Technical Articles

The Story of the Super-Heterodyne   PDF (17.3M)
Its origin, development and some recent improvement - A Radio Club of America paper
by Edwin H.Armstrong, Marcellus Hartley Research Laboratory, Columbia University, New York
Published in Radio Broadcast, July 1924.

Vacuum Tubes and Their Uses   PDF (.6M)
Includes a non-technical explanation of the operation of the vacuum tube.
by M.L. Muhleman
Published in Radio News, August 1926.