You can introduce a potentiometer in the biasing network of each transistor to adjust the base bias voltage gradually. This will allow you to control the conduction angle from class-C towards class-B. To use a single potentiometer for controlling both transistors simultaneously, you can use a dual-ganged potentiometer.
You can introduce a potentiometer in the biasing network of each transistor to adjust the base bias voltage gradually. This will allow you to control the conduction angle from class-C towards class-B. To use a single potentiometer for controlling both transistors simultaneously, you can use a dual-ganged potentiometer.