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 constructed, 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 Pleasant, Illinois was ultimately selected as 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.
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 its second, low-powered Chicago station, located at the McCormick building and broadcasting on 1120 kHz, change its call sign from WSAX to WJAZ.
Portable station (1924-1925)
Many communities surrounding Chicago expressed interest in becoming the permanent location for the re-established WJAZ. Zenith's president, E. F. McDonald, Jr., was quoted as saying "...the station will be erected where the community desires it. It goes without saying that a lot of advertising benefits will accrue to the place that will get the new WJAZ". However, the communities may not have been fully aware that they would only be hosting the transmitter site, with the station's studios remaining in Chicago.
In order to evaluate the various locations, as well as generate publicity for the parent company, in the fall of 1924 Zenith constructed a 100-watt portable broadcasting station, mounted on the back of a 1-ton Federal-Knight truck. The WJAZ call sign was transferred to this mobile outfit, which also transmitted on 1120 kHz. Befitting a portable, the station was completely self contained: the storage batteries which provided power for the transmitter were charged by an on-board generator, and it carried its own antenna, with gold-plated antenna wires supported by telescoping masts.
Zenith reported that it would be evaluating sites within 100 miles (160 km) of Chicago.  Broadcasts from each community featured entertainment plus speeches by local dignitaries.  During the solar eclipse of January 24, 1925, the station was transported to Escanaba, Michigan, to document the effects of the dimming sun on radio transmissions.
Following the selection of Mount Prospect as the permanent transmitter site, the portable station began making publicity tours, first through the midwest, followed by the western states, including Pikes Peak, Colorado. During the summer of 1925, in order to free up the call letters for transfer to the new permanent station, the portable's call sign was changed to WSAX, which it held until its deletion in the summer of 1928.
Following completion of the Mount Prospect transmission site, Zenith's revived WJAZ was licensed on October 1, 1925. Its new studio was located on the 23rd floor of the Straus Building in Chicago. The station's quality equipment and high power qualified it for classification as a "Class B" station. However, during the previous year the number of well-financed stations had steadily increased, and regulators at the Department of Commerce initially believed that there were no unused "Class B" assignments available for use by the station.
In response, E. F. McDonald developed a compromise. He noted that KOA, the powerful General Electric station in Denver, Colorado which had been exclusively assigned to the Class B frequency of 930 kHz, did not broadcast on Thursday nights, when it and other local stations observed "silent night", staying off the air in order to allow local listeners to receive distant stations. Thus, McDonald proposed that, with KOA off the air, WJAZ could be permitted to broadcast on 930 kHz on Thursday evenings for two hours, from 10:00 p.m. to midnight Central time. In addition, McDonald reassured the Department of Commerce that "Our station is concerned with the sole purpose of giving to the public the highest form of entertainment in but a limited time. We have felt that to do this, sufficient high class talent could not be secured continuously throughout the year for more than two hours a week." KOA management, plus two Cincinnati stations operating on an adjacent frequency, consented to this arrangement.
"Wave piracy" legal dispute (1926)
Despite E. F. McDonald's initial expression of satisfaction with a broadcast schedule of just two hours per week, he soon began demanding expanded hours after partnering with the Chicago Herald for additional programming, and Zenith's general counsel, Irving Herriott, later testified that "At no time was it the intention to be satisfied with two hours a week." The United States at this time had an informal agreement with Canada that six designated AM band frequencies would be used exclusively by Canadian stations. In early January 1926, McDonald directed WJAZ to move from its 930 kHz assignment to 910 kHz, one of the restricted Canadian frequencies, and begin expanded hours of operation. The U.S. government accused WJAZ of "pirating" the Canadian frequency and ordered the station to return to 930 kHz, while threatening legal action if it did not comply. However, McDonald was defiant, countering that "...Zenith Radio Corporation intends to litigate in every possible way the questions involved". On February 5, 1926, WJAZ broadcast the operetta "The Pirate", and publicity photographs of engineering staff dressed as "wave pirates" were distributed to newspapers and magazines.
