How to Check a Magnetron with a Multimeter

This site contains affiliate links to products. We may receive a commission for purchases made through these links.

Even though they have applications at the highest level of scientific studies, magnetrons are utilized regularly by non-scientists who like to heat their food while in a hurry.

Most typically used in microwave ovens, a magnetron can convert magnetic and electrical currents into a strong and powerful form of heat. The key component of a magnetron is a filament radiating heat after getting an electrical charge. It then produces electrons as the heat rises. 

As the electrons move away from the filament to latch into positive electrodes, they are then influenced by a negative magnetic field. The negative field then resists the electrons, limiting them to an area where they start spinning in a circular motion. It produces even more heat, eventually creating energy that is powerful and hot enough to cook food. 

Brief History of Magnetron 

Early in the twentieth century, general electric employee Albert Hull created the magnetron. He could not discover any practical uses for his creation, and the device sat inactive for at least a decade.

During the pre-World War II era, engineers John Randall and Harry Boot encouraged their exploration of the magnetron, making one important change. Instead of encasing it in a glass, the two engineers utilized copper, which enables output of approximately four hundred watts in an area less than a half-foot.

Throughout those times, the tubes were utilized to boost the capability of sonar equipment. It also helps submarine crews locate hostile vessels right away. 

After the way finished, it wasn’t long before the magnetron was on its way to everyone’s kitchen. Percy Spenser from Raytheon Corp. started experimenting along with magnetron tubes in his lab. He noticed a candy bar in his pocket had melted into a sticky mess while he was meddling with the equipment in one scenario. 

Now curious, he threw some popcorns by the magnetron to discover what would occur. Shockingly, the kernels popped. In just a matter of months, he invented the first microwave oven, which weighed over a quarter ton, was more than five feet tall, and cost approximately $5,000. 

Apart from radar and ovens, magnetrons—ranging in output power from 600 watts to 1 million watts—are utilized in different scientific apparatus like plasma screens. Power should be generated in a microwave frequency. 

How Does a Magnetron Work?

The operation of a magnetron is based on the theory that energy generated by the motion of electrons under the combined effect of electric and magnetic fields can be utilized to cook food. The electrons must flow from the cathode end to the anode end for the tube to be functional. It generates RF energy, and that energy is radiated into the cooking cavity, where the food absorbs it. 

The tube uses a half-wave voltage double circuit and a permanent magnet to fluctuate and convert voltage supply into 2450MHz cooking frequency microwave energy. Remember that a microwave normally needs 1100 watts of energy to produce microwave energy of 700 watts. 

Microwave heating is very effective on liquids such as water, particularly frozen water, instead of fats and sugars. It’s a myth that a microwave oven cooks food from the inside. However, microwaves are absorbed by the food’s outer layers.

Furthermore, microwave ovens support deeper initial heat, unlike other methods, as it penetrates non-conductive dry substances at the surface of common foods. The microwave’s depth of penetration depends on its frequency and food composition. 

Take note that lower microwave frequencies penetrate better. 

Important Things to Consider When Using a Magnetron 

You won’t find any change in the intensity of radiation while cooking. However, as driven by a linear transformer, the magnetron is turned on and off in cycles of several seconds at a time. 

Bear in mind that food should be present in the microwave when it’s being operated. If there’s no food, the waves will be reflected into the wave field, causing arcing because of their intensity. When that arcing continues for longer periods, the magnetron might be damaged. 

Modern microwaves often come along with a rotating center plate to make sure the food is evenly heated from every side. That plate can absorb microwaves that make it possible for smaller amounts to get heated and avoid arcing-causing resonant reflections.

Moreover, exposure to microwave radiation might involve risks to the human body. For instance, the eye lens doesn’t have a cooling blood flow. In turn, that makes it more liable to be harmed because of overheating on exposure to microwave radiation. 

Please don’t buy a microwave with a warped door or poor sealing, as it can be extremely risky. 

How Do You Test a Magnetron Using a Digital Multimeter?

Take note that the magnetron is the core of your microwave oven. Once the capacitor, transformer, and diode communicate with one another to convert AC to DC current, the magnetron then kicks in. It starts sending microwaves into the inner cavity to heat the drink or foods you want to consume.

To test your magnetron, kindly follow the steps outlined below.

  1. Use your digital multimeter to measure for a continuous electrical pathway.
  1. After you have accessed and detached the magnetron, you will see two terminals on each end of the part.
  1. Put the prongs of your digital multimeter on each of the terminals. The reading you receive should be less than 1 ohm if the magnetron is working fine. 

Final Thoughts 

A magnetron cannot be fixed; hence, you should replace it right away if you find you have a bad or malfunctioning magnetron. It is not a costly component, running at least $150 to $200. At this point, replacing your entire microwave appliance might be a better and practical option. Of course, that will depend on how much value your microwave has for you and your entire family. 

In case troubleshooting and DIY work are not your forte, feel free to seek the help of a professional electrician and see if they can answer any concerns you may have. We hope you find this guide informative and helpful. Please share your thoughts with us by leaving your comments below.

Special offer for our visitors

Get your Soldering Iron Guide For DIYERS

We will never send you spam. By signing up for this you agree with our privacy policy and to receive regular updates via email in regards to industry news and promotions