US2487078A - Tube - Google Patents

Description

D. H. SLOAN y Nov. 8, 1949 TUBE 2 Sheets-Sheet 2 Filed March 17., 1945 l\\\ \lk INVENTOR Davia H Sloan ATTORNE Patented Nov. 8, 1949 UNITED STATES ATENT GFFICE TUBE Application March 17, 1945, Serial No. 583,257

16 Claims. (Cl. 315-5) This invention relates to an ultra-high-irequency tube and has particular relationto a tuning device for an ultra-high-frequency tube.

An ultra-high-frequency tube of the resnatron type is disclosed in my copending applications, Serial Nos. 526,882 and 526,883, nled on March 17, 1944, and assigned to the Westinghouse Electric & Manufacturing Company. Application 526,882 was patented January 18, 1949, as Patent Number 2,459,593, and application 526,883 was patented October 19, 1948, as Patent Number 2,451,987. The tube so disclosed comprises a pair of evacuated, cavity resonators adapted to have electromagnetic field oscillations of a high frequency established therein. The resonators are of a generally cylindrical shape and are mounted coaxially, the first resonator being positioned within a coaxial cylindrical reentrant protuberance in the second resonator. A generally cylindrical cathode of sho-rter length than the iirst resonator is positioned coaxially within the first or cathode resonator. An anode, also having a generally cylindrical form, is mounted within the second or anode resonator and encircles the cathode. jacent walls of the two resonators, to permit electrons to flow radially from the cathode to the anode.

In this tube of my copending applications, the

grid in the wall of the cathode resonator is known as the control grid. It is insulated from the cathode in that there is no metallic path for a flow :of current therebetween. The grid in the wall of the anode resonator is, of course, in the wall of the protuberance and is known as the aci accelerating grid from the anode, the anode res-` onator is formed in two parts, Then the anode resonator may be tuned by moving the two parts with respect to each other, to vary the capacitance between the end of the protuberance and the adjacent end of the anode resonator.

The resnatron tube operates generally as a tuned-plate, tuned grid class C oscillator, with the cathode resonator in the control grid-cathode circuit and the anode resonator in the anode or y plate circuit. The two resonators are tuned to Grid-like structures are formed in the adsubstantially the same frequency and each is designed to have a principal mode of loscillation in which the electric field is substantially parallel to the electron path between the cathode andv anode and the field Within the resonators have a definite phase relationship, preferably with the eld voltage of the cathode resonator lagging by an amount of the order oi 90 behind the eld voltage of the anode resonator. Relatively high, positive direct-current voltages between the anode and cathode and between the accelerating grid and cathode tend to liberate electrons from the cathode; but the control grid, while originally at a zero voltage, has a negative voltage during operation such that a group of electrons are liberated from the cathode only during the peak portion of each half-cycle of the iield in the cathoderesonator in which that field tends to aid in effecting liberation of the electrons and movement thereof toward the anode. Thus, sharp pulses of electrons are liberated at regular intervals from the cathode.

AThe liberated electrons rst receive energy from the neld of the cathode resonator as well as the direct-current voltage elds between the accel` eld. The speed of the electrons is such, with` respect to the Spacing of the elements, that the electrons cross the field of the anode resonator while that elol is in a direction opposing their motion. As a result, the electrons give up energy to the eld of the anode resonator to generate the desired oscillations therein. A portion of the power developed in the anode resonator is fed back to the cathode resonator, to maintain the desired oscillations therein. The power is extracted from the anode resonator by some means such as a coupling loop and is supplied to an output transmission line.

A tube constructed in accordance with the teachings of my aforesaid copending applications operates quite satisfactorily in many systems.`

However, it has been found that in such a tube the Q, dened as the ratio of energy stored toI the energy dissipated, of the anode resonator is too high for some systems. In addition, the maintenance of the anode and the accelerating grid at diierent potentials introduces complications in the structure of the anode resonator. The use of a quarter-wave chokearrangement between two parts of the anode resonator to iin-I sulate the anode from the accelerating grid and remaining permit varying the capacitance for tuning, makes is necessary in the prior tubes to provide an additional chamber' enclosing the anode resonator to permit the resonator to be evacuated. There was also a leakage of a certain amount of power into this outer chalmber through various necessary openings.

