The station began broadcasting October 17, 1950 and held the call sign WOPA-FM.[1][2] It was a sister station to WOPA 1490, the present-day WEUR.[6] The call letters WOPA stood for the Oak Park Arms, a hotel on Oak Park Avenue where the station's studios and transmitter were located.[7][2] The station originally broadcast at 102.3 MHz, and had an ERP of 1,000 watts at a HAAT of 250 feet.[2] In 1958, the station's frequency was changed to 102.7 MHz, and its ERP and HAAT were increased to 3,550 watts and 260 feet respectively.[2]
In 1962, the station's ERP was increased to 8,100 watts, while its HAAT was decreased to 231 feet.[2] In 1965 its ERP was increased to 17,000 watts, and in 1967 its ERP was increased to 50,000 watts.[2]
On May 21, 1967, WOPA-FM began airing progressive rock Sunday nights.[10] On March 4, 1968, the station began airing a two and a half hour nightly progressive rock program titled "Rock Garden".[11] Another overnight progressive rock program was added in October 1968.[10]
In May 1969, the station's call sign was changed to WGLD.[2] The station adopted an oldies format.[12][13] On January 5, 1970, the station switched to a full time progressive rock format.[14][15]
In 1972, the station's transmitter was moved to the John Hancock Center, and its ERP was reduced to 6,000 watts.[2]
In 1973, the station aired a sex talk show hosted by Morgan Moore called Femme Forum, weekdays from 10 a.m. to 3 p.m.[16][17] The Federal Communications Commission fined the station $2,000 for an episode which dealt with the subject of oral sex, and stated that the show's "titillating, pandering fashion" of the episode's discussions constituted "broadcast obscenity".[16][18] The station's owner, Sonderling Broadcasting, did not appeal the ruling.[18]Femme Forum was dropped from the station shortly thereafter and the station returned to airing an oldies format.[18][7][19]
In 1974, the station's call sign was changed to WBMX, standing for "Black Music EXperience", and the station adopted an urban contemporary format.[2][20][21] The station continued airing an urban contemporary format into the late 1980s.[22][21]
During this era the station helped give rise to a new generation of DJs whose formats brought dance music to Chicago's airwaves. The Hot Mix 5 went on to help define what became known as Chicago House music.
In 1988, the station was sold to Sky Broadcasting for $27 million.[23][24][25][26] Sky Broadcasting was taken over by Broadcasting Partners later that year.[27]
At 5 p.m. on October 18, 1988, the station shifted to an urban adult contemporary format and the station was branded V103, with its call sign changing to WVAZ.[28][29][30][3]
Broadcasting Partners was acquired by Evergreen Media in 1995, which in turn merged with Chancellor Broadcasting in 1997.[31][32] Chancellor restructured as AMFM, Inc. in 1999, and in 2000 merged with Clear Channel Communications.[33][34]
