US3287080A - Electron tube mount and method of making the same - Google Patents

Description

Nov. 22, 1966 J. A. GAUSZ 3,237,080

ELECTRON TUBE MOUNT AND METHOD OF MAKING THE SAME Filed June 27, 1963 I I I I I I 4 I 5 I INVENTOR .ffl/m/ A 641/52 -fl, d4 how United States Patent 3,287,080 ELECTRON TUBE MOUNT AND METHOD OF MAKING THE SAME John Alexander Gausz, Watchung, NJ., assignor to Radio Corporation of America, a corporation of Delaware Filed June 27, 1963, Ser. No. 291,084

15 Claims. (Cl. 3162) The present invention relates to electron tube mounts and to a method of making such mounts, and also to a method of salvaging mounts when one or more parts thereof have been damaged during assembly.

The invention is particularly advantageous in connection with the manufacture of a receiving type electron tube having a cathode-heater structure comprising a tubular cathode having a folded insulated heater therein, and an insulated helical spacer member disposed between the heater and cathode for increasing the insulation between the cathode and heater beyond that provided by the insulating coating on the heater. The insulation on the helical spacing member thus supplements the insulation provided by the coating on the heater for effectively electrically isolating the heater from the cathode. This is of particular advantage when the cathode and heater are operated at a relatively large voltage difference, such as in high voltage rectifiers.

In the manufacture of one kind of high voltage half wafer rectifier, a tubular anode and a tubular cathode are first assembled in concentric relation and mounted between and supported by two insulating wafers to provide an electrode cage. As a separate operation, an insulated folded heater is threaded through or inserted into an insulated helical spacing member, to provide a heaterspacer assembly. In the heater-spacer assembly, adjacent end portions thereof are bare of insulation for later fixing as by welding to lead-in wires of a stem. The heater wire is relatively thin so that the bare end portions or legs thereof can be deflected to appropriate ones of the lead-in wires. However, the wire of which the insulated spacer member is made, is relatively thick and rigid so that it cannot be readily deflected. In view of this difliculty in deflecting the bare portion of the spacer member, a desired bend therein is provided during formation of the spacer member to helical shape. After the heater is inserted into the spacer the heater-spacer assembly so formed is threaded into the cathode from the cathode end that is eventually to be adjacent to the stem in the finished mount. The electrode cage, with the heater-spacer within the cathode of the cage, and with bare end portions or legs of the heater and spacer extending from one end of the cage, is then mounted on a stem with the bare end portions referred to adjacent to the stem. When so mounted, ears of an anode of the cage engage one or more of the lead-in wires in the stem, to which they are then welded. A tab extending from the cathode is bent to engage another of the lead-ins and is welded thereto. In like manner, the flexible bare heater legs are deflected to engage others of the lead-ins and are welded thereto. The spacer member is then rotated within the cathode to dispose its previously bent bare end portion in engagement with a selected stud, or inner stem lead, to which it is then welded.

The stud and the lead-in wires in the stern are disposed in a circular array of larger radius than the cathode, and the bent bare end portion of the spacer extends laterally beyond an axial projection of the cathode. This lateral extension of the spacer places a limitation on the manner in which the heater-spacer assembly can be threaded into the cathode. Thus, the heater-spacer assembly can be threaded into the cathode only from the end thereof that eventually is to be adjacent to the stem in a finished mount. This limitation has heretofore precluded a salvaging of the mount parts when the heater or spacer are damaged as by loss of insulation.

Such loss of insulation is likely to occur as a consequence of engagement of the coated portions of the heater and spacer with a relatively sharp edge defining the cathode end from which the bare end portions of the heater and spacer protrude. Such engagement (occurring in rotating the spacer for engagement with its associated stud, deflecting the heater legs into contact with their respective lead-ins, and in the application of a force to these elements during the several welding operations), often causes chipping and loss of insulation from the heater and/or spacer at portions thereof adjacent to the cathode.

Once such loss of insulation has occurred, which can be determined by a visual inspection of a mount, it has heretofore been necessary to scrap at least a major part of the entire mount. This is a consequence of the fact that it is not readily feasible to separate an electrode cage from a stem to which it has been fixed, to permit substitution of a new heater-spacer assembly for the damaged one.

