Question

The tank circuit used in a radio transmitter should have

• A. high effective $Q$.
• B. loosely coupled load.
• C. both (A) and (C).
• D. low effective $Q$.

Answer 1

Answer: (C)

Harmonics and fundamental frequency voltages cross-modulate with each other producing fundamental frequency currents whose relation with the normal fundamental current vary with amount of harmonics in the oscillator circuit. The phase angle of the resultant fundamental frequency current thus varies resulting in frequency variation. Such, frequency variation can be minimized by using a tank circuit having high effective $Q$ having loosely coupled load.