US2396170A

US2396170A - Electron discharge device

Info

Publication number: US2396170A
Application number: US573343A
Authority: US
Inventors: Jr Oliver H Fulton
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1945-01-18
Filing date: 1945-01-18
Publication date: 1946-03-05
Anticipated expiration: 1963-03-05

Description

March 5, 1 946. o. H. FULTON, JR I 2,396,179

ELECTRON DISCHARGE DEVICE Fild Jan. 18, 1945 2 Sheets-Sheet 1 j 53 H U FI m 132 v J! I I? :1 35 4 1 I '17 i '1 f 18 i 1 a f March 5; 1946. Y O FULTON, JR 2,396,170

ELECTRON DISCHARGE DEVICE Filed Jan. 18, 1945 z'sheets-sheet 2 [5% "1 I INVENTOR.

OLIVER H, FULTON JR associated. circuits, particularly where Patented Mar. 5, 1946 Oliver Fultom'Jh, Montclaii'; 3., assignor to Radio- Corporation of America, a corporation of Delaware Application January 1-8, 1945, Serial No.-57.3,343

'9 Claims.

My invention relates to electron discharge devices and particularlyto such devices useful-at. very high frequencies.

When an electron discharge device: is to be used as an amplifier or as a mixer at ultrahigh. frequencies, a lownoise. level is a primary con.- sideration. Best results require the useiof a high vacuum triode. Howevenin triodes used as: radiov frequency amplifiers, feedback beco'mesa prob.- lem. To eliminate the need for neutralization due to undesired regeneration, when the device is used as a radio frequency amplifier, it is coerated as a grounded grid triode and the input and output must be well shielded from each other to bring about low feedback capacity, that is plate-to-cathode and heater.

Since lead inductance and interelectrode'capacity are limiting factors in high frequency op eration, these must be kept at-a minimum. At high frequency, transit time loading is a problem which must. be overcome by closespaci ng of ele* ments introducing. a manufacturing problem in assembly. High transconductance and amouerately high amplification factor'a're also desirable features. Lightweight construction with all electrode leads coming through one end of the envelope simplifies and reduces the size of the lumped p'arameters are used.

It is, therefore, an object of my invention to provide an improved electron discharge device useful as an amplifier or mixer at ultra high frequencies of the order of 500 megacycles. V

Another object of my inventionis to provide such a device having a low noise level, that is a high signal-to-noise ratio.

A particular object of my invention is to pro vide an electron discharge device of the triode type, suitable for use as a grounded grid amplifier or mixer and particularly adaptable for use with circuits having lumped parameters; 7

A further object of my invention is to provide such a device having a high transconductance and moderately high amplification factors,

Another object of my invention'i'stoprovide a device of this kind having. low inductance high radio frequency conductance. v

A further object of my invention is to provide such a device in whichsmallinterelectrode ca- 50 pacityl with resultant low inputand outputcapacitiesand low feedback capacity are provided.

V A still further object of my invention is to provide, such adevice in which: the transit time load-- ing factors are small; f

(01. zoo-#275) These and other objects will appear hereinafter. The novel features which I believeto be characteristic of my invention are-set forthwith particularity in the appended claims, but the invention itself will best be understood by reference-to the following description taken in connection with the accompanying drawings in which Figure l is a side elevation of an electron discharge device made according to; my'inventio'n; Figurerz is a view of Figurel turned 90, Eigure 3 is a section taken along the line 3".3 ofFigure 1, Figure 4 is asection taken along the line' l l of Figure 1, Figurefi is a-sectioh taken along the line'5-.5:of Figure 1,. Figure 6 shows a typical. groundedgrid circuit utilizing a tube made according to my in.- vention, and Figures 7 to 9,. inclusive, are enlarged viewsofa. detail of the construction used in an electron discharge device made according to my invention.

Referring to the drawings, an electron discharge device made according to my invention includes an evacuated envelope I0 having a'fiat press H. and. the usual plurality oflead l2 sealed therethrough and arranged in av circle, the press the usual emitting coatingare a pair of anode members l1 and [8 having a U-shaped transverse section, the closed ends of the ui'being fiat andoppositely disposed to the emitting surfaces of the cathode. These anode elements arecut back as at I1 and I8 to'reduce the cathode-- anode capacity While at the same time providing the'necessarysurface registering with the emitting surfaces of the cathode to receive-all'the electrons "therefrom. These anode elements are strapped together bymeans of strapping

elements

19 and 20. This mount assembly-is received between and supported by a pair of spaced insu-' lating spacer members 2| and '22, preferably of mica. They are provided with the proper apertures for receiving the ends of the-cathode, grid side rods andthe anode or plate ears, such as I'8"'a'nd' IT.

