US2141303A - Electric discharge tube - Google Patents

Description

Dec. 27, 1938. J. L. H. JONKER ELECTRIC DISCHARGE TU-BE Filed FbVze, 1937 INVENTOR JO/MNLODEW/JKl/E/VDR/KJONKER ATTORNEY Patented Dec. 27, 1938 UNITED STATES PATENT :O'FFIE;

ELECTRIC DISCHARGE TUBE Application February 26, 1937, Serial No. 12'7,815 In the Netherlands March 9, 1936 3 Claims.

I The invention relates, to an electric discharge tube, more particularly to 'a discharge tube provided with a plurality of grids and to a circuit arrangement comprising such a tube.

It is known to utilize discharge tubes having, for example, four or more grids, as so-called mixing tubes, for example, in superheterodyne receiving systems. These tubes usually have two grids which are employed as oscillator electrodes for the generation of local oscillations, one grid which acts as a control grid and if, required, one or two screens while in a so-called octode a suppressor grid may be arranged in the tube between one of the screen grids and the anode.

There are various possibilities of distributing the functions among the electrodes present in the tube. the cathode, may act as generator electrodes, the subsequent grid as a screen grid, the fourth grid as a control grid while between this grid and the anode there may be located a screen grid and a suppressor grid. It is also possible, however, to utilize the first grid, reckoning from the cathode, as a control grid and to set up in this case the local oscillations between the third grid and the fourth grid.

Although it is permissible to form all the electrodes located between the anode and the cathode as complete. grids it has been found to be very advantageous to constitute the anode of the oscillator by only a few preferably rod-shaped parts.

Although with the constructions above-described satisfactory results may be obtained, there arise in some cases disadvantages which, as has been found, may be due to the fact that electrons return from the control grid and strike the oscillator anode and thus act upon the frequency of the local oscillator.

The invention concerns a device comprising an electric discharge tube, which tube is provided with at least four grids, at least two of these being control grids, which are separated from each other by means of one or more positive electrodes while one control grid completely surrounds the cathode and an electrode, consisting of only a few, preferably rod-shaped parts. Owing to this, electrons issuing from one of the following grids can no longer reach the above mentioned electrode consisting of rod-shaped parts while notwithstanding the second grid cannot be struck by elec trons coming from the cathode. Owing to this the tube according to the invention may be employed with great advantage as a mixing tube in superheterodyne receiving systems in which these grids, which are located in closest proximity with Thus, the first two grids, reckoning from 1 the cathode, that is to say the electrode which consists of rods and the grid which surrounds said electrode, act as generator electrodes, that is to say as the anode and the grid respectively of the generator.

It has been found to be advantageous to construct the second grid, reckoning from the cathode, in such manner that those portions which are located in the neighbourhood of the rod-like portions of the first grid do not consist of grid shaped material but consists, for example, of grids bent so as to take the shape desired. I

As set out hereinbefore, a discharge tube according to the invention may be employed in superheterodyne receiving systems. According to one particular embodiment of the invention, the tube comprises at least five grids of whichthe third grid and the fifth grid are connected to one another. According to another form of construction there may be provided, in addition, a sixth grid which is connected inside the tube to the cathode.

It has previously been proposed to mount the anode of the local oscillator in closer proximity to the cathode. In this case the anode constituted the third grid, reckoning from the cathode, so that there was not any question of the effect aimed at with the construction according to the present application.

The invention will be explained more fully by referring to the accompanying drawing which shows diagrammatically, by way of example, the arrangement of the electrodes of an electric dis charge tube according to the present invention.

In the drawing I denotes the cathode of a discharge tube. In close proximity with this cathode are arranged two rods 2 which form auxiliary anodes, the cathode and said auxiliary anode being completely surrounded by a grid 3. This grid consists of a grid-shaped portion 4 and at both ends that is to say at the points located nearest to the rods 2, of two screens 5, The tube further cornprises grids 6, 1, 8 and 9 and an output anode Hi. As is diagrammatically shown in the drawing, the grid 9 is connected to the cathode while the grids B and 8 are connected to one another. If the tube is employed as a mixing tube in a superheterodyne receiving system, the first grid and auxiliary anodes may be utilized as generator electrodes, the second and the fourth grid as screen grids, the third grid as a control grid and the fifth grid as a suppressor grid. It would, however, also be very well possible to utilize such a tube in another manner, for example as a triode-hexode.

What I claim is:--

1. An electron discharge device having a cathode, an auxiliary anode adjacent said cathode, a control electrode surrounding said cathode and anode, a screen electrode, a second control electrode and an output anode, said first control grid being provided with a solid sheet metal shield for shielding said auxiliary anode from all the electrodes but said cathode and first control electrode.

2. An electron discharge device having a cathode, a pair of auxiliary anodes disposed on opposite sides of said cathode, a control grid surrounding said cathode and auxiliary anodes, a screen grid, a second control grid and an output anode, said first control grid being provided with solid sheet metal shields adjacent and partially surrounding the auxiliary anode for shielding said auxiliary anodes from all of the electrodes but said cathode and first control grid.

3. An electron discharge device having a cathode, a pair of auxiliary anodes disposed on opposite sides of said cathode, a control grid provided with oppositely disposed side rods adjacent said auxiliary anodes and surrounding said cathode and auxiliary anodes, a screen grid, a second control grid and an anode, and U-shaped solid sheet metal shields secured to said side rods and shielding said auxiliary anodes from all of said electrodes except said cathode and first control grid.

J OHAN LODEWIJK HENDRIK J ONKER

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