US2831139A - High-frequency electron discharge device having adjustably spaced electrodes - Google Patents

Description

Apnl 15, 1958 J. E. BEGGS 2,831,139

HIGH-FREQUENCY ELECTRON DISCHARGE DEVICE HAVING ADJUSTABLY SPACED ELECTRODES Filed Oct. 12, 1955 INVENTOR. Jhmzs t. 35445 United States Patent HIGH-FREQUENCY ELECTRON DISCHARGE DE- VICE HAVING ADJUSTABLY SPACED ELEC- IRODES James E. Begg s, Schenectady, N. Y., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application October 18 1955 Serial No. 541,317

com 931. 3513-148 This invention relates to electrical apparatus and, more particularly, to a high frequency "electron discharge device.

It is well known that the ,high frequency performance of an electron discharge device, such as a triode amplifier tube, is improved as the spacing between the grid electrode and cathode electrode is reduced. The structure contemplated by this invention permits ,very close and accurate spacings to be obtained between electrodes of electrical apparatus, such as those of a triode electrode discharge device.

It is an object of this invention to provide a device including at least two spaced electrodes in a sealed envelope, wherein the spacing between the electrodes first can be varied to achieve adesired spacing, and then hired at this desired spacing. i i

It is a more specific object of this invention to provide a triode electron discharge devicewherein a very close predetermined spacing between the cathode electrode and grid electrode thereof, and a predetermined spacing between the anode electrode and grid electrode thereof, may be achieved after evacuation of the envelope and aging of the cathode electrode.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood byreference to the following detailed description when considered in connection with the accompanying drawing wherein the sole figure is an elevation view, partly in section, of a preferred embodiment of the invention.

Referring to the figure, there is shown a triode electron discharge device including a filament 10, a cathode electrode 12, a control grid electrode 14 composed of a nonresilient permanently deformable metallic foil, and an anode electrode 16. Filament is connected to metallic terminal 18 which forms the top of the envelope of the electron discharge device. Anode electrode 16 is connected to metallic terminal 20 which forms the bottom of the envelope of the electron discharge device. Spaced from anode metallic terminal 20 by insulating section 22 of the envelope of the electron discharge device is metallic terminal 24 which is connected to control grid electrode 14. Spaced from grid metallic terminal 24 by insulating section 26 of the envelope of the electron discharge device is metallic terminal 28 which is connected to cathode electrode 12. Cathode metallic terminal 28 is spaced from filament metallic terminal 18 by insulating section 30 of the envelope of the electron discharge device.

Metallic terminal 24, which is connected to control grid electrode 14, includes a single annular flange 32. Metallic terminal 28, which is connected to cathode electrode 12, includes a first annular flange 34 and a second annular flange 36. Annular flanges 34 and 36 are interconnected by a deformable right-angle metallic band 38 located at the innermost portions thereof. Cathode electrode 12 is connected to the inner end of flange 36, as shown. A rigid second metallic band 49, shown in dotted outline, is later connected between the outer ends of annular flanges 34 and 36. This is done after band 38 has been deformed to provide the desired predetermined spacings among electrodes 12, 14 and 16, in a manner described below.

The method of achieving the desired spacings among electrodes 12, 14 and 16 will now be described. In the electron discharge device, as originally constructed, the spacing between cathode electrode 12 and control grid electrode 14 is between five and fifteen mils. The electron discharge device is evacuated and sealed ina conventional manner. Cathode electrode 12 is then aged. This is accomplished by heating cathode electrode 12 to a much higher temperature than its normal operating temperature, by means of filament it for a time sufficient to stabilize the emission characteristics of cathode electrode 12. During this aging process, cathode electrode 12 expands, and if cathode electrode 12 were not initially placed at a sufficient distance from control grid electrode 14, the expansion of cathode electrode 12 during aging wouldcause damage to control giid electrode 14 due to contact with highly heated cathode electrode 12.

After aging of cathode electrode 12 is completed, a capacitance meter is connected between anode metallic terminal 20 and grid metallic terminal 24 and, with cathode electrode 12 cold, pressure is applied between flanges 32 and 36. This applied pressure causes deformation of the horizontal portion of band 38 so that cathode electrode 12 is moved into contact with control grid electrode 14, deforming it and pushing it toward anode electrode 16. This varies the spacing between control grid electrode 14 and anode electrode 16 and also conforms the surface of control grid electrode to that of the contacting end of cathode electrode 12. The applied pressure is increased slowly until the capacitance between metallic terminals 26 and 24 measured by the capacitance meter indicates the desired predetermined spacing between control grid electrode and anode electrode '16.

Tension, rather than pressure, is then applied between metallic flanges 52 and 36 which, by deforming the horizontal portion of band 38, causes cathode electrode 12 to be moved away from control grid electrode 1 4. Since control grid electrode 14 is composed of a non-resilient permanently deformable metallic foil, control grid electrode 14 is not affected by moving cathode electrode 12 away therefrom.

