US2605421A - Tuner for lighthouse tube cavity resonators - Google Patents

Description

July 29, 1952 L SCHULTZ EAL 2,605,421 TUNER FOR LIGHTHOUSE TUBE CAVITY RESONATORS l ad@ Filed Sept. 17, 1945 n WW.,

,fs FIGJ l/Zl l' l l /9 /7 I l i y ,/'SA l H ./-u 5` 13A l 5 l 6" I g 6 l '3` I MI Il I7 I3 n 4 ,1| |11 l l5 f INVENTORS HOWARD l.. SCHULTZ HAROLD G. COOPER ATTORNEY Patented July 29, 1952 UNITED STATES PATENT OFFICE TUNER FOR LIGHTHOUSE TUBE CAVITY RESONATORS Navy Application September 17, 1945, Serial No. 616,922

9 Claims. (Cl. Z50- 36) This invention relates to apparatus for generating electrical oscillations of very high frequency and more particularly to arrangements for tuning resonator apparatus adapted for operation with triode vacuum tubes having closely spaced plane elements and constructed in a manner such as to bring the grid connection outside the vacuum tube to a ring shaped terminal surface, that is, tubes of a type commonly referred to as lighthouse tubes.

For the production of stable oscillations in the very high frequencies utilizing triode vacuum ytubes of this type there has come into use resonator apparatus comprising three coaxial conductors, namely, an outer resonator cylinder connected effectively to the cathode, an inner resonator cylinder connected effectively to the anode and an intermediate resonator cylinder connected to the grid. The outer and the inner cylinders electrically define a closed space and the intermediate cylinder, partially enclosing the inner cylinder in the neighborhood of the anode connection. acts as a partition in such space.

The manner of operation of such resonator and an improved method of tuning the same by axial movement of the irmer of these three cylinders is found in our patent application Serial No. 493,778, filed July 7, 1943, entitled Tuning of Electrical Resonators. and now U. S. Patent No. 2,561,727. This application is a continuation in part of said application. As there described, tuning eiect is produced by axial movement of the inner cylinder relative to the other two cylinders and the triode tube, direct mechanical sliding contact being maintained meanwhile between the cylinder and a relatively small cylindrical anode terminal on the tube. Such direct sliding contact between the anode terminal or stud and contact fingers on the sliding cylinder imposes mechanical stresses upon the anode stud and its seal with the glass of the tube, which may lead to damage to the tube. Also the travel of said inner resonator cylinder is restricted within a range not larger than the length of the anode stud, which is a limitation of the tuning effect to va narrower range than might be desirable.

Accordingly itis one object of this invention to provide an electrical connection between the inner of the three resonator cylinders and the lighthouse tube anode stud so as to permit relative axial movement of the inner cylinder with respect to the stud without having direct mechanical contact therebetween, thereby to avoid imposing undue stresses on the anode stud due to said movement while nevertheless maintaining electrical connection.

It is another object to provide a fixed auxiliary cylindrical conductor fitted over and mechanically and electrically connected to said anode stud with which the sliding inner resonator cylinder may make mechanical and electrical contact thereby making the desired electrical connection indirectly with the said anode stud.

It is another object to provide in effect by such auxiliary cylindrical conductor a much longer anode stud length so that the distance of axial travel of said inner conductor resonator may be increased and thereby the range of frequency tuning effect increased substantially.

Other objects, features and advantages will appear in the following detailed description together with the drawings illustrative of the principles of the invention.

Fig. l is a sectional view of the type of tuning device fully and particularly described in our earlier patent application above referred to.

Fig. 2 is a sectional view showing the preferred embodiment of our present improvement in the method of making the anode connection.

Referring now to Fig. l, there is shown a conventional lighthouse tube I having its radio frequency cathode (not shown) connected through its metallic shell 2 near its base 3 for radio frequencies, its grid (not shown) connected to a metallic ring II and its anode (not shown) connected to a metallic cylindrical stud 5 and disk 6.

