US2441224A - Electron discharge device - Google Patents

Description

y 1948. G. HECTOR ETAL 2,4412% ELECTRON DIS CHARGE DEVICE Filed Aug. 2, 1945 4 Sheets-Sheet 1 INVENTORS L. G-fiHNi' warm, 65026: M BAKE/f 6WD Pffflifi. Mum

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HT 7' GENE) y 1943- I L. G. HECTOR ETAL 2,441,224

' ELECTRON DISCHARGE DEVICE Filed Au 2, ,19 45 I 4 Sheets-Sheet 2 ZJI.

HND PETER 19. Mil/'0 mmvroxs I 1.. aim/w Harv/t, GEORGE M Mlrtk May 11, 1948.

L. G. HECTOR ETAL ELECTRON DISCHARGE DEVICE Filed Aug. 2, 1945 F/G a.

VIIIIIIIIIIII m sets-Sheet 3 HTTORNL'Y vide an ultra-high Patented May 11,;l 948- ELECTRON DISCHARGE DEVICE Luther Grant Hector, Summit, N. 1., George W. Baker, New York, N.

East Orange, N. J Radio Corporation, of Delaware assignors to Newark,

Y., and Peter A. Muto, National Union N. J., a corporation Application August 2,1945, Serial No. 608,490

' '2 Claims. (Cl.250-27.5)

relates to electron disparticularly to vacuum The present invention charge devices and more tubes specially designed to operate at ultra-high frequencies and having greatly increased power capacity at the upper end of the frequency region.

More specifically, the invention pertains to a construction and an assembly technique, including the treatment of parts, which results in the fabrication of a tube of the aforesaid type characterized by simplicity of construction, ruggedness and improved electrical characteristics.

It is an object of the present invention to profrequency, high-power vacuum tube of the triode, concentric cylindrical type which is particularly adapted for incorporation, as an amplifier or as an oscillator, in a grounded grid circuit, commonly known as a grid separation circuit, which includes a resonant cavity between the anode and grid, a resonant cavity between the grid and cathode, and shielded co-axial coupling lines or other forms of coupling between the cavities.

Another object of a tube of the type the invention is to provide mentioned which, when used in a circuit of the kind above identified, is capable of functioning, for example, as an oscillator at frequencies ranging between at least 500 and 1000 megacycles with an available power output, at the upper end of this range, of the order of at least to 25 watts, while the tube is operating substantially continuously (as distinguished from pulse operation).

Another object is the provision of a tube structure in which the electron transit time is substantially reduced by close spacing obtained between the cathode and the grid, and by designing the cathode to increase the current density therefrom.

Another object of the invention is to provide a construction in which the tube elements may be accurately and solidly mounted, thus avoiding misalignment 0r disalignment, respectively, of said elements, which may occur in the initial assembly'of the parts or because of'changes in temperature of the tube in use.

A further object is to provide a tube structure in which the electrode assemblies minimize the effect of inductance at ultra-high frequencies by having the electrode elements concentrically and co-axially arranged.

A still further object of the invention is the provision of a vacuum tube construction, adapted for ultra-high frequencies, composed of subassemblies which are fabricated into main assemblies' by a technique which permits all of the 55 and i but so facilitate the internal metal parts to be cleaned before mounting within the tube, whereby unclean metal surfaces are avoided which at operating frequencies with consequent tube losses resulting in inefl'icient operation.

A special object is to provide a tube structure in which the final seals are made glass-to-glass, thus avoiding the danger of disalignment of metal parts which may be caused through sealing.

In order to provide a tube having the struc-' tural and electrical characteristics stated above, the various electrodes of the tube must be spaced close to each other and must be properly aligned and supported with sumcient rigidity to prevent short circuiting expansion of the to electrodynamic forces developed between the various elements. quirements, suchv siderable dimculties would ordinarily be encountered in constructing a tube having the desired electrical characteristics, and. because of these requirements and culties, such tubes would usually have to be custom-made. However, the structure and mode of handling the several component parts of the tube, as contemplated by this invention, not only assure adequate construction and provide the desired electrical characteristics manufacture of the tube that it can readily be produced on mass-production basis. Particular as provided by this invention, makes it possible to manufacture the individual parts in quantities for stock storage. to assemble such parts into units, assemble such units into main sections, and finally assemble such sections to complete the tubes.