In order to achieve the proper spacing between cathode elcctrode 12 and control grid electrode 14, the electron discharge device is operated with a fixed positive anode voltage and a fixed negative control grid bias voltage, and pressure is slowly reapplied between flanges 32 and 36. This causes band 38 to again be deformed result ing in the movement of control cathode electrode 12 toward control grid electrode 14. The plate current flowing in the electron discharge device is a measure of the spacing between cathode electrode 12 and control grid electrode 14. When this current indicates a very close predetermined spacing between cathode electrode 12 and control grid electrode 14, the pressure between flanges 32 and 36 is removed. In order to prevent any further deformation of band 38, rigid band 40 is at this time secured to the outer ends of flanges 34 and 36.

It is clear that the same type of spacing could be achieved if grid metallic terminal 24 were dual flanged and cathode metallic terminal 28 were single flanged, rather than the other way around, as shown.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. A method of obtaining selected operating characteristics in a stacked triode having, in a sealed envelope, a cathode having a substantially flat surface, a substantially flat deformable non-resilient foil-like grid, and an anode having a substantially flat surface, said grid being disposed between but spaced from said cathode and anode and in face-to-face substantially parallel relationship with said surfaces of said cathode and anode, said method comprising the steps of forcing the cathode against the control grid to deform the control grid to decrease the spacing between the control grid and anode until the capacitance between the control grid and anode is a predetermined amount, then withdrawing the cathode from the control grid so that there is a space therebetween,-

applying a fixed positive voltage between anode and cathode and a fixed negative voltage between control grid and cathode, then forcing said cathode to move relative to said control grid to change the spacing therebetween until the anode current is a predetermined amount, and then immovably securing said cathode, anode, and control grid relative to each other in the above established relationship in order to retain the abovementioned characteristics.

2. A method of obtaining in a stacked triode having a sealed envelope, selected spacings between a rigid cathode electrode having an active face, a grid of thin deformable non-resilient foil-like metal, and a rigid anode electrode having an active face, wherein said control grid is disposed between said electrodes face-to-face with the active faces of both said electrodes and spaced short distances from said respective electrodes, said method comprising the steps of first, while said envelope remains sealed, forcing one of said electrodes against said grid face-to-face to decrease the space between the other electrode and said grid by deforming the grid until the spacing between said grid and said other electrode is a selected amount, then, while said envelope remains sealed, withdrawing said one electrode from the deformed grid until the spacing between said grid and said one electrode is a selected amount.

3. A stacked electron discharge device comprising a sealed envelope having, arranged in succession in the same direction lengthwise of the envelope and between the ends ofv the overall length of the envelope, one end trodes within the chamber of the envelope, one carried by each of said end sections, said electrodes each having a surface, said surfaces being face-to-face and spaced 9. short distance apart, whereby when said rigid wall portions are positively forced toward or away from one another lengthwise of said envelope without breaking the envelope seal, the overall dimension of the envelope is changed accordingly and the face-to-face spacing of said electrodes is thereby adjusted, the latter remaining unchanged until said rigid wall portions are again positively forced toward or away from one another, and whereby said rigid portions of said intermediate section thereafter may be positively held against change in the spacing therebetween by a rigid member aflixed thereto.

4. An electron discharge device as defined in claim 15 further comprising a deformable non-resilient foil-like grid secured to one of said end sections and disposed between said electrodes and face to face with said surfaces of both said electrodes, whereby said rigid wall portions of said envelope may be forced toward one another so that one of said electrodes engages said grid face-to-face deforming said grid thereby decreasing the spacing between said grid and said other electrode until the spacing is a selected amount, and whereby said rigid wall portions thereafter may be forced away from one another thereby moving apart said grid and said one electrode until the spacing between said one electrode and said grid is a selected amount.

References Cited in the file of this patent UNITED STATES PATENTS 2,252,118 Dallenbach et 'al. Aug. 12, 1941 2,416,318 Hotine Feb. 25, 1947 2,445,993 Beggs July 27, 1948 2,716,199 Diemer et a1 Aug. 23, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N09 2,831,139 April 15, 1958 James E. Beggs It is hereby certified that error appears in the printed specii'i cation of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 4, line 22, for the claim reference numeral "15" read Signed and sealed this 19th day Of August 1958.

(SEAL) Attest:

KARL H0 .AXLINE ROBERT C. WATSON Attesting Officer Comissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N09 2,831,139 April 15, 1958 James E, Beggs It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below,

Column 4, line 22, for the claim reference numeral "15" read as 3 an,

Signed and sealed this 19th day of August 1958.,

(SEAL) Atiest:

KARL mINE ROBERT cu WATSON Attesting Officer Comisaioner of Patents

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