KGTT/KGGC had been a minor station in the Bay Area through the twenties and thirties. That changed in 1939 when Sherwood Patterson purchased the station and changed the call letters to KSAN. New studios were constructed in the Merchandise Mart near Market Street. A radio tower was erected on the roof of the building, and a 250 watt transmitter was installed.
The reborn station attracted considerable attention with its programming of popular music and disk jockeys. Two popular KSAN personalities in 1941 were Les Malloy and Vic Paulsen. Evening host Malloy called himself the "Midnight Son," while Paulsen, who held down the morning shift, was known as the "Rising Son." After the Pearl Harbor attack later that year, however, Paulson's nickname was quickly dropped.
Dave Crosatto had the first sponsored all-night program in the Bay Area on KSAN, supported by the Mark Hopkins Hotel and the Yellow Cab Company. Perhaps the most notable aspect of KSAN's programming, however, was its devotion to horse race results. At any time of the day, programs were interrupted to announce the latest results from Golden Gate Fields. The station found instant success with this policy, as Vic Paulsen told it. He explained that even people who didn't like the station would listen, just to keep up on their bets. This policy did not win any fans at the F.C.C., however, and the station reportedly lost its bid for a 1,000 watt frequency to a Santa Cruz station because it gave more attention to race results than to public service features.
KSAN remained as a popular music station in the Bay Area throughout the forties and early fifties. In the mid fifties, the music format was changed to feature rhythm and blues music, aimed at a primarily black audience. This continued to be the station's reason for existence for a number of years. In 1964, the station was purchased by Les Malloy, who changed the call letters to KSOL, reflecting the evolution of rhythm and blues into "Soul" music.
The station competed for the black audience with KDIA in Oakland (formerly KLS and KWBR) until 1971. That year, the station was sold again, and the call letters were changed to KEST. Programming was changed to feature mainstream adult-oriented music, despite many complaints from the station's loyal black listeners. KEST was acquired by Douglas Broadcasting, Inc., in December of 1988.
Radio Service Bulletins, 1922 and 1925.