US2253208A - Electron discharge device - Google Patents

Description

1 Aug. 19, 1941. c. FIMILLER' 2,253,208

ELECTRON DISCHARGE DEVICE Filed Aug. 10, 1939 INVENTOR Cwu J? Patented Aug. 19, 1941 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE Carl F. Miller, Emporium, Pa., assignor to Hygrade Sylvania Corporation, Salem, Mass, a corporation of Massachusetts Application August 10, 1939, Serial No. 289,365

13 Claims. (01. 250-275) This invention relates to electron discharge devices and more especially to devices having a plurality of structural independent electron discharge sections.

A principal object of the invention is to provide a multi-section electron discharge tube in which there is a minimum of parasitic or fortuitous electron coupling between the sections.

Another object is to provide a multi-section electron discharge tube wherein the electrode systems of the various sections are so arranged that mutual electromagnetic induction between corresponding electrodes of the several sections is substantially reduced.

Another object is to provide a multi-section electron discharge tube wherein the axis of one section is substantially at right angles to the axis of another section whereby undesirable 'coupling between the sections is reduced.

Another object is to provide a multi-section electron discharge tube with the axes of the sev-. eral sections so arranged that outgassing of the parts by electromagnetic induction or bombardment is facilitated. V

Another object is to provide a multi-section electron discharge tube with the sections so mounted as to increase the mechanical rigidity of the electrode assembly as a whole, while at the same time-reducing the likelihood of microphonics or tube noise.

A feature of the invention relates to a multisection electron discharge tube of the frequency converter type wherein the electron emitters are at substantially right angles and are electrically independent.

Another feature relates to a simplified multisection mount for such tubes as frequency mixers, including for example triode-hexodes, triode-pentodes and the like. 1 i

Another feature relates to 3 a multi-section mount forsuch tubes as diode-triodes, diodepentodes and the like, wherein the sections are efiiciently shielded from each other while preserving a simplified mount structure and one which lends itself to emcient and rapid outgassing of all the mount parts.

A further feature relates to the novel organization, arrangement and relative location of parts which constitute an improved and efiicient mu'lti-section electron discharge tube, particularly where the tube is of a type wherein all the lead-in connectors are'brought out at the same end of the tube.

Other features and advantages not specifically enumerated will be apparent after a considerationof the following detailed descriptions and the appended-claims.

While the invention will be illustrated in one particular type of tube, namely a triode-hexode, it will be understood that various features of the invention may be embodied in other tube structures. Accordingly in the drawing:

Fig. 1 is a vertical sectional view of a typical radio tube embodying the invention.

Fig. 2 is a sectional view of Fig. 1 taken along the line 2-2 in the direction of the arrows.

Fig. 3is a sectional view of Fig. 1 taken along the line 33 in the direction of the arrows.

Fig. 4 is a schematic-perspective view to explain certain features'of the invention.

Fig. 5 is a right-hand end' View of the triode unit of the tube shown in Fig. 1.

It is well-known in the art to build multi-sectional tubes, in particular tubes containing two or three sections, as e. g., in diode triodes, double diode triodes, or pentodes, mixer tubes containing a separate oscillator-section from which a local oscillation is injected to one of the grids of the mixer section. In the majority of cases, these tubes are constructed with a single cathode, and the various sections of the tubes are arranged concentrically on, top of each other, the common cathode forming the common axis of the different sections.

The types constructed along these lines have a number of mechanical and electrical disadvantages, which are well-known to those familiar with the art. From the mechanical point of view there is diificulty in mounting, and as a rule it is not possible to give as good a mechanical sup- 7 port to the main section of the tube and to the tion generally does not common cathode as can be attained in single section tubes. This results in noise and electrical leakage.

