This disk contains scans of the pages of a Collins 75A-4 Receiver Service/Operations Manual. These pages are in .PDF format, and the disk also contains the distributable version of the Adobe Acrobat reader, which is required to view and/or print the pages. This manual covers just about everything you need to know to adjust, align, repair, maintain, or just understand the 75A-4 Receiver. What's nicest about this is that it's text-searchable .PDF format. That way, not only can you print pages (or entire manuals) as you need them and mark them up as needed, since you can always print a fresh one, but if you're interested in something about (for instance) the AVC circuit, you can do a "find" with the parameter "AGC" and then control-G your way to each use of the term "AVC" in the book. It's only a little over sixty pages, but that still is a mighty useful function. Please note that this is made specifically from the 15 July 1957 revision of the manual. It includes all service and operations information current at that time, including schematics, parts lists, circuit descriptions and etceteras.