US2250409A - Cathode locating and anchoring means for discharge tubes or the like - Google Patents

Description

y 2 1941. w. L. KRAYHL 2,250,409

CATHODE LOCATING AND 'ANCHORING MEANS FOR DISCHARGE TUBES OR THE LIKE Filed March 2-9, 1940 '2 Sheets-Sheet 1 INVENTOR.

W Mi?" July 22, 1941. w. L. KRAHL 2,250,409 CATHCDE LOCATING AND ANCHORING MEANS FOR DISCHARGE TUBES QR THE LIKE Filed March 29. 1940 2 Sheets-Sheet 2 A TTORNEYS.

Patented July 22, 1941 I CATEODE LOCATING AND ANCHORING' MEANS FOR DISCHARGE TUBESOR THE LIKE .Walter L. Knoll, Swampscott, Mass, assignor to Hygrade Sylvania Co p ration, Emporium, la., a corporation of Massachusetts Application March 29, 1940, Serial No. 326,571

8 Claims.

This invention refers to electric discharge devices and in particular to radio tubes with tubular electrodes such as cathode sleeves.

An object of the invention is to provide improved means for holding tight at least one cross section of a tubular cathode by one of the members which spaces the electrodes of an electrode in longitudinal array and with a common coextensive cathode, together with improved means for anchoring the cathode in the region between said assemblies. 7

A further object is to provide an improved manner of assembling a coated cathode and of anchoring it intermediate its ends, without liability of scraping the coating during assembly or use.

A feature of the invention relates to an improved unitary electrode spacer for radio tube mounts and the like, arranged to be permanently fastened to one or more electrodes such as through the plate supports or the like, and which is provided with an integral flexible tongue for clamping the cathode.

Another feature relates to an improved method of mounting and anchoring cathodes having a plurality of discrete coated sections.

Other features and advantages not specifically v enumerated will be apparent after a consideration of the following detailed descriptions and the appended claims.

In a large number of types of radio tubes, the mount includes'a tubular cathode which is surrounded by one or more grids and a plate. These electrodes are spaced at their ends by the top and bottom mount spacer, usually made up of a disc-shaped or rectangular piece of mice sheet, provided with holes for receiving and spacing the supports or side rods of the electrodes. Some of these holes may be provided with eye let inserts to which at least two of the support members are welded, so as to insure that all the electrodes are firmly enclosed between the top and bottom mount spacers. Some of the support wires may be sealed through the stem or header, on which the tube is mounted. Others may be held in place by the mount spacers only, and are metallically connected to the stem leads (or to a top lead) by means of connectors, which may be welded to the short pieces of the electrode supports protruding from the holes in one of the mount spacers either at the top or at the bottom. The ends of the tubular cathodes may be provided with beads in order to prevent them from sliding through the holes in the mount spacers.

There are different ways of mounting or assembling the electrodes. An electrode-system may be completely assembled between two mount spacers, forming a rigid unit, and later on be fastened to the leads of a stem or header. 01, two of the stem leads may be developed or extended as supports for one of the electrodes (usually of the plate). In this case, the bottom mount spacer is first inserted into these leadsupports and fastened to them. The electrodes are then inserted into the holes provided for them in the mount spacer, and the top mount spacer is then assembled over the upper end of the electrode supports and fastened to them. Finally, those electrodes which are not yet metallically connected to their respective stem- (or top-) leads are then welded to special connectors, in the form of pieces of metal strip or wire, and the'other ends of the connectors are welded to the corresponding leads, as described above. In diode-triodes, diode-pentodes, triode-hexodes and other multi-sectional tubes, especially where the sections are mounted in longitudinal array, the cathode is frequently coextensive with and common to both sections, and it is often necessary to provide an additional, (third) mountspacer, between the top and bottom mount spacer, which additional spacer is provided with the holes necessary to space the electrodes near that part of the mount Where one of the two sections of the tube ends and the other begins. The hole provided for the cathode in the intermediate mount spacer must, of course, be large enough to let the cathode pass freely, in order to avoid scraping of the emitter coating when the cathode is inserted.

It has been found thatit is desirable to give a support to the cathode in the intermediate mount spacer,-in order to avoid microphonism. Several methods have been used to attain this objective, but they are either expensive, or do not avoid the scraping of the emitter coating.

