Peter Hucker wrote:

Is it really true that turning on a microwave with nothing in it will break it?

Even more worrying - will it catch fire or explode?

Don't they have a safety cutout? Can't it sense the Klystron overheating,

That would be a Magnetron tube, and yes, I thenk they all have a
thermostat on
the tube. This is also to prevent a fire if the cooling fan seizes up.
But, in the
case of no food to absorb the microwave energy, the reflected power can
build up
higher than normal voltages in the tube and cause permanent damage
before the
entire anode overheats.

or a build up of microwaves over a certain level?

I have purchased a new microwave which has an easier to grab control. I'm concerned one of my pet parrots will switch it on! (Seriously, they do stuff like that)



Parrots? What about kids? I suspect quite a few microwaves get "toasted"
by kids turning them on empty. I know they can survive a few seconds of
this abuse without noticeable damage. You could unplug it or leave the door
open (I'm pretty sure a parrot couldn't close the door.)

Jon