[Jeffhs]

It's probably a good thing these machines don't exist anymore, except for the one in Washington state on eBay. According to the eBay listing, they used four radio transmitting tubes and must have put out loads of RF when they were on, not unlike kilowatt linear amplifiers such as are used in amateur radio stations. The seller also said that if you were anywhere near one of these things when they were operating, you, as well as the food, were going to be cooked. Hardly seems safe to me.

The machine, IMO, looks ugly as well, not the kind of thing anyone would expect to find in a 1930s kitchen. Also, the external power supply needed to operate these things was probably as big (or perhaps even bigger) than the cooker itself. Not to mention the huge amount of electricity these machines drew from the AC line. In the 1930s, I doubt that many restaurants had high-amperage electric service; those that did, and had a cooker like this, probably had sky-high electric bills every month. I mention high-capacity electric service because I am sure these machines drew an insane amount of power from the line when they were in operation; any eatery with standard (15-ampere) electric service might find itself in flames (or with a blown main fuse if the fuse box itself didn't burn out or burst into flames from the overload) the first time one of these cookers was turned on.

This cooker may have been the forerunner of today's microwave ovens, but as unsafe as it was from a radiation standpoint, I'm not surprised it didn't catch on. The government probably confiscated most of them for just that reason--that they were unsafe and extra-heavy power hogs. Even the first microwave ovens that were introduced in the mid-1950s by Tappan were probably much better, to say nothing of safer and smaller, than any "radio sandwich machine" of the '30s.

BTW, I bought a package of 12 "White Castle" brand frozen cheeseburgers the other day. The instructions for heating these begin as follows: "Separate sandwiches in the package." (They are packaged in cellophane bags, two to a package.) So even today, some national brands of frozen hamburgers/cheeseburgers are still referred to as "sandwiches", and probably always will be. I don't know how long White Castle has been in business, but if they still call these small hamburgers sandwiches, they may have been around for quite a few decades. Some expressions never seem to go out of style, I guess.