Since the anode and the acceleratinggrid, and consequently the water pipes for cooling `the accelerating grid and anode, as well as the output coupling are at a high direct-current voltage in the prior tubes, further diiculties are encountered in mounting and properly insulating the tube for operation. The proper .insulation is, of course, imperative to avoid injury .to those operating the apparatus.

It is, accordingly, an objectof my invention to provide a new and improved'tube of the reshatron type.

Another object of my invention is to provide a novel tube of the resnatron type, having a new and improved tuning arrangement.

.Still another object of my invention is to provide a new and improved tuning arrangement for a cavity resonator.

.A further object of my invention is to provide a new and improved tube of the resnatron type in which insulation difliculties, in connection with the mounting thereof, are eliminated.

A still further object of my invention is to provide a novel tube of the resnatron type, having a greatly simpliled and more rugged construction.

In accordance with my invention, I have discovered experimentally that a resnatron tube may be operated with the accelerating grid and the anode both maintained at the` ground potential with the cathode being highly negative with respect thereto. This is contrary to the prior experiences of which I am aware of those skilled in the construction and operation of a tube of this type. With the anode and accelerating grid at ground potential insulation diiculties upon mounting of the tube are avoided. In addition, the anode resonator may be of a rugged construction, in which the accelerating grid and the anode are metallically interconnected. Consequently the large additional vacuum-tight structure surrounding the anode resonator may be eliminated as the anode resonator may itself be made vacuum-tight.

By my invention, the Q f the anode resonator is substantially reduced by a new tuning arrangement. Tuning is accomplished by the provision of movable short-circuiting contact means within the anode resonator and surrounding the reentrant protuberance. The contact means has a sliding contact with the side wall of the protuberance and the outer side wall or' the resonator to establish a short circuit therebetween at any desired point. The contact means are liquid-cooed and-are movable in a direction substantiallyparallel to the axis of the tube, by a manually adjustable apparatus which extends outside the anode resonator. 'Ihe movement of the contact means to change the location of the short circuit, causes a variation in the tuning of the resonator. As is discussed in detail hereinafter, the tuning arrangement reduces the Q of the anode resonator by reducing the energy stored by approximately thirty percent.

The novel features of my invention are set forth with more particularity in the appended claims. The invention itself, however, with respect to the details of operation 'and construction, as well as further advantages and `objects"=` thereof, may be best understood from the following description of a specific embodiment, when.k read in connection with the accompanying drawings, in which:

Figure 1 is a cross-sectional View of a resnatron tube, in accordance with my invention;

Fig. 2 is a partial View, inzcross-section, taken along. lines II-II of Fig. al.;

Fig. 3 is a detailed sectional view of a portion oifthe contact means; and

Fig. 4 is a partial view, in section, taken along lines IV-IV of Fig. 1.

As shown .in Figure 1, the tube comprises an anode resonator 15 fand a cathode resonator l.

ment wires il arranged to form a generally cy-A lindrical cage-like cathode i9 about the axis of the cathode resonator, a tubular cathode mounting 2i, and a pair of tubular members Z3 and 2"-3. surrounding the mounting 2| and arranged for cooperation with cylinder I3 to form quarterwave-length chokes closing the open end of the cathode-resonator cylinder i3. A small vacuum tight chamber 2l is secured to the bottom of body 9 over the end of the cathode resonator to seal the tube.

The mounting 2i for the cathode 'i9 includes leads for conducting heating current to the la ment wires and applying a direct-,current vvoltage thereto, as well as conduits for cooling the cathode unit which are not shown. 'Ihe cathode resonator 'i may be readily tuned by adjusting the handwheel 29 at the bottom of the tube which effects a vertical movement of capacitor plates 3i mounted on the end of a tuning rod v(not shown) which extends through the center of the cathode mounting 2l to the upper end of the cathode resonator. These details are fully described and illustrated in the aforesaid copending applications.