The present invention avoids all these disadvantages, and insures a positive locking of the cathode by one or more of the spacers. By means of the. invention it is even possible in certain cases, as in diode-triodes and diode-pentodes,

to eliminate the bottom mount spacer altogether,

without any sacrifice of mechanical strength or concession to microphonism.

The objects and features above enumerated are carried out by means of a specifically shaped intermediate mount spacer, into which the uncoated part of a cathode separating the two coated parts, can be introduced without threading the cathode through the hole which locks the uncoated part of the cathode to this mount spacer. In mounting a tube, the cathode and the mount spacer are fitted together before the mount spacer is attached to the mount supports. In other cases, grids and plates of an amplifier section may be secured to the mount spacer, in addition to the cathode, before the spacer is fastened to the mount supports.

In the attached drawings which illustrate the invention.

Fig. 1 is a top-plan view of a spacer and anchoring member according to the invention.

Fig. 2 is a front-edge view of Fig. 1.

Fig. 3 shows a modification of Fig. 1.

Figs. 4a, 4b and 4c, illustrate successive steps in assembling a cathode sleeve into the spacer of Fig. 1 or Fig. 3. I

Fig. 5 shows one well-known form of tube mount embodying the invention.

Fig. 6 shows another well-known form of tube mount embodying theinvention.

Referring now to Figs. 1 and 2, which show top and side views of the new mount spacer I made of a thin sheet of mica or the like, numerals 2, 3, 8, 1, indicate holes into which the grid andplate supports or side rods of a triode section of a radio tube are threaded for spacing the electrodes. More holes may be provided for tubes containing a larger number of electrodes and mount supports or side rods.

In most of the conventional radio tube mounts, the cathode is spaced from'the other electrodes by a hole at or near the center of gravity of the mount spacers. The hole (8) which is designed to hold the cathode in the new spacer is "made slightly smaller than the diameter of the cathode sleeve, and is continued by slots 4 and 5 thus providing a resilient tongue B which may be slightly tilted out of the plane of the spacer I approximately along an axis I indicated by a dotted line in Fig. 1, and as shown more clearly in Figs. 2, 4a and 4b.

In order to insert the cathode sleeve ill (Fig. 4b) into the hole I, the uncoated intermediate portion C is placed at the entrance D of slot 4, and the tongue B is slightly pressed out of the plane of the mount spacer as shown in Figs. 2. 4a and 4b. The cathode is held at a small angle with respect to the mount spacer, and the cathode as a whole is moved along the slot 4 in a direction substantially parallel to the plane of spacer i and finally inserted into the hole I. Care is to be taken that the uncoated portion 0 of the cathode stays between the margins oi slot 4 during this motion.

When the cathode has'reached hole I at the end of the slot 4, it is tilted into its final position perpendicular to the plane of the mount spacer as shown in Fig. 4c. The hole I has a diameter slightly smaller than the outer diameter of the cathodesleeve, and the cathode is therefore prevented from sliding through the hole as well as from moving in the plan of the mount spacer by reason of the resilient clamping or gripping effect between the tongue B and the remaining peripheral edge of hole I.

Depending on the particular construction and used to cut vthe spacer.

the type of the tube, the unit composed of the cathode and the new mount spacer as shown in Fig. 40, may now either be inserted in and fastened to the main supports of the stem or header, or it may be advantageous to insert the grids and plate of the upper section of the mount into the new mount spacer before fastening the spacer to the main supports.

For the type of tube mount illustrated in Fig. 5, it is advantageous to insert grid II and plate i'l into the mount spacer before fastening the mount spacer in its final position E on the main supports II and I2 above the previously mounted diode-plates and shield. Fig. 5 shows a diodetriode of the lolrtal type, in which all the leads are brought out through the stem-base or header l8 as described in detail in application Serial No. 189,295. As the space between the diode shield l3 and the grid and plate supports II and i2, sticking out from under the mount spacer I in its postion E is very limited, it is preferred to weld the .grid and plate connectors Ila and Ila to their respective electrodes before the mount spacer is inserted into the main supports II and I2.

In mounting the diode-triode shown in Fig. 6, in which the grid lead goes through the top of the bulb. and the plate is fastened directly to the main supports, the grid may be inserted either before or after the unit shown in Fig. 40 has been fastened to the main supports II and 22. The plate of such a tube must, of course, be inserted after the mount support is in its final position E.

The examples illustrated in Figs. 5 and 6 are diode-triodes. ing a pentode-diode or a triode-hexode with the new mount spacer are similar and need not be described in detail.

