WJAZ was the call sign used from 1922 to 1931 by a series of four separate, but closely related, broadcasting stations located in Chicago, Illinois and operated by the Chicago Radio Laboratory/Zenith Radio Corporations.
The original WJAZ was first licensed in the summer of 1922, and the next year began broadcasting from the Edgewater Beach Hotel in Chicago. However, it was soon determined that a suburban transmitter location would be preferable, and Zenith began preparations to re-establish WJAZ's operations at a more suitable site. Following operation for a few weeks by the Chicago Tribune as WGN, the station license for the original WJAZ was sold to the hotel management, and the call letters changed to WEBH.
In order to maintain control of the well-known WJAZ call sign until the new facility was ready, in 1924 Zenith briefly renamed a second Chicago station, WSAX, to WJAZ. Later that year, Zenith prepared a portable broadcasting station, mounted on a truck body, in order to evaluate potential new transmitter locations, and this mobile unit inherited the WJAZ call letters. Roving test broadcasts were made from various sites surrounding Chicago, and Mount Prospect, Illinois was ultimately selected for the new transmitter location. In 1925, the replacement facility was completed, and the WJAZ call sign was transferred from the portable unit to the new station.
The next year WJAZ gained national notoriety, when Zenith made an unauthorized change in its transmitting frequency, directly challenging the Department of Commerce's authority under the Radio Act of 1912 to assign frequencies. The courts sided with WJAZ; as a result the Radio Act of 1927 was enacted, which strengthened the government's regulatory powers and established the Federal Radio Commission.
WJAZ was deleted in 1931, after a co-channel station in Kentucky successfully petitioned for full-time use of the shared frequency.
History
Initial authorization (1922-1924)
WJAZ was first licensed on August 17, 1922 to the Chicago Radio Laboratory (reorganized in 1924 as the Zenith Radio Corporation), for operation on the standard "entertainment" wavelength of 360 meters (833 kHz). Its call letters were randomly assigned from a sequential alphabetical list maintained by the Department of Commerce.
WJAZ initially had a very limited broadcasting schedule. It gained prominence when it began broadcasting from a newly constructed studio located on the ground floor of the Edgewater Beach Hotel on May 12, 1923. For publicity, the general public was invited to watch performances through soundproof three-ply plate glass windows. The transmitter and antenna were located adjacent to the hotel building.
The station provided general entertainment programming, and was primarily used to promote the sale of Zenith-brand radio receivers. One unusual feature was a series of midnight transmissions, operating under the experimental call sign "9XN", as one of the stations communicating with Dr. Donald B. MacMillan's Arctic expedition aboard the schooner Bowdoin, which became icebound and isolated 11 degrees below the North Pole.
Effective May 15, 1923, government regulators allocated a band of "Class B" frequencies, reserved for stations that had quality programming and more powerful transmitters. 670 kHz was allocated for use in the Chicago area, and both WJAZ and WMAQ (now WSCR) were assigned to this frequency on a timesharing basis. Zenith soon found that operating a high-powered station within Chicago city limits caused extensive "blanketing" interference to nearby receivers, and decided to relocate WJAZ to a suburban transmitter site. A short-term agreement was made with the Chicago Tribune to take over the existing station's programming, which went into effect on March 29, 1924, and at the same time the station's call letters were changed to WGN and the transmitting frequency to 810 kHz. The Tribune agreement only lasted a few weeks, and the station was then sold to the Edgewater Beach Hotel management, which changed the call letters to WEBH.
Temporary transfer (1924)
In order to maintain control over the WJAZ call letters while the new suburban facility was under construction, Zenith arranged to have the call sign of its second, low-powered Chicago station, located at the McCormick building and broadcasting on 1120 kHz, changed from WSAX to WJAZ.
Portable station (1924-1925)