US2288812A - Electron discharge device - Google Patents

Description

Jul 7, 1942. NDER 2,288,812

ELECTRON DISCHARGE DEVICE Filed Sept. 30, 1939 vpclparllll, k

Zmventor i; Er ne 'it G. Linder Patented July 7, 1942 ELECTRON DISCHARGE DEVICE Ernest G. Linder, Philadelphia, Pa", assign'or to Radio Corporation of America, a corporation of Delaware Application September so, 1939, Serial No. 297,224 8 Claims. (01. a so-27.5)

This invention relates to thermionic devices, and particularly to a thermionic device suitable for use at ultra high frequencies.

'In a copending application Serial No. 210,968, filed May 31, 1938, issued as Patent No. 2,333,482, on March 4, 1941, and entitled Anode tank circuit oscillators,. I have described an internal The interelectrode capacities of the tube are uniformly distributed over the standing wave tank circuit and, therefore, do not limit the maximum attainable frequency of oscillation, as is the case in a lumped inductance and capacitance oscillatory circuit.

The present invention describes a thermionic tube suitable for use either as a feedback or as a Barkhausen oscillator. In either case, a grid electrode is provided. For operation as a Barkhausen oscillator, the grid is concentrically disposed about the cathode and is coextensive with the anode. For operation as a feedback oscillator, the grid is preferably a portion of a closed oscillatory circuit, like the anode.

The primary object of this invention is to provide an improved tube structure for ultra high frequency operation. Other objects of this invention include the provision of a thermionic discharge device having grid and anode electrode which at the same time constitute standing wave oscillatory circuits; the provision of a thermionic discharge device in which grid and anode oscillatory circuits are entirely enclosed within the tube; and the provision of an ultra high frequency discharge device in which self-oscillation may be maintained with no other coupling or connections than those required to supply operating potentials to the various electrodes.

This invention will be better understood'from the following description when considered in connection with the accompanying drawing, in which Figure l is a perspective view of one embodiment of this invention; Figure 2 is a circuit diagram showing in section a device of the type illustrated in Figure 1; Figure 3 is a perspective view of an alternative embodiment of this invention; Figure 4 is a sectional end view of the device illustrated in Figure 3; and Figure 5;is a schematic diagram, partly in section, of a similar oscillator.

Referring to Fig. 1,an evacuated envelope 1 contains cathode 9, anode H and grid l3 electrodes. The anode H is a cylindrical electrode concentrically disposed about the linear cathode 9 which extends through the length of the tube. The anode II is longitudinally divided into two semicylindrical segments l5, I! by a plane which includes the cathode 9. The anode segments I5, ll are jointed at one end by a conducting ring l9, which also serves to support the segments. The grid I3 is also concentrically disposed about the cathode 9, and in the illustrated form comprises a helical wire, although any of the well-- known mesh-like grid structures may be employed. Output is taken from the tube by a pair of leads 2|, 23 which are connected to the two anode segments at points along their length which are determined by the impedance of the load device 25.

The tube illustrated in Fig. 1 is best adapted means of a. battery 29 and potentiometer 3| connected between ground and the radio frequency voltage node on the anode ll. Cathode emission is produced by a battery 33, or the like. The theory of operation of a Barkhausen, orpositive grid oscillator, is well known and need not be explained herein. The illustrated construction, however, makes possible higher frequency operation because external leads to the oscillatory circuit have been eliminated. In addition, interelectrode capacities are uniformly distributed over the entire oscillatory circuit, and their effect is, therefore, greatly reduced. This permits the electrode structure to be made larger than is customary so that greater heat dissipation can be obtained without decreasing the maximum frequency of operation, or the maximum frequency of operation may be increased if the size of the electrodes is keptsmall.

In the modification illustrated in Figs. 3 and 4, aresonant circuit for the grid electrode has been provided. The anode structure is identical to that illustrated in the preceding figures. The grid 35, however, is cylindrical, and is concentrically disposed about the cathode 9. Like the anode, the grid 35 is longitudinally divided into two semicylindrical segments 31, 39, which are jointed at one end by a supporting ring 4|. The anode II and grid 35 electrodes are placed so that their open ends are adjacent, the open end of the grid extending within the open end of the anode.

The grid electrode 35 may comprise perforated semi-cylindrical segments of wire mesh, or it may be partly perforated and partly imperforate. In the latter case that portion of each grid segment within the anode must be perforated, as illustrated in Figs. 3 and 5. The lengths of the anode ii and grid 35 oscillatory circuits, measured longitudinally in a directional parallel to the axis of the cathode, is such that both circuits are resonant at the operating frequency. A consideration of the circuit will show that the tube is equivalent to a push-pull tuned-plate tuned-grid oscillator, in which the feedback coupling is supplied by the interelectrode capacities.

