US2380496A - Electron discharge device - Google Patents

Description

July 31 1945. J, BEARD 2,380,496

ELECTRON DISCHARGE DEVICE Filed Nov. 29, 1943 Ismaentor JDSIEI-PH l1 EJEHRD fidw r (lttorneg evacuated envelope I. having a flatpress Patented July 31, 1.945

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'PATE 2.380.496 mcraonmscnanaa nevrcs 1 Joseph G. Beard, Baddoniield, s.;.'. o i to RadioCo'rporation Delaware Application 6 Claims. (curls-s My invention relates to electrondischarge devices and more particularly to such devices useful in oscillators.

During operation of electron discharge de-' vicechanges in temperature of the tube elements occur, particularly during the warm-up period.

- This results in changes in spacing between the various electrodesand thusgcauses a change in the inter'-electrodecapacities. Particularly when the device may be-fused in an oscillator, these capacity changescause a shiftin the frequency of operation of. the oscillator, resulting in instabillty which may "be quite pronounced, at time4 higher frequencies. 7 v

In the past, efforts have'been made to compen sate for these changes due to thermal expansion? and contraction of the tube elements by th "'iise through ported irointhepress by means of .the' su port;

rods 2| an22.- Thespacermember I! has enof bimetallic strips attached tothe tube elements or adjacent the tube'elem'ents'. However, all-.- of these arrangements are subject to the fault that a considerable time lag exists between memcrejese or decrease of the inter-electrode ca acity resultof a corporation 11i.

November 29'. 1e43, serial No.;; siz ,'17'ii 1 t sealed-the various 'ieiectrode leadsjan'd supports-for themount. Ti'lemount comprises preferably an indirectly heated cathode'll surrounded by a grid 13 provided with side rods H l5 and an anode 'llhaving side between: a pair. 01- insulating spacer'fmembers it and II ,I0r' eX8mD1e of mica and which'aresupincrease indiameter and thusmove closer to the ing from the change in temperatureof thetfibe elements and the following inter-electrode-capaq citycompensation' j It is, therefore, a principal object of my invention to provide an electron discharge device of itrgiproved design particularly useful as an oscillar. Another object of my invention is to provide an electron discharge device which has stable operatingcharacteristics under varying operating temperature conditions.

More specifically it is an object of my invention to provide such a device in which the inter-electrode capacity changes du to thermal expansion and contraction of the electrode elements are anode. This increases the inter-electrode capac-1 rods 311 and. 1|; 'These electrodes are mounted.

xtendzto er it' relative movement of the'side t ity between the gridand anode. If the grid and v anode were moved longitudinally with respect to each other, so that there would be partial uncov- -erin'g of the grid and anode, the inter-electrode .capacitycould be reduced to the inter-electrode capacity of these electrodes during the cold condition and thus stabilized. It is to accomplish 'this purpose that the grid is supported on the thermostatic members and '21, which by absorbing heat from radiation and through side automatically compensated for within the device.

It is a further object of my invention to provide such, a device in which automatic compensation for change in interelectrode capacityv is provided and in which the time lag is eliminated or substantially eliminated.

The novel features which acteristic of my invention are set forth with particularity in the appended claims. but the invention itself wiilbestbe understood by reference to the following." description taken in' connection with the accompanying drawing in'which Figure 1 is a longitudinal section or an electron discharge device made according to my invention and Fig- 7 rods l4 and II expand and cause the grid to move upwardly with respect to the spacer l9 and anode I. to partially uncover so that the inter-gridanode capacity remains substantially constant.

Onthe other hand, if the anode should expand due to absorption or heat it will mov away from the grid. thus reducing the inter-grid-anode capacity. However, heat transmitted through the I believe to be charanode side rods l1 and it to the thermostatic loops 2i and 28 will cause these loops to expand thus moving the anode longitudinally upward to again register with the grid, thus increasing the inter-electrode capacity between these two .electrodes,- and again maintaining the inter-electrode are 2 is a top viewoi the electrode mount assembly shown in Figura In accordance with my invention I provide an capacity constant. takes place. Thus with a-device of the kind described, interelectrode capacities remain substantially constant, thus making the device particularly suitablefor'a stable oscillator.

While I have indicated the preferred embodiil mentcofmyinventionotwhichlamnowaware Upon cooling the reverse .ing to neutralize the change of capacity and have also indicated only one speciilc application for which my invention may be employed,

it will be apparent that my invention is by nomeans limited to the exact form illustrated-or the use indicated, but that many variations may rality of electrodes, said electrodes being mounted to have relative longitudinal movement, supporting means for said electrodes and thermostatic means between said electrodes and said supporting means for causing relative longitudinal movement ofsald electrodes upon temperature changes of said electrodes, said movement being in a direction tending to neutralize the change of capacity caused by heating the electrodes.

2. An electron discharge device having a plurality of electrodes and including a grid and an anode, supports for said grid and anode and thermostatlc means positioned between said supports and said grid and anode for causing relativelongitudinal movement of said grid and anode upon temperature changes within the said electrodes, the relative longitudinal movement of said grid and anode being in a direction tending to neutralize the change or capacity caused by heating said grid and anode.

v3. An electron discharge device having a cath- Ode surrounded by a grid and an anode, supports for said grid and anode, and. thermostatic supporting loops positioned between said supports and said'grid and anode for causing relative longitudinal movement of said grid and anode upon changing of temperature of said electrodes, said longitudinal movement being in a direction tendcaused by heating said grid and anode.

4. An electron discharge'device including anenvelope having a press, support'and lead wires extending from said press, a mount supported from said press and including a pair of spaced aseaeee r insulating supports. a cathode. grid and anode supported between said insulating supports, and having relative longitudinal movement, and loops or thermostatic material connected between said support and lead wires and said grid and said anode and causing relative longitudinal movement. of said grid and anode in a direction tendin: to neutralize the change or capacity caused by heating or the grid and anode.

5. An electron discharge device having an evacuated envelope and having a mount comprising a coaxial grid and anode, said gridand anode being provided with side rods. support and lead-in wires for supporting said grid and anode and loops or thermostatic material connected between said support and lead-in wires and the side rods of said grid and anode ior causing relative longitudinal movement of said grid and anode in response to temperature changes ofsaid grid and anode, said relative longitudinal movement being in a direction tending to neutralize the change ,oi capacity caused by the heating or said grid and anode.

6. An electron discharge device having an evacuated envelope and having a mount comprising a coaxial grid and anode, said grid and anode being provided with side rods, support and lead-in wires for supporting said grid and anode, and loops of thermostatic material connected between said support and lead-in wires and the side rods oi said grid and anode for causing'relative longitudinal movement of sai grid and anode in response to temperature a anges of said grid and

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