KNBR began as KPO on April 17, 1922, at the Hale Bros. Department Store, on the corner of Fifth and Market in San Francisco. The San Francisco Chronicle purchased a 50% interest in the station in 1926.
The station was moved from 710 kc. to 680 kc. -- its current dial position -- in November 1928.
KPO became affiliated with NBC's Red Network in 1931, and was sold to General Electric in July 1932. General Electric, in turn, leased the station to NBC. On April 5, 1933, KPO's transmitter was moved to Belmont, where it remains to this day. In 1938, full ownership was transferred to NBC.
In April 1942, KPO and co-owned KGO moved to NBC Radio City at 420 Taylor Street. On November 23, 1947, KPO became KNBC. The commemorative broadcast can be heard on the Bay Area Radio Museum's website at:
http://www.bayarearadio.org/audio/kpo/kpo-knbc_nov-23-1947.shtml
In November 1962, KNBC became KNBR, after the FCC denied NBC's request to reinstate the original KPO call letters. The station broadcast a Full Service middle-of-the-road music and entertainment format through most of the 1960s, including an abortive attempt at some light rock in 1965 when Al Hart -- previously program director at KABL -- programmed KNBR; he moved over to KCBS a few years later, where he became a San Francisco radio legend.
In April 1967, KNBR moved from 420 Taylor Street to Fox Plaza -- where KTRB recently to up quarters.
The Giants moved over to KNBR in 1979 after twenty years on KSFO. KNBR began emphasizing more sports programming in the 1980s, and was sold by NBC to Susquehanna in May 1989.
As always, more info, photos and recordings at
http://www.BayAreaRadio.org