In accordance with the invention, it is proposed to control the amount of feedback produced by the interelectrode capacity by rotating the grid electrode about its longitudinal axis with respect to the anode. This rotation is illustrated in Figs. 3 and 4, but may be best understood from the latter figure. It will be seen that the plane of division X-X of the anode is a horizontal plane which contains the cathode, while the plane of division Y--Y of the grid contains the cathode, but is at an angle to the former plane. The effect of the rotation of the grid with respect to the anode is to provide coupling from each anode segment to both grid segments, the relative amounts of coupling depending on the degree of rotation. Since the two anode segments are oscillating in phase opposition, the effective feedback voltage depends upon the relative amplitudes of the two components, which is a function of the angle of rotation. The amount of rotation may be predetermined, or a mechanism may be provided for rotating the grid within the tube, so that adjustments may be made during operation.

Referring now to Fig. 5, a circuit diagram of a feedback oscillator is shown, the tube being of the general type illustrated in Figs. 3 and 4. The grid 35 and anode H structures are shown in section. Inorder toreduce electron emission in the non-active regions of the grid and anode, the cathode 9 is active only in the central region when the grid and anode are in alignment. The cathode itself is supported by two supporting members 43 and 45 which are non-emissive. Cathode supporting members 43 and 45 are in turn supported by insulating members not shown in the supporting rings [9 and 4|, or any other suitable manner. Battery 41 is connected between ground and the voltage node of the anode. Battery 49 supplies negative bias for the grid 35. As before, a battery 33 is utilized to energize the cathode.

I have not illustrated details for supporting the various elements of the device within the envelope, since mounting means are well known to those skilled in the art, and their illustration would serve no useful purpose.

Output leads have been shownponnected to the open end of the anode segments, but it is to be understood that output may be derived froma similar connection on the grid segments.

I claim as my invention:

1. An electron discharge device comprising a cathode, a concentric cylindrical anode longitudinally divided into two semi-cylindrical segments comprising a closed oscillatory circuit, said segments being connected together at one end, and a second cylindrical electrode longitudinally divided into two semi-cylindrical segments comprising a closed oscillatory circuit, said second electrode being coaxially mounted with respect to said anode, and extending within the open end of said anode for a portion of its length, said portion being formed of a grid-like mesh.

2. An electron discharge device comprising an evacuated envelope containing a linear cathode and cylindrical anode and grid electrodes, said anode electrode being longitudinally divided into two semi-cylindrical segments connected directly together at one end and comprising a first closed oscillatory circuit, said grid electrode being longitudinally divided intotwo segments connected directly together at one end and comprising a second closed oscillatory circuit, the open end of said grid being within the open end of said anode, said anode and grid electrodes being coaxially disposed with respect to said cathode electrode.

3. An electron discharge device comprising an evacuated envelope containing a linear cathode and cylindrical anode and grid electrodes, said anode electrode being concentrically disposed about said cathode and longitudinally divided into two semi-cylindrical segments by a first plane which includes said cathode, said segments being connected directly together at one end to form a first closed oscillatory circuit, said grid electrode being similarly longitudinally divided into two segments by a second plane which includes said cathode and is at an angle to said first plane, said segments being connected directly together at one end to form a second closed oscillatory circuit, a portion of the open end of said grid electrode being in the space between said cathode and the open end of said anode electrodes.

4. An electron discharge device comprising an evacuated envelope containing a linear cathode and cylindrical anode and grid electrodes, said anode electrode being concentrically disposed about said cathode and longitudinally divided into two segmerts each approximately a quarter wave long, said grid electrode being concentrically disposed'about said cathodeand'longitudinally divided into two segments each approximately. a quarter wave long, a portion of the inner end of said grid electrode being within the inner end of said anode electrode, the outer ends of said electrodes being connected directly together to form, respectively, anode and grid oscillatory circuits.

5. The device ofclaim 4 in which the active portion of said cathode is coextensive with said.

portion of said gridelectrode which lies within said anode electrode.

6. An electron discharge device comprising an evacuated envelope containing cathode, anode and grid electrodes, said anode comprising a. pair of semi-cylindrical segments of the order of a 2,288,812 said segments being connected together at one with.

7. A high frequency discharge device comprising an evacuated envelope containing cathode, anode and grid electrod said anode and grid electrodes each comprising a pair of semi-cylindrical segments concentrically disposed about 8. A high frequency discharge device comprising an evacuated envelope containing cathode, anode and grid electrodes, said anode and grid electrodes each comprising drical segments concentrically disposed about the axis of said cathode and being of the order of a quarter wave long, said anode segments being connected together atone end to form a first halt wave oscillatory circuit, said grid segments being connected together at the opposite end to form a second half wave oscillatory circuit, the open end of said grid electrode beingwithin the open end of said anode electrode, the active portion or said cathode being substantially coextensive with the overlapping portions of said grid and anode electrodes.

ERNEST G. LINDER.

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