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?

The rejection ratio (R) of a superheterodyne receiver can be calculated using the formula ( R = Q \times \frac{f}{\Delta f} ), where ( Q ) is the loaded quality factor, ( f ) is the frequency of interest, and ( \Delta f ) is the bandwidth of the receiver. Given that the loaded Q is 100 and the intermediate frequency (IF) is 455 kHz, the bandwidth can be approximated as ( \frac{f_{IF}}{Q} = \frac{455 \text{ kHz}}{100} = 4.55 \text{ kHz} ). At 25 MHz, the rejection ratio becomes ( R = 100 \times \frac{25,000 \text{ kHz}}{4.55 \text{ kHz}} \approx 550,000 ). Thus, the rejection ratio at 25 MHz is approximately 550,000.