Volume control is one of the best extra features a microwave can have, but it’s pretty rare. Some models allow you to mute the beeping, but few microwaves let you adjust the actual volume. We also prefer models that stop beeping when the oven door is opened. It’s a small perk but one that many of our testers appreciated, particularly those who find the beeping annoying.
Frequently used microwaves need to be cleaned at least once per week, because any food remnants stuck to the walls can get overheated and cause damage to the microwave itself. A simple trick (courtesy of Wirecutter deputy editor Christine Cyr Clisset) is to nuke a bowl of water for a few minutes on high: The steam will loosen most gunk, and you can wipe it out with just a plain paper towel or a sponge. For cleaning the outside of a microwave, Good Housekeeping recommends spraying cleaner onto a towel and not on the actual surface, where it can get into the perforations and damage the internal elements.
The Panasonic NN-T945SF offers 2.2 cubic feet of interior space and 1,250 watts of power to heat food in less time than much of the competition. “It offers power levels from 1-10 with 10 being the highest,” explained one of our testers, “and I found that even using level 5, the microwave is able to heat the food very quickly and evenly.” Other pluses include the sleek stainless steel appearance and 14 auto cook options. If you frequently use your microwave to cook, steam, or defrost, you’ll appreciate the built-in inverter, which delivers consistent heating power that won’t leave food rubbery or unevenly heated. People find the display and controls to be easy enough to use, but a few online reviewers said they experienced button failure for the door after several years. The microwave is also quite large, so it's not a good choice for small homes.
The plasticizers which received the most attention are bisphenol A (BPA) and phthalates, although it is unclear whether other plastic components present a toxicity risk. Other issues include melting and flammability. An alleged issue of release of dioxins into food has been dismissed as an intentional red herring distraction from actual safety issues.
Its high-tech capabilities don’t seem to cause complications, and reviewers find it easy to set up. A visually impaired reviewer writes: “I’m always hesitant when I buy something that needs to be paired with something else in order to get the full benefit of it. Sometimes, something on the screen needs to be entered which we can’t see. There might be on-screen prompts or whatnot. This microwave had none of that. It was a cinch to set up and works beautifully.” Others love its small size. “We have a VERY small kitchen with barely any counter space so I was very pleased with how compact it is,” writes one commenter.
The cooking chamber is similar to a Faraday cage to prevent the waves from coming out of the oven. Even though there is no continuous metal-to-metal contact around the rim of the door, choke connections on the door edges act like metal-to-metal contact, at the frequency of the microwaves, to prevent leakage. The oven door usually has a window for easy viewing, with a layer of conductive mesh some distance from the outer panel to maintain the shielding. Because the size of the perforations in the mesh is much less than the microwaves' wavelength (12.2 cm for the usual 2.45 GHz), microwave radiation cannot pass through the door, while visible light (with its much shorter wavelength) can.
Sir Henry Tizard travelled to the U.S. in late September 1940 to offer the magnetron in exchange for their financial and industrial help (see Tizard Mission). An early 6 kW version, built in England by the General Electric Company Research Laboratories, Wembley, London, was given to the U.S. government in September 1940. The magnetron was later described by American historian James Phinney Baxter III as "[t]he most valuable cargo ever brought to our shores". Contracts were awarded to Raytheon and other companies for mass production of the magnetron.