US1542366A

US1542366A - Vacuum-tube base

Info

Publication number: US1542366A
Application number: US427807A
Authority: US
Inventors: William R Brough
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1920-12-02
Filing date: 1920-12-02
Publication date: 1925-06-16
Anticipated expiration: 1942-06-16

Description

June 16, 1925. 1,542,366

w-. R. BROUGH VACUUM TUBE BASE Filed Deb. 2. 1920 June 16. 1925.

UNITED STATES,

PATENT OFFICE.

WILLIAM R. BROUGH, OF EAST ORANGE, NEW JERSEY, ASSIGNOB"TO WESTERN 'TRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION- OF NEW YORK.

VACUUM-TUBE BASE.

Application filed December'2, 1920. Serial No. 427,807. I U

To all whom .z'tmywdnce'rn:

Be it known that I, WILLIAM R. BROUGH,

' a citizen of the United States, residingfat East Orange, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Vacuum-Tube Bases, of .which the followin is a full, clear, concise, and. exact description.

This invention relates to vacuum tubes and more especially to the construction of a base therefor.

In the use ofvacuum tubes in high voltage, high frequency circuits, much difficulty has been experienced in insulating the lead wires of the grid and anodeselectrodes. Attempts have heretofore been made to prevent discharges from and corona effectsalong these lead wires by surrounding them with bodies of insulating material carried by the bottom of the base. These attempts have failed because with currents of high frequency and at high voltages the heating of the insulating bodies due to dielectric hysteresis is so great as to qulckly cause deterioration and deformation of the insulation resulting in a breakdown thereof and allowing discharges from the lead wires.. 1

It is an object of this invention to provide abase for vacuum tubes using highvoltages and high frequencies in which the lead wires for the electrodes of thetube are insulated from each other and in which the heating of the dielectric of thebase is reduced to such an extent that'no injurious effects result.

This object is accom lished by using as a part of the base a thin disc composed of material having a low specific dielectric loss as, for example, phenol fibre or electrosote and providing terminals in the disc for the electrodes of the tube, said terminals being so proportioned and arranged in the disc as to isolate the anode terminal from the rest and to obtain a minimum potential gradient between the terminals themselves and between the terminals and the shell of the base.

This invention will be better understood b having reference to the following speci vacuum tube is cemented a metallic shell 12, -the free end of which is turned-in as at 13 and in which is rolled an inwardly extending flange 14 near the ed 0 13. Arranged between the in-turned e go 13 and the flange 1 1 is the thin disc 15 composed of an insulate ing .material having a very low specific dielectric loss. In this disc are provided 16 for the anode of the tube, the terminal 17 for the grid and the terminals 18 for the cathode. These terminals comprise cylindricalmembers having flanges 19 to contact with one side of the disc to position them in their apertures and collars 20 to contact with the opposite side of the disc to clamp said members in place. These terminals areprovided with small axial holes which are countersunk at their ends. The lead wires 21 for the anode, 22 for the grid and 23 for the cathole are threaded through the holes in the

terminals

16, 17 and 18 respectively and soldered into the outer ends as at 24 and then flushed off. This arrangement avoids theconcentration of dielectric stresses around the small diameter of the lead wires and confines the stresses to the periphery of the terminals, thereby-avoiding the possibility of breakdown of the insulation from corona or high dielectric stresses at the surface of the lead wires.

q The

terminals

16 and 17 are so arranged in the disc 15 that the electrical stresses in the disc adjacent the points of nearest approach of the terminals to the shelland adjacent the'point of nearest approach of the terminal 16 to the terminal 17 are all approximately equal. The terminals 18 are so apertures in which arelocated the terminal located in the base relative to the terminals terminals 18. are equal to each other and to. the aforementioned stresses. Furthermore,

the diameter of the terminals 16,17 -and18 approximately the smallest possible consistreducing mechanical stren h.

This effect is accomplis ed' in a 2 50 watt tube, by making the disc of electrosote is so adjusted that these equal streses are ent'with the diameter of the disc. The: disc is made as thin as posible 'withoutmnduly.

about 3 3/10" diameter and ap roximately. 5/32 thick and making the e ective diameter of the terminals approximately 1/2". These. terminals I are then so arranged that16 and 17 lie on a diameter of the disc and are about 1 1/16" apart, the terminal 16 being about 7/ and the terminal 17, 5/16" from the periphery of the disc. The terminals 18 are approximately 1 from the terminal 16 and approximately 19/32" from 17.