Other objects and advantages of the invention will be apparent from the following detailed description, based upon the accompanying drawings. in which: r

Fig. 1 is a perspective view of an electron discharge tube constructed in accordance withthe invention:

Fig. 2 is an enlarged longitudinal cross-sectional view taken substantially on line 2-2 in Fig. 1;

Fig. 3 is a transversal cross-sectional View looking generally in the direction of arrows 3-3 in 2; Fig. 4 is a transversal cross-sectional view looking in the general direction of arrows H in Fig. Fig. 5 is an exploded view showing, in section on an enlarged scale,

the particular conproduce high resistance Because of the technical reas those indicated above, conthe construction of the tubes 3 struction of the parts forming the anode and grid-ring unit;

Fig. 6 is an exploded view showing, partly in elevation and partly in section, the preferred construction of the parts forming the grid unit;

Fig. '7 is an exploded view showing the assembled anode and grid-ring unit in section and the assembled grid unit partly in elevation and partly in section, and illustrating the preferred mode of connecting said units together to form the anodegrid assembly section;

Fig. 8 illustrates, in section, the particular construction of the parts forming the cathode base unit and the mode of assembling the same;

Fig. 9 illustrates the preferred mode of sealing the heater rod to the cathode base unit;

Fig. 10 is an exploded view illustrating the mode of assembling the heater and heat balile means with the heater rod of the cathode-base unit;

Fig. 11 is a longitudinal cross-sectional view showing the completed cathode assembly section;

Fig. 12 is a perspective view of a device particularly adapted for use with the improved tube to air-cool the same;

Fig. 13 is an enlarged cross-sectional detail illustrating the cooperative association of the tube with the device shown in Fig, 12;

Fig. 14 is a perspective view of a device particularly adapted for use with the improved tube to water-cool the same; and

Fig. 15 is an enlarged cross-sectional detail i1- lustrating the cooperative association of the tube with the device shown in Fig. 14.

TUBE Swa s-rune As hereinbefore indicated and as will more ticularly adapted for cooperative association with concentric co-axial lines or other cavity resonator circuits of the grid separation type. Thus, the physical embodiment of the tube is such that it can become, in fact, an integral part of the complete electrical system and provide therefor a walled-off and evacuated section to house the electronic activity. Accordingly, the tube 20 preferably has a substantially cylindrical configuration and includes exposed disk-like anode, grid, and cathode connections 2i, 22 and 23 respectively, which are arranged in spaced superposed relationship, the space between the anode and grid connections being sealed by a cylindrical envelope 24 and the space between the grid and cathode connections being sealed by a cylindrical envelope 25.

Also, as hereinbefore indicated, the tube 20 is especially devised to operate substantially continuously at ultra-high frequencies with relatively high-power outputs. This is best attained, in accordance with the present invention, by providing, as more clearly seen in Figs. 2 and 3, a cathode 26, a grid 21 and an anode 28 respectively arranged in concentric and co-axial relationship.

The cathode 26 is particularly constructed to have the same high frequency potential throughout, and is adapted to produce by electron emission relatively high current density. It is P eferably made short and wide. (its effective length being less than its diameter). It essentially comprises an inverted cuphaped body having a substantial thickness to insure uniform heat distribu-' tion. A coating 29 (Fig. 3), of suitable material is applied on the outer peripheral surface of the cathode to assure the proper emission of electrons.

The cup-shaped cathode 26 is supported in position by means of a tubular thermal insulator 30 of metal which, in turn, is carried by a cylindrical reentrant portion 3| of a base member 32 which forms the cathode connection 23. It is to be noted that the opposite end portions of the thermal insulator 30 respectively overlap a substantial portion of the cathode 26 and of the re-entrant portion 3|, the latter having a shoulder 33 in abutting engagement with said thermal insulator so that mechanical rigidity and accurate alignment of the cathode assembly is readily achieved without use of a supporting wire frame structur or the like, or without dielectric supports.

The re-entrant portion 3| terminates with a reduced neck section 34 cooperating with a seal 35 to support a centrally disposed heater connector rod 36 extending into the cup-shaped cathode 26' and projecting outwardly of the tube through the said re-entrant portion. That section of the rod 36 which projects outwardly of the tube is preferably partially enclosed in a-tubular connector member 31 snugly fitted within and securedly fixed, as by brazing as shown at 33, to the base re-entrant portion 3|, whereas that section of the rod 36 which extends within the cup-shaped cathode 26 carries a coil-shaped heater element 39 provided with a depending extension 40 fixedly connected, for instance as shown at M, to the reduced neck portion 34 of said base re-entrant portion 3|. Disposed on the rod 36 between the heater element 39 and seal 35, is a heat-bafile structure preferably consisting of a pair of spaced flanged disks 42 interconnected by means of rods 43 and having apertures 44 to accommodate the heater'connecting extension 40 without allowing electrical contact between the extension 40 and the said discs 42. The baflie disks 42 may conveniently be insulated from the rod 36 by means of ceramic inserts 45 retained in position by means of a spacer rod 46 welded or otherwise suitably afflxed to the said rod 35.

