US2311658A

US2311658A - High frequency tube structure

Info

Publication number: US2311658A
Application number: US343528A
Authority: US
Inventors: William W Hansen; Russell H Varian; Sigurd F Varian
Original assignee: Leland Stanford Junior University
Current assignee: Leland Stanford Junior University
Priority date: 1940-07-02
Filing date: 1940-07-02
Publication date: 1943-02-23
Anticipated expiration: 1960-02-23
Also published as: GB650420A; GB650421A; USRE22795E; GB650443A; NL71847C

Description

Feb. 23, 1943. w. w. HANSEN Emu.- 2,311,658

HIGH FREQUENCY TUBE STRUCTURE Filed July 2, 1940 5 Sheets-$heet 1 INVENTORS. lA/ILL [AM W HANSEN,

Russ-Eu. H. VAR/AN,

6/ u 0 VAR! N. g av A may.

Feb. 23, 1943. w. w. HANSEN ETAL.

HIGH FREQUENCY TUBE STRUCTURE Filed July 2, 1940 5 Sheets-Sheet 2 .INVENTORJ, WILLIAM W HANSEN. Husszu. H. VAR/AN, 5/ UR E VAR AN BY V M ATT RNEY.

HIGH FREQUENCY TUBE STRUCTURE Filed July 2, 1940 5 Sheets-Sheet 4 F/CT.5

I01 INVENTORS,

\A/ILLIAM W HANSEN.

Russzu. H. VARIAN.

Feb. 23, 1943. w w HANSEN ETAL 2,311,658

1mm mmmuc'r TUBE swans-runs Filed Jul 2, 1940 5 Sheets-Sheet 5 SIG- RD VAR! N.

ATT RNEY.

Patented Feb. 23, 1943 HIGH FREQUENCY TUBE STRUCTURE William w. Hansen, Russell a. Varian, and Sigurd F. Varlan, Stanford University, CaliL,

asst

gnors to The Board oi Trustees of the leland Stanford, Junior, University. Stanford University, Calil'., a corporation of California AppllcationJuly 2, 1940, Serial No. 343,528

17 Claims.

This invention relates, generally, tohigh irequency tube structures having enclosed oscillatory circuits of the type disclosed in Patent No. 2,242,275, issued May 20, 1941, in the name of Bussell H, Varian, one of the inventors herein, and the invention has reference more particularly to novel improvements in this type of structure operating at frequencies of the order of cycles per second.

The principal object of the present invention is to provide a novel practicable embodiment of high frequency tube structure utilizing principles disclosed in the above identified application, the device of the present invention employing a pair of hollow resonators and being operable not only as a self-oscillator but also as an amplifier and detector. at will.

Another object of the present invention lies in the provision of a noveltube structure wherein the resonant circuits are provided with novel tuning means for eii'ecting either individual or gang tuning of said resonant circuits.

Another object of the invention is to provide a nigh frequency tube structure having hollow resonators provided with concentric line terminals having energy transfer loops extending into the interiors of said resonators for selectively removing energy therefrom or delivering energy thereto, said concentric line terminals being adapted to have concentric lines removably attached thereto for effecting use of this tube structure either as an oscillator, amplifier, or detector, whichever is desired.

Still another object of the present invention is to provide a novel high frequency tube having the elements thereof rigidly supported so as to mini mize microphonic noises during the operation of the tube.

Other objects are to provide a novel non-magnetic emitter heater coil and to provide a novel and easily assembled grid structure.

Other objects and advantages will become apparent from the specification, taken in connection with the accompanying drawings wherein the invention isembodied in concrete form.

In the drawings,

Fig. 1 is a longitudinal view partly in section of one embodiment of the invention.

Fig. 2 is an end view partly broken away of the apparatus of Fig. l.

Fig. 5 is a cross-section along the line 5-5 of Fig. 3.

Fig. 6 is a longitudinal cross-section of a modi fled structure.

Fig. '7 is a longitudinal view partly in section of a modified structure.

