Editing AM broadcasting (section)

====Arc transmitters====
Almost all of the continuous wave AM transmissions made prior to 1915 were made by versions of the [[arc converter]] transmitter, which had been initially developed by [[Valdemar Poulsen]] in 1903.<ref>[https://worldwide.espacenet.com/publicationDetails/originalDocument?CC=US&NR=789449A&KC=A&FT=D&ND=1&date=19050509&DB=&locale=en_EP# "Method of Producing Alternating Currents With a High Number of Vibrations"] U.S. patent 789,449, filed June 10, 1903, and granted May 9, 1905, to Valdemar Poulsen.</ref> Arc transmitters worked by producing a pulsating electrical arc in an enclosed hydrogen atmosphere. They were much more compact than alternator transmitters, and could operate on somewhat higher transmitting frequencies. However, they suffered from some of the same deficiencies. The lack of any means to amplify electrical currents meant that, like the alternator transmitters, modulation was usually accomplished by a microphone inserted directly in the antenna wire, which again resulted in overheating issues, even with the use of water-cooled microphones. Thus, transmitter powers tended to be limited. The arc was also somewhat unstable, which reduced audio quality. Experimenters who used arc transmitters for their radiotelephone research included [[Ernst Ruhmer]], [[Quirino Majorana]], [[Charles Herrold|Charles "Doc" Herrold]], and [[Lee de Forest]].