On January 20, the federal suit United States versus Zenith Radio Corporation and E. F. McDonald was filed in Chicago. McDonald expected a narrow ruling in his favor, claiming that only a small number of stations, including WJAZ, held the "Class D Developmental" licenses that were free from normal restrictions. However, some earlier legal challenges had raised doubts about the extent that the Department of Commerce, under the provisions of the Radio Act of 1912, could restrict licenses and designate transmitting frequencies, and the actual outcome was sweeping. On April 16, 1926, Judge James H. Wilkerson's ruling was announced, which stated that under the 1912 Act the Commerce Department in fact could not limit the number of broadcasting licenses issued, or designate station frequencies. The U.S. government reviewed whether to appeal this decision, but Acting Attorney General William Donovan sided with the original decision.
The immediate result of the court case was a large increase in the number of stations, reaching over 730 by the time the Radio Act of 1927 was passed in February 1927 to restore government control. This act formed the Federal Radio Commission (FRC), which was tasked with undoing the disruption which the WJAZ case had triggered. On May 3, 1927 the first of numerous reassignments shifted WJAZ away from the Canadian frequency to 760 kHz, and this was followed the next month by a move 1140 kHz. On November 11, 1928, implementation of the FRC's General Order 40 resulted in a major reorganization of the AM broadcasting band. WJAZ was reassigned to 1480 kHz, and required to divide hours on this frequency with two other Illinois stations: WHT in Deerfield, and WORD in Batavia.
Station deletion (1931)
In early 1929 a newly licensed station, WCKY in Covington, Kentucky, was added as a fourth assignment to the three Chicago-area stations broadcasting on 1480 kHz. The grant specified that WCKY would receive 4/7ths of the available broadcasting hours, with WJAZ and the other two stations allocated 1/7th time each, moreover, WCKY "was to have first choice of the broadcasting time". In early 1930 all four stations were reassigned from 1480 kHz to 1490 kHz. WHT changed call letters twice, to WSOA in early 1929, and WCHI in early 1930, and was subsequently deleted on October 31, 1930, after which its former timeshare partner, WORD, changed its own call sign to WCHI and relocated to Deerfield.
Unsatisfied with its somewhat limited schedule, WCKY petitioned the FRC to delete the two remaining Chicago-area stations, and give it unlimited use of the frequency. An FRC examiner recommended that this request be denied, however a review by the full commission ruled on October 30, 1931 in favor of WCKY, and ordered both WJAZ and WCHI deleted. As part of its justification, the Commission noted that, even though WJAZ was only allocated two hours a day, it was not broadcasting during all of its available hours, in addition to operating with less than its full authorized power of 5,000 watts.
WJAZ was deleted on November 23, 1931, however WCHI appealed the ruling, arguing that not only should it be allowed to remain on the air, but it, rather than WCKY, should have been assigned the hours previously used by WJAZ. The appeal was unsuccessful, and WCHI was formally deleted on May 7, 1932.
- "The March of Radio" (WJAZ studio photograph), Radio Broadcast, July 1923, page 277.
- "Thirteen Stations Licensed" (during the week of August 12–19, 1922), New York Evening World, August 23, 1922, page 15.
- "New Stations", Radio Service Bulletin, September 1, 1922, page 3.
- "Radio News", Forest Park (Illinois) Review, May 12, 1923, page 2.
- "World's Most Powerful Broadcasting Station", Popular Science Monthly, September 1923, page 62.
- "In the Crystal Studio at WJAZ", Radio Broadcast, October 1923, page 456.
- "Peeps into Broadcast Stations: Chicago Enters Northern Solitude", The Wireless Age, February 1924, page 42.
- "With MacMillan and Radio, North of Civilization", Radio Broadcast, October 1923, pages 500-507.
- "Allocation of New Wave Lengths for Class B Stations", Radio World, April 28, 1923, page 6.
- "Alterations and Corrections", Radio Service Bulletin, June 1, 1923, page 11.
- WGN: A Pictorial History, WGN, Inc., 1961, pages 9-16.
- "Alterations and Corrections", Radio Service Bulletin, April 1, 1924, page 9.
- "Alterations and Corrections", Radio Service Bulletin, June 2, 1924, page 7. (WEBH was eventually deleted in November 1928 when it was consolidated with KYW: "Strike out all particulars" Radio Service Bulletin, November 30, 1928, page 12.)
- "Three Chicago Stations Change", Radio Age, July 1924, page 53.
- "Alterations and Corrections", Radio Service Bulletin, June 2, 1924, page 8. (WSAX was originally licensed in the summer of 1923: "New Stations", Radio Service Bulletin, August 1, 1923, page 3.)
