US2320045A - Electron discharge tube - Google Patents

Description

y 1943- c.- F. MILLER v 2,320,045

ELECTRON DI SCHARGE TUBE Filed Oct. 25. 1941 WWI llm. v I! IHMIP m CARL F. MILLER INVENTOR Patented May 25, 1943 ELECTRON DISCHARGE TUBE Carl F. Miller, Corning, N. Y., assignor to Sylvania Electric Products Inc., a corporation of Massachusetts Application October 25, 1941, Serial No. 416,433

' 4 Claims. (01. 250-275) This invention refers to electron discharge tubes and in particular to vacuum tubes used in ultra short wave circuits.

In the region of ultra short waves, and in particular in the region of decimeter waves, the capacitances of the tube electrodes, and that of the leads of the tube electrodes carried through the tube envelope must be kept as low as possible, as is well-known in the art. The structure of the circuits used in ultra short wave work makes it, furthermore, desirable to provide an arrangement of the lead wires of the tube, which insures a minimum capacity and inductance coupling bre- In the design of such tubes, convenience of connection between the tube electrodes and the wires or members constituting the tuned transmission line must be taken into account, as well as the shortness of such connections. As a result the conventional tube design with the tube prongs extending from the base of the tube parallel to its longitudinal axis, has not in all cases been satisfactory. For ultra-high frequency work therefore, this has led to compromise designs represented for example by the Acorn tube, which designs preclude their manufacture and processing on conventional tube-making machines. As a result, these compromise designs have been manufactured in most cases as individual hand-made units, particularly as regards the sealing-in of the mount into the tube.

Such designs are particularly undesirable for small size ultra-high frequency tubes of intrinsically low power, which would have to be made up Very nearly as individual hand made jobs, at least in the sealing-in of the mount into the tubes.

It is, therefore, a principal object of the present invention, to provide an ultra-high frequency tube of small size, high efiiciency, and minimum losses, which can be made up of standard parts generally used in the production of certain wellknown types of radio tubes.

It is another object of the invention, to, provide an ultra-high frequency tube, in which the.

tube mount is so arranged that the connections between the tube electrodes and their leads through the tube envelope are of minimum length. I

A further principal object of the invention consists in the positioning of the tube mount in a tube header in such a way, that at least one of the tube electrodes can be connected symmetrically to two of the lead pins of the tube header which lead pins extend perpendicular to the tube header.

A feaure of the invention refers to the symmetrical connection of the two ends of the oathode of a tube mount to a pair of lead pins of the tube header.

Another feature of the invention refers to the symmetrical connection of certain electrodes of an ultra-high frequency triode to pairs of lead pins of a tube header, and wherein the connectors between each electrode and the corresponding pairs of header lead pins are of minimum length.

It is another object of the invention, to locate the axis of the tube mount parallel to the main surface of a tube header, whereby symmetrical, short connections of at least one of the tube electrodes to one symmetrical pair of lead-in conductors of the tube header is provided.

One feature of the invention refers to the reduction to a minimum of the capacities and inductances of the members connecting the tube electrodes to the leads of a tube header.

Another feature refers to the adaptability of the tube leads for direct connections to a tuned transmission line circuit, in particular for double ended operation, whereby a minimum reflection loss of the oscillations in the circuit is insured.

It is an object of the invention to provide an ultra-high frequency tube, which allows a complete separation of the grid and plate circuits of the tube, due to the symmetrical arrangement of two leads connected to the cathode.

A feature of the invention refers to an ultrahigh frequency tube of extremely low losses and high efficiency which is easily assembled and mounted.

In the drawing which shows certain preferred embodiments,

Fig. 1 is a vertical cross-section of a triode tube embodying the invention.

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

Fig. 3 is a modification showing the invention embodied in a pentode.

Referring to Figs. 1 and 2, the tube envelope may be of any well-known construction, but is preferably of the type shown in Patent No. 2,250,184 comprising a cup-like glass header having a relatively thick flat bottom I and a tapered upstanding rim 2. Rim 2 is arranged to be sealed to the corresponding edge or lip of the glass bulb portion 3. The header I is formed with a central downwardly extending exhaust tabulation 4 which can be tipped off after proper evacuation of the tube. It will be understood of course that the invention is not limited to glass envelope tubes but may be equally well embodied in a tube having a metal envelope closed off by a flattened or button-1ike header through which the contact pins are insulatingly sealed in a vacuum-type manner.

Rigidly mounted in header I and disposed symmetrically around the center thereof, for example in a circular path, are the rigid rods 5 to I2 which constitute the lead-in pins for the tube. Pins 5 to I2 are sealed in a vacuum-tight manner through the header and the latter preferably is thickened as by integral beads I3 in the regions where the prongs are sealed.

For the purpose of supporting the tube in a suitable socket or receptacle, there is cemented to the bulb a metal cup-shaped member having a substantially flat bottom I4 and a cylindrical rim I5. The bottom I4 is provided with a series of circularly disposed openings to receive the corresponding glass beads I3 whereby the end I! and an intermediate peripheral groove I8 adapted to engage a suitable detent contact I9 to lock the tube in its socket; it being understood that the socket has suitable spring contacts to engage the respective pins 5 to I2.