An anode 33 is supported from the body S of the anode resonator 5 within the annular space defined between the side wall vof the reentrant protuberance Il and the outer side wall of the body 9 and encircles the cathode i9, The anode 33 is a ring like structure formed of two ring members 35 and 3?. The iirst ring member 35 encircles the cathode i9 and is of approximately the same height as the cathode. The second ring member 37 surrounds the first ring member 35 with a space between the inner diameter of the second ring member 3i and the outer diameter of the first ring member 35. Flanges 39 and 4l at opposite ends of ring members 35 and 37, ren spectively, extend over the space between the rst and second ring members '35 and 3'! so that a passageway i4 for cooling fluid is formed through the anode. Inlet and outlet pipes 43 and 45 communicating with the passageway 44 are adapted to be connected to a supply line for cooling fluid, such as water.

The surface of the rst ring member 35 of the anode which is facing the cathode, is provided with a series of straight, crosswise grooves il having a semi-circular cross-section, therebeing one groove radially opposite each lament wire I1 of the cathode I9. These grooves are shaped to trap the electrons provided by secondary emission when other electrons strike the anode. The trapping of the secondary electrons is aided by the flanges 39 and 4I which extend over the ends of the grooves and have an inner diameter less than that of the first ring member 35. Of course, the grooves 41 need not necessarily be semi-circular in cross-section as other shapes, such as V- shaped grooves, may be used satisfactorily. In addition, other anode structures may be used so long as they provide a, good trap for secondary electrons, for reasons set forth hereinafter.

The adjacent walls of the cathode and anode resonators 1 and 5 between the cathodey I9 and the anode 33, that is the walls of the cylinder I3 and protuberance Il, are provided with a plurality of openings therein, so that grids 49 and 5I are formed through which electrons may pass from the iilament wires I1 to the anode 33. The grid 49 in the Wall of the cathode resonator is known as the control grid, and the wall containing the grid is arranged to be cooled by a cooling-fluid, such as water, provided through suitable pipes 53 and 55. Details of this cooling arrangement may be found in my copending applications.

The grid I in the wall of the anode resonator 5 is, of course, in the wall of the reentrant protuberance II. The reentrant protuberance is made up of a metal wall with a plurality of cooling pipes 51 against the running vertically along the wall, the pipes 51 being spaced about the wall so that a space between adjacent pipes is radially opposite each filament wire I1. Consequently, the accelerating grid 5I may be provided by a gap in the metal wall with the spaced cooling pipes 51 and the edges of the gap forming the grid. If desired the pipes 51 may be bent slightly toward the control grid 49 at the accelerating grid position to increase the accelerating effect. The pipes 51 are connected to conduits which in turn are to be connected to the cooling fluid supply.

A plurality of feedback coupling wires 59 are attached at one end to the cathode unit I5 in the cathode resonator 1 and extend radially through suitable openings in the walls of -the cathode resonator 1 and the reentrant protuberance II into the anode resonator 5. The end portion of each coupling wire 59 within the anode resonator is curved at substantially right-angle, to form a conducting member adjacent and parallel to, but spaced from, the anode 33. Each coupling wire, in effect, provides a capacitor connected between the anode 33 and cathode I9.

As explained in my aforesaid copending applications, the two resonators are designed so that their electric eld vectors are along radial lines. Consequently, alternate points of minimum and maximum voltage appear along the length of the cathode unit within the cathode resonator. The coupling wires 59 are preferably connected to the cathode unit at a point of maximum voltage with respect to the control grid 49 which is the point of minimum current. The anti-resonant impedance of the cathode-grid circuit, with the two resonators tuned to the same resonant frequency, then acts as a resistance connected in series with the capacitance between the coupling wire and the anode. The voltage drop across such a resistance is, of course, shifted by roughly 90 in phase, relative to the high-frequency voltage between the anode and accelerating grid. The voltage drop across this resistance is eiiective to 'G9 in the other.

maintain the oscillations in the cathode resonator with the iield of the anode resonator rising to a maximum in the direction aiding movement of the electrons 90 behind the field in the anode resonator. The amount of the phase shift is generally considered as being about 90 though it may be as little as 45 or as much as 135.

