MALRITE BUYS COX'S RADIO STATION UNIT <Malrite Guaranteed Broadcast Partners L.P.> said it bought WTRK Inc from <Cox Enterprises Inc> for 13.8 mln dlrs in cash. It said WTRK owns and operates WTRK-FM, a Philadelphia radio station. Transfer of the license for the sation has been approved by the Federal Communications Commission. Malrite Guaranteed said it is a limited partnerhip formed to acquire and operate radio and tv stations. It said Malrite Communications Group Inc <MALR> is the general partner.