Fig. 8 is a sectional view taken along line 8-8 of Fig. 7, and Figs. 9, 10, 11 show details.

Similar characters of reference are used in all of the above figures to indicate corresponding parts.

Referring now to the drawings, the novel tube structure is shown in Fig. 1 comprising a central tubular shell i, having spaced hollow resonators 2, 3 contained therewithin that are secured at their peripheries to the inner wall of shell i. Resonators 2, 3 form enclosed electron-excitable resonant circuits of the type disclosed in Patent No. 2,242,275. These cavity resonators are shown of toroidal or substantially doughnut shape, the inner walls terminating in opposed grids I, 5, and B, I. The walls supporting grids 5 and 6 are shown interconnected by a central tube 8. The wall supporting grid 4 is connected by a tube 9 to an end plate III, which supports a tubular membe:- H to which an end bell l2 of glass is fastened by a metal to glass seal 13. Similarly, the wall supporting grid I is connected by a tube H to an end plate l5 which supports a tubular member ii to which an end hell I! of glass is fastened by a metal to glass seal IS.

The end bells i2 and II, the cavity resonators 2 and 3, and connected aligned tubes 8, 9 and I4 are evacuated, the bell l2 being sealed off, as at l9. End bell l2 contains an electron emitter structure 20, having an electron emitting surface 21 heated by a filament 22, having supply leads 23 and 24 passing through a press 25 supporting the electron emitter structure 20. Emitter structure 20 is shown arranged and constructed so as to minimize heat losses in undesired directions. The electron emitter structure is so arranged, as with a projecting ring 26, that the electrons emitted from surface 2| are collimated into a stream that will pass through the grids 4, 5, 8 andl.

End bell [2 contains the getter coils 21, 28 with end leads 2! and 30 passing through press 25 and a center lead 3| which may be connected to f lament lead 23. While not essential, these getter coils of suitable material, such as zirconium, are

' preferably heated to difierent temperatures to Fig. 3 is a longitudinal view partly in section of a somewhat modified structure.

Fig. 4 is a cross-section with parts broken away along the line 4-4 of Fig. 3. v

control the vacuum. Thus, coil 21 may be heated to approximately 400 C. for absorption oi hydrogen. and coil 28 may be heated to approximately 1700 C. for absorption of other gases, such as oxygen and nitrogen. A lead I! passing through end bell i1 supports a collecting plate element It Grid 34 is an accelerating grid, and grid ii is used to obtain a more uniform electrostatic field.

The structure of Fig. l is shown connected for serving as an oscillator, although by changing the connections, the same may be made to serve as an amplifier and if desired, also as a detector. In this figure, hollow or cavity resonator I acts as a "catcher" for electromagnetic energy and is back coupled to cavity resonator 2 acting as a "buncher" by means of a concentric line 36 terminating in loops 31 and 38, as is disclosed in the above mentioned patent No. 2,242,275. A concentric line terminal post 38 extends through an aperture provided in shell I and is attached to catcher" resonator 3. This concentric line is provided with a loop 40 extending into the oscillating electromagnetic field within-resonator 3 for the purpose of removing energy therefrom. The outer end of concentric line terminal 39 is sealed as by a glass bead II. A concentric line ll is adapted to be removably connected to terminal post 39 for the purpose of conveying the energy to any desired point, as to a radiating antenna.

Atmospheric pressure, acting upon the outer end walls of cavity resonators 2 and 3 supporting grids 4 and I, tends to cause these walls to deflect longitudinally inwardly so that grid 4 tends to approach grid 5, and grid I tends to approach grid 6. The amount of deflection of these grids under the effect of atmospheric pres sure is controllable at will by the use of the novel tuning means of this invention. This tuning means comprises end plates Hi and II that are rigidly connected to'tubes 9 and I4 respectively. Inward movement of end plates in and I5 is micrometrically controlled by means of struts l2 and I4. three of which struts are used in connection with each of the plates ill and IS, the struts being spaced angularly 120 apart. These struts have pressure balls 43 at the ends, which bear respectively upon adjustable screws 60 carried by end plates l and BI, and upon socket bearings it carried in ring members SI! and ii that are tumably mounted upon collars l1 and 48 fixed upon central shell I, as by a bolt 49. A thrust ring is rigidly mounted upon central shell i is engaged by balls 53 carried by retainers M and 55, which balls in turn bear against the socket bearings l to thereby transmit the thrust of struts i2 and H to stationary thrust ring .6.