To tune the anode resonator 5, a short-circuiting contact unit SI is provided, surrounding the reentrant protuberance II above the anode 33 and within the annular space between the side wall of the protuberance II and the outer side wall 9 of the anode resonator. The contact unit 6I comprises a plurality of contactors 53 each of which extends across the annular space and has a sliding contact with the side wall of the reentrant protuberance Il and the outer wall 9 of the resonator. The contactors 63 are arranged radially about the reentrant protuberance II and are positioned to interconnect a plurality of points on the two walls. The details of an individual contactor are set forth in the copending application of R. L. Treuthart, Serial No. 583,295, tiled March 17, 1945, now Patent No. 2,456,902.

Each contactor 63 comprises a flexible metallic bellows 64 of a generally cylindrical shape, with contact buttons 65 and 66 mounted Within and at opposite ends and completely closing the bellows. A passageway for cooling-fluid is provided through the interior of the bellows structure from an inlet 61 in one contact button 66 to an outlet A cooling-huid, such as water, is supplied to the bellows structure under pressure through an inlet pipe 1I and an outlet pipe 13 connected to inlet and outlet manifolds 15 and 11, respectively, which, in turn, are adapted to be connected to a source of the cooling-fluid through a pair of conduits 19 and 8|. The manifolds 15 and 11 are mounted on a flat ring structure 83, suspended from an adjusting arm on the outside of the anode resonator by a pair of hollow pipe supports 81 and 89 through which conduits 19 and 8| extend. The contactors 63 are supported by the inlet and outlet pipes 1I and 13 and are held in position by a second flat ring structure 9| mounted directly above the contactors 63 and suspended from the iirst ring structure 83 by posts 93, the second ring structure 9| having slots therein through which the inlet and outlet pipes extend.

When cooling water under pressure is supplied to the contactors 93, it causes them to be expanded so that the contact buttons 65 and 66 engage and form a good pressure contact with the side wall of the protuberance II and the outer side wall 9 of the resonator. Consequently, these contactors 63 form an eective short circuit between the side wall of the protuberance and the outer wall of the resonator, and the resonant frequency of the resonator depends upon the location of the short circuit.

To change the location of the short circuit, the supporting arm 35 located outside the resonator is threadedly engaged with a rotatable shaft 91 supported vertically on top of the tube. This shaft 91 may be conveniently rotated by means of a handcrank 99 and gears IIJI, as illustrated. When the shaft 91 is rotated, the arm 85 is moved up or down, depending upon the direction of rotation of the shaft. Such movement of the arm 85 is obviously effective to move the supports 81 and 89 and the contact unit 8 I one Way or the other, in a direction substantially parallel to the axis of the tube. As a result, the location of the short circuit in the anode resonator may be varied, to tune the resonator.

The pipe supports 81 and 89 extend through the top of the anode resonator with a sliding fit, permitting the supports to be moved relative to the resonator for tuning purposes as described. The anode resonator and the cathode resonator are adapted to be evacuated by means of a vacuum pump, not shown, to be connected across a flanged opening ID3 in the anode resonator. To aid such evacuation, vacuum-tight seals are provided about the supports 81 and 89. The seals |95 are of the type known as a Wilson seal and include a tight tting fiber or leather ring IDB about each support which is clamped at its outer edges in a stationary cliamp |01 mounted on top of the tube. Such a seal permits the supports to be moved or slid therethrough while maintaining a vacuum within the resonator. Of course other types of seals permitting movement of the supports, such as bellows, may be used if desired.

As set forth in the aforesaid copending application of Treuthart, the contactors insure a good electrical connection between the side wall of the protuberance and the outer side wall of the resonator. The cooling fluid is supplied through the contactors under pressure and serves not only to cool the contacter, a necessary operation because of the heat developed by current conducted through the contactor, but also to expand the contactor axially into pressure engagement with the walls. Consequently a good short-circuiting connection is maintained while the contact unit is moved back and forth for tuning even though the surfaces of the walls might be irregular and non-uniformly spaced. It is apparent that sliding contactors of a different construction may be used in the contact unit ii each one has a means for insuring pressure engagement with the walls as well as a provision for cooling.

