Vacuum tube technology. Tube technology covered in other major categories (i.e. RCA and GE) are covered in those sections.
Dumont - Data and application notes from Allen B. Dumont Labs.
Eimac - Data and application notes from Eimac.
Electrons Inc. - Data from Electrons Inc.
FTR - Data from FTR (Federal Telephone & Radio).
Hughes - Tube-related data from Hughes, Inc.
Hytron - Data from Hytron.
Ken-Rad - Data from the Ken-Rad Co., before the 1945 aquisition by General Electric.
Machlett - Tube data from Machlett Laboratories Inc.
National Union - Data and application information from National Union.
Raytheon - Tube data from Raytheon Production Co.
RCA - Tube-related data from RCA
Signalite - Data and application information from Signalite, a neon glow tube manufacturer.
Sylvania - Tube data from Hygrade Sylvania, later known as just Sylvania.
Tung-Sol/Chatham - Data and application information from Tung-Sol, as well as its Chatham division.
United - Tube data from United Electronics, a Newark tube company that specialized in industrial power tubes, mostly low-tech.
Vacuum Tube Products/H.W. Ulmer/MU - Documents and specs from the three companies formed by Harold. W. Ulmer: Vacuum Tube Products, H.W. Ulmer Co., and MU Inc.
Westinghouse - Data and application notes from Westinghouse's tube department.
Military - US military documents on tube technology.