Bench Talk

When in 1945 Raytheon’s engineer Percy Spencer accidently discovered the potential of RF energy for heating food (or in Spencer’s case, for melting a chocolate bar in his pocket), the device generating that energy was a magnetron. Sixty years later, this venerable “vacuum electron device” is still powering everyone’s microwave ovens, making it the only consumer product still using a vacuum tube rather than a semiconductor for any purpose. However, this last bastion of vacuum tubes in consumer electronics may soon be relegated to history now that RF power transistors have achieved the required RF output power, efficiency, and ruggedness required to replace them.