MadSci Network: Engineering

Re: Do microwave ovens lose power after several years of use?

Date: Thu May 28 08:07:49 1998
Posted By: Rick Cousins, Regional Mgr/Chemist-Industry
Area of science: Engineering
ID: 896270478.Eg

Yes, home microwave ovens do lose power over time. There are several
reasons for this: These days, many electronic devices are all solid 
state--using transistors, integrated circuits, etc--instead of vacuum
tubes. But microwave ovens still utilize a specialized vacuum tube,
called a magnetron, to create microwaves. These tubes age due to many
factors including oxidation of the metallic elements within the tube,
and destructive feedback which occurs when some of the microwave
energy is not absorbed by the food (load) in the chamber, but reflects 
back into the magnetron tube.

A patented device called an isolator can help prevent destructive 
feedback. It places a device in the waveguide which deflects the
reflected raditation away from the tube.

More details are available:

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