According to my invention the device is pri .-marily to operate with a grounded grid circuit In accordance with. invention I provide cathode and thecath'ode heat which extend through appropriate apertures in the mica spacer 2| and are folded over to securely lock the mica shield and grid together. The

shield is provided with a pair of arcuate shaped flaps or aprons 30 and 3! which, as shown in Figures 1 to 3 inclusive, are formed to provide the necessary shielding. Flap 3| is folded over the trough to completely shield the upper end of the cathode from the ears of the anode and the flap is bent over the upper ears of the plate member I1. Thus no part of the cathode directly sees the anode outside the grid-cathode space and complete shielding results.

Mounted at the lower end of the mount assem bly is a second shield member 25 substantially like that at the top of the mount assembly. This bottom shield member, however, is provided with a strap 36 at the lower end of which is mounted a transverse shielding disc 31 which extends close to the top of the press I l and is received between the various leads arranged in a circle.

. The bottom shield 25 is electrically connected to the lower ends of the grid side rods 15 and IE.

However, in this case the tabs corresponding to 26 and 21 are removed from the shield. In their place U-shaped elements 4| and 49 are used, the end view of which is shown in Figure l, the side view in Figure 2 and in section in Figure 3. These U-shaped elements have a pair of oppositely disposed dependent legs such as 40' and 4! which may be wrapped around and welded to the lead wires. nected to a pair of oppositely disposed leads in the press, the leads lying in the sameplane so that the press is bisected by the shield and leads.

The downwardly extending legs are con In assembly the elements 40 and Al are first The cathode is provided with a strap 42 connected to. another lead I2 oppositely disposed to the anode lead, and the two heater leads l3 are connected to two other leads [2. These connectors and leads are shielded from the strap 39 and its associated lead by the apron or skirt 35, and the lower ears on the anode element l8 are shielded from the cathode and cathode heater leads by the skirt 25 which is formed to extend transversely of the mount and parallel to the'base and extends between the lower ears of anode element l8 and the cathode strap and heate leads.

Thus it is apparent that the anode and cathode are completely shielded from each other at all points, including the connectors and leads, and that this arrangement permits an external shield to be connected to the oppositely disposed contact leads and pins connected to the bottom shield so that externally the input and ouput circuits may also be shielded from each other, thus preventing regeneration.

A getter ring 32 may be secured to this top shield by means of the strap 33. All of the connectors between the contact pins and leads and the various electrodes are wide straps which have low loss and low conductance. Because of the high turns-per-inch of the grid wires, in the example shown 240 turns per inch of 1.2 mil wire was used, and the close spacing between plate and grid of the order of 15 mils, high transconductance and low transit time loading results. A

transconductance of between 11,000 and 12,009

. micromhos with an amplification factor of 55 has been obtainedwith devices made according to my invention, the whole arrangement being placed in an envelope less than two inches in length and three quarters of an inch in diameter.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is: v

1. An electron discharge device having an envelope including cathode, grid and anode electrodes, said cathode electrode and said anode electrode having leads, said grid electrode having a shield provided with a skirt adjacent the anode electrode leadand positioned between the anode lead and the cathode lead, said envelope having a, press, a pluralityof leads extending through said press, said'grid shield being con nected to leads oppositely disposed across said press whereby the space between the press and said electrodes is dividedinto two shielded compartments.

2. An electron discharge device having an envelope provided with a press at one end thereof, a plurality of leads extending through said press, a mount within said envelope comprising a cathode, grid and anode supported on said leads, said grid being provided with shields for shielding said anode from said cathode, said cathode and said anode being connected to leads oppositelydisposed across said press, said grid shield being connected to leads atopposite sides of said press, said last leads lying in a-plane passing between said cathode lead and said anode lead. 1

3. An electron discharge device having an envelope provided with a press atone end thereof, a plurality of leads arranged in a circle extending through said press, a mount Within'said envelope comprising a cathodagrid and anode supported on said leads, said grid having a shield for shielding said anode from said cathode, said cathode and said anode being connected to leads disposed on opposite sides of said circle, said grid shield being provided with connectors connected to leads on opposite sides of said circle, said last leads lying in a plane passingbetween said cathode lead and said anode lead. r

