Explain the working principle of slug tuned inductor.
The value of inductor increases, when the slug (moving coil) is moved into the coil winding and hence decreases the resonant frequency of the tuned circuit. Similarly, when the slug is moved out of the coil winding, the inductance decreases and hence the resonant frequency of the tuned circuit increases.
The value of inductance can be varied by using movable core which can be moved up or down by using screw driver.