The station first signed on the air on February 15, 1950 as KEYL; channel 5 was the second television station to sign on in the San Antonio market, debuting three months after primary NBC affiliate WOAI-TV (channel 4). The station has been a primary CBS affiliate since its sign-on, however it initially carried secondary affiliations with DuMont, ABC and the Paramount Television Network—the former two affiliations were shared with WOAI-TV. The station was originally owned alongside KABC radio (680 AM, now KKYX). KEYL was one of Paramount's strongest affiliates, carrying nearly the network's entire lineup. Among the Paramount programs that KEYL aired were "Armchair Detective", "Latin Cruise", "Hollywood Reel", "Hollywood Wrestling," "Time for Beany" and "Movietown, RSVP".