On Thu, 15 Oct 2009 09:02:27 -0700 (PDT), mynick
wrote:

no shorts between magnetron contacts or ground but when plugged it
does not heat the oven contents and has loud hum
Is it dead(how to make sure) or perhaps requires say 1v higher cathode
heating voltage than what transformer supplies?

This is tube that came with a microwave oven, and the tranformer that
came with it too?

Did it used to work?

I think it unlikely that it requires a mere 1 volt more voltage, or
that the working transformer doesn't provide the right voltage. The
transformer may be the most expensive part ot replace.

Be careful running the thing with the cover off. I presume there is
still a shield around the microwave tube, but if so, absolutely don't
run the thing without the shield. Radio Shack used to sell
inexpensive (10$) microwave detectors, for testing leakage around
microwave ovens. Maybe they still sell them. I know that mine
worked well, because I had an overn without a latch, and by pulling
the door open a little, I was able to watch the meter reading rise
from very very low to quite a bit higher.