A yoke 56 is fastened to rings ill and SI, and a lug 52 is fastened to thrust ring 48.

Members

51 and 56 are (see Fig. 2) urged toward each other by a coil spring 58, and are held apart by a strut 51 having pressure balls 43 at its ends which bear into depressions provided in yoke 58 and in an adjusting screw is threaded through lug 52, as shown in Fig. 2. When screw 59 is adjusted, ring members 50 and il are caused to turn relative to stationary thrust ring 8 causing the angular positions of struts "and H to be altered at will, thereby varying the distance between end plates III and I5 and stationary thrust ring 46, and hence effecting relative movement of grids 4 and I with respect to stationary grids i and i, thereby altering the tuning of the resonators, i. e., effecting the gang tuning thereof.

The positions of end plates l0 and I5, and hence the position of grids I and 1, are initially adjusted by means of the screws ill and lock nuts ill, while the angularity of the struts l2 and 44 is adjustable as a group by means of screw 58.

End plate II comprises an outer ring ll which is mounted tofrotate with respect to an inner supporting ring I. Headed screws I! are threaded into ring I! and are adapted to engage outer ring CI for locking this ring in desired angular position upon supporting ring 02. A cam plate 64 is fixed upon supporting ring 82 and has a slot 85 therein cooperating with an eccentric G1 which is fixed upon a bolt l8 tumable in an aperture provided in outer ring II. with screws ll loosened, then by turning bolt 80, eccentric 01 cooperates with cam plate ll to turn ring 8| relative to supporting ring I, thus changing the angularity of all the three struts M similarly, and eifecting the individual tuning of "catcher" resonator I. Thus, "catcher resonator I can be tuned readily to buncher" resonator 2. It is desirable to adjust screws ll so that when resonators I and 5 are adjusted to resonance, the

angularity oi struts I! will be substantially the same as that of struts N. This will'perrnit gang tuning of resonators 2 and 3 by means of adjusting screw as over the widest possible range. Owing to the toggle action of struts l2 and N, a very minute adjustment of the frequency of the resonators 2 and 3 is easily attainable, thereby readily tuning these resonators together, or with other resonators if desired, even at the high frequencies of the order of 10 cycles per second at which the present device is intended to operate. The value of this tuning mechanism will be realized when it is noted that a relatively large movement of rings 50 and it produced through turning screw 58 eifects but a slight change in the spacing of the grids l! and 8-1.

The form of the invention of Fig. 3 is similar to that shown in Fig. 1, except that instead of the tuning mechanism operating to adjust the angular position of all the struts simultaneously this apparatus is set up to adjust only one strut 92 and one strut 92' simultaneously, the remaining struts being unadjusted by the gang tuning equipment of this figure. Also, the tube 0! Fig. 3 is shown operating as a receiver, the same being provided with grids II and II for eifecting detection. End bell l1 contains the getter coils 21 and 28 and a cylinder 10 carrying grids H and 1!. Cylinder l0 surrounds and shields plate element 33 and is maintained through supply lead II at such a voltage that a part of the electrons passing grid 35 will be reflected by grids II and 12 and hence are prevented from reaching plate element 83. Grid II is preferably placed at an angle to the axis of the tube to prevent the reflected electrons from again passing through grid I. The number of electrons reaching plate element 3% can thus be made to vary with the strength of electromagnetic oscillations in cavity resonator 3, resulting in detection oi such oscillations.

The supply leads for getter coils 21, 28 are brought out through press 25' at a, an and u',

surrounding plate lead 32, thus serving to shield lead 32, as shown in Fig. 5.