Another difiiculty arises, from the usually different sizes of the mounts of the two sections, in the high frequency outgassing during exhaust. As a rule, the smaller section of these tubes is located at the lower end of the tube, near the stem of the tube, through which the leads for connection with the outside circuit are sealed. Due to this location of the smaller sectional mount, two difficulties arise. The smaller secpick up enough energy from the high frequency field applied during exhaust, because it is shielded by the larger section, which absorbs most of the magnetic lines of force of the high frequency field. This is particularly true when the mount as a whole is provided with an electrostatic shield or cage. It

is necessary in many cases to apply several induction coils of different shapes during exhaust in order to compensate for this absorption of the magnetic field by the larger section mount. In this case generally a new trouble arises. The leads through the stem are heated to such a temperature by the special auxiliary coils used for heating the lower section that the shrinkage due to stem cracking increases.

Another undesirable feature of the conventional construction is the difiiculty of shielding the two sections of the tube from each other. This is particularly bad in case of the mixer tubes, where it is necessary to introduce a lead from one of the elements of the oscillator section to one of the elements of the mixer section. This undesirable feature is also avoided by the construction according to the invention, as can be understood from the following description and the attached drawing, which shows an embodiment of the invention for the case of a triodehexode, which is the most complicated case for the designer and is therefore taken as an example to show all the possibilities of the new construction according to the invention. It is of course understood that in a general way the advantages are similar for diode triodes, or double diode triodes.

A particular advantage of the separation of the two cathodes for the case of a mixer tube is the fact that it is possible to make the connection from the oscillator section to the mixer section in either of two ways, namely, either from the oscillator cathode or from the oscillator grid. The first named connection, which is called cathode-injection is impossible with the conventional multi-sectional mixers which apply a common cathode to the two sections.

Referringrto the drawing, the tube comprises preferably an all-glass enclosing envelope con- 1 sisting of a stem I having a rim 2 which is sealed to the bulb portion 3. Sealed through the stem I in a'vacuurn tight manner, are a series of rigid metal rods 4 to II which also serve as the plugin contact prongs for the tube. Preferably a metal cup-like base (not shown) is cemented or otherwise attached to the lower end of the tube. For a detailed description of an enclosing envelope and base, reference may be had to U. S. Patent No. 2,238,025 or U. S. Patent No. 2,250,184.

The mount is supported mainly by connection to the prongs 5 and 9, and for this purpose the mount is provided with a pair of main metal uprights I2, I3, which have fastened thereto by means of eyelets I4, a pair of electrode spacer discs I5, I6, of mica or other suitable insulation material. Assembled between the spacers is an electrode assembly of the hexode type comprising a central electron-emitting cathode sleeve IT, a series of wire wound grids I8, |9,'20 and 2|, and a plate or anode which is preferably made in two cylindrical sectors 22, 23, which have their opposed edges spaced from each other and electrically connected by metal straps 24, 25. The purpose of not making the plate in the form of a complete cylinder is to facilitate heating of the various grids and associated parts by induction for outgassing and the like.

While the drawing shows the grids each in the form of a fine wire helically coiled around and with each turn fastened to a corresponding pair of vertically disposed metal side rods, it will be understood that other well-known forms of grids may be employed. Preferably the grids are held in place by the members I5 and I6, which engage the end turns of each grid. The plate electrode sections are held in place by oppositely disposed shouldered lugs 26, the shoulders of which engage the corresponding faces of the discs I5 and I6 and the projecting ends of which pass through the said spacer discs and are bent back as shown more clearly in Fig. 3. It will be understood of course that the members I5 and I6 are also provided with corresponding openings to receive the projecting ends of the various grid side rods and also to receive the ends of the cathode sleeve H. The above described electrode assembly is a unitary one in the sense that all the electrodes are mounted and held in place between the discs I5 and I6 as a unit.