.'A coupling loop |09 is provided within the-anode resonator and is connected to a coaxial transmission line I I I of the usual type to extract power from the resonator. Cooling pipes II2 may also be provided to carry cooling uid about the outer wall of the tube.

Direct-current voltages are impressed on the anode, cathode and grids of the tube, as shown schematically in Fig. l. The anode 33 and accelerating grid 5I are grounded and are connected to the positive terminal of a suitable direct-current voltage source H3 illustrated as a battery. The negative terminal of the voltage source I I3 is connected through a wire I I5 and the leads within the cathode mounting 2l to the cathode I9. The negative terminal of the voltage source I I3 is also connected through a resistor I I1 to the control grid 49. An alternating voltage, for supplying heating current through the filament wires I1, is provided from a source II9 through a suitable transformer I2I.

To operate the tube, the two resonators 5 and 1 are rst tuned to substantially the same frequency, by means of the handwheel 29 and the handcrank 99. The direct-current voltages, `as well as the filament-heating current, are then applied to the elements in the tube and oscillations are initiated, building up in the well-known manner. The control grid 49 is initially at the same potential as the cathode i9, but, as the oscillations build up, current through the resistor II1 causes the control grid 49 to becornenegative with respect to the cathode I9 and ,so restricts the liberation of electrons to the peak-portion ofthe half-cycle in which the field within the cathode resonator 1 is ina direction to aid the movement.4

trons give up energy to the field of the anoderesonator producing the oscillations therein. The

spacing of the elements is such that the electrons. reach the anode during, or near the end of, the

half-cycle in which the field of the anode resonator opposes their motion.- As previously indicated, some of the power generated in the anodeA resonator is fed back to the cathode resonator,

while the remaining power is fed to the output:

transmission line.

It is to be noted that, with the anode and accelerating grid at the ground potential, the.

tube may be mounted without special diculty involving insulation of these parts. For the same reason, the anode resonator may be ruggedly constructed and very little, if any, power escapes through openings in the resonator. In addition, the output transmission line is also at ground potential and its connection to other suitable apparatus is facilitated. As previously indicated, the anode and accelerating grid may now be maintained at substantially the same direct current potential in view of my discovery that a resnatron tube may be operated under such conditions. Formerly it was believed necessary to maintain the anode and accelerating grid at different direct current potentials. Various reasons were advanced for this belief including the theory that such potential difference was necessary to keep the electron path clear of ions and to keep the interaction space in the anode resonator free of secondary electrons. Some of the early experiments with resnatron tubes seemed to support this former contention but my recent experiments have shown it unnecessary to have the anode and accelerating grids at different potentials.

It is to be noted that the tuning of a reentrant cavity resonator by means of short-circuiting connections between the side wall of the protuberance and the outer side wall of the resonator introduces many diiiicult problems which are solved by the structure described. These difliculties involve the provision of some means for connecting a plurality of points on the wall of the protuberance with Va plurality of points on the outer wall of the resonator with means' for adjusting or changing the points of interconnection while maintaining a vacuum within the resonator and supplying cooling fluid to each connector.

While the tuning arrangement described herein is slightly more complicated than that employed in the earlier resnatron tubes, it is worthwhile because of the decrease in the Q of the anode resonator afforded thereby. The variable capacitor at the end of the protuberance in the earlier tubes necessitated three quarters of a wave length between the capacitor and the other end of the resonator to provide a maximum electromagnetic field at the electron path. ,Howeven the present tuning arrangement necessitates only one-half. or two quarters of a wave length within thev resonator to provide the same maximum field, at the electron path. -Since each Lquarter wave length stores up a certain amount of' energy, it is With the approximately phase,

then apparent that with the present system only two-thirds as much energy is stored. Consequently the Q is lowered by more than thirty percent.