The buncher renonator 2 in this form of the invention is equipped with a concentrig line terminal post 39 adapted to be connected to a receiving antenna for supplying the signal to resonator 2. Additional concentric line terminal posts are shown attached to-the buncher" and catcher" resonators for the purpose of altering the functions 01' the tube, when desired. Thus, if a terminal post 39 of the "catcher" is coupled back as by a concentric line to a terminal ost l! or the buncher." the apparatus will serve as an oscillator. v

This tube structure is also shown Provided with a space charge control grid as when modulation is desired. this grid being shown provided with a terminal lead 88. This grid is shown carried by tocussing ring III, which in use would normally have a collimating efl'ect upon the electron stream.

In Fi 3 end plates III and II are urged toward each other by springs It, the thrust of the springs It, in addition to that produced by, atmospheric pressure, being resisted-by struts I2, 92' and 83, 02. Three pairs of substantially aligned struts angularly spaced 120 apart are used. Of these. two pairs of struts 93, II rest directly upon stationary ring 00, whereas the remaining pair of struts 82 and I! bear upon the outer sides of the arcuate levers l4 and I4 that are pivoted at I! on stationary thrust ring 06, as seen in Fig. 4.

The thrust of strut 02 is transmitted to lever 94 and then through ball 03 constrained to move in a race It concentric with pivot 15 to stationary thrust ring 46. The thrust of strut 82' is simi larly transmitted through lever 9| to ring It. Levers 04 and N are fastened together by a yoke 95. A lug I8 is fastened to thrust ring 46 and threaded for an adjusting screw 01. A coil spring 90 urges members 05 and 06 toward each other and these members are held apart by a strut 99. By adjusting screw 91, levers SI and 94' are caused to rotate about pivot 15, thereby changing the angularity of struts 02 and 92' and causing the end plates I0 and II to tip slightly relative to stationary thrust ring I. This tipping of the end plates changes the average spacing of grids l and 5 of the buncher" and grids I and 8 of the "catcher," eil'ecting an alteration in the gang tuning of these hollow resonators.

Grids 4, 5, i and I are shown shaped like very shallow cones with their apexes facing each other. The electrostatic field between opposed grids 45 and 0-1 is of such a nature that low velocity electrons are caused to move radially outward and beyond the strong electrostatic field existing between these opposed grids, where the presence of such electrons may be undesirable.

The inner walls of both cavity resonators 2, 3. supporting grids 5 and'! are oi large cross-seclion and thereby serve to readily transmit the heat generated in grids 5, 0 to central shell I. wherefrom it may be dissipated in a known manher. The cross-section of the electron path between grids 5 and i is enlarged transversely of the stream which structure minimizes diffusion of the electron stream due to electrostatic forces.

In Fig. 6 the end shells II and I6, and their associated parts, are modified to provide an extremely rigid mounting for the various elements to minimize microphonic noises. In this figure, the space charge control grid 60 is carried by a tubular member II, which is rigidly attached to shell II and spaced in concentric relation therewith by a seal I9. Similarly, the emitter structure 20 is carried by a tubular member II, which is rigidly supported in concentric relation to tube II by glass seal 80. Also, the filament lead IIII is attached to a. tube 85, which is rigidly held in concentric relation to tub II by means 01' a seal 84. Tube 80 is sealed by a glass bead 88. In this manner the electron emitter assembly is rendered extremely rigid to minimize microphonic noises. Similarly, the tube carrying th detector grids II and I2 is rigidly supported cona,a11,oss

Iii

-rectly against stationary thrust ring it.

centrically with the shell I! by means oi a glass seal II'. Also the plate element 38 is rigidly supported in isolating relation with respect to a tube ll fixed by seal 81 concentrically with respect to tube ll.

In the structure shown in Fig. 6, wherein in operation it is generally only necessary to tune one resonator to the other, gang tuning is not illustrated. Instead, three pairs oi struts 93 and 83 are used which bear at their inner ends di- The frequency adjustments are made by adjusting the screwsil.