Vacuum tubes equipped with this type of base may be operated for indefinite periods in circuits in which the eak voltages of the anode and grid at comp ete modulation are minimum the dielectric stresses in the disc adjacent the points of nearest approach of the high tension terminals to the low potential terminals and because the large surface of the disc for the volume thereof allows a considerable heat dissipation therefrom.

' While it is preferable to utilize the described arrangement of the terminals in combination with a thin'insulating disc, it is to be understood that they may be arranged as described irrespective of the particular means used for supporting them in the base.

What is claimed is:

1. A base for a vacuum tube having electrodes, said base comprising a sheet metal shell, a disc mounted therein, said disc being of insulating material having a low specific dielectric loss, terminals for the electrodes of the tube mounted in said disc, each of said terminals being arranged at one vertex of congruent scalene triangles to establish for the operating voltages of the grid and anode an approximate minimum potential gradient between the terminal-s for the grid and cathode, between said terminals and the shell and between said terminals and the terminals of the cathode.

2. A base for a vacuum tube having electrodes, said base comprising a sheet metal shell, a thin disc mounted therein, said disc being composed of insulating material having low specific dielectric loss, terminals for the electrodes of the tube mounted in said base, said terminals being arranged 'at the vertices of congruent-scalene triangles the electrical stresses in'the disc adjacent the 'points of nearest approach of the anode terminal to the grid terminal, the cathode terminals and the shell, and the electrical stresses in the disc adjacent-the pdints of nearest approach of the grid terminal to'the cathode terminals and the shell established therein at the operating voltages of said .grid

and anode are reduced to a minimum.

3. A base for a vacuum tube having electrodes, said base comprising a sheet metal shell, a thin disc mounted therein, said disc being composed of insulating material having a low specific dielectric loss, terminals mounted in said base for the electrodes of .said tube, the anode and grid terminals being arran ed on a diameter of the disc, the distance between said grid and anode terminals being approximately 1/3 the diameter of the disc, and the distance between the shell and the anode terminal bein approximatel 2/5 of said diameter, the cat ode terminals eing arranged in the same half-disc with the grid terminal atpoints equally distant from said grid terminal and also equally distant from and from the shell a distance approximately 2/5 of said diameter.

5. A base for a vacuum tube having electrodes, said base including a sheet metal shell, a thin disc mounted therein, said disc being composed of insulating material having a low specific dielectric loss, terminals for the electrodes of the tube mounted in said base, said terminals being arranged in the disc with the anode terminal in a different half-disc from the grid and cathode terminals, said cathode terminals being equally spaced from said grid terminal and also being equally spaced from said anode terminal.

6. A base for a vacuum tube having electrodes, said base comprising a sheet metal shell, a thin disc mounted therein, said disc being composed of insulating material having a low specific dielectric loss, terminals for the electrodes of the tube mountedin.

said base, said terminals being arranged in the disc with the cathode and grid terminals grouped in one half of the disc and said anode terminal in the other half, said grid and anode terminals being on a diameter of the disc and said cathode terminals being equally spaced from said grid terminal and also from said anode terminal.

7. A base for a vacuum tube having electrodes, said base comprising a sheet metal shell, a th1n dlse mounted therein, said disc being composed of insulating material hav ing a low specific dielectric loss, terminals for the electrodes of the tube mounted in said base, said terminals being arranged in the disc with the grid and anode terminals on a diameter of the disc at different sides of and at different distances from the center of'the disc. and the cathode terminals being located on a chord of the disc at right angles tosaid diameter and lying between the center of the disc and said grid terminal, said cathode terminals being equally spaced -for the electrodes of'the tube mounted in said base, said terminals being symmetrical with respect to one diameter only, whereby the anode terminal is isolated from the others to establishlat operating voltages a minimum potential gradient between the anode and the other terminals and between the anode and the shell.

9. A base for a vacuum tube having electrodes, said base comprising a sheet metal shell, a thin disc mounted therein, said disc being composed of insulating material having a low specific dielectric loss,'terminals for the electrodes of the tube inounted in said base,

each of said terminals being arranged in the disc at an apex oi a scalene trlangle, the anode terminal being isolated from the others whereby at operating voltages the electrical stresses in the disc adjacent the points of nearest approach of the anode electrode to the shell and to the other terminals are equal.

