Question about Sharp R-820B Convection/Microwave Oven

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Measure microwave oven heating efeciency or effectiness

This is not a problem, but a test.
I ran across this test 25 or more years ago while experimenting with a Heath Kit microwave oven. The objective was to measure the temperature rise in a beaker of water to determine the heat rise over a period of time.
This experiiment placed about a liter of water in a glass jar larger than a liter size (1.25 liter, aprox). Measure the temperature before heating and after heating to determine the temperature rise over a measured time (before and after). There was a formula for this test and I have misplaced or lost it. I am trying to test the heating effeciency of one microwave over another. This would also alow measurements over time to determine if the microwave oven continues to produce the same power in the future to decide if it is time to replace the oven. If you could find this formula or come up with a new one, I would be very appreciative.
Many Thanks! John Q. Adams,

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Re: Measure microwave oven heating efeciency or...

For 1 liter of the oven for 60 seconds....then multiply the difference in temperature (the increase) by 35 to get an estimated output in watts.

There are variations on the procedure...this web site recommends a slightly different time and multiplication factor. This one describes a more accurate looking procedure.

Good luck...and I hope this is helpful!!

Posted on Jan 17, 2008

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The following test will provide a suitably accurate measurement of the output power of any microwave oven. Variations or errors in performing this test will produce uncertain results. If the line voltage (from the electrical outlet) is low, the magnetron output will be correspondingly low.

Equipment needed:

- Microwave safe container with 1000 mL (1 Liter) gradation.

- Fahrenheit or centigrade thermometer


Pour exactly 1000 mL (1 Liter) of cool tap water into the container. Using the thermometer, stir the water, then measure and record the temperature. For accurate results the water should be about 60 degrees F (20 degrees C).

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