Such separation requires severance of elements that would irreparably damage the separated cage and stem and preclude their use in a repaired mount. One area where such severance would be particularly objectionable is that which involves the welded connection of one or more lead-ins to anode ears. The severance of the anode cars from their leads involves a cutting of the anode leads, thereby shortening the portions of such leads remaining in the severed stem. The shortened leads would be used to engage the anode ears in the repaired mount. As a result the spacing between the cage and stem of the mount would be reduced. Such reduced spacing would require a commensurate modification in the lengths of the other leads in the stem, for appropriate engagement with other cage elements. Such length modification, in turn, would involve a new stem forming operation to bend the shortened leads to desired shape. The cost of performing these operations on a stern after severance thereof from the cage would be such that it would be economically preferable to scrap the entire defective mount.

In addition to this unfavorable cost relation, is the fact that a severance of the anode lead-ins would leave short lengths of the lead-in wires welded to the ears of the anode. This would interfere with the subsequent welding of the shortened lead-ins or the lead-ins in another and new stem, to the anode ears. And finally, a use of the stem having the shortened lead-ins, would lower the position of the cage on the mount, to a degree that might be adverse to proper operation of the eventual electron tube. It is thus apparent that the increased handling of the cage and stem during salvage operations would be prohibitive in labor cost and result in a port salvage yield.

Accordingly, it is an object of the invention to provide an improved electron tube and method of making the same.

Another object of the invention is to provide a method of tube fabrication that includes an improved technique for salvaging a tube mount in which one or more parts thereof have been damaged.

A further object of the invention is to provide an improved method of salvaging an electron tube mount when a cathode heater and/ or a heater-cathode spacer employed therein, have been damaged.

According to one method of the invention, when a visual inspection of a mount reveals that insulation has inadvertently been removed from either or both of the heater and spacer, at regions thereof where electrical shorts to the cathode are likely to occur, the heater and spacer are removed from the mount without adversely affecting the remainder of the mount. The removal is accomplished by severing the legs of the heater and the spacer from their associated lead-ins and stud, and then pulling the heater and spacer from the cathode end remote from the stem. The spacer leg is severed at a region thereof sufliciently close to the cathode axis to prevent obstruction by the spacer leg to the removal of the spacer from the cathode.

According to another method of the invention, a new heater and spacer are inserted into the cathode in a novel manner. The insertion is effected at the cathode end remote from the stern, since access to the other end of the cathode is obstructed by the stem. Before the heater and spacer are inserted into the cathode, they are assembled by threading the heater through the helical spacer, so that the legs of the heater extend from one end of the assembly, and the bent leg portion of the spacer extends from the other end. The assembly is inserted into the aforementioned remote end of the cathode, with the said one end of the assembly from which the heater legs extend, leading. After a full insertion of the heater-spacer assembly into the cathode, the bare legs of the heater protrude from the cathode end adjacent to the stem, and the bare bent end portion of the spacer protrudes from the other end of the cathode. The protruding heater legs are then Welded to their associated lead-ins. The short lengths of the previously welded heater legs remaining on these lead-ins, do not interfere, because of their relatively small cross-sections, with the Welding of the lead-ins to the legs of the new heater. The bent leg portion of the spacer is welded to a clip anchored in a novel manner in an electrode spacing wafer engaging the end portion of the cathode remote from the stem. In this way, it is feasible to insert a new heater-spacer assembly into the cathode without the need to extend the laterally projecting bare leg end portion of the spacer through the cathode.

Further objects and features of the invention will become apparent as the present description continues.

In the drawing, to which reference is now made for an example according to the present invention:

FIG. 1 is a side elevation of an electron tube mount in which a salvaging operation according to the invention, may be performed;

FIG. 2 is a longitudinal cross-section of an assembly comprising a tubular cathode, a folded heater within the cathode, and an insulated helical spacer between the cathode and heater, employed in the tube mount shown in FIG. 1;

FIG. 3 is a longitudinal transverse view of an assembly of parts similar to that shown in FIG. 2 but in which the parts are arranged in a novel manner to provide a salvaging operation in accordance with the invention;

FIG. 4 is a top view of an electron tube mount salvaged in accordance with the invention;

FIG. 5 is a side view partly in section taken along the line 55 of FIG. 4 and rotated 90, of a clip anchoring an end of a helical spacer in a salvaged mount; and

FIG. 6 is a side view of the clip prior to insertion into an insulating wafer.

