I just tested my microwave diode where, unfortunately, it seems to be good:
http://farm8.staticflickr.com/7358/9...dac4708b_o.fig

Forward biased with a 9 VDC battery, I measure 7 VDC across the diode;
reverse biased, I read 9 VDC across the diode (given a 200 ohm
current-limiting resistance in series with the battery).

I was hoping the diode was bad, because otherwise, I don't know what's
wrong with the microwave. It does everything but heat up the food.

It makes noise, the lights light up fine, the controls all work,
and it beeps when done, etc. - but it just won't heat up anything.

Did I test the diode properly?