Few are aware of the fact that today's microwave is almost exactly the same as WWII radar, which is why the first microwave oven was called a "Radarange."
A lot of radars still use a Magnetron of some type. Magnetrons are still used in microwaves, and for RF-active paints and dyes, it's a pretty robust thingamabob.
For a radar that doesn't have to do much fancy stuff, or avoid RF jamming and Electronic Warfare, it's still the go-to choice. Simple and it lasts.
Solid-State has taken over in many cases but there's a time-limit on those items. Cheaper tho. Get an older GE microwave, like from the 2000s. Should last a Millenial until they pass away from old age.