In FIG. 1 the mount of an electron tube includes a stem 10 made ofglass for example, and having lead-in wires extending therethrough. The portions 12 through 18 of the lead-in wires extending above the stem 10 as viewed in FIG. 1 are relatively thick, i.e. 30 mils, for preserving their initially formed positions in the mount and to provide rugged supports for the cage to be described. The portions 20 through 26 of the lead-in wires extending below the stem 10 engage contact prongs in a base, not shown. In addition to the lead-ins referred to, two studs 28, 30 are anchored in the stem and extend from the upper face thereof only, for support purposes.

The electrode cage portion of the mount includes a tubular anode 33 having side wings or flanges 34, 36 provided with cars 38, 40, 42 and 44 extending through two 7 ample.

spaced insulating wafers 46, 48, for support thereby. Within the anode 33 is disposed a tubular cathode 50 extending snuggly through openings in the wafers 46, 48 and kept in desired position by means of embossments 52, 54. The cathode 50 has an emitting coating SI thereon (FIG. 2) of conventional composition. Within the cathode is disposed a folded tungsten heater 56 having thereon an insulating coating 58 of aluminum oxide, for ex- The heater wire 56 has a minimum thickness of 2.5 mils. Bare end portions 60, 62 of the heater are welded to lead-in portions 14, 16. Between the inner wall of the cathode 50 and the folded heater. 56 is dis- 7 posed a helical spacing member comprising a wire 64 made of tungsten for example, and having a thickness of 5 mils. An insulating coating 66 is provided on the wire 64. This coating may be made of aluminum oxide. The lower end portion of the spacer 64 as viewed in FIGS. 1 and 2 is bent laterally away from the axis of the cathode for convenient welding of the bare portion 68 thereof, to stud 28. It will be noted that this requires that the bent portion of the spacer extend laterally appreciably beyond the lower end of the cathode 50. The anode ears 38, (FIG. 1), are welded to lead-in 12 and stud 30.

This lead-in and stud constitute a major support for the electrode cage. To the lower end portion of the cathode is welded a connector tab 69 which is bent into engagement with lead-in portion 18 and to which it is welded.

In the mount structure described, adequate insulation is provided on the heater 56 and the spacer 64 to electrically isolate'the cathode 50 from the heater. However, as a consequence of the need to deflect the heater legs 60, 62 into engagement with their associated lead-ins and.

to urge a welding tool against them in welding the legs to the lead-ins, the portion of the heater insulation im-.

mediately above thelegs thereof as viewed in FIGS. 1

and 2, may be brought into forceful engagement with the lower edge 70 of the cathode. This edge is relatively sharp and a forced engagement therewith of insulated portions of the heater sometimes causes the insulation to chip from the heater. Such chipping exposes the heater wire and may result in electrical shorts between the heater and the cathode.

In a similar way, the insulation 66 on the lower end portion of the spacer 64 may also be chipped off by engagement of this portion with the relatively sharp lower edge of the cathode 50. While the lower end portion of the spacer 64 is bent laterally before it is assembled in the mount, it usually requires some axial rotation thereof to bring it into engagement with its stud 28. Such axial rotation and particularly when further accompanied by a thrust on the bare end portion of the spacer by a welding tool during a welding operation, sometimes results in the' application to the coating '66 'by the lower edge 70 of the cathode 50, of a sufiiciently large force to chip the insulation from the spacer. While such loss of insulation might have no immediate effect, it would defeat the purpose for which the spacer is provided. This purpose is to increase the insulation between the cathode 50 and the heater 56 by means of the insulating coating on the spacer.

This supplemental insulation is desirable in rectifier tubes of the type illustrated, wherein the cathode and heater may be operated at a voltage difference of at least 4400- volts.

When such loss of insulation occurs in a mount, salvaging thereof has heretofore been considered impractical and the mount has been scrapped. This has 'been due in This" fore precluded insertion of the spacer through the upper end of the cathode.

Such preformed lateral extension is desirable in order to avoid applying any appreciable bending stress to the spacer after its incorporation in a mount. Due to the relatively rugged character of the spacer, bending stress applied after extending the spacer 64 into the cathode 50, would require such forceful engagement between the spacer and the lower edge 70 of the cathode 50, as to prohibitively increase incidents of coating loss from the spacer.