Thus. it will be seen that tuning means is provided in the several figures. not only eflectini; gang tuning of the resonators, as by angularly adjusting all three Pairs of struts simultaneously as shown in Fig. 1'. or by adjusting a single pair of struts. as shown in Fig. 3, or if desired, individual strut adjustment may alone be used. as shown in Fig. 6.

In the form of the invention shown in Figs. 7 to 10, the hollow resonators I0! and I04 are shown carried by the inner ends of tubular members I05 and Ill. The inner opposed and walls I01 and ill of resonators I03 and I00 are annularly corrugated and flexible and carry a drift space providing tube I09. A collar 0 is shown fixed on tube Ill and has a ring member III turnably mounted thereon. Anti-friction end thrust bearings I I2 are shown interposed between member III and collar IIII. washer 3 may be interposed between collar 0 and one 01' the bearings H2. Three pairs of spaced tuning struts Ill and III are shown interposed between the opposite sides of ring II I and screw plugslll carried by end plates H8 and Ill fixed on tubular members I05 and I00.

A tuning screw III is threaded through a lug II! provided on collar II! and acts through a strut I20 to engage ring III for turning the lather. A return tension spring Iil connected between ring III and lug H9 eliminates back-lash. By turning screw II! the ring III is shifted or turned angularly with respect to tube I 0! causing toggle struts I" and Ill to move collars III and I" toward or away from one another as the case may be, thereby deflecting end walls I01 and I00 of the resonators to eflect the gang tuning thereof. This tuning arrangement employing the single ring III may be used in the preceding figures oi the drawings if desired. Individual tuning adjustment or the resonators I03 an: I" may be accomplished by adjusting screws If desired, external tuning resonators I20 and III may be used for tuning resonators I03 and I04 from a remote point. Resonators I20 and I2i are shown connected by concentric lines I22 and I23 to resonators I03 and I04, respectively. loops I24 at the ends of the lines serving to link the resonant fields within the resonators. Tuning resonators I20 and III are provided with suitable variable impedance means shown as a loop I25 in resonator I 20 and as a plate I28 in resonator I2I which loop and plate are tumable by knobs I21 and I21. By turning these knobs the frequency of oscillation within resonators I20 and HI is varied thereby effecting a variation in the frequency of the connected resonators I03 and I04. Obviously when the remote tuning resonators I20 and HI are employed the local tuning means lit-4H may be omitted, if desired. Also if this local tuning means is used. a remote tuning means may be omitted if desired. The

A thrust spring length of the concentric lines I22 and I2! is variable depending on the location of resonators I25 and Iii. Actually the tuning of resonators lb! and llll may be eilected by varying the length of lines I22 and I23. 1

The outer ends of resonators III and! I are shown formed by the use of dished plates I28 and I29. By using dished plates instead of flat disks, variations in tuning due to thermal expension and contraction are greatly reduced. The plates I28 and III and the ends of tube I" carry grids I30 for operating on the electron stream. These grids, as illustrated in Fig. 9, may be formed out of a metal ribbon, as by the use of suitable dies, and then folded to shape. Thus, in Fig. 9, the grid is shown or cruciform shape having angular indentations interconnected by arcuate portions and produced from a single ribbon or copper, for example, which grid is set into the apertures of members I25, I28 and m. The spring tension of these grids will hold them in place while the same are being welded or otherwise secured permanently in place, thereby facilitating the assembly of these grids in the resonators. Although these grids are shown of cruciform shape having four internal projections, the same may be formed with a greater or even lesser number of internal projections if desired, the main idea being that the same is formed from a continuous ribbon of metal that is deformed to the desired shape.

If desired, mica {disks I32 may be interposed between the emitter and the glass press carrying the same and between the electron collector and the press carrying such cpllector. Such a disk, shown in Figs. '1 and 8, not only prevents excessive heat from reaching the glass press but the same is so supported as to prevent shorting oi leads by the presence thereof. Thus, in Fig. 8, the disk I32 is shown carried by dead end leads or wires I331 which wires pass snugly through apertures in the disk. Apertures I in disk I accommodating the live leads are made large as shown in Fig. 8 so as not to touch the live leads. Thus any volatile conducting material, produced as by heating of the electron catcher or emitter in use, upon condensing on the mica disk I32 does not short the live leads, which would otherwise happen were the apertures IN the same size as these live leads.

