US2428020A - Electron discharge tube for ultra high frequencies - Google Patents

Description

Sept. 30, 1947.;

F. D. GOODCHILD EI'AL' 2,428,020

ELECTRON DISCHARGE TUBE FOR ULTRA HIGH FREQUENCIES Filed Sept 9, 1942 5' Shee tS-Sheet l I A/l E/V TORS Q1 5mm Arrow/5V P 1947. F. D. GOODCHILD E r L 2,42 2

ELECTRON DISCHARGE TUBE FOR ULTRA HIGH FREQUENCIES 5 Sheets-Sheet 2 Filed Sept. 9, 1942 Sept. 30, 1947.-

F. D. GOODCHILD EI'AL ELECTRON DISQHARGE TUBE FOR ULTRA HIGH FREQUENC:

Filed Sept. 9, 1942 ES I 5 Sheets-Sheet 5 Sept. 30, 1947.

ELECTRON DISCHARGE TUBE FOR ULTRA HIGH FREQUENCIES Filed Sept. 9, 1942 s Sheets- Sheet 4 I //VI/ENI URS 6 2m mew F. D. GOODCHILD EI'AL 2,428,920-

Sept. 30, 1947 I F.- D. YGOODCHILD ETAL ELECTRON DISCHARGE TUBE, FOR ULTRA HIGH FREQUENCI 5 Sheets-Sheet 5 Filed Sept. 9, 1942 Patented Sept. 39, 1947 UNITED STATES PATENT ELECTRON DISCHARGE TUBE FOR ULTRA HIGH FREQUENCIES Frank Douglas Goodcln'ld and Willem Harry Wolsey, London W. C. 2,

England, assignors to Standard Telephones and Cables Limited,

London, England, a British Application September 9, 1942, Serial No.

company In Great Britain October 24, 1941 14 Claims.

This invention relates to improvements in electron discharge tubes for ultra high frequencies of the type disclosed in United States application Serial No. 445,509, filed June 2, 1942, by John Foster.

The tube disclosed in the above application consists of a bulb having a copper disc sealed in the middle, a stem carrying the grid and cathode sealed at one end and another stem carrying the anode sealed at the opposite end. This construction has been found to give rise to certain manufacturing difficulties, inasmuch as it is very difficult to control the spacing between the grid and the anode. Hence the tube characteristics are subject to very wide variations. The difficulty is enhanced by reason of the fact that the copper disc which is a reference point for registering the other electrodes is very soft after sealing to the glass, and cannot be made thicker.

The present invention aims to overcome these difficulties by providing a modified form of tube structure in which the complete assembly of anode, cathode and grid may be mounted on one stem which is then sealed into the bulb so that the two electrodes which it is necessary to shield, namely the anode and cathode, appear on opposite sides of the disc.

The accompanying drawings illustrate various methods of carrying the invention into effect, in which Fig. l is a sectional view of one form of tube in accordance with the invention;

Fig. 1A is a fragmentary view illustrating a modified form of connection between the anode and anode stem.

Fig. 2 is an exploded View showing the various tube elements of Fig. 1;

Fig. 3 is an exploded view of the anode, grid and cathode structure;

Fig. 3A is a perspective view of the anode shown in Fig. 1A.

Fig. 4 is a sectional view of a modified form of tube according to the invention;

Fig. 5 is an exploded view thereof;

Fig. 6 is an exploded view of the anode, grid and cathode structure of this modified tube.

Fig. 7 is a sectional view of another form of tube in accordance with the invention;

Fig. 8 is an exploded view showing the various parts thereof; and

Fig. 9 is an exploded view of the cathode, grid and anode structure of this modified construction.

In the drawings, i and 2 represent the cylindrical glass envelope portions, and 3 the copper screening disc which is sealed between them and which projects well beyond the glass envelope portions to form an effective screen between the two halves of the tube, and also to provide a Y mounting device for connecting the tube directly in the grid circuit. The centre of the disc is provided with an aperture 6 to accommodate the grid 5. In the constructions shown in Figs. 1 to 6 the grid 5, together with the cathode t and the anode l is mounted on the pinch 3 in the envelope portion l, whereas in the modification shown in Figs. 7 to 9, the grid and cathode are mounted on the anode as will be hereinafter described. A stem 26 comprising two Wires is sealed in the pinch 8. These wires are connected by supports 2! and 29 to rods 28 and 39 which are supporting the frame iii. One of the wires of the stem 25 is connected electrically to the cathode and the two wires together serve as heater connections. The grid is Wound around two spaced grid supporting rods indicated at 9, carried by mica end plates iii, and provided with contact springs H to make contact with the screening disc.

In the example shown in Figs. 1 to 3, the anode plate 7 is mounted on supporting rods I2 which are carried in the mica end plates iii, and the anode plate has secured to it a tubular extension piece i3 which is split for resilience and which fits within the recess [4 formed by a re-entrant portion iii of the anode stem it which is sealed into the base of the envelope portion 2. Figs. 1A and 3A show a modified construction in which the anode plate l is provided with a solid conical extension piece (130.) which fits within the recess [4 formed by the re-entrant portion id of the anode stem iii. In the construction shown, the anode plate consists of a solid block of copper with integral supporting lugs (l2a) at the ends adapted to fit within slots in the mica end plates ii].

In the example shown in Figs. 4 to 6, the construction is substantially the same, but in this case the anode plate l is provided with a pair of resilient fingers i! which may be of molyb-= denum and which embrace the anode stem is.

