I need microwave oven with temperature control range of 0 - 50 degrees centigrade for checking of thermal stability of paint samples.

It does not work that way. The microwave OVEN generates (electromagnetic) microwaves that are absorbed by the molecules of the food in the oven, the container and the air.
The absorption rate depends on the molecular composition. After enough microwave energy is absorbed the overall temperature increases and the food is warmed, heated or cooked. If your mixture is inhomogeneous some parts absorb more energy while other absorb less and you can have hot spots.

The power level by itself won't give you an indication of the temperature because you need to know the time that the power has been applied. In simple terms Energy =time*power. The temperature reached is somewhat proportional to the energy, that makes it dependent on the time and the power.

1 minute to cook a piece of bacon sounds pretty fast, really.

Try this:

MICROWAVE HEATING POWER TEST

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or by 70 if you're using a centigrade thermometer.

If the oven is grossly underheating or overheating, then you probably have a bad magnetron.

There should be a "mini-manual" (tech sheet) hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting, testing, and locating components.

At our Web site, we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

You can find helpful exploded view diagrams and order parts by entering your full model number from the tag on the oven here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Place a 1/2 litre of water in a plastic microwaveable container. Record its temperature and place it in the microwave. Microwave on full power for 1 minute. Leave for 30 seconds and measure the temperature again.
If the temperature rise is at least 10 degrees Centigrade, the magnetron is fine.

Unfortunately, the old owner's manual doesn't say, but you can do a test to see what its heating power is:

MICROWAVE HEATING POWER TEST

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or by 70 if you're using a centigrade thermometer.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Oddly, the owner's manual doesn't say.

You can contact GE customer service here, or if it's working properly, here's a test that will tell you how much output power it has:

MICROWAVE HEATING POWER TEST

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or by 70 if you're using a centigrade thermometer.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

The owner's manual (which you can download here) does not say, but most of their ovens from that era were 700 watts.

There is a way to check:

MICROWAVE HEATING POWER TEST

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or by 70 if you're using a centigrade thermometer.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

MICROWAVE HEATING POWER TEST

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or by 70 if you're using a centigrade thermometer.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

1) MICROWAVE HEATING POWER TEST

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or by 70 if you're using a centigrade thermometer.

2) If it's not hidden either behind the grille or control panel, they may have left it out as a cost-savings measure.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

If the cooling fan is not running, then that definitely needs to be addressed to prevent magnetron damage.

-.htmThere should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting & testing.

-.htmYou can usually find helpful exploded view diagrams and order parts by entering your full model number here.

It might be useful to first do a standard heat test.

-.htmMICROWAVE HEATING POWER TEST

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or 70 if you're using a centigrade thermometer.

-.htmWe're happy to help and we appreciate your thoughtful rating of our answer.

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

Procedure:

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).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or 70 if you're using a centigrade thermometer.

We're happy to help and we appreciate your thoughtful rating of our answer.