A 50,000-watt Modesto radio station, KTRB-AM 860, is moving to San Francisco and begun testing its new 50,000-watt transmitter near San Antonio Reservoir (I-680 and Vallecitos Road) in Alameda County. KTRB’s studio is at 1700 Montgomery St. in San Francisco. It be the market’s fifth 50,000-watt station, after KGO, KCBS, KFAX and KNBR.

For now, as KTRB fine tunes its new transmitter, it is playing what it calls “The San Francisco Sound” — rock music performed live and recorded by San Francisco artists and groups from the mid-1960s to the early 1970s such as The Beau Brummels, The Syndicate of Sound, The Grateful Dead, Jefferson Airplane, Quicksilver Messenger Service, Big Brother & The Holding Company, as well as Santana, Creedence Clearwater Revival and Journey.

On March 1, the station will go to its permanent format, which hasn’t been disclosed, though the station’s vp and gm Jim Pappas told the Mercury News that they’re still trying to decide between talk and music.

KTRB was founded by T.R. McTammany and Bill Bates (the “TR” and “B” in KTRB) in 1933 in Modesto, according to a press release. In 1973, brothers Pete, Mike, and Harry Pappas bought the station and made it apart of their broadcasting empire, reportedly the largest privately held group of TV and radio stations in the country. GM Jim Pappas, 40, is the nephew of the company’s CEO, Harry Pappas.

• David Ferrell Jackson’s Bay Area Radio Blog documents what KTRB played when it hit the air in the Bay Area.