US1850559A - Vacuum tube and mounting - Google Patents

Description

March 22, E, MARSHALL 1,850,559

VACUUM TUBE AND MOUNTING Filed April 21, 1928 25 1 y l g: 15 6 23 INVENTOR TTORNIEYA.

Patented Mar. 22, 1932 UNITED STATES PATENT OFFICE ALBERT E. MARSHALL, OF BALTIMORE, MARYLAND, ASSIGNOB TO CORNING GLASS WORKS, OF CORNING, NEW YORK, A CORPORATION OF NEW YORK vacuum 'rman AND monn'rme Application filed April 21,

This invention relates to vacuum tubes and mountings therefor and more particularly to the arrangement of the elements through which contact is established between the tube 5 and the transmitting or receiving circuit.

For some time engineers and others interested in improving the transmission and reception of communications have recognized certain inherent faults in the vacuum tubes 0 and sockets commonly employed. These tubes are characterized by a cylindrical base, usually in the form of a metal shell which encloses a flat insulating body, from the bottom of which project four prongs constituting the terminals of the plate, grid and filament structure of the tube. These prongs form contacts by which their respective elements are connected to the other parts of the receiving or transmitting circuit, and in some instances serve as anchors for holding the tube in place in its socket. The majority of the sockets employed rely on horizontally disposed springs, to make contact with the prong tips, while other types use side wipe contacts to overcome the difliculties resulting from weak springs and tubes having prongs of irregular length. The present standard vacuum tubes require sockets which provide for the correct relative location of the prongs. This is accomplished 0 by enveloping the tube base and providing a locating device such as a bayonet lock. Without/such means it would be possible, when inserting a tube into the socket. to make contact with the wrong prongs, and since the filaments are usually built for 6 bolts while the plate carries voltages up to 200 any wrong location of the tube in itssocket would very likely result in the plate voltage being applied to the filament, with disastrous effect upon the latter.

One difficulty with these types of tubes and sockets is that imperfect electrical contact, between the contact members of the socket and the prongs, is frequently experienced, resulting in annoying vibration, loss of power and generally poor operation. Another serious difficulty with such tubes is'the close proximity and parallel relation of the plate and grid terminal prongs to each other, which introduces undesirable electrostatic capacity, and

1928. Serial No. 271,962.

' minimize this.

The object of my invention is to improve communication apparatus and to overcome the difficulties and disadvantages encountered 1n the use of the vacuum tubes now commonly employed.

Among its important features my invention embodies the wide separation of the grid and plate leads by which the electrostatic capacity efiects are minimized, and the use of positively gripping contact members for engaglng the grid, plate and filament terminals so as to insure good electrical contact between the tube elements and the transmitting or receiving circuit. These features will become more evident upon consideration of the following specification taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a perspective view of a socket or mounting constructed in accordance with this invention;

Fig. 2 is a bottom plan view of Fig. 1 with the metallic contact portions removed;

Fig. 3 is a transverse sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged fragmentary sectional view taken on the line 4-4 of Fig. 1;

Fig. 5 is an enlarged fragmentary sectional view taken on the line 55 of Fig. 1;

Fig. 6 is a side view in elevation of a vacuum tube for use in conjunction with the mounting herein described;

Fig. 7 is a bottom plan view of Fig. 6; and

Fig. 8 is a side view of a vacuum tube constructed in accordance with this invention and supported by a modified form of mounting. the latter being shown in section.

Referring to the drawings in detail, a socket or mounting designated generally 12, comprises a disk 13 of non-conducting material such as glass. This disk is provided with openings 14, 14a, 15 and 16, and at diametrically opposite points with peripheral notches 17 for the reception of anchoring screws (not shown).

As illustrated in Fig. 1, the openings 15 and 16 are formed at diametrically opposite l points near the periphery of the disk and receive studs '18 to the upper ends of which are secured bifurcated contact springs 20.

5) are metallic bushings 24 which are formed with heads 25, the latter being received in countersinks 26 formed in the upper face of the disk 13 in longitudinal alignment with the openings 14 and 14a. The lower portions of the bushings are split as illustrated in the drawings to provide yieldable gripping jaws in which the prongs of a vacuum tube are clamped. The lower ends of the openings 14 and 14a communicate with recesses 27 for the reception of conductors through which current is supplied to the filament of the vacuum tube.

The vacuum tube with which the above type of socket is used, contains the conventional grid, plate and filament structure all mounted within the customary glass envelope 28 to which is secured a base 29. The latter consists of a cylindrical body provided with a pair of spaced depending prongs 30 and 30a to which the filament terminals are electrically connected. Extending radially from the base are substantially ii-shaped contacts 31 and 32, the former of which is electrically connected to the grid, while the latter forms the terminal of the plate. These contacts are arranged in diametrically opposed rela tion. and extend well beyond the periphery of the base 29 so that when the tube is in position, on the mounting, the contacts 31 and 32 will engage the contacts 20.

In the modification illustrated in Fig. 8,

y the socket 12 comprises a disk 13 which, like the disk 13, is formed with openings to receive the grid and plate contact elements. Formed in the upper face of the disk 13 is a recess, 33 for the reception of a cushion 3d.

35 which register with the filament contact receiving openings 36 formed in the disk, and fitted in the openings 35 are contact bushings 25' by which contact is established between the filament of the vacuum tube and its power source. The interposition of a cushion between the tube base and socket effect-ively reduces microphonic'efi'ects such as are frequently experienced with uncushioned mountings. The grid and plate contact springs conform in structure to, and are s..- cured in their respective openings, in the same manner as the bifurcated contact springs 29 above described.-

in use, the tube is placed in the socket by The latter is provided with countersunk openings releases entering the prongs 30 and 30a into the openings 14 and 140 respectively. Upon pressing the tube firmly into place, the V-shaped contacts 31 and 32 will enter between the respective jaws of the bifurcated contact springs 20, forcing the same apart and forming good electrical contact therewith. In the meantime the prongs will frictionally wipe against the walls of the bushings 24 to insure proper contact therewith. Owing to the unsymmetrical location of the filament contacts with relation to the grid and plate -contacts, proper location of the tube in the socket is assured. Furthermore, danger of burning out the filament is precluded, as in no position is it possible to place the latter across the plate circuit. Wide separation of the grid and plate terminals overcome much of the dificulty experienced with the ordinary type of vacuum tube, as the electrostatic capacity between these two elements is reduced to a minimum.

While in the foregoing there has been shown and described the preferred embodiment of this invention, it is to be understood that minor changes in the details of construction, combination and arrangement of parts may be resorted to without departing from the spirit of the invention as defined in the appended claims.

1 claim:

l. A vacuum tube mounting including a disk of insulating material having diametrically opposed peripheral notches, openings near its periphery in diametrically opposite relation and openings near its center in staggered relation, said disk also having recesses in one face communicating with the openings and extending to the periphery.

2. A. vacuum tube mounting comprising a disk of insulating material having diametrically opposed peripheral notches, openings near its periphery in diametrically opposite relation and openings near its center in staggored relation, said disk also having recesses in one face communicatin with the openings and extending to the periphery, and contacts mounted in the openings.

A vacuum tube mounting comprising a disk of insulating material having diametrically opposed peripheral notches, openings near its periphery in diametrically opposite relation and openings near its center in stagered relation, said disk also having recesses in its lower face communicating with the openings, a depression in the upper face and a cushion fitted therein.

ALBERT E. MARSHALL.

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