It will be seen that with these constructions the anode plate 7 is held at the correct distance from the grid by means of the mica end plates In. The anode stem iii is previously sealed in the tube in the normal manner and it will be seen that the arrangement is independent of any slight variations in the spacing between the anode stem I 6 and the copper disc 3. Whilst the arrangement illustrated in Figs. 4 to 6 has been found to work satisfactorily the constructions illustrated in Figs. 1 to 3A are to be preferred because during exhaust the anode expands by heat into the recess 14 in the anode stem, whereas there is a tendency for the spring fingers I! to expand away from the anode stem.

In the tube construction shown in Figs. 7 to 9, the complete triode assembly is built up on the anode which is specially shaped with a rectangular end portion 20 having shoulder portions 2| which co-operate with an anode guide formed by metal strips 22 secured in slots 23 in the mica end ode leads extending through the aperture in the screening plate and sealed through the wall of a said other envelope portion, means on said frame rect spacing between the anode, grid and cathode is ensured.

The assembly in this case carries a small copper I disc 24 which on assembly engages with the main screening disc 3 which has already been sealed in position in the envelope. A single drop seal is made as in sealing-in an ordinary tube, and the heater and cathode leads indicated at 25 are then finally pinched into the other envelopeportion as indicated at 26 as a last operation.

What is claimed is:

1. An electron discharge tube comprising an envelope, an apertured metal screening plate sealed through the walls thereof and dividing the envelope into two portions, a grid in the envelope electrically connected to the screening plate and located in the aperture thereof, an anode and a cathode in the envelope at opposite sides of the grid, 9, frame carrying the cathode, grid and anode,'an anode connecting structure extending through the envelope, and means carried by said frame engaging the anode connecting structure.

2. An electron discharge tube comprising an envelope, an apertured metal screening plate extending transversely across said envelope, sealed through the walls thereof and dividing said envelope into two portions, an anode connection sealed into one portion, a cathode connection sealed into said other portion, a frame mounted on said cathode connection, a cathode, a grid and an anode member supported in spaced relation in said frame, said anode member comprising means connecting said member with said anode connection, and means in the envelope electrically connecting said grid and said screening plate.

3. An electron discharge tube according to claim 2 wherein the frame carrying the complete assembly of the anode, grid and cathode is mounted on a base member which is sealed in one envelope portion, the grid being electrically connected to the screening plate, and a part of the anode member projecting through the aper ture in the screening plate to one side thereof, the cathode being on the other side of said screening plate.

4. An electron discharge tube comprising an envelope, an apertured metal screening plate extending transversely across said envelope and sealed through the walls thereof dividing said envelope into two portions, a thi rrble-like metal member sealed into one portion and constituting an anode connection, a stem sealed in the other Q portion, a frame carrying an anode, a grid and a cathode supported on said stem, an extension on said anode engaging said anode connection, and spring means carried by the frame making electrical connection between the grid and said screening plate.

5. An electron discharge tube according to claim 4 wherein the extension on said anode comprises a resilient member engaging the thimblelike metal member.

6. An electron discharge tube comprising an envelope, an apertured metal screening plate extending transversely across said envelope and sealed through the walls thereof dividing said envelope into two portions, a thimble like metal member sealed into one portion and constituting an anode connection, a rectangular anode block on the end of said thimble-like member, a frame carrying a grid and a cathode and having cathgrid and screening plate comprises an auxiliary apertured metal disc mounted on said frame and contacting a resilient member attached to the grid and engaging said screening plate.

8. An electron discharge tube comprising a cathode element, a grid element and an anode element, a mounting frame engaging the elements and holding them in fixed relation to each other, said elements and frame constituting a unitary sub-assembly, a sealed envelope, an anode connecting structure extending through the envelope, a cathode connecting structure extending through the envelope, and means mounting said subassembl in the envelope with the cathode element connected to the cathode connecting structure, and the anode element connected to the anode connecting structure.

9. A tube as set forth in claim 8 including longitudinally adjustable means connecting one of said elements and a connecting structure.

10. A tube as set forth in claim 8 including means slidably connecting one of said elements and a connecting structure.

11. A tube as set forth in claim 8 in which the anode connecting structure comprises a hollow metallic member having a substantial heat radiating area projecting into and sealed to the envelope, and including a member connected to the anode element and frictionally engaging the hollow member.

12. A tube as set forth in claim 8 in which the sub-assembly is mounted on one of said connecting structures and includes a slidable connection with the other connecting structure.

13. A tube as set forth in claim 8 including a shield plateextending through the envelope and in alignment with the grid element.

14. An electron discharge tube comprising a cathode element, a grid element, and an anode element, a mounting frame engaging said elements and holding them in fixed relation to each other, said elements and frame constituting a unitary sub-assembly, a sealed envelope, an anode conecting structure extending through the envelope and provided with a recess, a cathode connecting structure extending through the envelope, and means mounting said sub-assembly in the envelope comprising a connection between the cathode element and the cathode connecting structure and a projecting member mounted on the anode element and slidably fitting into the recess in the anode connecting structure.

FRANK DOUGLAS GOODCl-IILD. WILLEM HARRY WOLSEY.

REFERENCES CITED ihe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,164,905 Clavier July 4, 1939 2,235,414 White Mar. 18, 1941 2,228,939 Zottu et al. Jan. 14, 1941 2,107,387 Potter Feb. 8, 1938 2,091,443 Heintz Aug. 31, 1937

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