INDIRECTLY HEATED ELECTRON TUBE HEATER

PROBLEM TO BE SOLVED: To provide an indirectly heated electron tube heater, which has large mechanical strength and small heat generation at a heater end part, and is easily processed. SOLUTION: A first tight-pitch core wire coil 21 continuing to a heater main part 20 is wound a pitch which is twice the diameter of a core wire. Then, the same core wire is turned back, and a second core-wire coil 22 is wound at a coarse pitch of 9 times or more of the tight coil pitch, forming a double- coil-winding part. Furthermore, a third tight-pitch core-wire coil 23 is formed with the same core wire at a pitch same as the first tight pitch, the both tight- pitch core-wire coils form a single tight-coil winding part which bite into in-between each other's valleys.