The grid 21 is particularly constructed for minimum high frequency losses and uniform transit time in all parts of the tube. It is preferably of the squirrel-cage type and comprises a circular grid-cap 41, an annular grid-support 48 and a plurality of closely spaced grid-wire elements 49 rigidly secured to said grid-cap and grid-support. The grid-wire elements 49 are supported in parallel relation to the axis of the cathode 23 and are formed to extend in close proximity to the effective or electron emitting surface of the latter, the spacing between the cathode and the grid being of the magnitude of ten mils. Reinforcing connector or tie rods. 50 are preferably provided at widely spaced points between the grid-cap 41 and grid-support 48 to add to the rigidity of the grid structure. In order to add further to the rigidity of the grid structure and also to facilitate mounting, the grid-support 4B is constructed with a rigid outwardly and downwardly flaring skirt, and is provided with an annular lateral flange 5| for the attachment of said grid structure to a grid-ring 52 which forms the gridconnection 22. The grid structure is attached to the grid-ring 52 preferably by means of screwthreaded elements 53 passing through openings 54 (see Figs. 6 and 7) in the grid support flange 5| for engagement with screw-threaded apertures 55 in said grid-ring (see Fig. 7).

The anode 28 is particularly devised to obtain the desired amplification factor with the partainlng a good ratio of Gm to grid-plate capacisadness tance. Moreover, since the anode must dissipate relatively high wattage and since its area is relais preferably accomplished by submerging and tively small in keeping with the overall dimensions of the tube (which in accordance with one embodiment, has an overall length of approxi-;

.outside the tubeand to form a part of the envelope. It is provided with an inset or well portion db and an annular lateral flangefportion til offset from said well portion 56 to constitute the anode connection ti. The provision ofsuch well and ofiset portions permits proper concentric alignment of theanode body with the grid 21 and cathode 2t and afiords sumcient'spacing between the anode and grid connections for effective association with the resonant cavity circuit. An aperture be is provided in the top surface of the anode for evacuating the tube, which aperture may be adequately closed, after evacuation, by sealing an exhaust tubulation til.

From the foregoing description, it will be appreciated that the particular constructional features of the tube make it possible to standardize the several parts forming such a tube and that, therefore, the parts may be manufactured in quantities for stock storage to be subsequently assembled and processed in assembly line techniques. The preferred mode of assembling and processing the parts will now be described. 7

In accordance with the invention and as will clearly appear from Figs. 5 through 11, the parts are first assembled into units which are then assembled into main sections, these. main sections being finally assembled to complete the tube. While there is no particular order in which the units and main sections must be manufactured and assembled, the following sequence is adopted a practical-expedient, the metal parts maybe agitating the metal parts in several carbon tetrachloride solutions successively, allowing sufilcient time for the parts to drain after each submerging and agitating operation, and completely drying the parts. after the last draining operation. As

placed in a wire basket which may readily be transferred from one solution container to another, suspended and rotated therein to agitate the, parts, and withdrawn. from and hung over each container for drainage of the solution. P It for convenience in describing the mode of manufacturing the tube.

Axons-Gum Assamsmr Sao'rrorr Anode-grid-ring unit and tubing sections are preferably made of glass suited for use with that kind of metal. Glass known as Corning-7052" has beenfound suitable for the purpose.

In practice, the glass parts, that is the exhaust tubulation 5S and tubing sections Edaand 2511., are cut and cleaned in accordance with any suitable process known in the art. For instance, the glass parts may be cut on a wet Carborundum wheel and placed in a beaker of water immediately after cutting, and upon removing these parts from the water, theout surfaces may be scrubbed with a brush before drying to prevent Carborundum powder from adhering to the glass.

has been found that the metal parts will be degreased wlth'sumcient thoroughness if the wire basket, with the parts therein, is dipped into three separate carbon tetrachloride solutions, rotated'in each solution for about two or three minutes, drained after-each dipping and, after the last draining, placed in a drier for about three mine utes. The degreased metal parts are then fired at approximately 900 C. in an atmosphere of wet hydrogen for about thirty minutes and thereafter cooled for about five minutes. The degreased and fired metal parts are finally oxidized in air at approximately 900 C. for about three minutes.

