James Sweet writes:

Michael A. Terrell wrote:
wrote:

I've read that the very first microwave ovens had no interlock, you
could open the door with them cooking. Basic switches were retrofitted
following injuries.



I find that damn hard to believe, since they were developed by
Litton. Litton had a lot of experience in manufacturing RADAR and
Microwave transmitter parts as well as the safety requirements. These
fields have extreme safety requirements. The RADAR equipment I worked
on had multiple interlocks. The 2 MW pulse RADAR at Ft Rucker had three
sets of keyed interlocks that shut down different parts of the
transmitters. You had to remove the key to open each gate as you went
up the steps to the antenna on the roof. You kept the three keys in
your pocket while you were up there, and had to lock the gates in the
right sequence to turn the system back on.




The oldest microwave I've ever used was an ancient Amana RadarRange my
grandparents had, I believe it was early 70's vintage. When I was a kid
we had an enormous Litton 1200W oven from the late 70s, both of those
would stop when the door was opened.

I did encounter an early 80's microwave once that would keep running, it
was obviously a defective interlock setup, I opened the door and it took
a moment to register that it hadn't shut off.

I've seen a microwave oven where due to most likely an interlock problem,
the turntable and fans will continue to run if the door is opened, but
the microwaves are off.

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