Vintage Radio Service Manual - HARVEY-WELLS model AT-3B-6 & AT-3B-12  (battery operated) Aircraft Transmitter (3105KC). Manufactured by Harvey-Wells Electronics, Inc., of Southbridge, MA. Dated 1948. 4 pages. Original old Sams Photofact manual includes schematic, layout, adjustment after installation instructions, voltage & resistance test chart, repair parts list and description. This manual would make a sensational accompaniment to your retro radio equipment.