My oldest brother worked for an electric shop when microwave ovens first hit the market. I don't remember the exact year, but it was in the 70s. For Christmas that year, he gave my mom an Amana Radarange. The thing was (and still is) huge, at least by today's standards. Very heavy also. The thing had a dial timer on it and three buttons, an "on" button, an "off" button and a "defrost" button. Interesting enough, the defrost cycle had the manetron be on for about 20 seconds and off for about 20 seconds at a time. My mom used it until the late 90s without it ever failing and eventually just replaced it with something newer.
About a dozen years ago, I worked for a shop that had about 10 guys in it. During lunch, we all used a tiny, weak microwave oven that took a long time to heat our food. So I had this idea to bring in the old Amana Radarange. It still worked great and would heat our food in about half the time of the other microwave oven. Pretty soon I was still waiting in line to use a microwave oven because everyone was using my microwave oven instead of the shop-supplied microwave oven. After I moved on, I took the Amana Radarange with me and it still works great. I no longer use it, though, as I wonder about how much microwave leakage it has and I'm not going to buy a microwave radiation leak detector just to find out.