Editing AM broadcasting (section)

====Alternator transmitter====

Fessenden's work with high-frequency spark transmissions was only a temporary measure. His ultimate plan for creating an audio-capable transmitter was to redesign an electrical [[alternator]], which normally produced alternating current of at most a few hundred ([[hertz|Hz]]), to increase its rotational speed and so generate currents of tens-of-thousands Hz, thus producing a steady continuous-wave transmission when connected to an aerial. The next step, adopted from standard wire-telephone practice, was to insert a simple [[carbon microphone]] into the transmission line, to modulate the [[carrier wave]] signal to produce AM audio transmissions. However, it would take many years of expensive development before even a prototype alternator-transmitter would be ready, and a few years beyond that for high-power versions to become available.<ref>Aitken (1985), p. 69.</ref>

Fessenden worked with [[General Electric]]'s (GE) [[Ernst Alexanderson|Ernst F. W. Alexanderson]], who in August 1906 delivered an improved model which operated at a transmitting frequency of approximately 50&nbsp;kHz, although at low power. The alternator-transmitter achieved the goal of transmitting quality audio signals, but the lack of any way to amplify the signals meant they were somewhat weak. On December 21, 1906, Fessenden made an extensive demonstration of the new alternator-transmitter at Brant Rock, Massachusetts, showing its utility for point-to-point wireless telephony, including interconnecting his stations to the wire telephone network. As part of the demonstration, speech was transmitted 18 kilometers (11 miles) to a listening site at Plymouth, Massachusetts.<ref name="experiments">"Experiments and Results in Wireless Telephony" by John Grant, ''The American Telephone Journal''. [https://babel.hathitrust.org/cgi/pt?id=mdp.39015057240221;view=1up;seq=111 Part I]: January 26, 1907, pp. 49–51; [https://babel.hathitrust.org/cgi/pt?id=mdp.39015057240221&view=1up&seq=147 Part II]: February 2, 1907, pp. 68–70, 79–80.</ref>

An ''American Telephone Journal'' account of the December 21 alternator-transmitter demonstration included the statement that "It is admirably adapted to the transmission of news, music, etc. as, owing to the fact that no wires are needed, simultaneous transmission to many subscribers can be effected as easily as to a few",<ref name="experiments"/> echoing the words of a handout distributed to the demonstration witnesses, which stated "[Radio] Telephony is admirably adapted for transmitting news, stock quotations, music, race reports, etc. simultaneously over a city, on account of the fact that no wires are needed and a single apparatus can distribute to ten thousand subscribers as easily as to a few. It is proposed to erect stations for this purpose in the large cities here and abroad."<ref>[https://www.radioworld.com/columns-and-views/dec-21-1906-a-very-significant-date-in-radio/338869 "Dec. 21, 1906: A Very Significant Date in Radio"] by James E. O'Neal, December 22, 2016 (radioworld.com).</ref> However, other than two holiday transmissions reportedly made shortly after these demonstrations, Fessenden does not appear to have conducted any radio broadcasts for the general public, or to have even given additional thought about the potential of a regular broadcast service, and in a 1908 article providing a comprehensive review of the potential uses for his radiotelephone invention, he made no references to broadcasting.<ref>[https://babel.hathitrust.org/cgi/pt?id=mdp.39015068171985&view=1up&seq=638 "Wireless Telephony: G. Possibilities"] by Reginald A. Fessenden, ''Transactions of the American Institute of Electrical Engineers'', Vol. XXVII (1908), Part I, pp. 606–608.</ref>

Because there was no way to amplify electrical currents at this time, modulation was usually accomplished by a carbon [[microphone]] inserted directly in the antenna wire. This meant that the full transmitter power flowed through the microphone, and even using water cooling, the power handling ability of the microphones severely limited the power of the transmissions. Ultimately only a small number of large and powerful [[Alexanderson alternator]]s would be developed. However, they would be almost exclusively used for long-range radiotelegraph communication, and occasionally for radiotelephone experimentation, but were never used for general broadcasting.