__1955: __The first domestic microwave oven is introduced.

Walk into almost any American kitchen today and there's one appliance that is likely to be sitting on the counter somewhere – a microwave oven.

The microwave oven didn't come from humble beginnings. It's an appliance born of the radar systems used in World War II – and the labs of what is now one of the biggest U.S. defense companies.

Early in World War II, physicists invented the magnetron, an electron tube that could generate microwaves and improve the capability of British radar systems to spot Nazi warplanes.

Raytheon engineer Percy LeBaron Spencer was working on an active radar set a few years later when it accidentally melted a candy bar in his pocket. He figured microwaves could cook food. Spencer then tried popping popcorn and making an egg using microwaves.

Raytheon had filed a patent for the microwave cooking process by 1945. Two years later, it built Radarange, the first microwave oven in the world.

The Radarange was as large as a refrigerator, but heavier. The tubes in the magnetron had to be water-cooled, so plumbing installation was required. Result: The first microwave oven weighed about 750 pounds and was nearly 6 feet tall.

The beta microwave was placed in a restaurant in Boston for testing. Raytheon introduced a commercial microwave oven, the 1161 Radarange, in 1954. It was expensive – priced at $2,000 to $3,000 (the equivalent of $16,000 to $24,000 in today's cash).

Raytheon licensed its technology to the Tappan Stove company. Tappan introduced a large 220-volt wall unit as a home microwave oven in 1955. It sold for $1,295 (figure $10,500 today).

It had two cooking speeds (500 and 800 watts), stainless steel exterior, glass shelf, top-browning element and a recipe card drawer. But the price was high, and microwave cooking was an unknown.

Consumers stayed away from the device. Sales were slow.

A Studebaker subsidiary called Franklin Manufacturing had been making magnetrons and selling microwave ovens similar to the Radarange. Litton Industries bought Franklin from Studebaker in the 1960s and made a big breakthrough.

Litton developed the short, wide shape of the microwave that we're familiar with today. And it created an oven that could survive even when there was no object in it to heat.

Prices began to fall rapidly. Raytheon, which had acquired a company called Amana, introduced the first popular home model in 1967, the countertop Radarange. It cost $495 (about $3,200 today).

Consumer interest in microwave ovens began to grow. About 40,000 units were sold in the United States in 1970. Five years later, that number hit a million.

The addition of electronic controls made microwaves easier to use, and they became a fixture in most kitchens. Roughly 25 percent of U.S. households owned a microwave oven by 1986. Today, almost 90 percent of American households have a microwave oven.

Source: Various

Photo: 1967 promotional image for the Amana Radarange

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