The resonator structure comprises an outer tubular member 1 adapted to be connected to the base shell 2 (and hence electrically connected to the cathode), an inner cylindrical member 9 adapted to be connected slidably to the anode stud 5, and a cylinder or sleeve II of a diameter intermediate between the outer diameter of the cylinder 9 and the inner diameter of the tubular member 1, usually less than the mean of those two diameters and adapted to be mounted upon the grid terminal ring 4 and to be held in place thereon by one or more screws I3 and I3A.

As more fully discussed in our earlier application, cited above, the frequency of oscillation is believed to be mainly determined by the length of sleeve II. Furthermore, it has been observed that because of an intense magnetic eld near the base of cylinder I I this region is appropriate for magnetic coupling to an outside circuit and hence the coupling loop I5 and a coaxial line having inner conductor I1 and outer conductor I9 are provided as shown in Fig. l. The type of coupling however is not critical.

The upper end of the resonator space 2| is effectively closed off by means of a cup-shaped structure 2,3 mounted on the sleeve -9 which is adapted to furnish a radio frequency short circuit between the cylinder 1 and the cylinder 9. An actual mechanical short circuit is undesirable both because it is desired to adjust the position of the cylinder 9 and because the two are at different direct current potential levels. They are supported and insulated from each other by the end structure 25.

The tuning effect which is relatively wide in range results from the provision of an adjustable sliding anode connection between the lower end of cylinder 9 and the anode stud 5. When the cylinder 9 is slid axially on the anode stud 5 a very strong effect on the resonant frequency develops. This is believed to result from the conguration of the elds produced by the presence of the annular gap or channel between the anode disk 6 and the bottom end of the sliding cylinder 9. The usual size anode stud is about a quarter of an inch long. With greater length f anode stud a greater tuning range could be obtained because the amount of axial travel of cylinder 9 could be increased.

At the upper end cylinder 9 is threaded and engaged in a bushing 21 which is suitably embedded in the insulating terminating structure 25. The axial position of the cylinder 9 may be adjusted by turning a knob 29 mounted on the end of cylinder 9 and made preferably of insulating material.

The knob 29 is provided with an axial opening 3| to permit introduction of an electrical conductor (not shown) for connection to the anode of the tube. A knurled nut 33 of insulating material is provided for locking the cylinder 9 at any desired position of adjustment. Locking pairs of nuts 34 and 35 and 36 and 31 provide for limiting the extent of axial movement of cylinder 9 so that it cannot be moved downwardly so far as to exert undue pressure on the anode stud and disk 6 and structure of the vacuum tube 1, and so that it cannot be retracted upward far enough to lose contact with the anode stud 5. As will be seen this latter pair of nuts 36, 31 may be omitted in the later version claimed by this application since the range of retraction is greatly increased.

Our earlier application cited above made general reference to the possibility of diiferent types of sliding anode connection for example such as a sliding joint provided between two portions of the cylinder 9 in the neighborhood of the stud 5. Referring now to Fig. 2 there is shown a particular embodiment of the present invention which permits greater range of tuning and also a reduction of mechanical stress on the anode stud 5 and structure of the tube I, through utilization of a different construction of the inner resonant cylinder 9A and its manner of connection with the anode stud 5.

All the rest of the structure shown in Fig. 2 is identical with that of the earlier form shown in Fig. 1 including vacuum tube l, outer resonator cylinder 1, intermediate resonator cylinder ll and their various supporting and adjusting means previously described (some not being shown in Fig. 2). Likewise the shorting member 23 is unchanged.

In this improvement shown in Fig. 2 the anode resonator cylinder 9A which is caused to slide axially to produce tuning effect does not slide directly along the surface of the anode stud 5 but upon an auxiliary cylindrical member 5A which is in stationary contact with the anode stud 5. This auxiliary member 5A may be solid or hollow and is suitably supported so as to remain in stationary contact with the anode stud 5. The anode resonator cylinder 9A is supported and attached in an adjustable manner as in the pre- 5 vious invention so that its axial position is adjustable.

Because the member 5A is in stationary contact with it, the stress upon the anode stud 5 caused by movement of cylinder 9A is greatly 10 reduced. Also the travel of member 9A along member 5A is not restricted by the size of the anode stud 5 as was the case in the previous invention, hence the tuning range is increased.

