US2644086A - Electronic discharge tube with current-traversed grid supports - Google Patents

Description

June 30,- 1953 w, MLLER 2,644,086

ELECTRONIC DISCHARGE TUBE WITH CURRENT-TRAVERSED GRID SUPPORTS Filed June 9, '1950 Patented June 30,l 1953 ELECTRONIC DISCHARGE TUBE WITH CUR- vRENT-TRAVERSED GRID SUPPORTS Werner Mller, Bernau-Sud, Germany, assignor to Siemens.& Halske, Aktiengesellschaft, a corporation of Germany Application J une 9, 1950, Serial No. 167,038

The present invention relates to electronic discharge tubes and is particularly lconcerned with means for reducing the stream of electrons hitting the supports carrying the grids of such discharge tubes.

For the purpose of attaching the individual elements of the grids, supporting members must be provided within the area through which the stream of electrons flows from the cathode to the anode. Such supports, therefore, are hit by electrons and are heated thereby. In order to keep Vthe temperature of the supporting members within permissible limits, it has been proposed to cover the parts of the cathode which are coexten'sive with the grid supports by metallic or nonmetallic screens. The present invention provides for this purpose means for connecting the grid supports to a voltage source so as to produce a magnetic eld surrounding such supports.

The various objects and features of the invention will appear from the detailed description of an embodiment which will be described below with reference to the accompanying drawings. In these drawings,

Fig. 1 is a diagrammatic view of a, discharge tube showing essential parts thereof in elevation, the anode cylinder being partly broken away to indicate interior parts; and Y Fig. 2 is a diagrammatic plan View of the structure of Fig. 1 as seen from either end thereof.

Referring now to the drawings, numeral I denotes the cathode, 2 the grid supports and 3 the cylindrical anode of a transmitting tube. Wound about the grid supports 2 are the windings 4 serving as grids. The grid potential may be connected at 5. 'I'he cathode I is in the form of a hairpinlike filament having terminals 6. Part of the stream of electrons emitted by the cathode I would in the absence of special provisions hit and heat the grid supports 2. In a transmitter tube having an output of one kilowatt, equipped with four grid supports having an emission current of 1.3 amp., the portion of such emission current hitting the grid supports amounts to 40 milliampereswhile 260 milliamperes hit the wire windings of the grid and one ampere hits the anode. Hence, 40 milliamperes are converted into heat in the grid supports. This amount will increase considerably, e. g., in an arrangement in which the grid supports carry the effective elements not of a control grid but of a screen grid. Since such a screen grid has a potential corresponding substantially to that of the anode, the amount of current would become even larger.

1 Claim. (Cl. Z50-27) For example, in a tube having the above stated current conditions, it would amount to about 500 milliamperes. In a transmitter tube, having an output of 100 kilowatt there would be 30 kilowatt converted into heat in the screen grid. Highpower transmitter tubes have therefore not been constructed as multigrid tubes. The novel arrangementextends the grid supports 2 to the outside of the discharge vessel (notshown) and connects these grid supports by way of conductor 'I to a voltage source, e. g., a battery 8, thereby placing the grid supports in a closed direct current circuit to produce a magnetic eld around such grid supports, which operates to reduce the impact of the electrons upon the supports. This arrangement offers the possibility of providing additional grids to produce for instance, tetrodes or pentodes as high power transmitter tubes.

The current flowing through' the grid supports apparently causes the magnetic field set up around the individual supports to divert the electrons from their paths extending towards the` r supports so that the electrons will join the stream directed towards the anode without hitting the grid supports. When the invention is applied to a 1 kilowatt tube having the previously mentioned current conditions, the portion of the electronic stream ofv 40 milliamperes which in prior structures was taken up by the grid braces will now be taken up by the anode and an emission current of 260 milliamperes will hit the wire windings of the grid. Y

In case the cathode is Vsurrounded by supports without windings, which constitute the grid, such supports should theoretically not be hit by any electrons. In fact, however, the supports will take up about 150 milliamperes in a tube having the above -stated current conditions while the anode will take up 1.15 amperes. Y

The arrangement provided in accordance with the present inventiontherefore permits redesign of the grid supports, which heretofore were made slender in thevdirection of the stream of electrons, making them more rugged and thus more such supports to a Voltage source (direct current or alternating current) it is also possible to provide instead additional supports in the neighborhood of the grid supports proper and to cause a current to flow through such additional supports in order to produce the magnetic eld.

An electronic discharge tube comprising a cathode, an anode and at least one grid therebetween, supports holding said grid, a Voltage 1 source, a means connecting such source with said supports for producing a current flow therei l through in a closed circuit in series with said voltage source so as to create magnetic elds surrounding said supports for the purpose of red-ucing the stream of electrons emitted by said cathode and hitting said supports.

WERNER MLLER.

ReferencesV Cited in the le off this patent UNITED STATES PATENTS 0 Number Name Date l2,228,895 Linder Jan. 14, 1941 2,345,115 Hall Mar. 28, 1944

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