How A Vacuum Tube Can Be Used as A Radio Amplifier

The reason a vacuum tube detector is more sensitive than a crystal detector is because while the latter merely rectifies the oscillating current that surges in the receiving circuits, the former acts as an amplifier at the same time. The vacuum tube can be used as a separate amplifier in connection with either: (1) a crystal detector or (2) a vacuum tube detector, and (a) it will amplify either the radio frequency currents, that is the high frequency oscillating currents which are set up in the oscillation circuits or (b) it will amplify the audio frequency currents, that is, the low frequency alternating currents that flow through the head phone circuit.