A novel type of emitter heating coil or winding is shown in Fig. 10. This winding is formed by first doubling the heater wire upon itself thereby forming two strands or wires I35 and I35 connected at one end by a loop I". The looped wire is then wound around two somewhat spaced fixed pins as shown in Fig. 11, thereby forming a series of figure 8's, (see also Fig. 10). To cover the wire with a suitable insulator, it is merely necessary to separate the ends I35 and I35, the several figure 8's separating readily, forming two sections connected by loop I36 and enabling the wire to be completely coated with insulating material, such as aluminum oxide. The two sections of the heater coil are then again closed as shown in Fig. 10 and then folded or turned upon themselves into a cylinder for sliding into the hollow interior of the emitter casing I89. The end llli of the emitter casing is coated with a suitable emitting oxide. The emitter heating coil, as thusly produced, not only is non-magnetic, since the two wires I55 and I35 carry the currents in opposite directions and do not influence the electron stream leaving the front the emitter, but this type of construction also enables all of the wire surfaces to be uniformly coated with insulating material and prevents shorting of portions of the wire which would take place were the same merely wrapped around a single pin or cylinder.

As many changes could be made in the above construction and many apparently widely diffferent embodiments 01 this invention could be made without departing from the scopethereof. it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A high frequency tube structure comprising a shell, a hollow resonator carried by said shell, an end plate disposed adjacent said shell and connected to said resonator, and tuning means comprising toggle mechanism interposed between said end plate and said shell, said end plate having means for angularly shifting said toggle mechanism for eifecting the tuning of said resonator.

2. A high frequency tube structure comprising, a tubular shell, a pair of spaced hollow resonators contained within said shell and carried thereby, a pair of end plates disposed adjacent to the opposite ends of said shell and connected respectively to said resonators, and tuning means comprising toggle mechanism interposed between said shell and said end plates for effecting simultaneous movement of said end plates with respect to said shell. to cause simultaneous distortion of said resonators and effect the gang tuning thereof.

3. A high frequency tube structure comprising, a tubular shell, a pair of spaced hollow resonators contained within said shell and carried thereby, a pair of end plates disposed adjacent to the opposite ends of said shell and connected respectively to said resonators, and tuning means comprising toggle mechanism interposed between said shell and said end plates, said toggle mechanism comprising angularly adjustable rings turnably supported on said shell, toggle struts interposed between said rings and said end plates and screw means for simultaneously 7 turning said rings.

4. A high frequency tube structure comprising an open ended shell, a pair of spaced hollow resonators within said shell and carried thereby, said resonators having flexible walls adjacent the ends of said shell, end plates positioned adjacent the ends of said shell and connected to the flexible walls of said resonators, and tuning mechanism connected to said shell and said end plates, said tuning mechanism comprising a thrust ring carried by said shell, anti-friction thrust bearings engaging said thrust ring. toggle struts in terposed between said thrust bearings and said end plates, and means for angularly shifting said toggle struts to vary the distance between said end plates and effecting the tuning of said resonators by deflecting the flexible walls thereof.

5. A high frequency tube structure comprising a shell, a hollow resonator carried by said shell, an end plate disposed adjacent said shell and connected to said resonator, and tuning means comprising toggle mechanism interposed between said end plate and said shell, said end plate having means for angularly shifting said toggle mechanism for cheating the tuning of said resonator, said angular shifting means comprising an eccentric for angularly shifting a nortion of said end plate to cause the angular shiitlng of said toggle mechanism.

6. A high frequency tube structure comprising a cylindrical shell, spaced hollow resonators within and attached at their peripheries to said shell, said resonators having reentrant central portions, end plates disposed on opposite sides of said shell and having tubular projections connected to the reentrant central portions of said shells, an emitter for directing electrons through said resonators by way of said tubular projections, and electron collecting means, one of said end plates having an additional tubular projection rigidly supporting said emitter and the other of said end plates having an additional tubular projection rigidly supporting said electron collecting means.