Thus treated, the anode-grid-ring unit may be assembled by sealing the glass parts to the metal parts. This may readily be accomplished by arranging the parts on a rotary lathe in the relationship shown in Fig. 5 but with the adjacent surfaces of the anode flange 51, the tubing section Eta, the grid-ring 52 and the tubing section 2% in snug abutting engagement, and with the exhaust tubulation d9 supported in spaced relationship to the top of the anode. With the parts thus arranged, firing flames are directed, substantially as indicated by arrows A and B in Fig. 7, to s1. multaneously contact the points of engagement between the glass tubing section Ma, and the anly rises to approximately 1000 C. or 1100 C. when seals,.such as indicated at 80 in Fig. 7, begin to form. Thereafter, each seal is separately heated for about two minutes at the mentioned temperatures, blowing out the seal whenever necessary. In this manner strong hermetic seals are established between the metal parts and glass tubing sections.

When these seals or are established, the top surface of the anode 28 is heated to a temperature 7 of approximately 1000 0., whereupon said surface and the confronting edge of the tubulation 59 are brought together and heated to said temperature by directinga firing flamesubstantially as indicated by the arrow C in Fig. 7-. This heating is continued for about one to one and one-half minutes or until, an effective stronghermetic seal,

such as represented at 6| in Fig. 7, is obtained.

This seal is .blown out, if necessary, to prevent closing of the tubulation.

Immediately upon finishing the seals 60 and M, the unit is subjected to a bushy annealing fiafne, allowing the temperature of the seals to drop to a dull red heat. The unit is then removed from the lathe and covered with asbestos powder, thus causing the seals to cool slowly and accordingly The metal parts, that is the anode 2a and grid ring 52, are initially treated by subjecting them to a degreasing process. The degreasing process assuring proper setting of said seals. The sealed anode-grid-ring unit is annealedpreferably in an oven capable of operating at 500 C. and insulated to cool at a rate of 3 C. per minute. The unit is placed in the oven and the temperature is raised toapproximately 500 C. This temperature is maintained for about two hours after which the heat is turned ofl'and the unit is left in the oven until the temperature drops be- I low approximately 200 C.

ly cleaned to remove dirt and oxides from the parts. For that purpose, the following solutions 7 are'preferably used:

Solution 1: y Boric acid gm 100 Distilled water -..cc- 500 Hydrochloric acid ..cc 500,

' Solution II:

Distilled water cc 500 Hydrochloric acid"; -cc .l 500' Nitric acid cc 500 Solution III:

Chromic acid gm.. 25 Sulfuric acid ..cc 80 Distilled water cc 1000 Solution 1v:

Ammonium hydroxide cc 300 Distilled water cc 600 To clean the anode-grid-ring unit, solution I is heated to the boiling point. The unit is then immersed and constantly agitated in this boiling solution for about fifteen seconds. The unit is then removed from solution I and rinsed in running tap water. Thereafter, the unit is placed, for about three minutes, in solution II which is kept in a water jacket, while in use, to maintain said solution substantially at room temperature. When removed from solution II, the unit is again rinsed in running tap water and placed in solution III for about thirty seconds, after which the unit is removed, rinsed once more in running tap water and then placed in solution IV for, about three minutes. Upon removal from solution IV, the

welding operation, thus assuring the accurate location of the grid elements circumferentially of the cap and support to provide the "squirrel-cage like grid as more clearly shown in Fig. 7. The reinforcing connector rods 50 are likewise readily weided'at widely spaced points circumferentialiy of grid unit and in the plane of the grid elements The assembled gridunit is subjected to a final firing treatment at approximately 900 C. in an atmosphere of wet hydrogen for about ten min- '-utes, to remove all the oxide traces which may unit is washed in running tap water for about two minutes and allowed to dry thoroughly. When dried the inside of the unit is polished, for instance, with steel wool.

Grid unit Fig. 6 shows the several parts which form the grid unit 21. These parts include the grid cap 41, the grid support, the plurality of grid-wire elements 49 and grid reinforcing members 50'. These parts' are made of suitable metal, the grid cap and support being preferably made of nickel and the grid elements and reinforcing rods being made of tungsten. These parts are first degreased and hydrogen fired in the same manner as previously described in connection with the metal parts of the anode-grid-ring unit, excepting that the firing time may be cut down to ten minutes.

