KOGO was originally licensed on June 30, 1925, at 1220 kHz at 250 watts from the top of the U.S. Grant Hotel. The call letters in 1925 were KFWV. In 1926 the callsign was changed to KFSD and the station moved down the dial to 620 AM. KFSD stood for First in San Diego, as the station was the first commercially licensed station in San Diego. (KFBC/KGB was an amateur station that was not full-time.) In 1928, the station was facing bankruptcy, so it was sold to Thomas Sharp (who founded Sharp Health Care in San Diego). In 1931 KFSD became an affiliate of the NBC Blue Network.