Although I have shown and described a preferred embodiment of my invention, I am aware that many modifications thereof are possible, without departing from the spirit of the invention. I do not intend, therefore, to limit my invention to the specific embodiment disclosed.

I claim as my invention:

1. A cavity resonator comprising a hollow conductive body with an elongated conductive member extending within the body from and connected to an end thereof dening a ring-like space between the member and a portion of the body longitudinally coextensive with said member, short-circuiting contact means surrounding said member within said space and comprising a plurality of flexible contactors mounted about said member and extending transversely across said space and having sliding pressure contact with both said member and said body portion, and a unitary element slidably mounted within said body supporting said contactors, and adjustable means connected to said element for moving said unitary element to effect movement of said contactors lengthwise of said member to tune the resonator.

2. A cavity resonator comprising a hollow conductive body with an elongated conductive member extending within the body from' and connected to an end thereof defining a ring-like space between the member and a portion of the body longitudinally coextensive therewith, shortcircuiting contact means surrounding said member and including a plurality of flexible contactors mounted substantially radially about said member and extending across said space, said contactors having sliding pressure contact with both said member and said body portion, and a ring-like plate within said body supporting said contactors, supporting means for said plate mounted on the outside of said body and including a support extending through an opening in the body and connected to said plate, and adjustable means connected to said support and operable from outside said body for moving said support to effect movement of said plate and contactors lengthwise with respect to said member to tune the resonator.

3. A cavity resonator comprising a hollow, conductive body with an elongated conductive member extending within the body from and connected to an end thereof, short-circuiting contact means within the body interconnecting the member and another portion of the body, said contact means having a sliding pressure contact with said member and body portion and having a passageway therethrough for cooling fluid, conduit means connected to said passageway and extending outside said body for connection to a source of cooling fluid, and adjustable means connected to said contact means for moving the contact means to tune the resonator.

4. A cavity resonator comprising a hollow conductive body with an elongated conductive member extending within the body from and connected to an end thereof defining a ring-like space between the member and a portion of the body longitudinally coextensive therewith, shortcircuiting contact means surrounding said member and including a plurality of contactors mounted about said member and extending across said space, each of said contactors being flexible and having sliding pressure contact with said member and said body portion, and also having a passageway for cooling fluid, conduit means connected to all of said passageways and extending outside said body for connection to a source of cooling fluid, and adjustable means connected to said contact means for moving said Contact means lengthwise of said member to tune said resonator.

5. A cavity resonator comprising a hollow conductive-body with an elongated conductive member extending within the body from and connected to an end thereof defining a ring-like space between the member and a portion of the body longitudinally coextensive therewith, shortcircuiting contact means surrounding said member and including a plurality of contactors mounted about said member and extending across said space, each of said contactors having sliding pressure contact with said member and said body portion, and also having a passageway for cooling fluid, and a ring-like plate within said body supporting said contactors, hollow supporting means for said contact means mounted on the outside of said body and extending and slidable through an opening in the body and connected to said plate, said hollow supporting means having conduits therein communieating with said passageways and adapted to be supplied with cooling fluid from a source outside said body, and adjustable moving means operable from outside said body for moving said hollow supporting means to effect movement of said contactors lengthwise with respect to said member to tune the resonator.

6. A resonator according to claim' 5 in which said supporting means also includes a rotatable shaft mounted outside said body and extending in the same general direction as said member and an arm connected to said hollow supporting means and threadedly mounted on said shaft, and in which said moving means includes means for rotating said shaft whereby said arm is moved to move said hollow supporting means.

7. A cavity resonator comprising a hollow conductive body with an elongated conductive member extending within the body from and connected to an end thereof defining a ring-like space between said member and a portion of the body longitudinally coextensive therewith, said body being adapted to have electromagnetic field oscillations established within saidspace having a substantially radial electric vector, contact means within said space having a sliding pressure contact with said member and body portion in a plane substantially parallel to said vector and providing a short-circuit interconnection therebetween substantially in said plane, said contact means also having a passageway therethrough for cooling fluid, conduit means connected to said passageway and extending outside said body for connection to a source of cooling fluid, and adjustable means connected to said contact means for moving the contact means to tune the resonator.

