US2518121A - Indirectly heated cathode for valves operating on decimetric waves - Google Patents

Indirectly heated cathode for valves operating on decimetric waves Download PDF

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Publication number
US2518121A
US2518121A US781432A US78143247A US2518121A US 2518121 A US2518121 A US 2518121A US 781432 A US781432 A US 781432A US 78143247 A US78143247 A US 78143247A US 2518121 A US2518121 A US 2518121A
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United States
Prior art keywords
cathode
wire
washer
tube
indirectly heated
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US781432A
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English (en)
Inventor
Cahour Pierre
Andre J Velte
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
CSF Compagnie Generale de Telegraphie sans Fil SA
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Filing date
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Application filed by CSF Compagnie Generale de Telegraphie sans Fil SA filed Critical CSF Compagnie Generale de Telegraphie sans Fil SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J21/00—Vacuum tubes
    • H01J21/02—Tubes with a single discharge path
    • H01J21/06—Tubes with a single discharge path having electrostatic control means only
    • H01J21/08—Tubes with a single discharge path having electrostatic control means only with movable electrode or electrodes

Definitions

  • valves generating waves of very high frequency and adapted for coupling directly to high output circuits, such as resonant cavities and coaxial conductors, are well known.
  • These types of valves are designated generally under the term sealed disc valves and. their manufacture involves a number of problems of a mechanical nature, In particular, it is very important to be able to regulate with precision the cathode-grid space, whilst preserving strict parallelism of the electrodes: furthermore, the width of this space, when once determined, should remain permanent.
  • the device may permit of varied adjust- This method, therefore, increases both the space occupied and the cost.
  • Thepresent invention relate to a method. of constructing sealed disc valves which method affords great facility of adjustment of the distance between cathode and grid after the valve has been scaled. Said method eliminates. the dimculties enumerated above.
  • the process consists essentially in making the cathode movable within certain limits, its position depending upon the length of a wire enclosed in the evacuated space and adapted to expand under the action of heat due to the passage of an electric current. Furthermore, two forms of embodimentv may be provided.
  • the expansion of the wire may permit only of a single adjustment in the course of which merits.
  • the expansible wire a steady current of a definite value, such as to adjust the size of the cathode grid space to the valued'esired.
  • Figure 1 represents a device according to, the first form of embodiment.
  • the cathode proper I is connected to the coaxial conductor 2 by small clips or straps 6 which are non elastic but deformable and are made of a material. of high electrical conductivity.
  • a metal thrust washer 3 transmits to the cathode the effort of a spiral spring] which is pre-compressed, during assembly, between said washer 3' and an insulating washer T.
  • the said washer 3 is retained by an expansible wire 4, made of copper or nickel, for example, and fixed to it by any suitable mechanical process; this wire first passes through a washer I, then through a drop of glass 8 which closes"- the tube 2 hermetically, and finally it emerges from said tube as at 9,
  • the glass envelope of the vacuum tube or valve, partially represented at i0, is fused to the metallic tube 2 at a suitable zone of the latter.
  • the expansible wire 4' is electrically connected, through the washer 3, with the body of the tube 2 and constitutes therewith a circuit, the outer terminals of which are: on the one hand, the external portionv or extension 9 of the said -wire and, on the other hand, a conductor H welded to the exterior of 2.
  • a potential which is finely adjustable, for instance, by means of a ,poten tiometer device I! supplied with a potential then move the thrust washer 3 which,i 'in its turn;
  • the wire 4 cools and contracts, bringing the washer 3 to its original position in which it again compresses the spring-5.
  • the straps 6 are made of an annealed, non-elastic metal, the cathode I remains definitely located in the position to which it was brought when the wire 4 was expanded.
  • connection I I thus serves as common return for the filament heater current and for the current used to heat the expansible wire 4.
  • the triode is completed by a grid l4 and an anode I5.
  • I l J The arrangement is suchthat the washer 3 can shift without causing the wire IE to break; for instance, this wire may be. allowed to slide in an insulating sleeve which'. serves to guide and protect it in its pas'sage throughthe' member 3.
  • One way of applying'the method of adjust ment according to the present invention involves the construction or triodes, for example, with cathode-grid spaces which, in the first, instance, are intentionally ,oversized.
  • the finished or partly finished valvesuare then subjected'to the operation of a device allowing ofprecise meas-l urement of these cathode-grid spaces.
  • Such a measurement may, for example, be effected by an optical method if the anode is not yet. in position.
  • the finished tube which has to be ad.- justed may, however be introducedinto a circuit which permits of determining its electrical characteristies-more especially itscoefficient of cathode is thus caused to accompany the washer 3 in all its movements, that is to say, both outwards and inwards relatively to the tube 2. Consequently, if the wire 4 be heated, the expansion of this wire will bring the cathode closer to the grid but when the heating is stopped said wire will contract to its initial length, thus retracting the cathode from the grid.
  • This arrangement permits of continuous adjustment during the actual operation of the triode; it is sufiicient to have available an auxiliary current capable of maintaining the expansiblewire at the desired temperature;
  • cathodeegrid space can then be increased or diminished at will until a suitable spacing is found in each case.
  • Figure 3 represents a cathode according to the second modification of the invention.
  • the reference numerals still indicate the same elements as in Figure 1. It will be seen that here the thrust washer 3 is imprisoned betweentwo rings 3 and I 9 integral with the cathode I.
  • the extensible wire may be coated with an appropriate substance enabling it to serve as a getter. Its location outside the bulb proper is favourable for obtaining a good vacuum without causing trouble in the operation of the triode.
  • An electron discharge tube comprising an electron emissive cathode, a metallic tube connected to said cathode by deformable metallic clips, said metallic tube being sealed through the glass envelope of said discharge tube and closed at its end opposite to said cathode by a cap, a thrust washer in mechanical connection with said cathode, a thermally extensible metallic conductor having one end attached to said washer and the other end fixed at a point in the vicinity of that end of said metallic tube which is opposite to said cathode, elastic means urging the thrust washer toward the interior of said discharge tube, and connection means for heating the thermally extensible metallic conductor. 7 2.
  • An electron discharge tube according to claim 1, wherein the said thrust washer is conductive, the said thermally extensible metallic conductor is electrically insulated from the said metallic tube at the end thereof opposite to said cathode, said cap closing the metallic tube consists of insulating material and has a conductor sealed therethrough in contact with the extremity ofthe extensible metallic conductor in the vicinity of said cap.
  • An electron discharge tube including a heating filament and wherein a second sealed-in conductor traverses the said cap, an insulating sleeve is provided in said conductive thrust washer traversed by the extension of said second conductor, said second conductor being connected to one end of the heating filament, and connection from the other end of said heating filament to the cathode itself.

