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.
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