JPS6352420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a method for manufacturing cathodes of electron tubes such as VHF output tubes and microwave output tubes, and provides a simple and inexpensive manufacturing method.

Conventionally, cathodes for microwave output tubes such as VHF output tubes and magnetrons are made by argon arc welding between a thermionic emitting filament made of thorium tungsten, etc., and a support that supports the filament and supplies heating current to the filament. There are two methods: assembly by welding such as plasma arc welding and laser beam welding, and a method of heating and brazing using heat radiation or the like in a hydrogen atmosphere using a brazing material such as platinum, ruthenium molybdenum alloy, or rhenium. However, the former method, that is, the welding method, has the disadvantage that the welded part tends to become brittle and is difficult to work, and requires skill, while the latter method, that is, the brazing method, has the disadvantage that the brazing metal is expensive, and the process of incorporating the brazing metal is difficult. There were also some drawbacks that made it necessary.

The present invention eliminates the above drawbacks and will be described below with reference to FIG. In Fig. 1, 1 is a filament made of thorium tungsten, etc.;
3 is a support made of Mo that supports it, 4, 5
is a lead wire made of Mo that fixes the filament 1 and the supports 2 and 3 and supplies current to the filament 1. In the present invention, the support 2,
For 3, apply Ni plating of about 5μ in advance. It is then heated in a built-in hydrogen atmosphere as shown in FIG. Heating is performed by making the heating filament 6 incandescent and using its radiant heat. In this case, the Ni to be plated first melts and causes filament 1, support 2,
3. It gets into the gap between the lead wires 4 and 5. Ni eluted by further heating
A NiMo alloy solder is produced by heating and reacting with Mo of the base, and the support and the filament or the support and the lead wire are brazed and fixed to complete the cathode structure.

With this method, the NiMo alloy can have a higher melting point than Ni, so there is no risk of sputtering during operation unlike with Ni, and the brazing strength is sufficient.

As described above, according to the method of the present invention, the supports 2 and 3 can be easily plated with Ni, and expensive brazing filler metals are not required. It has the advantage of increasing the

Note that the support and the leads are not limited to Mo, and may be made of an alloy containing Mo as a main component, or may be one whose surface is plated with Mo.

[Brief explanation of the drawing]

The figure is a sectional view of a main part for explaining the present invention. 1... filament, 2, 3... support, 4,
5... Lead wire, 6... Heating filament.

Claims (1)

[Claims] 1. A method for manufacturing a cathode assembly for an electron tube having a filament for emitting thermionic electrons, a support molded from Mo that supports the filament and supplies a heating current to the filament, and a lead wire, in which the support is plated with Ni. a step of combining the Ni-plated support, a filament, and a lead wire; a step of heating the combined support, filament, and lead wire in a predetermined state to elute Ni; manufacturing a cathode structure for an electron tube, comprising the steps of: heating and reacting Mo of the substrate to produce a NiMo alloy solder; and brazing the support and the filament or the support and the lead wire. Method.