Browning-Drake was the company that got the National Company into radios. Along with several period articles and pictures, this site lists parts sources needed to build your own 1920s broadcast receiver.
Many consider Collins Radio to be the Cadillac of ham radio equipment. A large exhibit area with plenty of equipment pictures, details and specifications, a historical summary of Collins Radio and lots of good articles, references and links makes this a great place to find out more about this company and their products.
In the late 50s RL Drake equipment demonstrated that "built like a battleship" was no longer the mark of a great radio. Lots of information about the RL Drake Company and their products can be found on this site. Included are also forums of interest to RL Drake Company enthusiasts and pdf "reprints" of many manuals and magazine articles.
Along with a short account of the history of the British Eddystone Company and their major radio models, this site includes a directory of Eddystone models covering the 1920s to 1973.
Where Collins is the Cadillac of ham radio equipment, Hallicrafters is the Chevy. The Hallicrafters line of equipment started at the lowest priced short wave listener radios to the newest single sideband gear of the 60s. This site provides a good sampling of their gear along with a short history of the company.
Hammarlund introduced the first commercially produced short-wave superheterodyne receiver, the Comet-Pro, in April of 1932. This site includes company history, valuable equipment information, downloadable manuals, service articles and repair tips that help the visitor appreciate radios from this company.
In the 30s Harvey Radio was known as the poor man's Collins. This site offers a detailed perspective of this company along with great scans of original articles and brochures covering more than just Harvey Radio.
Many hams starting out in the 50s, 60s and 70s began with a Heathkit. Ham radio Heathkits are now gone but the company is still around. This site includes lots of good information about Heathkit including an article detailing the changes of the last 15 years.
James Millen led the National Radio Company development efforts that created classic receivers like the SW-3, HRO and NC-100. In 1938 he left National to form the James Millen Company. This virtual museum, created and maintained by the James Millen Society, does an excellent job of documenting this company, their products and their history.
Swan began in 1960 by building and selling transceivers that were an inexpensive alternative to the Collins KWM-2. This site includes good technical information about Swan equipment, a little history and reprints of the Swan Newsletter.
World Radio Labs was founded by Leo Meyerson. This site displays a few items from the WRL product line along with reproducing several vintage ads.
Hampedia lists equipment from over 20 amateur radio equipment companies. Besides a small photo, many entries include a summary of the equipment specifications.
LA5KI's Vintage Ham Radio Photos offers equipment specifications and supplementary photos of tube ham radio equipment from over 50 manufactures.
RigPix has photos and a short specification block for each of over 3000 ham radios.
Radiomuseum.org includes search capability into a catalog of Old Time Radios including Crystal Receivers, Loop Antennas, Speakers, Rectifiers, Hi-Fi Amplifiers, Record Players, Tape Recorders, Mirophones, Old Time Amateur gear, Boatanchors, etc. Extensive data of more than 115,000 Old Time Radios, with over 300,000 pictures including over 120,000 printable schematics are available. The site also shows 45,000 collector prices and data for 27,000 tubes.