7. A high frequency tube structure comprising hollow resonator means. an emitter for producing an electron stream for passage through said resonator means, a modulating grid interposed between said emitter and said resonator means for modulating the electron stream, tubular supports carrying said emitter and said modulating grid, and vitreous sealing means interposed between said tubular supports and between said supports and said resonator means and rigidly supporting said emitter and modulating grid with respect to said resonator means.

8. A high frequency tube structure as defined in claim 7, wherein a detector grid is provided for changing the velocity of electrons leaving said resonator means, a tubular support carrying said grid, vitreous means interposed between said tubular support and said resonator means rigidly supporting said detector grid with respect to said resonator means.

9. A high frequency tube structure comprising a hollow resonator, said resonator being apertured for receiving a concentric line terminal post, said terminal post comprising a tube member extending into the aperture oi said resonator and secured thereon, a lead disposed centrally within said tube member, a vitreous seal between the outer portion of said tube member and said central lead, and a loop provided on the inner end of said lead projecting into the interior of said resonator and connected to said tube member.

10. A high frequency tube structure comprising a cylindrical shell. hollow resonators provided at the end portions said shell, end plates attached to said resonators and extending radially beyond said shell, a thrust member provided on said shell, adjustable screws carried by said end plates, and toggle struts interposed between said screws and said thrust member, the adjustment of said screws eil'ecting relative movement between said end plates and said thrust member to thereby eilect tuning of said resonators.

ii. A high irequency tube structure comprisin a cylindrical shell, hollow resonators provided at the end portions of said shell, end plates attached to said resonators and extending radially beyond said shell. a thrust member provided on said shell.levers pivoted on opposite sides of said thrust member, toggle struts interposed be tween said levers and said end plates, and screw means interposed between said levers and said end plates, and screw means interposed between said levers and said shell for angularly moving said levers to eflect relative movement of said end plates with respect to said thrust member,

thereby distorting said resonators and tuning the same.

12. A high frequency tube structure comprising hollow resonator means, an emitter for producing an electron stream for passage through said resonator means, a coilimating ring interposed between said emitter and said resonator means for concentrating the electrons of said stream into a beam, and a modulating grid carried by said collimating ring for modulating said electron stream.

13. A tube structure comprising a pair of spaced resonators, end plates attached to said resonators, tubular means interconnecting said resonators and providing a driitispace therebetween, adjustable displacing means carried by said tubular member and struts interposed between said displacing means and said end plates. the adjustment of said displacing means effecting movement of said struts and relative movement or said end plates thereby deflectinge walls of said resonators to gang-tune the same.

14. A tube structure comprising an emitter casing, a cathode heater coil wound annularly therein, said coil comprising a series of il-shaped coil windings, the adjoining windings of said coil for carrying currents in opposite directions to thereby render the coil non-magnetic.

15. The method of forming an emitter heating coil comprising bending a wire upon itself, winding the thusly bent wire about two spaced pins to form l-shaped convolutions, separating said convolutions by pulling the free ends of the wire apart, applying insulating material to the windings and again assembling the windings together.

16. A hollow resonator comprising a body having an electron beam aperture therein, a grid retained in said aperture; said grid comprising a deformed strip of metal, said deformed strip having alternate arcuate portions conforming to the perimeter of said aperture, said arcuate portions being of substantially the same curvature as said aperture perimeter, and intervening V- shape portions projecting toward the center of said aperture.

17. An electron discharge tube comprising means for producing an electron stream, a hollow resonator spaced therefrom. and detector means comprising a pair of spaced grids in the path of said electron stream beyond said resonasaid grids being conductively connected to- Eether so as to be at substantially the same potential for providing a substantially iield free space therebetween.

WIILIAMW. HANSEN. RUSSEL- H. VARIAN. SIGURD 1". VAR-IAN.