US2315510A - Electronic tube - Google Patents

Description

April 6, 1943. w. w. ElTEL ETAL,

ELECTRONIC TUBE Filed June 50, 194?.

2 Sheets-Sheet 1 ,Z'ZYE'XP ake A. M

E/TEL E EQLLEZUGH THEIR ATTORNEY April 6, 1943. w. w. E|TEL- ET AL ELECTRONIC TUBE 2 Sheets- Sheet 2 Y Filed June 30, 1942 WI'ZZSWS Elm BYJAC A. EULZOUCil-l THEIR ATTORNEY Patented Apr. 6, 1943 UNITED ELECTRONIC TUBE William W.

Cullough, Millbrae,

ration of California Eitel, San Bruno, and Jack A. Mc-

Calif., assignors to Eitel- McCullough, Inc., San. Bruno, Calif, a corpo- Application June 30, 1942, Serial No. 449,148

6 Claims.

Our invention relates to an electronic tube particularly adapted for transmission purposes.

Itis among the objects of our invention to provide an improved structure of, arrangement for and mounting of the electrodes and leads in the envelope.

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

Referring to the drawings:

Figure 1 is a perspective view of a tube embodying the improvements of our invention; and

Figure 2 is a vertical sectional view of the same.

In terms of broad inclusion, our tube comprises an envelope having a re-entrant stem at one end. A plurality of coaxial electrodes includ ing a plate and grid and cathode are arranged in the envelope, the plate being provided with a cap at one end thereof. The plate is supported by a bracket on the cap secured to a lead disposed coaxially with the electrodes and sealed to the envelope end opposite the stem. Leads for the grid and cathode are sealed to the stem.

In greater detail, and referring to the drawings, our tube comprises an envelope of glass or the like having a cylindrical body I terminating at the top in a dome 2 and at the bottom in a reduced neck 3 carrying a re-entrant stem 4 having an exhaust tubulation 5. The envelope is fitted with a cup-shaped base 6, say of porcelain, secured to neck 3 by a suitable cement 'l. Prongs 8 of the usual type project from the base.

Within the envelope are arranged a pluralit. of electrodes including a cathode 9, grid H and plate or anode l2. The plate is cylindrical in shape, and may be of any suitable metal, such as tantalum. It preferably comprises a pair of half-cylinder sections with flanges welded together to form heat radiating fins l3. Annular beads H in the sections hold their shape when formed in a die. After welding, the fins are corrugated.

A hemispherical cap I6 of tantalum is secured over the upper end of the tubular plate by depending tabs Il' welded to the rim. Arched recesses l8 formed in the cap between tabs ll provide vent openings. This cap protects the glass dome against electron bombardment, and also adds to the heat radiating surface of the plate structure.

Plate lead It, preferably of tungsten, is arranged coaxially with the electrodes and projects through dome 2 at seal 26. The plate is supported by a bracket 2| welded at the lower end to cap 16 and at the upper end to lead [9. This bracket preferably comprises a pair of tantalum straps shaped with curved feet at the bottom to fit the cap for convenience in welding. The upstanding ends of the straps are grooved to embrace the lead, with laterally projecting portions providing heat radiating fins 22 extending along the lead.

One of the problems in tubes is to prevent heat from flowing out to the glass and cracking the seal. Our structure overcomes this difficulty by reason of the mounting structure above described. As already mentioned, end cap [6 stops electron bombardment of the glass, and helps to dissipate heat by radiation before it reaches lead I9. Fins 22 on the bracket also function to dissipate heat tending to flow out along the lead. Angularly disposed slits 23 in fins 22 serve to retard outward flow of heat by conduction. These features, together with the fact that tantalum is not a good heat conductor, cooperate to thermally isolate the plate lead and its seal from the heat zone at the electrodes.

Another feature of the plate mounting structure is that a nickel sleeve 24 is interposed between tungsten lead I!) and the tantalum bracket. Nickel alloys or fluxes readily with both tungsten and tantalum, insuring a good welded joint between the parts. Furthermore, the weld is clean and free of oxides and contamination which, if present, make outgassing diflicult during evacuation.

Grid I I is of the cage type, preferably of platinum wire, terminating in a tantalum base ring 26. This electrode is supported by brackets 21 on a pair of tungsten rods 28 sealed in a press 29 on stem 4. Each bracket comprises a hairpinshaped tantalum wire welded at the ends to grid ring 25 and at the bight to a rod 28. One of the supporting rods 28 serves as a lead and is connected by a flexible extension lead 3| to a base prong 8.

Filamentary cathode 9 comprises a coil of thoriated tungsten welded at top and bottom to a pair of tungsten leads 32 sealed to the stem. The cathode leads are disposed intermediate the grid leads, all lying in a common plane passing through the axis of the electrodes. Flexible extensions 33 connect the lower ends of leads 32 with a pair of base prongs 8.

A rectifier tube may be made in accordance With the above structure by omitting the grid, in which case the cathode only is supported from the stem.

We claim:

1. An electronic tube comprising an envelope having a re-entrant stem at one end thereof, a plurality of electrodes including a plate and grid in the envelope, a lead sealed to the other end of the envelope, a cap on one end of the plate, means on the cap for supporting the plate on said lead, a lead sealed to the stem, and means supporting the grid on the last mentioned lead.

2. An electronic tube comprising an envelope having a re-entrant stem at one end thereof, a plurality of coaxial electrodes including a plate and grid in the envelope, a lead coaxial with the electrodes and sealed to the other end of the envelope, a cap on one end of the plate, means on the cap for supporting the plate on said lead, a lead sealed to the stem, and means supporting the grid on the last mentioned lead.

3. An electronic tube comprising an envelope having a re-entrant stem at one end thereof, a plurality of electrodes including a plate and grid and cathode in the envelope, a lead sealed to the other end of the envelope, a cap on one end of the plate, means on the cap for supporting the plate on said lead, a lead sealed to the stem, means supporting the grid on the last mentioned lead, and leads for the cathode sealed to said stem.

4. An electronic tube comprising an envelope having a re-entrant stem at one end thereof, a plurality of electrodes including a plate and cathode in the envelope, a lead sealed to the other end of the envelope, a cap on one end of the plate, means on the cap for supporting the plate on said lead, and leads for the cathode sealed to the stem.

5. An electronic tube comprising an envelope, an electrode in the envelope, a tungsten lead sealed to the envelope, a tantalum bracket secured at one end to the electrode and welded at the other end to the lead, and a nickel sleeve interposed between the bracket and lead at the weld.

6. An electronic tube comprising an envelope. a grid in the envelope terminating in a ring, a lead projecting into the envelope, and a support for the grid comprising a hairpin-shaped wire having its ends secured to said ring and the bight secured to said lead.

WILLIAM W. EITEL. JACK A. MCCULLOUGH.

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