In 1963, the station became a CBS affiliate and joined WHP-TV (channel 21) in Harrisburg and WLYH-TV (channel 15) in Lebanon to form the Keystone Network. The three stations provided a strong combined signal with about a 55% overlap. Initially, WHP-TV, WLYH, and WSBA aired the same programming despite separate ownership. By the late 1960s, while all three stations ran most of the CBS programming schedule, WHP-TV ran different local programming during non-network hours, while WLYH and WSBA continued to simulcast for nearly the entire broadcast day. WHP ran CBS shows that WSBA and WLYH preempted, while the latter two stations ran programming that WHP preempted, allowing most of the market to view the entire CBS schedule. All three ran most of the CBS lineup, duplicating over three-quarters of the network's programs. This arrangement was necessary for the days before cable gained significant penetration.