong RF stage helps ensure a strong signal is passed to the rest of the receiver, allowing the more selective IF stages to do their job effectively. However, the RF stage's selectivity isn't the *primary* factor here.

Option C: Increase the tuning range of the receiver
Incorrect. The tuning range is determined by the tuning circuits (usually variable capacitors) in the RF and mixer stages. The RF amplifier doesn't directly affect this range.

Option D: Improve the rejection of the image frequency
Correct. The image frequency is an unwanted frequency that can mix with the local oscillator frequency in the mixer to produce the same intermediate frequency (IF) as the desired signal. A strong RF amplifier, with good selectivity before the mixer, can significantly reduce the amplitude of the image frequency before it reaches the mixer. By attenuating the image frequency before mixing, the RF amplifier helps prevent the image from interfering with the desired signal, greatly improving the receiver's image rejection.

In summary: The primary function of the RF amplifier in a superheterodyne receiver is to amplify the weak received signal and, importantly, to improve the rejection of the image frequency by providing initial signal selection and reducing the interference before it reaches the mixer stage.