US3337933A - Screen grid tube with coaxial tubular mesh grids - Google Patents

Screen grid tube with coaxial tubular mesh grids Download PDF

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Publication number
US3337933A
US3337933A US397043A US39704364A US3337933A US 3337933 A US3337933 A US 3337933A US 397043 A US397043 A US 397043A US 39704364 A US39704364 A US 39704364A US 3337933 A US3337933 A US 3337933A
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United States
Prior art keywords
grid
mesh
grids
openings
electrodes
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Expired - Lifetime
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US397043A
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English (en)
Inventor
Seiffarth Werner
Weissfloch Andreas
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Siemens and Halske AG
Siemens AG
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Siemens AG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/28—Non-electron-emitting electrodes; Screens
    • H01J19/38—Control electrodes, e.g. grid
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/42—Mounting, supporting, spacing, or insulating of electrodes or of electrode assemblies
    • H01J19/46—Mountings for the electrode assembly as a whole
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
    • H01J2893/0002—Construction arrangements of electrode systems
    • H01J2893/0005—Fixing of electrodes
    • H01J2893/0006—Mounting
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
    • H01J2893/0012—Constructional arrangements
    • H01J2893/0015—Non-sealed electrodes
    • H01J2893/0016—Planar grids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
    • H01J2893/0012—Constructional arrangements
    • H01J2893/0015—Non-sealed electrodes
    • H01J2893/0017—Cylindrical, helical or annular grids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
    • H01J2893/0012—Constructional arrangements
    • H01J2893/0019—Chemical composition and manufacture
    • H01J2893/0022—Manufacture

