US2471005A

US2471005A - Base structure for electron tubes

Info

Publication number: US2471005A
Application number: US693223A
Authority: US
Inventors: Robert L Norton
Original assignee: Eitel Mccullough Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1946-08-27
Filing date: 1946-08-27
Publication date: 1949-05-24
Anticipated expiration: 1966-05-24

Description

May 24, 1949. R. NORTON BASE STRUCTURE FOR ELECTRON TUBES Filed Au 27, 1946 0 Z Z 5 l U 4 Q M w w 2. A a m v 4 A U 7 5 2 w a \N 2 J 2 Z w W a L Y E no Q U Q INVENTOR.

0 0 7 m 6 1T w w n ATTORNEY Patented May 24, 1949 BASE STRUCTURE FOR ELECTRON TUBES Robert L. Norton, Belmont, Calif., assignor 'to Eitel-McCullough, Inc., San Bruno, Califl, a corporation of California Application August 27, 1946, Serial No. 693,223

4 Claims.

My invention relates to electron tubes, and more particularly to the electrode arrangement and envelope structure of such tubes.

It is among the objects of my invention to provide improvements in multi-grid tubes such astetrodes.

Another object is to provide an improved headerstructure for the tube envelope.

Another object is to provide an improved terminal arrangement for the electrodes of a tetrode.

Still another object is to provide a tube design which particularly adapts it to tubes of small physical size.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of my invention. It is to be understood that I do not limit myself to this disclosure of species of my invention as I may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawing:

The single figure of the drawing is a vertical sectional view of a tube embodying the improvements of my invention.

In terms of broad inclusion, my tube comprises an envelope having a disk-like vitreous header at one end and an anode adjacent the other end. Electrodes are provided in the envelope .and contact prongs for certain of the electrodes are sealed to the header. A plurality of these prongs are preferably arranged in arcuate formation, and another prong is located inside this formation. In my preferred tube, comprising a tetrode structure, the cathode is connected to one of the prongs of the arcuate formation and the control grid is connected to the inside prong. Another feature of my tube is that the screen grid is connected to a terminal ring surrounding the header. The preferred tube embodies an indirectly heated type of cathode having a heater connected to other contact prongs of the arcuate formation, and has an external type of anode supported from the grid terminal ring by a vitreous section of the envelope. It is understood, however, that an ordinary filamentary cathode may be used instead of the indirectly heated type, and that a conventional internal anode may be employed instead of the external anode type.

In greater detail, and referring to the drawing, my invention is illustrated by an external anode tetrode structure comprising an envelope having a vitreous section 2 sealed between a flange 3 on tubular anode 4 and a metallic terminal ring 6 located below the anode. A disklike vitreous header 1 is sealed to ring 6. By the term vitreous I mean 'a material having insulating and vac-tight properties such as glass, ceramic or the like. Ring 6 and anode flange 3 may be of a suitable glass-sealing metal, such as Kovar, and cup-shaped anode 4 may be of copper. The tube is preferably exhausted through a metal tubulation 8 on the anode, which tubulation is .pinched oil? at tip 9. Heat is removed from-the anode by a finned cooler H having a core l'2 bonded to the anode by solder l3.

The internal electrodesof my preferred tube comprise a cathode l4, control grid l6 and screen grid l'l.v These are tubular electrodes projecting into the anode and coaxial therewith. The two grids have upper free ends and lower fixed ends and are preferably made of wire bars, the screen grid preferably being capped by top piece 18. Screen grid I1 is supported from its lower end by a bracket l9 fastened by screws 20 to a flange 2| secured to envelope ring 6. By this arrangement the ring 6 serves as a terminal for the screen grid." 7

The remaining electrodes are connected to and supported by rigid contact prongs sealed to header 1. As shown, a plurality of

prongs

22, 23, 24 and 26 arranged in arcuate formation such as in a circle concentric with the header. Another prong 21, preferably of larger diameter than the others, is located inside the arcuate formation, the preferred location being at the center of the header. All these prongs are rigid rods so that they are adapted to be plugged directly into a socket. Being of heavier stock, the center prong gives added support for the tube in the socket.