4. An electron dischargedevice including an envelope having a press provided with a plurality of leads extending therethrough, a mount supported within said envelopeand including a cathode,- a grid surrounding said cathode, and an anode outside of said gr'idQa connector connected between the anode and a lead in'said press, and a.

connector connected between said cathode and a lead in said press oppositely disposed to said lead connected to said anode, said grid being provided with a shield connected thereto and positioned between the press and said grid, said shield being provided with a skirt adjacent said anode lead for shielding said anode lead from said cathode lead, said shield being connected to other leads in said press, said other leads lying in a plane passing between the anode lead and the cathode lead.

tween said spacing members, and an anode outside of said grid and positioned between said spacing members, said cathode, grid and anode extending through said spacer members, a low inductance lead connected between the anode and a lead in said press, and a low' inductance lead connected between said cathode anda lead in said press oppositely disposed to said lead connected to said anode, said grid being provided with a shield connected thereto and positioned between the press and one of said insulating spacer members, said shield being provided with a skirt adjacent said anode lead for shielding said anodev lead from said cathode lead, said shield being provided with a pair of oppositely disposed low inductance connectors connected to other leads lying in a plane passing between the anode lead and the cathode lead.

6. An electron discharge device including an envelope having a press, a plurality of leads extending through said press and arranged around said press, a mount supported by said leads and including a fiat cathode, a flat grid surrounding said cathode and provided with a pair of side rods lying in a plane parallel to the fiat side of said grid, and anode elements positioned adjacent the flat sides of said cathode and grid, a shield connected to the side rods of said grid adjacent said press, an anode lead extending from one of said anode elements and connected to a lead in said press, a cathode lead extending from said cathode and connected to a lead in said press oppositely disposed to the anode lead, said shield having an apron adjacent said anode lead, a shield lying parallel to the press and within the space defined by the leads in said press and connected to said apron, a second apron on said shield extending parallel to the press and positioned between the anode and said cathode lead.

7. An electron discharge device including an envelope having a press, a pluralityof leads extending through said press and arranged in a circle, a mount supported by said leads and including a cathode, a grid surrounding said oathode and provided with a pair of side rods lying in a plane, and an anode adjacent the grid, a shield connected to the end of the side rods of said grid adjacent said press, said anode being connected to a lead in said press, said cathode being connected to a lead in said press opp sitely disposed to the anode lead, said shield having an apron adjacent said anode lead, a shield lying parallel to the pressand within the circle defined by the leads in said press and connected to said apron, a second apron on said shield extending parallel to the press andpositioned between the anode and said cathode lead, and connections between the shield and oppositely disposed 1eads lying inthe plane of said side rods.

8. An electron discharge device including an envelope having a press, a plurality of leads extending through said press and arranged around said press, a mount supportedby said leads and including a flat cathode, a flat grid surrounding said cathode and provided with a pair of side rods lying in a plane parallel to theflat sides of said cathode, and anode elements positioned adjacent the flat sides of said cathode and grid, a shield connected to the grid side rods at each end of said grid, an anode element being connected to a lead in said press, said cathode being connected to a lead in said press oppositely disposed to the anode lead, the shield adjacent thepress being provided with an apron adjacent said anode lead, a shield lying parallel to the press and within the space defined by the leads in said press and connected to said shield, a second apron on said last mentioned shield extending paralle1 to the press and positioned between an anode and said cathode lead, the shield at the end of said grid remote from said press having an apron folded over the ends of the grid side rods and the end of said cathode remote from said press.

9. An electron discharge device including an envelope having a press, a plurality of'leads extending through said press and arranged in a a flattened grid surrounding said cathode and provided with a pair of side rods lying in a plane parallel to the fiat sides of said cathode, and anode elements positioned adjacent the flat sides of said cathode and grid and having ears extending through said mica spacers, a shield connected to the side rods at each end of said grid on the outside of the space between said spacers, said anode elements being connected to a lead in said press, said cathode being connected to a lead in said press oppositely disposed to the anode lead, the grid shield adjacent the press having an apron adjacent said anode lead, a shield lying parallel to and adjacent the press and'within the circle defined by the leads in said press and connectedtosaid apron, a second apron on said last mentioned grid shield extending parallel to tho press and positioned between an anode ear and a said cathode lead, the shield at the end of said grid remote from said press having a skirt extending over an anode ear, and a second skirt folded over the ends of the grid side rods and the end of said cathode remote from said press.

OLIVER H. FULTON, JR.