The electrode assembly, which for purposes of illustration is of the triode type, is of so-called unitary construction wherein all the electrodes are rigidly mounted and spaced between end spacers 20, 2I, in the form of rectangular mica discs having aligned sets of openings to receive respectively the opposite ends of cathode sleeves 22; the ends of the control grid side rods 23, 23' and 24, 24'; and the bent-over lugs 25, 25, 26, 26' of the rectangular box-like plate electrode 21.

In accordance with the present invention, the electrode unit is positioned so that the electrodes are longitudinally parallel to the bottom I of the header. Furthermore, the electrodes are dimensioned so that the entire unit is sym metrically centered within the circle defined by the pins 5 to I2, and so that the plate electrode 21 is below the rim I5. In order to prevent rela tive movement between the electrode unit and the header, there are provided two rigid metal straps 28, 29, welded at their inner ends respectively to the flat sides of plate 21, and welded at their outer ends to the oppositely disposed pins 8 and I2. Likewise, the opposite ends of the cathode sleeve are connected symmetrically through respective short metal straps 30, 3I, to the oppositely disposed pins 5 and 9. The end metrically by respective short metal straps 32, 33,

to the oppositely disposed pins 6 and II). with this arrangement therefore, the entire electrode unit is surrounded by the pins and is connected thereto by the shortest possible wire lengths while at the same time being rigidly mounted with respect to the header.

As i well-known, during the evacuation of devices of this type, it is necessary to flash a getter and for this purpose the pin 9 may be extended upwardly towards the top of the bulb 3 and carries adjacent its upper end a getter carrier 34. In order to protect the electrode unit from the deposition of the getter, there is provided a disc 35 which is fastened to the rod 9 in any suitable manner, for example by means of an eyelet. Preferably the disc 35 is positioned slightly above the electrode unit and is slightly spaced from the interior wall of the bulb 3. If desired, the disc 35 may be of metal or other conductive material so that it cooperates with the members I4 and. I5 to complete the electrostatic shielding of the electrode unit within the tube.

Fig. 3 shows the invention embodied in a pentode tube, the parts which are the same as those of Figs. 1 and 2 bearing the same designations. The cathode sleeve 22 is connected at opposite ends by metal straps 30 to the oppositely disposed pins 5 and 9. The control grid is connected by metal straps 32 to pin 6, and the shield grid is connected by a metal strap 33 to pin III. The suppressor grid has one end connected by metal strap 35 to pin II and the opposite end of the suppressor grid is connected by strap 36 to pin 5. The plate is connected by members 28 and 29 to pins I2 and 8 respectively. One end of the filament heater (not shown) may be connected to prong 5, and the other end of the heater may be heated to prong I.

From the foregoing description, it will be seen that the electrode unit is mounted and sealed within a bulb of a well-known construction known to the trade as Sylvania lock-in type, and therefore the same standard sealing-in machinery that is used for the conventional lock-1n types can be used for tubes of the present invention. Furthermore, the electrode assembly forms in effect a rigid unit with the header. Instead -of fastening the electrode unit against displacement by the metal straps 28 and 29, the unit may be fastened in place by means of metal straps each fastened at one end firmly to a mica spacer and the other end of each metal strap welded to a corresponding base pin.

What I claim is:

1. An electron tube having an evacuated envelope with a flattened header extending transversely thereof, a plurality of rigid contactor pins sealed through said header with portions extending inwardly from the envelope, said pins being arranged symmetrically around the center of said header, a unitary electrode assembly mounted between and surrounded by the inwardly projecting portions of said pins}, and short metal straps extending from opposite ends of each electrode and substantially symmetrically connected to corresponding pairs of said pins.

2. A tube according to claim 1 in which the electrode assembly includes a central symmetrical cathode, a surrounding rid and a tubular plate electrode, and a pair of rigid metal struts are provided each fastened substantially symmetrically adjacent opposite ends of the plate electrode ,and the struts having the opposite ends welded to oppositely disposed pins.

3. In a tube of the character described, an envelope closed off at its lower end by a buttonlike header, a plurality of rigid contactor pins sealed through said header in a circular path around the center thereof, a unitary electrode assembly including cathode, control grid and anode rigidly supported between the internally projecting ends of said pins, the longitudinal axis of said electrode assembly extending substan tially parallel to the surface of said header, and means to substantially completely shield said unit electrostatically comprising a metal cuplike base within which the tube is fastened and having a rim extending above the electrode assembly exteriorly of the envelope, and a conductive disc mounted within the envelope and extending transversely above the electrode assembly.

4. An electron tube having an evacuated envelope with a flattened header extending transversely thereof, a plurality of rigid contactor pins sealed through said header with portions extending inwardly of the envelope, said pins being arranged symmetrically around the center of said header, a unitary electrode assembly mounted between and surrounded by the inwardly projecting portions of said pins, said assembly including at least two electrodes having separate connections to opposite ends thereof in the form of short metal straps substantially symmetrically connected to corresponding pairs of said pins whereby two separate external connections can be made to the opposite ends of said electrodes while the connections to all the electrodes are brought out at the same endof the tube.

CARL F. MILLER.

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