Collection on Jennings Technology

Finding aid created by History San Jose Research Library staff using RecordEXPRESS
History San Jose Research Library
1661 Senter Road
San Jose, California 95112
(408) 287-2290

Descriptive Summary

Title: Collection on Jennings Technology
Dates: 1945-2000
Collection Number: 2017-29
Creator/Collector: Harding, Henry Jennings Technology Corporation ITT Corporation
Extent: 6 linear feet
Online items available
Repository: History San Jose Research Library
San Jose, California 95112
Abstract: Records created by Jennings Manufacturing Company (later Jennings Technology Corporation) during operations in San Jose, California. Includes material acquired as part of the Perham Collection of Early Electronics as well as records collected when the plant closed down in 2017.
Language of Material: English


The collection is open to the public for research by appointment with the Curator of Library & Archives.

Publication Rights

In copyright.

Preferred Citation

Collection on Jennings Technology. History San Jose Research Library

Acquisition Information

The collection is a combination of materials originally donated by Jennings employee Henry Harding to the Perham Foundation at Foothill Electronics Museum, and transferred to History San Jose in 2003; and records given to History San Jose in 2017 with corporate approval by the facilities manager at Jennings Technology's McLaughlin Road factory in San Jose when the plant closed down.

Biography/Administrative History

At 12, Jo Emmett Jennings built his first radio receiver, with an oatmeal container to form the coil and a “catwhisker” detector. In 1931, the 20 year old ham operator was hired as the night and Sunday operator at San Jose radio station KQW. After graduating from San Jose State College in 1936, Jennings went to work for Eitel-McCullough, and soon decided to start his own vacuum tube company. Jennings Radio Manufacturing Company was born in 1940 in a chicken house in his father’s San Jose orchard. The first products Jennings developed were vacuum dielectric fixed capacitors with glass envelopes. His first big order was for 1,000 capacitors, a device used in nearly all radio systems in which an electric charge can be stored. Lacking tantalum to make them — a metal in very short supply during the war — he used sheet metal salvaged from old motor oil cans for his first capacitors. Since he couldn’t afford a Litton lathe, he built his own and trained his own glass-blowers. The company quickly expanded. In 1946, he patented a variable version of his capacitor, which made it possible to quickly change the frequency of a transmitter and use a broad range of frequencies. His employees were encouraged to offer ideas for improving both products and manufacturing processes. The firm developed vacuum switches and relays, widely used in electrical circuits. Vacuum relays were used extensively in the early space program to modify the direction of orbiting satellites. The company was sold to International Telephone and Telegraph Corporation in 1961. The Jennings brand continues to produce non-thermionic vacuum components including vacuum and gas filled capacitors and relays, vacuum interrupters, vacuum contactors, vacuum coaxial relays, switching matrices,a nd test and measurement equipment. The San Jose facility closed its doors in 2017 as manufacturing was distributed to other locations.

Scope and Content of Collection

The collection documents the products created at the Jennings San Jose facility at 970 McLaughlin Avenue, San Jose, from its founding in 1940 through the late 1990s, and the employees who worked there. Product records include schematics from the 1940s-1950s, catalogs, commercial photographs, and print advertisements. Employees are documented through marketing photographs of events and facilities productions, several technical notebooks, employee newsletters, and a video produced in 1995 that documents the production process. In addition, there are multiple photographs of the San Jose plant, as well as the Salinas, California, plant.

Indexing Terms

Vacuum capacitors
Electric relays
Jennings, Jo Emmett
San Jose (Calif.)
photographic prints
manufacturers’ catalogs
color slides
technical drawings
manuals (instructional materials)
laboratory notebooks
motion pictures (visual works)

Additional collection guides