In assembling the grid unit, the grid support 48 and grid cap 4'! are arranged and fixedly held in space aligned relation preferably on a welding mandrel. Tungsten wire sections forming the grid elements 49 may then be readily welded onto the grid cap and support which, for that purpose, are preferably provided with annular flanges as shown, in Fig. 6, at Ma and 4&0 respectively. In practice, the welding mandrel adapted to hold the grid cap and support, may conveniently be mounted for axial rotation and associated with graduated indexing means. In this manner the mandrel may be rotated in one division for each have been deposited on the parts during the welding operation.

The finally treated grid unit may then be mounted in the finally treated anode-grid-ring unit to complete the anode-grid assembly section. This is preferably accomplished on a horizontal lathe, or equivalent, fitted with collet type chucks at both ends. The anode-grid-ring unit is placed in one chuck and a grid alignment mandrel is held and lined up in the opposite chuck. The grid unit is then placed on the end of the mandrel and brought in position (see Fig. 7) within the anode-grid-ring unit so that the openings 54, in

the flange 5| of the grid support =38, register with the screw-threaded apertures 55 in the grid-ring 52, and the body of the grid is properly aligned with the body of the anode. For that purpose, the openings 54 are preferably .made slightly larger than the threaded openings 55 so as to allow the grid-unit a certain amount of play for obtaining accurate and precise alignment between the effective surfaces of the grid and anode. With proper alignment ofthe grid and anode, the

screw-threaded elements 53 are passed through the openings 54 of the grid support and into engagement with the screw-threaded apertures 55 of the grid-ring, and are/tightly driven home, thus establishing a, rigid connection between the grid and grid-ring to complete the anode-grid assembly section.

CATHODE ASSEMBLY SECTION "Base-connector unit Fig. 8 illustrates the parts forming the baseconnector unit. These parts include the base 32 and the tubular connector ,member 31 which are made of suitable metal alloy such as Kovar.

After these parts have been degreased in the manner already stated, they are assembled, as shown in Fig. 8, so that the tubular connector member I 31 snugly fits into the re-entrant portion 3| of the Cathode -base unit the seal 35 (see Figs. 2 and 10), and a tubing secsmall tubularv glass section is cut. cleaned and.

dried in the manner previously stated. This cut. cleaned and dried glass section may then be slipped in position onto the heater rod which is supported on a rotary lathe. Firing flames are then directed onto the rod and glass to heat the same to approximately 1000 or 1100 C. for about two minutes or until the glass becomes 7 sealed to the-rod as shown in Fig. 9.

I Informing the bead 35b, the glass ring 35a shown in broken lines in Fig. 9, is cut, cleaned and dried in the same manner as above specified, and is placed over the reduced neck section 34 of the base re-entrant portion ti which is supported in a rotary lathe. Firing flames are then di- Plating solution: Y Silver cyanide (ABCn) grams per liter... '86 Potassium cyanide (KCn) ..do. 52 Potassium carbonate (K:CO:) do 38 Carbon disulflde (CS1) cc./1 0.20 Specific gravity 1.080 pH 10.9

The solutions are prepared by dissolving the rected onto the glass. and, as the glass begins to melt, the top part thereof is folded inwardly of said neck section. The temperature is then increased to apprommately 1000 C. or 1100 C. and maintained at that degree for about two and onehalf or three minutes. or until proper sealing on the inside as well as on the outside of the neck section bdisobtained.

In forming the seal-35 (Figs. 2 and 10), the,

beaded heater rod 3b is assembled with the beaded cathode-base unit as shown in Fig. 9 so that the heads 35b and the contact each other. The contacting glass beads are then melted and fused by directing firing flames thereon for about two and one-half to three minutes or until said seal 35 is obtained.

In sealing the glass tubing b to the base at, said tubing and base, with the heater rod sealed thereon, are arranged on a rotary lathe in the relationship shown in Fig. 9 but with their adjacent surfaces in snug abutting engagement. Firing flames are then directed to slowly raise the temperature of the glass and metal to approximately 1000'C. or 1100 (3., this temperature being maintained for about two and one-half to three minutes or until there is obtained a seal such as is shown at $3 in Fig. 10, thus completing the cathode 'hase unit.

The completed cathode-base unit is first annealed and cleaned in the same manner specified above for the annealing and cleaning ,of the anode-grid-ring unit, and is then silver plated. The silver plating is preferably done with the followlg equipment and solutions:

Power supp y:

Direct. current volts 6 Silver anode:

Pure silver ..percent 99 Dip solution:

Potassium cyanide (KCn) grams per Men. 70 Strike solution:

Silver cyanide (AgCn) grams per liter 6 Potassium cyanide (KCn) do.. '10

potassium cyanide, the silver cyanide and the fluid is poured off and added to the bath as a brightener.