- "A Portable Broadcasting Outfit", Literary Digest, November 8, 1924 (Vol. 83, No. 6), page 23.
- "First Portable Broadcaster Will Be Zenith Built", Pittsburgh Daily Post, August 13, 1924, Radio Broadcasting News section, page 2.
- "New Stations", Radio Service Bulletin, October 1, 1924, page 3. (At the same time, Zenith's low-powered station reverted to its original call sign of WSAX, after it had been WJAZ for a few months: "Alterations and Corrections", Radio Service Bulletin, October 1, 1924, page 5. This restored WSAX was ultimately deleted the next year: "Strike out all particulars", Radio Service Bulletin, July 1, 1925, page 10.)
- "Radio Gossip and News: WJAZ's Portable Station", Washington (D.C.) Evening Star, November 16, 1924, Part 1, page 39.
- "Seek New Location With Portable Set", Radio Digest, October 25, 1924, page 8.
- "Tests of Radio During Eclipse Confirm Wave Length Theories", Washington (D.C.) Evening Star, January 25, 1925, page 3.
- "Musicians Here to Give Program", Findlay (Ohio) Morning Republican, May 2, 1925, page 2.
- "The Far West Gets its Radio Thrill", Radio Age, October 1925, page 72.
- Portable's call changed from WJAZ to WSAX: "Alterations and Corrections", Radio Service Bulletin, September 1, 1925, page 7; WSAX deletion: "Zone 5 Deleted Stations", Second Annual Report of the Federal Radio Commission For the Year Ended June 30, 1928, page 154.
- "New Stations", Radio Service Bulletin, October 1, 1925, page 3.
- "WJAZ's New Studio", Radio Broadcast, October 1925, pages 767-769.
- The Beginning of Broadcast Regulation in the Twentieth Century by Marvin R. Bensman, 2000, page 159-160.
- WJAZ "wave pirates" publicity photograph, Popular Radio, May 1926, page 90.
- Senate Radio Control Hearings, January 8-9, 1926, page 289.
- "U. S. Questions WJAZ's Wave Right", Radio Age, March 1926, page 19.
- "'Yo-ho-ho'" Sing Pirates Bold", Radio Digest, April 3, 1926, pages 5, 8.
- Benson (2000) pages 167-175.
- "Federal Regulation of Radio Broadcasting" by Acting Attorney William J. Donovan (July 8, 1926), Official Opinions of the Attorneys General of the United States, Volume 35, 1929, pages 126-132.
- "List of broadcasting stations issued temporary permits" (May 3, 1927), Radio Service Bulletin, April 30, 1927, page 12.
- "Broadcasting Stations" (Effective June 15, 1927), Radio Service Bulletin, May 31, 1927, page 6.
- "Broadcasting Stations, by wave lengths, effective November 11, 1928", Commercial and Government Radio Stations of the United States (edition June 30, 1928), page 176. WIBO, Des Plaines, Illinois, was originally said to also be moving to 1480 kHz, but instead was assigned first to 570 kHz, then 560 kHz.
- "New Stations", Radio Service Bulletin, February 28, 1929, page 5.
- "WCKY Schedule", Cincinnati Enquirer, August 7, 1929, page 6.
- "Alterations and Corrections", Radio Service Bulletin, February 28, 1930, page 23.
- "Radio Stations deleted", Fifth Annual Report of the Federal Radio Commission for the Fiscal Year 1931, page 13.
- "Strike out all particulars" (WCHI (Deerfield, Ill.)), Radio Service Bulletin, October 31, 1930, page 12.
- "Alterations and Corrections", Radio Service Bulletin, November 29, 1930, page 11.
- "Six More Stations Ordered Silenced", Broadcasting, November 1, 1931, page 12.
- "Broadcast Section", Sixth Annual Report of the Federal Radio Commission (Fiscal Year 1932), page 8.
- "Strike out all particulars", Radio Service Bulletin, November 30, 1931, page 8.
- "WCHI Asks Stay Order", Broadcasting, November 15, 1931, page 27.
- "Strike out all particulars", Radio Service Bulletin, May 31, 1932, page 11.
- "Portable Stations - The Radio Rovers of the 1920s" by John Schneider, Spectrum Monitor Magazine, December, 2014 (theradiohistorian.org)
- "Remembering Mount Prospect's Zenith radio towers" by the Mount Prospect Historical Society, October 11, 2017 (dailyherald.com)