Vintage Radio Service Manual - SENTINEL model 313-I, 313W, IU-313-I & IU-313W  6-tube Superheterodyne AM radio receiver. Manufactured by Sentinel Radio Corp., of Evanston, IL. Dated 1948. 4 pages. Original old Sams Photofact manual includes schematic, layout, alignment instructions, dial cord drive, voltage & resistance test chart, repair parts list and description. This manual would make a sensational accompaniment to your retro audio equipment.