8. A cavity resonator comprising a hollow conductive body with an elongated conductive member extending within the body from and connected to an end thereof defining a ring-like space between said member and a portion of the body longitudinally coextensive therewith, said body being adapted to have electromagnetic eld oscillations established within said space having a substantially radial electric vector, contact means surrounding said member and including aisance il a plurality of contactors mounted about said member and extending across said space, each of said contactors being flexible and having a sliding pressure contact with said member and body portion in a plane substantially parallel to said vect-01' and providing a short-circuit interconnection therebetween substantially in said plane, the contacts of all of said contactors being in substantially the same plane, each of said contactors also having a passageway for cooling uid therein, conduit means connected to all of said passageways for connection to a source of cooling uid, and adjustable means connected to said contact means for moving it lengthwise of said member to tune said resonator.

9. An electronic tube comprising ,a cavity resonator including a hollow conductive body with `an elongated conductive member extending within the body from and connected to an end thereof dening a ring-like space between said member and a portion of the body longitudinally coextensive therewith, said body being adapted to have electromagnetic eld oscillations established within said space having `a substantially radi-al electric vector, an anode mounted at one side of said space, a cathode mounted at :a radially opposite side of said space and adapted to project electrons through said space along a path from said cathode to said anode, contact means within sai-d space, said path bein-g between said -bcdy end and contact means and said contact means having a sliding pressure contact with said member and body portion in a plane substantially parallel to said vector and providing a short-circuit interconnection therebetween substantially in said plane, and adjustable means connected to said contact means for moving it to tune the resonator.

l0. An electronic tube comprising a cavity resonator including a hollow conductive body with an elongated conductive member extending within the body from and connected ito an end thereof dening a ring-like space between said member and a portion of the body longitudinally coextensive therewith, Isaid body being 'adapted to have electromagnetic eld oscillations established within said space having a, substantially radial electric vector, an anode mounted at one side of said space, a cathode mounted Iat a radially opposite side of said space and adapted to project electrons through said space along a path from said cathode to said anode, contact means Within said space, said path being between said body end and contact means and said contact means having a sliding pressure contact with said member and body portion in a plane substantially parallel to said vector and providing a vshort-circuit interconnection therebetween substantially in said plane, said contact means also having a passageway therethrough for cooling iiuid, conduit means connected to said passageway an-d extending outside said body for connection to a source of cooling fluid.

l1. An electronic tube comprising a cavity resonator including a hollow conductive body with an elongated conductive member extending within the body from and connected to an end thereof dening a ring-like space between said member and a portion of the body longitudinally -coeXtensive therewith, said body being adapted to have electromagnetic eld oscillations established within said space having a substantially radial electric vector, an anode mounted at one side of said space, a cathode mounted at a radially 4opposite side of said space and adapted to project electrons through .said space yalong a path from said cathode to said anode, contact means sur# rounding said member within said space, said' path bein-g between said body end and contact means and said contact means including a `plurality of contactors mounted about said member and extending across said space, each of said contactors being flexible and having a slidingpressure contact with said member and body portion in a plane substantially parallel tosaid vector and providing a short-circuit interconnection therebetween substantially in said plane, the contacts of all of said contactors being in substantially the same plane'. Y

l2. An electronic tube comprising a cavity res-- onator including a hollow conductive body with project electrons through said spaceV along a path from sai-d cathode to said anode, contact means surrounding said member within said space, said path being between said body end and contact- J means and said contact means including a pluin a plan-e substantially parallel li-,o said vector' and providing a short-circuit interconnection therebetween substantially vin saidl plane, fthel con-- tacts of all of said contactors being .in substantially the same plane,each of said contactors :also

having a passageway for cooling fluid therein, conduit means connected to all of said passageways for connection to a source of cooling uid.

