Vintage AIRADIO models TRA-1A, TRA-1B and TRA-1C single channel crystal controlled aircraft radio transmitter. Original old Sams Photofact manual includes schematic, layout, alignment instructions, voltage & resistance test chart, repair parts list and description. 4 pages. Dated 1947. Airadio Inc., of Stamford, CT. This manual would make a sensational accompaniment to your classic retro radio equipment.