While the spacer of Figs. 1 to dis primarily advantageous in so-called multi-sectional tubes, it will be clear that it also has advantages when used in single-section tubes such as diodes, trlodes, pentodes, etc. Thus the conventional upper or lower mica spacer used in such singlesection tubes, can be replaced by a spacer like that of Fig. 1 or 3.

While in Figs. 1 to 3, certain relative dimensions of the various holes and slots are shown, it will be understood that they are merely illustrative. Thus, the slots 4 and I may be as narrow as can conveniently be arranged while allowing the necessary strength to the die which is The slot I preferably terminates in the hole II, the size and shape of which is designed to avoid any tendency for ripping or cracking of the spacer when the tongue B is bent as shown in Figs. 2, 4a and 4b. The hole 23 also enables the cutting die to be strengthened at the corresponding end thereof.

Furthermore, while the drawing shows the slot 4 at right angles to the spacer edge, it will be understood that this is not necessary and the slot 4 may be at any suitable angle. While the spacer above described may provide sumcient clamping to prevent lomritudinal displacement,

'it is usually desirable to add other securing means, such as beads, as described in Patent No. 1,974,916 or pinching theends of the cathode. In this case of course, the sire of the hole I will be slightly less than the peripheral circumference at the base of the groove so that the spacer firmly grips the cathode sleeve and is at the same time mechanically interlocked therewith. While one particular configuration of spacer is shown. namely one which is substan- The steps necessary for mounttially rectangular, any other shape such as circular, elliptical or the like maybe employed.

From the foregoing, it will be seen that among other advantages of the invention, there is an increased tightness of the connection between the cathode and the remaining elements of the mount, and since there is no play between the cathode and the spacer, a more exact spacing relation between the cathode and the other electrodes can be maintained. Furthermore, the assembly of the cathode in the mount is simplilied and the liability of scraping the emission coating is avoided. As a result, a considerable saving of cost in the manufacture and assembly and the reduction of shrinkage are achieved. Finally, the assembly such as shown in Figs. and 6, provides a tube which in operation is singularly free from microphonic noises and the like.

Various changes and modifications may be made without departing from the spirit and scope of the invention. Thus, while the invention has been illustrated with one hole 8 and tongue B, a plurality of such holes and tongues may be provided where more than one cathode is employed, or where it is desired to anchor some other element such as a grid support in addition to, or in place of, the cathode. Furthermore, the spacer per se is applicable to any other device where a conductor is desired to be maintained in spaced relation to another surrounding member or conductor.

What I claim is:

1. A spacer device comprising a substantially planar insulator member having a slot in one edge terminating in a hole to receive an element to be electrically spaced from another element,

means to support said cathode comprising a substantially fiat sheet of insulation having an opening to receive said cathode and to grip it intermediate its ends at said uncoated area. and a slot extending from an edge of said sheet to said opening whereby said cathode can be in and space said cathode from said surrounding electrode including a sheet of insulation having an integral tongue said tongue defining .with an edge of said sheet an opening slightly smaller than' the cathode across section whereby said cathode is firmly gripped intermediate its ends, and means to'fasten said sheet to said uprights.

7. An electron tube mount comprising a. pair of electrode assemblies mounted in longitudinal array, a common cathode extending through said j assemblies and means to grip and support said said slot dividing said member into at least one tongue portion which is defiectable out of the plane of the member.

2. A spacer device comprising a generally fiat insulator member having an edge slot and an interior slot in communication with each other to define a defleetable gripping tongue and an opening to receive an element to be spaced from another element.

3. A spacer device according to claim 2, which is of mica and the said slots are substantially at right angles to each other.

4. In combination, a cathode having a coated and an uncoated. area along its length, and

cathode in the region between said assemblies, the last-mentioned means including a substantially planar insulator having an opening to receive said cathode, and an integral flexible tongue portion having an edge defining part of said opening, said opening being slightly smaller than the cross section of the cathode at the region where it is gripped.

8. The method of assembling a cathode sleeve into an insulator spacer member of the typehaving a slot defining a deflectable tongue and a cathode receiving opening which comprises, positioning the sleeve with its length transverse to the plane of said spacer, deflecting said tongue out of the plane of said spacer, producing relative motion between said cathode and said spacer, substantially parallel to.the plane of said spacer and along said slot until said cathode enters said opening and then allowing said tongue to spring back to its normal position whereby it firmly grips said sleeve.

WALTER 1.. KRAHL.

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