Supported above the hexode assembly is a tri- V ode assembly consisting of an electron-emitting cathode sleeve 21, a wire wound grid 28 and a flattened tubular plate or anode 29. This triode unit is assembled to form a unitary structure between a pair of insulator discs 36, 3|, of mica or other suitable insulation material. In accordance with the invention, the discs 3|] and 3| are mounted so that they are substantially perpendicular to the discs I5 and I6 and so that the electrodes 21, 28 and 29, extend longitudinally substantially perpendicularly with respect to the corresponding electrodes of the hexode assembly. For the purpose of heating the cathode sleeve there is provided a heater wire 32, which passes through the cathode sleeve and carries a coating of a suitable refractory insulating material to insulate it from the sleeve. Likewise, the cathode sleeve 21 is heated by a similar insulated heater wire 33 which is preferably connected in series with the wire 32.

In order to tie the hexode assembly and the triode assembly together as a mechanically rigid unit, there is attached to the upright I2 a metal rod 34, which passes through the discs 39, 3|, and is rigidly fastened thereto by suitable lugs or eyelets 35. The other main upright I3 has its upper end bent to L-shaped formation and the end of this L-shaped part is welded to the plate side rod 36. The plate 29 is preferably made in two half sections which are welded to the respective side rods 36 and 31, so as to form a substantially flattened tubular electrode. The plate side rods 36 and 31 pass through the spacer discs 30, 3|, and are held in place by suitable metal lugs 38. The wire wound grid 28 is like- Wise supported by two metal side rods the opposite ends of which pass through discs 36, 3|. Preferably, another metal rod 39 passes through the discs 3|], 3|, being held in place by suitable eyelets or lugs 46, the rod 39 having its righthand end bent upwardly substantially at right angles and to the end of which the heater filament 33 is welded. The other end of the heater filament 33 is welded to the main upright I2. The filaments 32 and 33 are connected in series by Welding the upper end of filament 32 to the rod 39. Preferably, the mica discs 30 and 3| have straight lower edges 4| as shown in perspective Fig. 4.

For the purpose of shielding the entire mount electrostatically, there is provided a cylindrical metal shield 42 which may be held in place in any suitable manner. Thus, the member 42 may be welded to the rim of a metal cup-like member 43 within which the disc I5 is seated. It will be understood of course that member 43 is provided with a central longitudinal Window to enable the cathode sleeve and the various side rods to pass therethrough Without being shortcircuited. Preferably, the upper end of the shield member '42 is provided with a series of slots 44 to facilitate heating of the triode mount by induction for outgassing purposes and the like. When the tube is to be used as a frequency converter tube, the triode section will be connected in any well-knownmanner to function as an oscillator. Since the cathodes of the triode and hexode sections are insulated from each other, it is therefore possible to connect the oscillator section of the hexode or mixer section either by cathode injection or by control grid injection as above pointed out. The drawing shows the control grid 28 of the triode oscillator connected by a metal strap 45 to grid of the hexode section for grid injection. If cathode injection is to be used the cathode 21 instead of grid 28, is connected directly to grid 20. In either case the grid I8 of the hexode section, serves as a signal input or control grid and grids I 9 and 2| are connected together by a metal strap 46 to form a screen for the modulator grid 20.

The connections from the various electrodes are made to the corresponding prongs 4 to 8. Thus one end of the series connected heater filaments is connected through support rod l2 to prong 9, the other end of the heater filament is connected to prong 8. The mixer plate 22--23 is connected to prong I; the triode plate 29 to prong 6; triode grid 28 and mixer modulator grid 20 to prong 5; screen grids l9 and 2i to prong 4; mixer control grid I8 to prong II; and both cathodes I! and 21 are connected to the shield 42 and thence to prong l0. Prong H) is adapted to be grounded or connected to some other suitable shielding potential when the tube is plugged into a suitable socket. For the purposes of simplicity in the drawing, the connections between the electrodes and the various prongs are schematically shown in Fig. 2.