13. An electronic tube of the resnatron type comprising a pair of cavity resonators each comprising a hollow, conductive shell, an anode mounted in and secured to one of ysaid shells, av

cathode mounted in the other shell, said shells being mounted adjacent leach other and having adjacent portions each with a grid therein whereby electrons may pass along a path from the cathode to the anode through the grids, and facilities yfor establishing in said shells electromagnetic eld oscillations having an .electric vector between the cathode and anode in the same direction as said path, said :facilities including circuit connections to impress direct current voltages between said anode, grids and cathode such that said anode is at ground potential and said cath--1 ode at a negative potential, the grid in said one shell being conductively connected to said anode by said one shell whereby :said vgrid in said one shell and said anode are maintained at ground potential.

14. `An electronic tube of the 'resnatron type comprising a first cavity resonator including a first. hollow conductive body with an elongated conductive member extending Within the body from and connected to an end ythereof defining a ring-like space between the .member and a kpor-- tion of the first body longitudinallycoextensivetherewith, a yring-like anode mounted within said space, -a second cavi-ty resonator Vincluding a second hollow, conductive body, a cathode mounted Within said second body, said lirst .and second` bodies being mounted adjacent each other and.

having adjacent Walls with grids therein, the position of said bodies and grids permitting electrons to pass along a path from said cathode to said anode through said space, each of said bodies being adapted to have electromagnetic field oscillations established therein having an electric ield vector between the cathode and anode in the same direction as said path, said anode, grids and cathode being adapted for connection to external circuit means to impress direct current voltages thereon with said anode and the grid of the first body at substantially the same direct current voltage, short-circuiting contact means extending across said space interconnecting points on said member and said first body portion, said contact means having sliding pressure contact with said member and first body portion, and adjustable means connected to said contact means and extending outside said rst body for moving said contact means longitudinally of said member to change the points of interconnection and thereby tune the rst resonator.

15. An electronic tube of the resnatron type comprising a first cavity resonator including a first hollow conductive body with an elongated substantially cylindrical hollow conductive member extending within the body from and connected to one end thereof dening an annular space between the member and a portion of the iirst body longitudinally coextensivetherewith, an annular anode mounted within said annular space and connected to said first body portion, said member having a side wall with a rst grid therein opposite said anode, a second cavity resonator including aV second hollow conductive body, a substantially cylindrical cathode mounted within said second body, said second body being substantially cylindrical and mounted within said member with a side wall adjacent the side wall of the member having a second grid therein adjacent the iirst grid whereby electrons may pass along generally radial paths from the cathode to the anode, each of said bodies being adapted to have electromagnetic iield oscillations established therein having substantially radial electric eld vectors between the cathode and anode, said anode, grids and cathode being adapted for connection to external circuit means to impress direct current voltages thereon, the first grid being conductively connected to said anode by said first body whereby said first grid and said anode are maintained at substantially the same direct current voltage, short-circuiting contact means extending across said annular space interconnecting points on said member and said irst body portion, said contact means having sliding pressure contact with said member and first body portion, and adjustable means connected to said contact means and extending outside said rst body for moving said contact means longitudinally of said member to change the points of interconnection and thereby tune the rst resonator.

16. An electronic tube apparatus comprising a pair of cavity resonators each comprising a hollow, conductive shell, an anode mounted in one of said shells, a cathode mounted in the other shell, said shells being mounted adjacent each other and having adjacent portions each with a grid therein whereby electrons may pass along a path from the cathode to the anode through the grids, and external circuit connections from said anode, grids, and cathode, said connections from said cathode and from said grid adjacent said cathode terminating in a common point, there being an impedance connected between said point and said grid adjacent said cathode.

DAVID H. SLOAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,304,868 Franklin May 27,1919 2,153,728 Southworth Apr. 11, 1939 2,214,894 Wilson Sept. 17, 1940 2,329,779 Nergaard Sept. 21, 1943 2,353,742 McArthur July 18, 1944 2,396,802 Mouromtseff et al. Mar. 19, 1946 2,408,927 Gurewitsch Oct. 8, 1946 2,416,315 Hartman Feb. 25,1947 2,416,565 Beggs Feb. 25, 1947 2,416,567 McArthur Feb. 25, 1947 2,427,752 Strempel et al. Sept. 23, 1947

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