PURPOSE: To eliminate bonding and removing processes of the bonding agent by fixing a cylindrical member with groove for locating a cylindrical member, which fixes a core narrower than a diameter part of an electron beam passage made of spiral wire and both ends of the spiral wire, and a multistage cylindrical member and a dielectric member supporting rod equally in the circumference of a spiral wire, the spiral wire and the dielectric member supporting rod with the cylindrical member, and heating a main frame of traveling-wave tube and inserting it.

CONSTITUTION: A spiral wire 7 is installed on a core 1 till it abuts on a cylindrical member 2, and next, a cylindrical member 3 with groove is installed on the periphery of the spiral wire 7. A cylindrical member 6 of a stage next to the maximum diameter of a multistage cylindrical member 4 is put on the core 1 within the inner diameter thereof, is pressed till a groove side end of the cylindrical member 3 with groove abuts on the stage end of the multistage cylindrical member 4, and a dielectric member supporting rod 8 is assembled to a groove of the cylindrical member 3 with groove for fixing the multistage cylindrical member 4 and the core 1 with a locking screw 5, and the cylindrical member 6 is slid to the outside of the dielectric member supporting rod 8 so that the dielectric member supporting rod 8 is along the periphery of the spiral wire 7 to perform sub assembly of a delay circuit. A main frame 9 of the traveling-wave tube is heated at 500-800°C in the atmospheric air of N2, H2 gas, and while the core is inserted.