The plating process is preferably carried out in accordance with the following procedure:

A. The solutions above identified are used at a.

temperature of approximately 20 C.; and,

The unit is treated in the following order:

1. Place unit in dip solution for approximately thirty seconds '2. Place unit in strike solution for thirty to sixty seconds using 6 volts and a current density of 2.0 amps. per sq. decimeter.

Time may vary but should be the shortest time possible to cover the metal completely;

. Place unit in plating solution. Time "may vary with the thickness desired. In practice two and one-half minutes using 2 volts and a current density of 1.0 amps. per sq. decimeter has been found satisfactory;

. Place unit in stagnant cold distilled water bath from which the silver can be reclaimed;

. Place unit in warm running tap water;

. Place unit in distilled water;

. my unit immediately in acetone and air;

and

8. Polish unit on hard cloth wheel.

Cathode-base-heater unit Fig. 10 shows the parts forming the heat-'bafie structure and cathode-heater, and the mode of mounting the same on the plated cathode-base unit.

The disks as and rods as and as of the same structure are made of suitable metal, the disks being preferably made of nickel and the rods being preferably made of Kovar." These parts are first degreased and hydrogen fired in the manner previously stated. The disks t2 and rods 03 are then joined as shown, for -instai'rce, in Fig. 10, by welding said rods to the inside surface of the disk flanges, making sure that the apertures 40 in the disks are aligned. The ceramic inserts t5 may then be associated with the disks of the baflle unit and slipped in position onto the heater rod 36, whereupon the spacer rod 06 may be welded on said heater rod between the 10.65 cleaned and hydrogen flred in the manner above of .008" to .010" with the following solution:

Alundum 38-500 (Norton Company) grams 500 Lacquer BL-1? (Rafil and Swanson) milliliters 500 In preparing this solution, the Alumium is baked, prior to mixing, for at least 12 hours at 200 C. in an oven with forced air circulation, the Alundum and lacquer are then milled in a quart porcelain Jar with 1 /2- lbs. of to 1 flint pebbles for 48 hours at 96 R. P. M.

The coated cathode-heater may then be attached to the heater rod 86. This is readily accomplished by passing the connecting extension 40 through the bafile disk apertures 44, and by snugly and rigidly engaging the tightly wound portion 64 of said heater to the end of the heater rod, after which the free end portion 86 of said section may be securely welded to the reduced section 34 of the base re-entrant portion 3| as indicated at 4! (see Fig. 11). It is to be noted that the mentioned end portion of the connecting extension 40 is provided with an offset section 61 to clear the seal 35 at said reduced section 34.

Cathode-insulator unit Fig. 11 shows the construction of the cathodeinsulator unit and its association with the cathode-base-heater unit. The cathode-insulator unit com-prises the cap-shaped cathode 28 and the tubular thermal insulator 30 both of which are preferably made of nickel. The cathode and thermal insulator are first degreased and hydrogen fired in the manner already stated, and then united by lapping a portion of the insulator over a portion of the cathode at the open end thereof. These over-lapping portions are welded thus joining the cathode and thermal insulator to form a rigid unit which may then he slipped in position, as shown, for example, in Fig. 11, onto the re-entrant portion 3| of the cathode base 32 and into engagement with the shoulder 33 thereon, to be fixedly secured on said re-entrant portion, as by welding. In constructing and mounting the cathode-insulator unit in manner above described, it will be appreciated that the cathode is properly and efiectively supported without the necessity of employing wire frames or dielectric supporters.

When the cathode-insulator unit and the oathode-base-heater unit have been assembled, the outer circumferential surface of the cathode is coated, as at 29, with a suitable solution to assist in the emission of electrons. The following solution has been found most satisfactory:

Radio Mixture #1 (J. T. Baker Chemical Co.) amsi. 300 Radio Mixture #2 (J. T. Baker Chemical Co.) grams 1200 Lacquer Rb-1 (Rani and Swanson) FINAL Tuna Assnmsnr In accordance with the present invention, the tube is finished by effecting a. final glass-to-glass seal between the anode-grid assembly section and the cathode assembly section. This may be readily accomplished on a rotary lathe which is fitted out with collet type chucks on both ends, and which is provided with means for injecting nitrogen while sealing, and with a microprojector for aligning the sections on the lathe.