Definitions

  • the invention relates to a screened grid tube, especially a power tetrode, with cylindrical coaxial electrodes, in which the grid surfaces consist of tubular mesh grids with mesh openings so formed and arranged that the grid elements of control grid and screen grid cover each other and their current supply connections or terminals are connected thereto either by substantially tubular or diskshaped structures.
  • Tubes of the type described are known, for example, as transmitting tubes, in which the tubular mesh grids consist of two layers of parallel wires of for example, tantalum, molybdenum or the like, which are so assembled that the wires of different layers cross each other and are welded or soldered at each of their crossing points.
  • the tubular mesh grids consist of two layers of parallel wires of for example, tantalum, molybdenum or the like, which are so assembled that the wires of different layers cross each other and are welded or soldered at each of their crossing points.
  • each wire layer consists of a large number of parallel wires extending at 45 to the long axis in such a way that the Wires of different layers are oppositely wound.
  • each grid element that is, each self-supporting wire portion
  • Such mesh grid electrodes are ordinarily employed with similarly constructed so-called mesh cathodes, as the mesh openings cannot fall below a certain size, while in a continuous surface cathode a certain troublesome island formation would occur.
  • the mesh grids described have good stability, they have, for a number of purposes, certain drawbacks.
  • the control elements do not lie in a common plane, but, so to speak, in two spatially separated surfaces, whereby, for One thing, there results a considerable disadvantage with respect to the formation of the potential surfaces determinative for the control process and, for another thing, with respect to maintenance of small electrode spacings.
  • uncontrollable voltages may arise in operation, for example, which may be released by thermal load and can lead to operational breakdowns.
  • the advance of the erosion tool in question is accomplished in the axial direction of the system for the simultaneous production of continuous longitudinal slits or else in radial direction for the production of individual discontinuous slits.
  • a very serious drawback of this known process lies in the fact that it is applicable only under great difficulties for high-melting metals of great strength, and, moreover, requires long processing times.
  • the system and wall parts are moistened with liquids which can be completely removed therefrom only with great difiiculty, and whose possible residues in the discharge vessel can lead to operational difliculties.
  • the tool itself undergoes a considerable abrasion in the production process, so that a continuous change of contour occurs in the mesh openings, which cannot be disregarded, so that the tool has to be frequently renewed.
  • the tools necessary for this are technically extremely complicated and their manufacture is expensive. The edges of the mesh openings thus produced are throughout of little exactness, i.e. are ragged.
  • the invention therefore, has as its problem to create a screen grid tube with tubular mesh grids, in which the grid electrodes have a very precise grid structure or division with very geometrically precise mesh openings, and whose grid elements are in exact alignment or superimposition without requiring special adjustments.
  • the grid elements forming the mesh openings should have equal or smaller cross sections than those of corresponding thin-wire grids, so that their width facing the emission source (eflfective surface) is smaller than that of corresponding wire grids.
  • their stability originating from the use of sheets of high-melting metal, for example, tantalum, molybdenum or the like, should be still higher and the effective surface, above all, more homogeneous than that of wire grids.
  • both mesh :grids consist in each case of seamlessly formed foil cylinders, with reinforced flanged edges, produced by a common type drawing and pressure process, from high-melting metal, such as molybdenum or the like, into which in the formed state, there are created by stamping, in both the control and screen grids, openings of like number and division mesh in rectangular form, such that their otherwise equal dimensions, corresponding to the ratio of the corresponding grid-cylinder diameters are greater in the screen grid than in the control grid, but width and thickness of the cross pieces between adjacent mesh openings are about equal, and of about 50p in thickness or thicker, and that the unperforated or mesh-free parts, especially the edges of the grids, serving for the mounting thereof, have in each case recesses, holes, lugs, protrusions or the like as marking
  • FIG. 1 illustrates, partly in cross section, the entire structure of a screen grid tube constructed with ceramic material
  • the system structure illustrated in cross section in FIG. 1 presents an example of construction utilizing ceramic elements according to the invention, in which the reference numeral 1 designates a pot-shaped anode, and 2 a cylindrical cathode, with 3 and 4 the tubular control and screen grids, respectively, which four electrodes comprises the electrode system.
  • Each of these electrodes is mounted, for external contacting as well as for support in the system structure, to a respective approximately disk-shaped feed connection element.
  • a ceramic spacing ring which is connected in vacuum-tight relation with the adjacent lead-through disks, by hard soldering after suitable metalizing according to one of the usual processes, and thereby forms a part of the tube wall.
  • the grid electrodes consist of pot-shaped sheet metal cylinders produced according to a drawing or pressure process, into which, in the formed state, mesh openings are created by stamping and which are so arranged that the grid or mesh elements of the control grid and screen grid are in enact alignment with each other, without the necessity of extensive and difficult adjusting operations which have heretofore been common in the assembling of wire grids.
  • This assumes, to be sure, that the individual grid units are very precisely finished, both with respect to their grid structure, that is, with respect to their mesh form and division, and also with respect to their other geometrical dimensions, so that in practice there is still necessary only an assembly of the parts with subsequent connection by a soldering process, especially by a rapid soldering operation.
  • the so-called grid blank in the form of a drawn pot-shaped sheet metal cylinder is first joined with the lead-through disk and other adjacent system parts into an assemblage part and only later, after suitable mechanical tooling or finishing, the corresponding grid structure is created.
