On Fri, 01 Jun 2018 16:21:19 +0100, Graham. wrote:

This is what I think of as a magnetron, as used in conventional microwave ovens with a turntable:
http://www.hokuto.co.jp/eng/products...dex_img_01.gif
It's about the size of a fist. So how do they make them flat under the food cavity in flatbed ovens? Does the magnetron sit under there and is redesigned to be flat? Or is there some kind of fancy rotating waveguide, and the magnetron sits at the side as before?


Basically the later I should think.

The one I had in the 1980s had a large aperture covered with mica on
the roof of the cooking cavity. The Magnetron was at the side of the
cavity with a brass wave guide leading up to the top. A squirrel-cage
fan blows air up the wave guide and not only cools the Magnetron, but
also rotates a paddle-wheel at the top, a rotating antenna, carrying
multiple reflectors thar distribute the radiation throughout the
cavity. I imagine modern bottom entry ones do a similar trick, but I
have yet to work on one.

I didn't realise they were available in 1980. So why aren't they all like that? Does it add a lot to the price?

--
"Flashlights are tubular metal containers kept in a flight bag for the purpose of storing dead batteries."