KPO/KNBR 100 -- April 17, 2022

San Francisco radio station KPO began broadcasting 100 years ago today, on 17-April-1922. I remember reading about the 50th anniversary of successor KNBR in the Chronicle. The photos of the early studios caught my attention. 

The original KPO studios were in the Hale Brothers department store at Fifth and Market. Hale Brothers owned the station. In 1929, the station moved to the Hale Brothers annex, seen behind the corner store. In 1927, the station became an early affiliate of the NBC Red Network. NBC acquired KPO in the 1930s and changed the call letters to KNBC. Later, they wanted to use the call sign for a Los Angeles station and changed the San Francisco station to KNBR.

San Francisco Examiner, 15-April-1922

Notice that the article does not mention call letters. KPO's planned content sounds exciting. 

San Francisco Examiner, 18-April-1922

The radio schedule for the day after KPO went on the air. Notice that no call signs are used, just the names of the owners ("The Emporium") or the location of the station ("Rock Ridge, Oakland"). All stations shared a single frequency. KPO started out with a one-hour slice from 9am to 10am.

KNBR has carried radio broadcasts of San Francisco Giants games since 1979. 

Radio history from John Schneider's wonderful site Voices Out of the Fog:
http://www.sfradiomuseum.com/schneider/articles.shtml