MARCHI

Raytheon entered tube history by addressing a practical problem of early radios: powering their circuits without bulky anode batteries. The company was founded in 1922 in Cambridge, Massachusetts, as the American Appliance Company. Work on gas rectifiers led in 1925 to the helium-filled Raytheon type B tube for power supplies then called “battery eliminators.” It made direct current from the alternating-current mains available to a receiver. The tube's name also became the company's name during its early growth.

The type B is distinctive as a cold-cathode rectifier: unlike many electronic tubes of its day, it needs no heated filament. Its construction and the later BH and BA versions reflect efforts to match voltage and current to the needs of radio receivers. A period example bears the name Raytheon Manufacturing Company and Cambridge on its base; that inscription links the object to a company and a city, not to every later production location of the group. The rectifiers' success opened the way to a broader range of tubes for radio and power supplies.

Raytheon later moved into special tubes, military components and microwave technology. This expansion makes the story of the brand much larger than its first rectifier, although that tube explains the technical origin of its identity. Historical records also mention connected companies and activities, such as ELSI and Raytheon-ELSI in Italy: these are industrial relationships to date and distinguish, rather than interchangeable names for one plant. The proper reading of a Raytheon tube always begins with its type, marking and period before assigning its maker and origin.