  • the drawn pot-like foil cylinder with its conical portion or skirt 41 is attached to the one side of the fiat portion 42 of the corresponding lead-through disk consisting of such fiat portion and the cylindrical edge portion 43 with the other side thereof attached to the ceramic spacing ring 44 and the later on its opposite side secured to the angle ring 35 carried by the disk lead-through for the control grid 3, with such attachments being effected in one operation.
  • the parts forming the inner and outer grid surfaces of the sheet metal cylinder, as well as the other seating and mating surfaces of the sub-assembly are tooled or finished to dimension by a shaving process.
  • control grid 3 and approximately analogously the cathode 2 are prepared and in each case completed into a sub-assembly.
  • anode 1 completed disk 12, 13, the ceramic spacing ring 14 and the angle ring 45 belonging to the screen grid leadthrough disk are first attached, following which the corresponding sub-assemblies of screen grid, control grid and the cathode can be successively installed with their cylindrical mating surfaces in engagement.
  • the final attachment or joining into a complete unit that is, to the finished discharge vessel, takes place after the two grid electrodes have been precisely brought into superimposition, by soldering, especially by dip soldering, at the individual soldering edges 47, 37 and 27.
  • the bringing into alignment or superimposition of the grid electrode is accomplished especially advantageously by means of the recesses, holes, studs, protrusions or the like arranged for this purpose on the grid electrodes, in the represented case by at least two corresponding holes 36 and 46 in conjunction with the concentric end openings in the grid 3 and 4, or through, in each case, at least three openings through which, for example, a fitting pin is inserted at least up to the reciprocal adhension of the two grid electrode units.
  • the holes in each case have a defined position v with respect to the grid structure.
  • this is achieved through the method that, for example, the holes concerned are introduced only in the stamping process of the mesh perforations, especially by punching. Obviously, they may also be previously made, that is, immediately after the drawing operation concerned for the sheet metal cylinder, so that they then serve as a marker or reference point for the stamping process and thereby provide an exact allocation of the marker and the grid structure.
  • the foil cylinder for example, for the screen grid 4, with its cylindrical edge, or instead thereof the corresponding subassembly part (41, 42, 43, 44 and 35) with its finished cylinder is received in an annular lining of a partial head device in such a way that in the interior of the foil.
  • a hollow mandrel which has on its circumference a matrix corresponding to the particular mesh openings.
  • a mating cutting punch movably mounted with respect to the matrix.
  • the introduction of the holes 48, 38 takes place in each case on a peripheral circuit by punching of hole beside hole and thereupon, in the manner on the adjacent circumference, possibly with a shifting in each case by a half division.
  • the advance is executed so precisely that the small crosspiece width 39, 49, 40, 50 of about 50 to always results in exactly the same manner.
  • the necessary division or advancing operation can 'be mechanized correspondingly by known means.
  • Grids stamped in the manner described have a very precise grid structure and present no burr of any kind on the mesh openings. Their durability is considerably greater than that of grids wound from corresponding wire.
  • mesh grids hitherto usual in transmitter tubes there is so selected for the mesh openings, for example, a square or, in the case of the screen grid a rhomboid form that according to FIG. 2 the continuous cross pieces 39, 49 cross an equatorial plane at less than 45".
  • This form has proved especially successful in the case of wire-wound grids for reasons of stability.
  • the durability of the mesh grids described is considerably greater.
  • a partial drawback of grids with square mesh form lies in the fact that with use of a surface oxide cathode the necessary fineness of the meshes for the avoidance of an island elfect yields too unfavorable a covering ratio.
  • the essential advantages of the mesh grids described where utilized in corresponding multi-gn'd tubes are many.
  • the stamped mesh grids described, as compared to the corresponding wire-wound grids, have, with the same cross piece cross section, a much greater stability.
  • the stamped grids, with equal stability as compared to corresponding wire grids have only about half the thickness of the grid elements concerned. Since all the grid elements lie an one surface, the surfaces facing the adj'acent electrodes are much more uniform than in the use of the wire mesh grids hitherto customary. Since through the uniform grid surface, simultaneously the potential surfaces forming in operation are uniform, in the end result the controllability of such tube is considerably improved.
  • a method for the production of a screen grid tube such as a power tetrode having cylindrical coaxial grid electrodes with grid surfaces in the form of tubular mesh grids, the mesh openings of which are so formed and arranged that the grid elements of the grid electrodes are operatively aligned with one another, comprising the steps of forming from seamless tubular stock respective seamless thin-Wall cylinders of a high-melting metal provided with reinforced edge portions, forming mesh openings in each of said formed cylinders, while in unassembled relation, in like number and arrangements, which are of quadrilateral shape, with the corresponding mesh dimensions in axial direction between the openings of respective grid electrodes being alike, and the corresponding circumferential dimensions thereof being greater in correspondence to the radial relationships involved, forming a respective marker element on a mesh-free portion of each grid electrode with each marker element being disposed in like relationship to the mesh openings in the associated grid electrode, and assembling said electrodes in operative relation, utilizing said marker elements to effect final operative alignment of corresponding mesh openings
  • a method according to claim 3 comprising the additional steps of attaching, in a single operation, a leadthrough disk to the cooperable cylinder, a ceramic insulating ring to saiddisk, and a second lead-through disk to said insulating ring in spaced relation to the first disk, to form an electrode subassembly, following which the cylinder surfaces for the grid element-forming surfaces, and surfaces to be mated in final assembly are trued to the desired measurements, and thereafter forming the mesh openings and marker element in such cylinder.
  • a method according to claim 9, comprising assembling the respective grid electrode subassemblies, each comprising the cooperable cylinder, attached leadthrough disk, ceramic insulating ring, and second leadthrough disk, with the second lead-through disk mating with the first lead-through disk of the adjacent electrode, and soldering respective pairs of mated lead-through disks.