When a heater 56 or spacer '64 is seen to have insulation chipped therefrom after these elements have been assembled in a mount, the heater and spacer are removed. In effecting such removal the legs of the heater and spacer are severed. The heater and spacer are then pulled, or removed, from the end of the cathode remote from the stem. After such removal, a new heater and spacer on which the insulation is intact, are assembled in a novel manner prior to extension into the cathode (FIG. 3). The assembling of the new heater 56 and spacer 64 involves threading the heater axially through the spacer, so that the legs 60, 62 of the heater extend from one end of the assembly and the laterally extending leg 68 of the spacer protrudes from the other end of the assembly. The assembly is then inserted into the cathode 50 by being initially extended into the cathode end remote from the stem 10, and with the heater leg end of the assembly in leading position.

A complete insertion operation exposes the heater legs at the stem end of the cathode, as shown in FIG. 3. The exposed heater legs are then deflected into engagement with their associated lead-ins and welded thereto.

A complete insertion operation also leaves exposed from the end of the cathode remote from the stem 10, the laterally extending leg 68 of the spacer 64. For supporting the spacer, a novel clip 72 is fixed to the insulating wafer 46 remote from the stem, andto which the bare leg portion 68 of the spacer is Welded, as shown in FIGS. 3 and 4. Since the clip 72 has utility only in salvaged mounts, it is desirable for economic reasons to provide the clip only in association with a mount salvaging operation. However, since such operation takes place with respect to a mount that is complete exceptfor the heater and spacer, a mounting of the clip 72 on wafer 46 is accomplished in such a way as to avoid damage to the wafer. Both the wafer 46 and the clip 72 are structurally designed to contribute to the preservation of the wafer from harm during the clip mounting operation.

During fabrication of the initial mount shown in FIG. 1, the upper wafer 46 is provided with two slots 74, 76, as depicted in FIG. 4. Each slot extends to an edge of the wafer to permit a lateral insertion of a clip 72 thereinto. The slots are disposed in closely spaced relation with respect to the cathode 50 to permit the lateral extension 68 of the spacer 64 to engage the clip when mounted in the slot. The slots are located at opposite edge portions of the wafer 46, and therefore are spaced 180 about the cathode 50. I

The presence of the two slots and their orientation limits the amount of rotation required of the spacer 64 for engagement with the clip 72. It will be seen that if the clip is mounted in a slot closest to the initial position of the lateral portion 68 of the spacer 64, the maximum amount of rotation of the spacer 64 needed for engagement of its lateral portion 68 with'the clip, is through an arc of 90. With one slot only, in the wafer 46, the maxi mum rotation required'of' the spacer 64 would be through an arc of 180. This reduced magnitude of rotation of the spacer for engagement with the clip 72 is of appreciable advantage in preserving the new spacer from coating loss.

The clip 72 has a structure that permits a mounting thereof on the wafer 46 in an operation involving reduced stress on the wafer. The clip is made of sheet metal such as nickel in ribbon form. It has a relatively small elastic limit, so that it preserves a shape to which it is formed by a tool. In its initial form, the clip is shaped to form four sides 77a, 77b, 77c and 77d defining a closed structure and two legs 78, 80, shown in FIG. 6. The legs include portions 82, :84 which extend in parallel contacting relation from the closed portion of the clip, a distance substantially equal to the thickness of the wafer 46.

The clip 72 in its initial form as shown in FIG. 6 is inserted into one of the slots 74, 76 closest to the lateral end portion 68 of the spacer 64. After such insertion one portion of a clamping tool (not shown) is inserted into the closed space defined by the clip, and a cooperating portion of the tool is disposed in engagement with the lower surface of legs 78, 80. The two portions of the tool referred to are then urged toward each other resulting in a flattening of sides 77c and 77d of the clip against the upper surface of wafer 46, as shown in FIG. 5. The force applied is sufiicient to cause a portion of the wafer to be firmly clamped between the legs 78, 80 and the sides 770 and 77d of the clip.

