Receivers

Explanation of question 6

The local oscillator frequency of a single conversion superheterodyne receiver for the HF bands is normally

1. fixed
2. equal to the signal frequency
3. higher than the signal frequency
4. lower than the signal frequency

The answer is :- 3 The r.f. amplifier tuning is ganged to the local oscillator such that the difference in frequency (the i.f.) is constant. The local oscillator frequency is normally higher than the signal frequency to simplify the problems of tracking.