In the embodiment where the modulation is effected by cathode injection, the connection to the various prongs of the base is as follows. One end of the series connected heaters is connected to prong 8; the mixer plate 22-23 is 1 connected to prong I; the triode cathode 21 and mixer modulator grid 29 are connected to prong 6; triode grid 28 to prong 5; triode plate 29 and mixer screen electrodes l9 and 2! to prong 4; mixer control grid [8 to prong ll; mixer cathode I! to prong IE]; and the other end of the series connected heaters is connected to prong 9.

While the invention has been embodied in certain specific forms, it will be understood that various changes and modifications may be made therein, for example While the triode unit is shown located above the mixer unit, it will be understood that it can be located below the mixerunit if desired.

What I claim is:

1. An electron discharge tube comprising a plurality of electron emission systems, each including at least an electron-emitting cathode and a cooperating anode, the electrodes of said systems being mounted at an angle to each other and in vertically superposed relation to reduce undesirable electron coupling therebetween.

2. An electron discharge tube comprising a plurality of electron emission systems, each including at least an electron-emitting cathode and a cooperating anode, said systems being mounted with the anodes in vertical superposition transversely to each other so that the anodes shield the said systems mutually from each other with respect to stray electron emission.

3. An electron discharge tube comprising a plurality of electron emission systems, each including at least an electron-emitting cathode and a cooperating anode, said systems being mounted in vertical superposition with respect to each other so that said anodes are approximately at right angles.

4. An electron discharge tube comprising a plurality of electron emissive systems, each including an electron-emitting cathode surrounded by an anode, one of said anodes being in the form of a substantially flattened tube disposed across the end of the other anode, whereby it effectively shields the open end of said other anode against stray electron coupling.

5. An electron discharge tube comprising a plurality of electron emissive systems, each includ-- ing an electron emitter, a control grid and a cooperating anode, said systems being mounted in close superposed relation and substantially at right angles to each other so that undesirable coupling between said grids is material-1y reduced.

6. A frequency converter tube of the type having an oscillator section including an anode, a cathode and a control grid and a mixer section including an anode, a cathode and a plurality of grids, said sections having the electrodes mounted at substantially right angles to each other and so that the anode of one section overlies the anode of the other section.

7. A mount for an electron discharge tube comprising a pair of parallel uprights, a first mount section supported by said uprights and having the electrodes extending substantially parallel thereto, and a second mount section supported by said uprights and superposed above the first mount section and with the electrodes extending transversely between said uprights.

8. A frequency converter tube according to claim 6, the cathode of the triode section being insulated from the cathode of the mixer section.

9. A frequency converter tube according to claim 6 in which the cathode of the triode section is insulated from the cathode of the mixer section and the control grid of the triode section is connected to the modulator grid of the mixer section.

10. A frequency converter tube according to claim 6 in which the cathode of the triode section is insulated from the cathode of the mixer section and the cathode of the triode section is connected to the modulator grid of the mixer section.

11. A frequency converter tube of the type having 'a triode oscillator section and a plural grid mixer section, each section having an electron emitter with a filament heater therefor, said sections being arranged substantially at right angles and superposed so that the anode of one section shields the anode of the other section from stray electron coupling, said filaments being connected in series but insulated from the associated emitters whereby said tube can be used as a converter by cathode injection or by controlgrid injection.

12. An electron discharge tube comprising a triode section with electrodes assembled to form a rigid unitary structure between a pair of insulator spacer members, another multi-grid section with the electrodes assembled to form a rigid unitary structure between another pair of insulator spacer members, means to support and fasten the first section adjacent one end of the second section whereby both sections are substantially rigidly united, said insulator members be ing in the form of discs with the edges of one pair of discs engaging the faces of the other pair of discs substantially at right angles.

13. A radio tube mount comprising a header, a pair of parallel vertical metal uprights supported from said header, a pair of horizontal spacer discs extending transversely between and fastened to said uprights, an electrode assembly supported between said spacer discs, a pair of vertical spacer discs, an electrode assembly supported between said vertical spacer discs, and means extending transversely between said uprights for fastening said vertical discs to said uprights.

. CARL F. MILLER.

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