Vintage Radio Service Manual - SONORA model WDU-233 portable, battery operated 4-tube Superheterodyne AM radio receiver.  Manufactured by Sonora Radio & Television Corp. Dated 1947. 4 pages.  Original old Sams Photofact manual includes schematic, layout, alignment instructions, voltage & resistance test chart, repair parts list and description. This manual would make a sensational accompaniment to your retro audio equipment.