The initial structure of the clip 72, as shown in FIG. 6, is of appreciable advantage in inserting the clip into a slot 74, 76 in the wafer 46, and in clamping it into a secure engagement with the wafer. The contacting leg portions 82, 84 have a composite thickness slightly less than the width of either of grooves 74, 76, and a length slightly greater than the thickness of the wafer 46. Each slot 74,76 has a depth dimension slightly larger than the width of the clip 72. These dimensions, coupled with the outward flare of clip sides 77c and 77d from the coplanar legs 78, 80, contribute to facility in fully extending the clip into one of the slots 74, 76 in the wafer 46. The subsequent clamping operation is aided by the initial coplanar disposition of the legs 78, 80. Such disposition prevents the clip from moving upwardly with respect to the wafer 46 during the clamping step. Downward movement of the clip with respect to the wafer in a clamping operation, is prevented by engagement between the flared sides 77c, 77d adjacent to the leg regions 82, 84, and the upper surface of the wafer 46. Thus, when the clip is fully extended into a slot and when the flared sides 77c, 77d are clamped against the upper surface of wafer 46 and into coplanar relation, the clip is in proper position on the wafer.

After the clip has been clamped to the wafer 46, the spacer 64 is rotated in a direction to cause its bare end portion 68, now extending above the wafer 46, to engage a side, for example side 77b, of the clip 72 and to which it is then welded.

This completes the salvaging operation. A mount so salvaged may now be further processed, as by enclosure in an envelope, evacuation of the envelope, and basing, for completion of an electron tube.

What is claimed is:

1. Method of making an electron tube mount comprismg:

(a) assembling a cage including a tubular cathode,

(b) fixing one end portion of said cage to a stem having lead-ins extending therethrough, whereby a first end of said cathode is adjacent to said stem,

(c) inserting through the second end of said cathode, an assembly comprising an insulated heater having a bare leg and an insulated helical spacer member surrounding said heater, to cause said leg of said heater to protrude from said first end and a portion of said spacer to protrude from said second end of the cathode,

(d) fixing said heater leg to a lead-in extending through said stem, and

(e) fixing said portion of said spacer to a support on said cage.

2. Method of making an electron tube mount comprismg:

' (a) assembling a cage including a tubular cathode,

(b) fixing one end portion of said cage to a stem, whereby a first end of said cathode is adjacent to said stem,

() inserting a heater and spacer assembly through the second end of said cathode, to cause leg portions of said heater to protrude from said first end and a leg portion of said spacer to protrude from said second end of the-cathode,

(d) fixing said heater leg portions to lead-ins extending through said stem, and

(e) fixing said spacer leg to a support on said cage.

3. Method of making an electron tube mount, compris- (a) assembling a cage having an insulating water at one end thereof, and including a tubular cathode,

(b) mounting a clip on said wafer,

(c) fixing the other end portion of said cage to a stern having lead-ins extending therethrough, whereby a first end of said cathode is adjacent to said stern,

(d) inserting a heater and spacer assembly through the second end of said cathode, to cause leg portions of said heater to protrude from said first end and a leg portion of said spacer to protrude from said second end of the cathode,

(e) fixing said heater leg portions to lead-ins extending through said stem, and

(f) fixing said spacer leg to said clip.

4. In a method of making an electron tube mount,

the steps comprising:

(a) fixing one end portion of a cage having a tubular cathode, to a stem, to dispose a first end of said cathode adjacent to said stem, and

(b) inserting through the second end of said cathode, an assembly comprising an insulated heater having a bare leg and an insulated helical spacer member surrounding said heater, to cause said leg of said heater to protrude from said first end and a portion of said spacer to protrude from said second end of the cathode.

5. Method of making an electron tube mount comprising:

(a) forming an elongated insulated heater structure having a bare leg extending from one end thereof,

(b) forming an insulated wire to helical structure,

(c) inserting said heater structure axially into said helical structure, to form as assembly wherein said bare leg extends from one end of the assembly and one end portion of the helical structure extends from the other end of the assembly,

(d) fixing an electrode cage having a tubular cathode to a stem, wherein one end of said cathode is adjacent to said stem,

(e) inserting said assembly into said cathode from the other end of the cathode, with said bare leg of the assembly leading, to cause said leg to extend from said one end of the cathode and said one end portion of the helical structure to extend from the other end of the cathode,

(f) fixing said heater leg to a lead-in in said stem,

and

(g) fixing said one end portion of the spacer to a support on said cage.

