Indicate the false statement. The superheterodyne receiver replaced the TRF receiver because the latter suffered from

Solution (By Examveda Team)

A superheterodyne receiver is a type of radio receiver that uses frequency conversion to intermediate frequencies (IF) to improve performance, such as selectivity, sensitivity, and stability. In contrast, a TRF receiver directly tunes to the desired radio frequency. Now, let’s break down each option:

Option A: Gain variation over the frequency coverage range
This option is correct. One of the key disadvantages of the TRF receiver is that its gain varies significantly over the frequency coverage range. This means that as the frequency changes, the amplification provided by the receiver changes, which causes the receiver to lose consistency in performance across the tuning range. The superheterodyne receiver solves this by converting the signal to an intermediate frequency (IF) that is stable, regardless of the incoming signal’s frequency. Therefore, gain variation is a problem in the TRF receiver, making this statement true.

Option B: Insufficient gain and sensitivity
This option is correct. The TRF receiver typically suffers from insufficient gain and sensitivity, especially at higher frequencies. This is because the TRF receiver must amplify the entire range of frequencies directly, which leads to lower overall sensitivity and gain. In comparison, the superheterodyne receiver improves both gain and sensitivity by using frequency conversion and amplification at the intermediate frequency (IF), leading to better overall performance. So, insufficient gain and sensitivity is one of the reasons the TRF receiver was replaced by the superheterodyne receiver.

Option C: Inadequate selectivity at high frequencies
This option is correct. The TRF receiver struggles with selectivity, especially at high frequencies. Selectivity refers to the ability of the receiver to isolate the desired signal and reject unwanted signals. The TRF receiver’s selectivity decreases as the frequency increases, due to the limitations in tuning and filtering. The superheterodyne receiver, on the other hand, achieves much better selectivity, especially at higher frequencies, because the frequency conversion process makes it easier to filter and select signals. Therefore, the TRF receiver is indeed inadequate in terms of selectivity at high frequencies.

Option D: Instability
This option is incorrect (False). While instability could be a problem for some receivers, it is not the primary reason the TRF receiver was replaced by the superheterodyne receiver. The TRF receiver is more prone to issues like gain variation and inadequate selectivity, as discussed in the other options. Instability is generally a more specific problem associated with certain types of circuits or designs, but it is not the main issue for the TRF receiver. The superheterodyne receiver provides improved stability through frequency conversion, which is one of the reasons it replaced the TRF receiver, but instability was not the primary concern. Therefore, Option D is the false statement in this context.

Conclusion:
The false statement is Option D: Instability. The superheterodyne receiver replaced the TRF receiver primarily because of issues like gain variation, insufficient sensitivity, and inadequate selectivity at high frequencies, but instability was not the main issue.