After the war Raytheon was in a quandary. The need for its radar equipment had dropped sharply. Raytheon hoped to continue to supply the government with magnetrons, but who knew when the government would want thousands of magnetrons a week again? The new heating apparatus seemed the answer to a corporate prayer.

Radarange.

The first "Radarange" weighed 750 pounds and cost three thousand dollars. It was a commercial product, attractive to restaurants, but not suitable for home use. Then Tappan formed an alliance with Raytheon. Skilled engineers were able to reduce the size of the magnetron and make a version marketable in 1955 as a home appliance. They were still expensive and bulky, though, because of the cost and size of components. Microwave ovens were not widely accepted for household use until the development of transistors made them compact and cheap to build in the...