Q. Transformer-coupled Amplifiers?
Transformer-coupled Amplifiers: The figure illustrates another type of coupling often used to couple audio frequencies - the untuned transformer. Because of the step-up property of the transformer, greater gain can be obtained with transformer coupling than with RC or impedance coupling. This greater gain, however, is obtained at the expense of narrowing the amplified bandwidth. Also, note that the transformer performs the double function of coupling ac variations and blocking the dc plate voltage from the grid of the next stage. The tuned transformer is usually used to couple radio-frequency amplifier stages. Capacitors (shown as dotted lines in figure) are placed parallel to the transformer primary and secondary,forming two parallel-tuned circuits. Greater gain and narrower bandwidth result from tuned transformer coupling if the merit factor (Q) of the tuned circuits is high.