6. Method of making an electron tube mount comprising:

(a) forming an elongated insulated heater structure having two bare legs extending from one end thereof,

(b) forming an insulated wire to helical structure, with an end portion thereof free of insulation,

(c) inserting said heater structure axially into said helical structure, to form an assembly wherein said bare legs extend from one end of the assembly and said end portion of the helical structure extends from the other end of the assembly,

(d) fixing to a stem an electrode cage having a tubular (f) fixing said heater legs to lead-ins extending through said stem, and (g) fixing said bare end portion to a support on said cage. 7. Method of replacing a folded insulated heater and a helical insulated spacer in a tubular cathode in an electron tube mount, comprising:

(a) severing leg portions of said heater and spacer,

(b) removing said heater and spacer member from said cathode,

(c) forming an'assembly of another heater and spacer by threading the new heater axially through the new spacer to cause bare legs of the new heater to extend from one end of the assembly and to cause a leg of the new spacer to extend from the other end of the assembly,

(d) extending said assembly through said cathode to cause said bare heater legs to protrude from said one end of the cathode and to cause said spacer leg to protrude from the other end of the cathode,

(e) fixing said heater legs to conductors in said mount,

(f) fixing a clip to said mount remote from said conductors, and

.- (g) fixing said spacer leg to said clip.

8. Method of salvaging an electron tube mount having a faulty assembly within a tubular cathode, wherein said assembly comprises a folded insulated heater, and a helical insulated spacer between said heater and the inner wall of said cathode, said heater and spacer having leg portions extending from said one end of the cathode and fixed to a stem said method comprising:

(a) severing said leg portions, 7 (b) pulling said heater and spacer member from said cathode,

(c) forming an assembly of a new heater andspacer by threading the new heater through the new spacer to cause bare legs of the heater to extend from one end of the assembly and to cause a leg of the spacer to extend from the other end of the assembly,

(d) extending said assembly through said cathode to cause said bare heater legs to protrude from one end of the cathode adjacent to said stem and'to cause said spacer leg to protrude, from the other end of the cathode,

(e) fixing said heater legs to conducting wires in said stern,

(f) fixing a clip adjacent to said other end of the cathode, and

(g) fixing said spacer leg to said clip.

9. Method of salvaging an electron tube mount having a tubular cathode supportedby an insulating wafer, an assembly within said cathode comprising a folded insulated heater and a helical insulated spacer between said heater and the inner wall of said cathode, and a stem adjacent to one end of said cathode and having conducting wires fixed to leg portions of said heater and spacer that are bare of insulation and that extend from said one end of the cathode, said method comprising:

. (a) severing said leg portions of said heater and spacer,

(b) pulling said heater and spacer member from the other end of said cathode,

(c) forming an assembly of a new heater and spacer by threading the new heater through the new spacer to cause a bare leg of the heater to extend from one end of the assembly and to cause a leg of the spacer to extend from the other end of the assembly,

( extending said assembly through the other end 9 of said cathode to cause said bare heater leg to protrude from said one end of the cathode and to cause said spacer leg to protrude from the other end of the cathode,

(e) fixing said heater leg to one of said conducting wires,

(f) fixing a clip to said wafer to cause a portion of said clip to extend from a face of said wafer remote from said stem,

(g) fixing said spacer leg to said portion of the clip.

10. Method of salvaging an electron tube mount having a tubular cathode supported by two spaced insulating wafers, an assembly within said cathode comprising a folded insulated heater and a helical insulated spaced between said heater and the inner wall of said cathode, and a stem adjacent to one end of said cathode and having conducting wires fixed to leg portions of said heater and spacer that are bare of insulation and extend from said one end of the cathode, said method comprising:

(a) severing said leg portions adjacent to said conducting wires,

(b) removing said heater and spacer member from the other end of said cathode,

(c) forming an assembly of a new heater and spacer by threading the new heater through the new spacer to cause bare legs of the heater to extend from one end of the assembly and to cause the bare leg of the spacer to extend from the other end of the assembly,

(d) extending said assembly through the other end of said cathode to cause said bare heater legs to pro trude from said one end of the cathode and to cause said bare spacer leg to protrude from the other end of the cathode,

(e) fixing said heater legs to two of said conducting wires,

(f) fixing a clip to one of said wafers adjacent to said other end of the cathode, and

(g) fixing said spacer leg to said clip.

