E. F. Johnson Company Catalog. Coder 12 Radio Paging Encoder Service Manual. Material: paper. Size: 8 1/2" x 11". Description: white cover; black and white photograph of Coder 12 Radio Paging Encoder; white and black print: "Service Manual, Coder 12, Encoder, Coder 12 Radio Paging Encoder, Model No. 244-412"; 21 pages.