10. A base for a vacuum tube having electrodes, said base comprisin a sheet metal shell, a thin disc mounted. t erein said disc being composed of insulating material having a low specific dielectric loss, terminals for the electrodes of the tube mounted in 7 said base, said terminals being arranged in the disc at the corners of a quadrilateral symmetrical with respect to one of its diagonals, said diagonal being coincident with the diameter of the disc, two of said terminals being at different distances from said shell. N

diameter of said disc being approirimately twenty times the thickness of said dlsc."

13. A base for a vacuum tube having electrodes, said base comprislng a cup shaped member, terminals for the electrodes of the tube mounted in said member, each of said terminals being arranged at an apex of one of two scalene triangles having a common leg, to establish atthe operating voltages an approximate minimum potential gradient between the terminals for the grid and anode, between said terminals and the wall of said member and between said terminals and the terminals of the cathode.

14. A base for. a. vacuum tube havlng an anode, a cathode. and a grid electrode, said 1 base comprising -a cup shaped member, terminals for the electrodes of the tube mounted in said member, each of sa 1d terminals being arranged at the vertices of congruent scalene triangles whereby the electrical stresses in the member adjacent the point of nearest approach of the anode terminal to the grid terminal, the cathode terminals and the wall of said member and the electrical stresses in thebase adjacent the points'of nearest approach of the grid terminal to the cathode terminals and said wall established therein at the operating voltages of said vacuum tube are reduced to an ap roximate minimum.

15. A base for a vacuum tube having'an anode, a cathode and a grid electrode, said base comprising a member having a circular bottom, terminals for the electrodes of the tube mounted in said bottom, the anode ter- Iminal being spaced from each of the other terminals a distance at least equal to 1/3 of the diameter of the base and from the wall of the base a distance approximately 2/5 of thediameter.

16. A base for a vacuum tube containinga cathode, an anode and a control electrode, said base comprising a metallic shell, .terminals for said electrodes associated with said shell, the terminals for said cathode and control electrodes being spaced apart a dis tance substantially thesame as the distance from the terminal of said anode to said shell, said cathode terminals being at a less distance from said shell than said control electrode terminal.

17 A base for a vacuum tube containing a cathode, an anode and a control electrode, said base comprising a metallic shell, terminals for said electrodes associated with said shell, the terminals for said cathode and control electrodes being spaced apart a distance substantially the same as the distance from the terminal of said anode to said shell, said last mentioned terminal being approximately twice as far from said shell as said other terminals.

18. A base for a vacuum tube having an anode, a cathode and a grid electrode, said base comprising a member having a circular bottom, terminals for the electrodes of the tube mounted in said bottom, the anode terminal being spaced from each of the other terminals a distance at least equal to 1/3 of the diameter of the base and from the wall of the base a distance approximately 2/5 of the diameter, said other terminals being spaced apart a distance approximately 2/5 of the diameter.

19. A base for a vacuum tube containing a cathode, an anode and a control electrode,

said base comprising a shell, terminals forsaid electrodes associated with said shell, I

said cathode terminals being symmetrically arranged with respect to the anode and control electrode terminals, each of the cathode terminals being spaced from the controlelectrode terminal a distance approximately equal to the distance between the anode terminal and the shell, and said anode terminal being spaced from the shell a greater distance than is any of the remaining terminals.

20. A base for a vacuum tube containing a cathode, an anode and a grid electrode, said base comprising a shell, terminals for said electrodes associated with said shell, said cathode terminals being symmetrically arranged with respect to the anode and grid terminals,' said grid terminal being at a greater distance from said' anode terminal than are the cathodeterminals, each of said cathode terminals being spaced from the grid terminal a distance less than the distance between the anode terminal'and the shell, said anode terminal being spaced from the shell a greater distance than is said grid terminal and said grid terminal being spaced a greater distance from said shell than are said cathode terminals.

21. A base for a vacuum tube having elecother terminals a distance at least equal to 1/3 of the diameter of the base and from the wall of the base a distance approximate ly 2/5 of the diameter.

22. A base for a vacuum tube having electrodes comprising a member having a circular bottom, terminals for the electrodes of the tube mounted'in said bottom, one of said terminals being'spaced from each of the other terminals a distance equal to 1/3 of the diameter of the base and from the wall of thebase a distance approximatel 2/5 of the diameter, said other termina s being spaced apart a distance approximately 2/5 of the diameter.

In witness whereof, I hereunto subscribe my name this 23rd day of November A. D., 1920.

WHJLIAM R. BROUGH.