11. Method of salvaging an electron tube mount including a stem and an electrode having an insulating wafer adjacent to the end of the cage remote from said stem, said wafer having -a slot extending to one edge thereof, said method of comprising:

(a) removing a defective part from said mount,

(b) inserting in said slot a clip having coplanar legs extending in opposite directions, with said legs engaging the inner face of said wafer, and with a support region of said clip extending from the outer face of said wafer,

(c) flattening a portion of said support region against the outer face of said wafer,

(d) mounting a substitute part for said defective part in said mount, and

(e) fixing said substitute part to said support region of said clip.

12. Method of salvaging an electron tube mount including a stern having lead-ins extending therethrough and a cage assembly supported on said lead-ins and including a tubular cathode and a pair of spaced insulating wafers between which said cathode is supported, a heater and an insulating spacer around said heater, said heater and spacer being within said cathode, one of said spacers having a 10 slot extending from one edge thereof, said method comprising:

(a) removing a defective part from said mount, (b) inserting a clip in said slot, 5 (c) mounting a substitute part for said defective part in said mount, and

(d) fixing said substitute part to said clip.

13. Method of salvaging an electron tube mount comprising:

(a) removing a defective part from said mount,

(b) loosely mounting on an insulation water of said mount a clip having coplanar legs extending in opposite directions, with said legs engaging the inner face of said wafer, and with angularly diverging sides of said clip extending from said outer face of said water,

(c) flattening said angularly diverging sides tightly against the outer face of said Wafer,

(d) mounting a substitute part for said defective part in said mount, and

(e) fixing said substitute part to said clip.

14. Method of mounting a clip on an insulating wafer forming part of an electron tube mount, comprising:

(a) forming a sheet metal strap to define a four-sided closed structure having two legs extending from the junction of two of the sides thereof, said legs including parallel portions adjacent to said structure and in contacting relation, said parallel portions having a length slightly more than the thickness of said wafer, said parallel portions having a Width slightly less than the depth of said slot, said legs including end portions extending in opposite directions in a common plane, said two sides of said structure defining an angle of less than 45 with respect to said plane,

(b) inserting said parallel portions of said clip into said slot, whereby said leg end portions engage in inner face of said spacer, and

(c) flattening said two sides of the clip against an outer face of said spacer for clamping a portion of said spacer between said two sides and said leg end portions.

15. Method of making an assembly comprising an elongated folded insulated heater structure having bare legs at one end of the structure and an insulated helical spacer 45 structure having a bare leg at one end, said method comprising:

(a) supporting said spacer structure in a position wherein said bare end thereof extends in one direction, and (b) threading said heater structure into said spacer structure to cause the bare legs of the heater structure to extend in a direction opposite to said one direction.

References Cited by the Examiner UNITED STATES PATENTS 1,872,344 8/1932 Robinson 2925.15 2,532,846 12/1950 Jonker 2925.15 2,815,465 12/ 1957 Shelton 313-337 2,870,366 1/1959 Van Tol 313337 RICHARD H. EANES, JR., Primary Examiner. D. I. GALVIN, Examiner.

Claims (1)

10. METHOD OF SALVAGING AN ELECTRON TUBE MOUNT HAVING A TUBULAR CATHODE SUPPORTED BY TWO SPACED INSULATING WAFERS, AN ASSEMBLY WITHIN SAID CATHODE COMPRISING A FOLDED INSULATED HEATER AND A HELICAL INSULATED SPACED BETWEEN SAID HEATER AND THE INNER WALL OF SAID CATHODE, AND A STEM ADJACENT TO ONE END OF SAID CATHODE AND HAVING CONDUCTING WIRES FIXED TO ONE LEG PORTIONS OF SAID HEATER AND SPACER THAT ARE BARE OF INSULATION AND EXTEND FROM SAID ONE END OF THE CATHODE, SAID METHOD COMPRISING: (A) SEVERING SAID LEG PORTIONS ADJACENT TO SAID CONDUCTING WIRES, (B) REMOVING SAID HEATER AND SPACER MEMBER FROM THE OTHER END OF SAID CATHODE, (C) FORMING AN ASSEMBLY OF A NEW HEATER AND SPACER BY THREADING THE NEW HEATER THROUGH THE NEW SPACER TO CAUSE BARE LEGS OF THE HEATER TO EXTEND FROM ONE END OF THE ASSEMBLY AND TO CAUSE THE BARE LEG OF THE SPACER TO EXTEND FROM THE OTHER END OF THE ASSEMBLY,

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