Vintage SENTINEL models 1U352, 1U352-2 and 352 5 tube Superheterodyne AM radio receiver. Original old Sams Photofact manual includes schematic, layout, alignment instructions, voltage & resistance test chart, repair parts list and description. 4 pages. Dated 1956. Sentinel Radio Corp., of Evanston, IL. This manual would make a sensational accompaniment to your classic radio equipment.