Control grid I6 is preferably connected to center prong 21 by a supporting bracket 28, which bracket may conveniently be of U-shape brazed at the center to the top of prong 21 and at the ends to opposite sides of grid band '29. By connecting the control grid to center terminal prong 21, which prong is concentric with terminal ring 6, it will be seen that the external terminals of the two grids are coaxially arranged. Such an arrangement is particularly desirable in circuits for higher frequency operation employing coaxial lines.

The indirectly heated cathode It comprises a cylindircal core 30 of metal, preferably cupshaped, carrying a suitable coating of emissive material on its outer surface. A coating of barium and strontium oxides, commonly used in cathodes of this type, may be employed. The cathode is connected to prong 22 by a support ing bracket 3|. In order to give added support and provide additional conductor means, other similar brackets may be connected between the cathode and other prongs (not shown) in the circular formation. Cathode heater 33 is a coil of resistance wire connected to other prongs 2t and 26 by

suitable brackets

34 and 36. If desired, the lower end of the cathode may be closed by an insulator 3'! fastened in place by a sleeve 38.

In addition to being connected to terminal rin 5, the screen grid I! is also preferably connected to a contact prong 23 of theheader by a strap 40 bridging the prong and grid supporting flange 2|.

As hereinbefore mentioned, the cathode may be of the conventional filamentary typ which case the two ends of the filament would be connected to a pair of the contact prongs in a manner similar to the cathode heater coil illustrated. Likewise, a conventional type of internal anode may be used instead of an external anode. I prefer the external type of. anode, however, because of the increased heat dissipation properties.

My tube structure has a numberof advantages, particularly in. multi-grid tubes such as the tetrode illustrated. The improved header and terminal arrangement enables the tube to be built in small physical sizes. For example, a power tetrode of the. character shown and with an anode dissipation capability of around 106 watts, has been made with. an overall height of about 2 inches. and a diameter of; about 1 /2- inches. Another advantage due to the improved terminal arrangement, is that my tube iscapable of operation in the higher frequency ranges.

Still another feature is that the screen grid support members l9 and 21 form a metallic shield extending transversely from the screen grid to the wall of the envelope, which shield is interposed between the anode and the control grid structure. This arrangement provides good shielding between the output and input electrodes.

I claim:

1. An electron tube comprising an envelope including a metallic ring and a disk-like vitreous header sealed along its periphery to said ring, a contact prong disposed centrally of the ring and sealed to the header, said prong having an inner end projecting into the envelope and an outer contact end projecting externally of the envelope, and electrodes in the envelope includ ing a control grid connected to and supported by the inner end of the prong and a screen grid connected to said ring.

2. An electron tube comprising an envelope including a metallic ring and a disk-like vitreous header sealed along its periphery to said ring, a contact prong sealed to the header, said prong having an inner end projecting into the envelope and an outer contact end projecting externally of the envelope, coaxial electrodes in the envelope including a control grid and screen grid, said grids being mounted above the header and each having an upper free end and a lower fixed end, means attached to the fixed end of the control grid supporting it on the inner end of said prong, and means attached to the fixed end of the screen grid supporting it on said ring.

3 An electron tube comprising an envelope ineluding a disk-like vitreous header at one end, a plurality of contact prongs mounted in arcuate formation and sealed to the header, another contact prong located inside said formation and sealed to the header, said prongs having inner ends projecting into the. envelope and having outer contact ends projecting externally of the envelope, and electrodes in the envelope including a cathode connected to and supported by the inner end of a prong of the arcuate formation and a grid connected to and supported by the inner end of the inside prong.

4. An electron tube comprising an envelope including a metallic ring and a disk-like vitreous header sealed along its periphery to said ring, a plurality of contact prongs mounted in arcuate formation and sealed to the. header, another contact prong located inside said formation and sealed to the header, said prongs having inner ends projecting into the envelope and having outer contact ends projecting externally of the envelope, a control grid connected to the inner end of the inside prong, a screen grid connected to said ring, and an indirectly heated cathode and heater therefor connected to the inner ends of prongs of the arcuate formation.

ROBERT L. NORTON.

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

UNITED STATES PATENTS Number Name Date 2,113,671 Zottu et al. Apr. 12, 1938 2,238,596 Mouromtself et al'. Apr. 15, 1941 2,278,278 Miller Mar. 31, 1942 2,288,380 Wing June 30, 1942 2,404,363 Chevign July 23, 1946