The anode-grid assembly section is aligned and held in the fixed end of the lathe, and the oathode assembly section is placed and held in the movable end of the lathe. With the lathe rotating, the coated portion of the cathode is adjusted with the aid of the microprojector until no lateral or angular movement is noticeable on the projection screen, thus indicating the proper alignment of the cathode assembly section with respect to the anode grid assembly sections. These sections may then be brought together so that the cathode extends longitudinally within and in accurate concentric relation with the grid and anode, the confronting edges of the glass tubing sections 25a and 25b abutting each other. The abutting glass tubing sections 25a and 25b may then be sealed and fused together, as represented at 68 in Fig. 2, blowing out where necessary to form the unitary envelope 25. It is particularly pointed out that since the final seal is made glassto-glass, the metal parts are not detrimentally affected by the heatapplied to effect such seal, and therefore the danger of disaligning said parts is eliminated.

Following the final sealing operation, the air within the tube may be exhausted in the customary manner through an aperture 69 in the top of the cathode 26, through the aperture 58 in the top of the anode 28, and through the tubulation 59 which, after exhaust of the tube, may be tipped ofi as represented at 5911 in Figs. 1 and 2, to hermetically seal the tube thus completing the same.

The completed tube may then be thoroughly cleaned, polished and the external metal parts silver plated in accordance with the processes hereinbefore specified.

While, in the preceding description, the treatment of the several parts, forming the individual units and sections, have been described in the order herein chosen, it is to be understood that, in practice, all the parts which are to be subjected to the same treatment, may be processed at one time, regardless of the unit or-section in which these parts are to be included. For example, all the metal parts may be initially degreased and fired, and all the glass parts may be initially cut, cleaned and dried. Thereafter, these metal and glass parts may be segregated and stored, to be subsequently selected for assembling the units and sections. Likewise, the units as well as the sections, may be made in quantities, and treated in one phase of operation, to be thereafter selected for final assembly in the manufacture of the tubes.

TUBE COOLING extension 15, and are extended longitudinally thereof so that said shank and extension may tightly grip the outer circumferential surface of 'the anode 28 (see Fig. 13) upon tightening a clamp l'l surrounding said shank.

The water-cooled device 1 i, as shown in Fig. 14, comprises an inner cylinder is and an outer cylinder 19 disposed concentrically with respect to each other and having a closed end 80 (Fig. 15) to provide separated chambers 8i and 82, as can be more clearly seen in said Fig. 15. The device II is adapted to be placed over the anode 28 and fixedly secured thereto for instance by soldering, as indicated at 83 (Fig. 15) so that the body of said anode lies within the chamber 8! in concentric relation with the inner cylinder 78 but slightly spaced therefrom, said inner cylinderthen lying approximately midway of the width of the anode I well portion 56. In this manner the anode and cylinders cooperate to constitute a restricted pathway for the circulation of water between the chambers 8i and 82. A water inlet 84- discharges into the chamber 8i, and a water outlet 85 discharges from the chamber 82. Thus in using the water-cooled device Ii, water admitted through the inlet 84 in the chamber 8|, flows in contact with the anode 28, through the restricted pathway, into the chamber 82, and out the outlet 85, as represented by the arrows in Fig. 15. Because of the restricted pathway in the immediate vicinity of the anode, it will be appreciated that the water, at that point, circulates under greatly in creased velocity which is most effective in carrying the heat away from the anode.

From the foregoing description, it will appear that the present invention materially simplifies the manufacture of ultra-high frequency vacuum tubes which are capable of relatively high power output at continuous or substantially continuous operation. Moreover the invention provides a tube, of the kind specified, with numerous characteristic structural and electrical features which make such a tube most dependable in its operation.

It is particularly pointed out that this tube is so constructed that the mounting of the electrode elements does not require the use of dielectric supports. This avoids losses at high frequencies that would take place in the dielectric material used as conventional supports for the electrodes.

Whereas the preferred specific embodiment of the tube and the preferred specific mode of handling and processing the parts thereof have been herein shown and described, it is to be understood that changes in the construction and treatment of the tube or any of the parts forming the same, may be made within the scope of the subjoined claims.

We claim:

1. A high-frequency vacuum tube of the triode type comprising coaxially and concentrically mounted cathode, grid and anode structures with the anode and grid co-axially surrounding the (Fig. 12) or a special water-cooled device ll (Fig. I. The air-cooled device 10, as shown in Fig. 12,

thermal insulator having one end portion connected with said re-entrant portion to extend,

coaxially therefrom, an inverted cup-shaped cathode element connected with the free end portion oi said insulator and supported thereby in coaxial alignment therewith, cathode heating means carried by said re-entrant portion of the base member and disposed concentrically within said cathode element, and a heat insulating baifle substantially closing oil the otherwise open end of said cup-shaped cathode element. I

2. A high-frequency vacuum tube of the triode type comprising coaxially. and concentrically mounted cathode, grid and anode structures; said grid structure including a pair of annular supports spaced axially from each other, a plurality of grid wire elements spanning the space between said supports and fixedly connected thereto and a separate series of rigid tie rods rigidly mounting said supports in spaced parallelism, one of said supports having an outwardly flaring skirt termlsupport the grid elements in parallel relation to the axis of the cathode and in close proximity to the electron emitting surface of the latter.

