Receivers

Explanation of question 10

A superheterodyne receiver is tuned to 7.1MHz and is receiving image interference from 8.03MHz. The local oscillator frequency and intermediate frequency will be respectively

1. 465kHz, 7.565MHz
2. 6.635MHz, 7.565kHz
3. 7.565MHz, 465kHz
4. 8.495MHz, 465kHz

The answer is :- 3

The local oscillator frequency will be midway between the two signal frequencies i.e. 7.565 MHz. The value of i.f. will be given by (8.03 - 7.565) MHz or (7.565 - 7.1) MHz, i.e. 0.465 MHz, which is 465 kHz.