105.7 signed on in 1963 as WCBC-FM, a 2,800-watt religious station owned by the Brinsfield family. It was sold to Key Broadcasting (WBMD) in 1968. Around 1972, tower was moved from I-95 South near I-285 to Moravia Road, and the station went 50,000 watts directional (with 2,800 watts toward York, PA).
Around 1978 after 98 Rock launched and took away WKTK's audience, WKTK's format was changed from rock to disco, which was short lived. The frequency went through a number of formats, none successful.
When the call letters were changed from WKTK to WQSR in 1982, it was because owner Carl Brenner signed with ABC for the network's new "Super Radio" satellite top-40 format that ABC canceled before it launched. WQSR went through a couple more formats; at one time, they were MOR with CBS News. Eventually--I'm guessing around 1986--they evolved into oldies, and the station became successful.