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US397043A 1963-09-19 1964-09-16 Screen grid tube with coaxial tubular mesh grids Expired - Lifetime US3337933A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES87401A DE1223959B (de) 1963-09-19 1963-09-19 Verfahren zur Herstellung einer Schirmgitterroehre mit zylinderfoermigen koaxialen Elektroden

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US3337933A true US3337933A (en) 1967-08-29

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US (1) US3337933A (de)
DE (1) DE1223959B (de)
GB (1) GB1028094A (de)
NL (1) NL6410924A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3533147A (en) * 1968-07-19 1970-10-13 Zenith Radio Corp Cathode inserting machine and process
US4076992A (en) * 1976-06-22 1978-02-28 Rca Corporation Vacuum tube grid structures of phosmic bronze having copper and copper alloy conical supports
US4153316A (en) * 1976-04-20 1979-05-08 N.V. Optische Industrie "De Oude Delft" Method of sealing an image intensifier tube, and an image intensifier tube thus produced
US4295077A (en) * 1980-02-14 1981-10-13 Rca Corporation Circumferentially apertured cylindrical grid for electron tube
US4359667A (en) * 1980-11-10 1982-11-16 The United States Of America As Represented By The Department Of Energy Convectively cooled electrical grid structure
US5166575A (en) * 1989-07-04 1992-11-24 Thomson Tubes Electroniques Grid tube with coupled-cavity output, with coupling element integral with said tube

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1764698B1 (de) * 1968-07-19 1971-03-25 Siemens Ag Gitterelektrode insbesondere steuergitter fuer elektronen roehren hoher leistung

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851628A (en) * 1951-06-13 1958-09-09 Philips Corp Grid structure
US2896307A (en) * 1954-05-14 1959-07-28 Sperry Rand Corp Grid manufacturing process
US2935783A (en) * 1957-09-19 1960-05-10 Eitel Mccullough Inc Method of making electron tubes
US2946915A (en) * 1954-07-21 1960-07-26 Gen Electric Grid construction
US2980984A (en) * 1957-08-19 1961-04-25 Rca Corp Art of fabricating electron tubes
US3130473A (en) * 1962-09-17 1964-04-28 Norman B Mears Screen grid for power tubes and method of making the same
US3146515A (en) * 1962-10-16 1964-09-01 Rca Corp Method of making an electron tube
US3164740A (en) * 1960-04-29 1965-01-05 Rca Corp Electron tube grids and method of making the same
US3200284A (en) * 1960-07-26 1965-08-10 Philips Corp Platinum coated molybdenum grid having an intermediate layer of nickel

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE874340C (de) * 1951-02-06 1953-04-23 Siemens Ag Gitteranordnung fuer Elektronenroehren
DE887681C (de) * 1951-03-17 1953-08-27 Bernhard Philberth Elektronenroehre

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851628A (en) * 1951-06-13 1958-09-09 Philips Corp Grid structure
US2896307A (en) * 1954-05-14 1959-07-28 Sperry Rand Corp Grid manufacturing process
US2946915A (en) * 1954-07-21 1960-07-26 Gen Electric Grid construction
US2980984A (en) * 1957-08-19 1961-04-25 Rca Corp Art of fabricating electron tubes
US2935783A (en) * 1957-09-19 1960-05-10 Eitel Mccullough Inc Method of making electron tubes
US3164740A (en) * 1960-04-29 1965-01-05 Rca Corp Electron tube grids and method of making the same
US3200284A (en) * 1960-07-26 1965-08-10 Philips Corp Platinum coated molybdenum grid having an intermediate layer of nickel
US3130473A (en) * 1962-09-17 1964-04-28 Norman B Mears Screen grid for power tubes and method of making the same
US3146515A (en) * 1962-10-16 1964-09-01 Rca Corp Method of making an electron tube

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3533147A (en) * 1968-07-19 1970-10-13 Zenith Radio Corp Cathode inserting machine and process
US4153316A (en) * 1976-04-20 1979-05-08 N.V. Optische Industrie "De Oude Delft" Method of sealing an image intensifier tube, and an image intensifier tube thus produced
US4076992A (en) * 1976-06-22 1978-02-28 Rca Corporation Vacuum tube grid structures of phosmic bronze having copper and copper alloy conical supports
US4295077A (en) * 1980-02-14 1981-10-13 Rca Corporation Circumferentially apertured cylindrical grid for electron tube
US4359667A (en) * 1980-11-10 1982-11-16 The United States Of America As Represented By The Department Of Energy Convectively cooled electrical grid structure
US5166575A (en) * 1989-07-04 1992-11-24 Thomson Tubes Electroniques Grid tube with coupled-cavity output, with coupling element integral with said tube

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Publication number Publication date
DE1223959B (de) 1966-09-01
GB1028094A (en) 1966-05-04
NL6410924A (de) 1965-03-22

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