Editing Amplitude modulation (section)

===Early technologies===
Early experiments in AM radio transmission, conducted by Fessenden, [[Valdemar Poulsen]], [[Ernst Ruhmer]], [[Quirino Majorana]], [[Charles Herrold]], and [[Lee de Forest]], were hampered by the lack of a technology for [[amplifier|amplification]]. The first practical continuous wave AM [[transmitter]]s were based on either the huge, expensive [[Alexanderson alternator]], developed 1906–1910, or versions of the [[Poulsen arc]] transmitter (arc converter), invented in 1903. The modifications necessary to transmit AM were clumsy and resulted in very low quality audio. Modulation was usually accomplished by a [[carbon microphone]] inserted directly in the antenna or ground wire; its varying resistance varied the current to the antenna. The limited power handling ability of the microphone severely limited the power of the first radiotelephones; many of the microphones were water-cooled.