the Herrold College of Wireless and Engineering, located in the Garden City Bank Building at 50 West San Fernando Street in San Jose. In order to promote the college, as well as provide practical experience for his students, a radio transmitter (then commonly known as "wireless telegraphy") with a large antenna was constructed atop the building. The earliest transmissions used spark-gap transmitters which could only transmit the dots-and-dashes of Morse code. Herrold was among the first to develop a radio transmitter that could also be used for audio transmissions. After limited success with an approach that used "high-frequency" sparks, he later began using a version of an "arc-transmitter" originally developed by Valdemar Poulsen. Although his primary objective was to create a wireless telephone that could be commercialized for point-to-point use, beginning in July 1912 Herrold also began making regular weekly entertainment broadcasts, with the debut program featuring phonograph records supplied by the Wiley B. Allen company. Radio communication was initially unregulated in the United States, and at first Herrold used a variety of self-assigned identifiers for his station, including FN and SJN, plus, for audio transmissions, "San Jose calling". The Radio Act of 1912 established the licensing of stations through the U.S. Commerce Department, and in late 1915 Herrold was issued an Experimental Station License with the call sign 6XF. Although Herrold reported success in developing his system, his arc-transmitters were low-powered and would only work at wavelengths above 600 meters (frequencies below 500 kHz). The concurrent development of vacuum-tube technology, which did not have the same limitations, started making arc technology obsolete. World War I In April 1917, with the entrance of the United States into World War I, the U.S. government took control of the entire radio industry, and it became illegal for private citizens to possess a working radio receiver. In addition, all civilian radio stations were ordered to be dismantled, so for the duration of the conflict Herrold left the airwaves. This wartime government ban on civilian stations was lifted effective October 1, 1919, and in early 1921 Herrold was reissued an Experimental license, again with the call sign 6XF. (He had previously been issued a license for a portable transmitter, with the call sign 6XE.) During the war impressive strides had been made in vacuum-tube transmitter and receiver design, and Herrold's arc-transmitters were no longer commercially competitive. In 1920 a number of radio stations in