KCBS operates with a transmitter output of 50,000 watts, and during the daytime can be regularly received as far north as Red Bluff and Hopland and south as far as San Luis Obispo.

Even with this restriction, KCBS's nighttime signal reaches a large slice of the Western United States with a good radio.

On rare occasions "DXers" (hobbyists who listen for distant stations) have reported receiving KCBS across the Pacific Ocean, and in Hawaii and Alaska.

KCBS also simulcasts a seven-minute block of the CBS Evening News East Coast feed live on weekdays, allowing listeners to hear the program's top stories two hours before the newscast airs on KPIX-TV.

The station hosts special segments each weekday with CBS News technology analysts Larry Magid and Brian Cooley, San Francisco Chronicle columnist Phil Matier, and others.

However, the original licensee, Charles Herrold, had begun making audio radio transmissions in 1909, as part of an experimental radio-telephone system, and KCBS has traditionally dated its founding to that year.

In order to promote the college, as well as provide practical experience for his students, a radio transmitter (then commonly known as "wireless telegraphy") with a large antenna was constructed atop the building.

After limited success with an approach that used "high-frequency" sparks, he later began using a version of an "arc-transmitter" originally developed by Valdemar Poulsen.

[6] Although his primary objective was to create a wireless telephone that could be commercialized for point-to-point use, beginning in July 1912 Herrold also began making regular weekly entertainment broadcasts, with the debut program featuring phonograph records supplied by the Wiley B. Allen company.

[7][8] Radio communication was initially unregulated in the United States, and at first Herrold used a variety of self-assigned identifiers for his station, including FN[9] and SJN, plus, for audio transmissions, "San Jose calling".

This wartime government ban on civilian stations was lifted effective October 1, 1919, and in early 1921 Herrold was reissued an Experimental license, again with the call sign 6XF.

)[13] During the war impressive strides had been made in vacuum-tube transmitter and receiver design, and Herrold's arc-transmitters were no longer commercially competitive.

Effective December 1, 1921, the Department of Commerce issued a regulation that stations making broadcasts intended for the general public now had to hold a Limited Commercial license specifying operation on a wavelength of 360 or 485 meters,[16] and, on December 9, 1921, a broadcasting station authorization with the randomly assigned call letters of KQW was issued in Herrold's name.

During this time its owner was Julius Brunton & Sons, and the station's operations were co-located with KJBS at 1470 Pine Street in San Francisco.

In March 1941, under the provisions of the North American Regional Broadcasting Agreement (NARBA), most U.S. radio stations were shifted to new dial positions, so KQW moved to 740.

In the early 1940s, the San Francisco Bay area affiliate for the CBS radio network was KSFO, which, because it operated on a regional frequency, was limited to a power of 5,000 watts.

KCBS already had a long history in news dating back to World War II, when it was the center of CBS' newsgathering efforts in the Pacific Theater.

Notable anchors and reporters who became popular during the early "Newsradio" era included Al Hart, Frank Knight, Dave McElhatton (whose KCBS tenure dated to the early 1950s, including hosting a popular morning show on the station before the all-news format was implemented; McElhatton moved to KPIX-TV in 1977, where he was a highly popular and trusted lead anchorman until his retirement in 2000), Ray Hutchinson (KCBS' first business anchor under the all-news format, delivering his updates from the floor of the Pacific Stock Exchange), Ken Ackerman (who began on the station in 1942, later hosting KCBS' version of Music 'Til Dawn and eventually becoming a news anchor under the all-news format, serving until his retirement in 1995), Bob Price, a longtime business anchor and editor for KCBS who worked for over 20 years at the radio station, anchored from the Pacific Stock Exchange until his retirement on November 5, 2009.

[31] In 1990, KCBS became the primary station for the Bay Area's Emergency Broadcast System after KNBR, the former primary EBS station, failed to activate the Emergency Broadcast System due to major technical malfunctions caused by the engineering department at KNBR during and the aftermath of the 1989 Loma Prieta earthquake.

The Federal Communications Commission called the situation "revoked" as the decision was made to move its primary EBS status to KCBS after the major fail on KNBR.

Local commercials which are heard on the radio signal are replaced on the internet stream for nationally and regionally sponsored ads, a few public service announcements, station promos, promos of CBS Television shows, and repeats of pre-recorded feature segments already on the broadcast schedule (including StarDate and Science Today, produced by the University of California).

In March 2010, KCBS and the other CBS Radio stations blocked Internet listeners outside the United States from accessing its live stream.

While CBS shareholders retained a 72% ownership stake in the combined company, Entercom was the surviving entity, separating KCBS radio from KPIX.

More contentious is whether KCBS can be considered the oldest radio station in continuous service, due to the fact that, following the end of World War I, Herrold did not resume regular broadcasting until May 1921.

[43] (Other candidates for oldest U.S. radio station include 8MK / WWJ in Detroit, which began regular broadcasts in August 1920; WOC in Davenport, Iowa, which traces its origin to station 9BY, beginning regular broadcasts around September 1920; 9ZAF/KLZ in Denver, with nightly concerts beginning in October 1920; and 8ZZ/KDKA in Pittsburgh, which began operating on November 2, 1920.)

[44] The program made the claim that KCBS is the oldest radio station, predating by eleven years both WWJ and KDKA.