3. A high-frequency vacuum tube of the externally exposed anode type comprising co-axially and concentrically mounted cathode, grid and anode structures; said cathode structure including a base member providing a cathode connection and having a cylindrical re-entrant portion, a tubular thermal insulator having one end portion connected to said re-entrant portion to extend coaxially therefrom, an inverted cup-shaped cathode element connected to the free end portion of said insulator and supported thereby in coaxial alignment therewith, a heat bafile member substantially closing off the otherwise open end of said cup-shaped cathode element, cathode heating means carried by said re-entrant portion of the base member and disposed concentrically within said cathode element; said grid structure including a grid body and a grid ring providing a grid connection and disposed for direct engagement with said grid body to rigidly support the same coaxially and concentrically of the cathode; and said anode structure including a cylindrical body having an annular well portion terminating with anannular lateral flange portion forming an anode connection, said well portion providing the anode body with a substantial portion closer to the grid ring than is the anode lateral flange to make eirective the portion of the grid adjacent thereto.

4. A high-frequency vacuum tube of the externally exposed anode type comprising coaxially and concentrically mounted cathode, grid and anode structures; said grid structure including a pair of annular supports spaced axially from each other, a; plurality of grid wire elements spanning the space between said supports and fixedly con-,

cathode; said cathode structure includinga base to the electron emitting surface of the latter;

said anode structure including a cylindrical body having an annular well portion terminating with an annular lateral flange portion forming an anode connection, said well portion providing the anode body with a substantial portion closer to the grid ring than is the anode lateral flange to make effective the portion of the grid adjacent thereto while providing adequate spacing between the grid and anode connections.

5. A high-frequency vacuum tube of the triode type comprising coaxially and concentrically mounted cathode, grid and anode structures; said cathode structure including a base member providing a cathode connection and having a cylindrical re-entrant portion, a tubular thermal insulator having one end portion connected with said re-entrant portion to extend coaxially therefrom, an inverted cup-shaped cathode element connected with the free end portion of said insulator and supported thereby in coaxial alignment therewith, and a heat baflle substantially closing oil the otherwise open end of said cup-shaped cathode element and cathode heating means carried by said re-entrant portion of the base member and disposed concentrically within said cathode element; said grid structure including a pair of annular supports spaced axially from each other, a plurality of grid wire elements spanning the space between said supports and fixedly connected thereto, a separate plurality of tie rods rigidly mounting said supports in spaced parallelism, one of said supports having an outwardly flaring skirt terminating with an annular lateral flange, a grid ring providing a grid connection and disposed for direct engagement with said flange and rigidly mounting the grid elements in parallel relation to the axis of the cathode and in close proximity to the electron emitting surface of the latter; and said anode structure including a cylindrical body having an annular well portion terminating with an annular lateral flange poition forming an anode connection, said well portion providing the anode body with a substantial portion closer to the grid ring than is the anode lateral flange to make effective the portion of the grid adjacent thereto while providing adequate spacing between the grid and anode connections.

6. A grid unit for high frequency vacuum tubes comprising, a pair of annular members, a plurality of rigid tie rods fastened to said members for maintaining them in fixed parallelism, a plurality oi grid wires fastened at their ends respectively to said annular members to form therewith a squirrel cage construction, one of said annular members terminating in a downwardly and outwardly extending flared skirt having a flat marginal flange for attaching the grid unit to a suitable support.

7. A grid unit according to claim 6 in which said grid wires are bowed inwardly at opposite ends adjacent their regions of connections to said annular members.

L. GRANT HECTOR. GEORGE w. BAKER. PETER A. MUTO.

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

UNITED STATES PATENTS Number Name Date 2,034,433 Heintz Mar. 17, 1936 2,320,941 Litton June 1, 1943 2,367,332 Bondley Jan. 16, 1945 2,395,043 Goodchiid Feb. 19, 1946 2,397,043 Glauber Feb. 19, 1946 2,398,609 Werner Apr. 16, 1946 2,402,602 Chevigny June 25, 1946

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