Prototype "Servodyne" Klystron-powered Microwave Oven

Roger F. French, Donald R. Lester, and John A. Gunnarson made this prototype microwave oven in 1961. Only two were produced. Instead of using a magnetron to generate the microwaves, this oven used a type of vacuum tube called a klystron. To see how the ovens would work in actual kitchens, Gunnarson used this one in his home and French used the other. Children of the inventors recall impressing their friends with the ease of cooking with microwaves, years before such ovens became commonplace.
French had founded Servodyne Corporation in 1960 to produce and sell microwave ovens for the home. But they faced stiff competition. Other companies like Raytheon, which had produced a large "Radarange" for commercial use in 1954, were working on home ovens that used magnetrons. Servodyne failed to attract enough funding to bring the invention to market, and the company folded in 1968.
Currently not on view
Object Name
electrical appliance
microwave oven
Date made
ca 1961
Gunnarson, John A.
Gunnarson, John A.
French, Roger F.
Lester, Donald R.
Physical Description
steel (overall material)
glass (overall material)
overall: 20 in x 24 7/16 in x 25 in; 50.8 cm x 61.99988 cm x 63.5 cm
ID Number
catalog number
accession number
See more items in
Work and Industry: Electricity
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
from John A. Gunnarson

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