KOSF (103.7 FM) is a commercial classic hits radio station that is licensed to San Francisco, California. Owned by iHeartMedia, the station serves the San Francisco Bay Area. The KOSF studios are located in San Francisco's SoMa district, while the station transmitter is based atop San Bruno Mountain near Daly City. KOSF broadcasts in HD Radio with two digital subchannels. History Early years The former ABC Radio-owned station started on November 3, 1947 as KGO-FM. In earlier days, it simulcast its sister station, KGO (810 AM), occasionally airing a stereo version of The Lawrence Welk Show. By the late 1960s, as the Federal Communications Commission (FCC) began requiring FM stations to offer separate programming from that of their AM counterparts, KGO-FM, like other ABC-owned FM stations, was an outlet for Love, an automated progressive rock format. KGO-FM changed its call sign to KSFX in early 1971, keeping its progressive rock format until May 1973. At that time, KSFX aired a top 40 "Musicradio" approach, similar to WABC in New York City. By late 1974, the station veered towards a dance/soul-flavored format. During the late 1970s, KSFX had a brief run with a disco format. In late 1980, KSFX switched to an album-oriented rock (AOR) format modeled after sister station KLOS in Los Angeles. This lasted until May 1982, when stiff competition from KMEL and CBS-owned KRQR prompted KSFX to drop AOR for talk, featuring the ABC-syndicated Talkradio network. Switching back to the KGO-FM call sign, the FM signal complemented the primarily local talk programming of its AM sister station. ABC sold the station on January 1, 1984, to Weaver, Davis, Fowler (WDF), which owned KLOK in San Jose; accordingly, the station was renamed KLOK-FM. KLOK-FM had an interactive adult contemporary format called "Yes/No Radio" in which listeners would call in their votes on whether songs should remain on or to be removed from the playlist. Smooth jazz In 1987, the station was sold to Brown Broadcasting Corporation, the call sign was changed to KKSF and under the direction of former KIFM programmer-turned-consultant Bob O'Connor and associate Michael Fischer, the format was switched to new adult contemporary (NAC), which would later evolve to smooth jazz. KKSF debuted on July 31, 1987 at midnight; the first song played was "Back In The High Life Again" by Steve Winwood. The general manager from 1987 to 1997 was David A. Kendrick. Liner notes of