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  • Solid Thermionic Cathode (AREA)
US781432A 1946-10-04 1947-10-22 Indirectly heated cathode for valves operating on decimetric waves Expired - Lifetime US2518121A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR265966X 1946-10-04

Publications (1)

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US2518121A true US2518121A (en) 1950-08-08

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US781432A Expired - Lifetime US2518121A (en) 1946-10-04 1947-10-22 Indirectly heated cathode for valves operating on decimetric waves

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US (1) US2518121A (fr)
CH (1) CH265966A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2814753A (en) * 1954-10-12 1957-11-26 Eugene N Wyler Cathode support
US2963608A (en) * 1957-08-07 1960-12-06 Sylvania Electric Prod Cathode ray tube structure

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1559714A (en) * 1919-12-12 1925-11-03 John H Brickenstein Art of releasing electrons in vacuum discharge devices
US2208406A (en) * 1938-08-17 1940-07-16 Westinghouse Electric & Mfg Co Cathode ray tube
US2218886A (en) * 1939-02-17 1940-10-22 Krause Karl Apparatus for replacing cathodes
US2424790A (en) * 1942-12-01 1947-07-29 Gen Electric Electron microscope

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1559714A (en) * 1919-12-12 1925-11-03 John H Brickenstein Art of releasing electrons in vacuum discharge devices
US2208406A (en) * 1938-08-17 1940-07-16 Westinghouse Electric & Mfg Co Cathode ray tube
US2218886A (en) * 1939-02-17 1940-10-22 Krause Karl Apparatus for replacing cathodes
US2424790A (en) * 1942-12-01 1947-07-29 Gen Electric Electron microscope

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2814753A (en) * 1954-10-12 1957-11-26 Eugene N Wyler Cathode support
US2963608A (en) * 1957-08-07 1960-12-06 Sylvania Electric Prod Cathode ray tube structure

Also Published As

Publication number Publication date
CH265966A (fr) 1949-12-31

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