What is claimed is: 1. An oscillator for high frequencies including a vacuum tube having an anode, cathode, grid, and external connectors therefor, a tunable circuit structure comprising a plurality of substantially coaxial conductive cylinders of differing diameters, a first of said cylinders being electrically connected to the cathode of said tube, an auxiliary cylinder being in stationary connection with the anode connector of said tube providing an extension of the anode connector, a second of said coaxial conductive cylinders being in axially slidable connection with the outer surface of said auxiliary cylinder, a third of said coaxial conductive cylinders intermediate said rst and second coaxial conductive cylinders being connected near one end to said grid connector and having at its other end a substantially open circuited termination, and means connected to said second cylinder for tuning said structure by causing axial motion of said second cylinder which is slidably connected with the auxiliary cylinder and thus indirectly connected to the anode connector, whereby the configuration of the oscillating eld in the neighborhood of said slidable connection may be varied and the frequency of oscillations varied in accordance with 5he axial position of said second cylinder.

""WZ. An oscillator for high frequencies including ,a" vacuum tube having an anode, a cathode, a grid and external connectors therefor, a tunable circuit structure which comprises a rst conductive cylinder connected to the anode connector of said tube, a second conductive cylinder substantially coaxial with said rst named cylinder and connected therewith by means of an axially slidable joint, a third conductive cylinder substantially coaxial with and partially enclosing said second conductive cylinder and connected to the cathode connector of said tube, a fourth conductive cylinder substantially coaxial with the aforesaid second and third cylinders and located therebetween, said fourthcylinder being connected near one end to the grid connector of said tube and extending a relatively short distance beyond said grid connector, the other end of said cylinder extending over but spaced from a portion of said second conductive cylinder and extending to a substantially open circuited termination, the said cylinders connected to said cathode connector and to said rst cylinder respectively being effectively joined for the frequency of operation by a conducting structure located between said cylinders at a point a substantial distance beyond the said Qpen-circuited end of said fourth cylinder, and means operative on said second cylinder for axial adjustment of the position of said second cylinder relative to the cathode connected cylinder and relative also to said rst cylinder, whereby said axially slidable connection may be operated and the configuration of an oscillating electrical eld in the neighborhood of said anode changed thereby varying the frequency of operation.

3. A lighthouse tube high frequency oscillator, a tunable circuit structure comprising four substantially coaxial conductive cylinders, the first of which is rmly axially juxtaposed in contact with the anode connection of said lighthouse tube, the second of which is in axially slidable contact with the outside of said first cylinder, the third of said cylinders being connected to the cathode connection of said tube, the fourth of said cylinders being positioned intermediate of the second and third named cylinders and connected to the grid connection of said tube, said second and third cylinders being eiectively short circuited at a point remote from the end of the third named cylinder, and means connected to said second cylinder for adjusting the relative axial position of said second named cylinder with respect to the remainder of said cylinders and said tube, said means being adapted to provide a variable annular space in the immediate neighborhood of the anode connection and thereby to enable frequency tuning of the said circuit structure.

4. A high frequency oscillator comprising, in combination, a vacuum tube of the lighthouse type having an external disk and stud connector for its anode and external ring connectors for its cathode and grid, first and second coaxial hollow conducting cylinder respectively connected to said cathode and grid connectors, a third cylinder having a, diameter slightly larger than the diameter of said stud axially juxtaposed in contact with said stud, a fourth conducting cylinder having a diameter intermediate said first and third cylinders axially slidably connected at one end to said third cylinder and mounted coaxially therewith, said one end of said fourth cylinder and the disk portion of said anode connector deiining an annular channel of variable axial dlmension in the immediate neighborhood of said anode connector, and means connected to said fourth cylinder for adjusting said fourth cylinder axially relative to said third cylinder thereby controlling said variable axial dimension.

5. An oscillator for high frequencies comprising, in combination, a vacuum tube of the lighthouse type having an external disk and stud connector for its anode and external ring connectors for its cathode and grid, a conductive cylindrical extension having a diameter substantially equal to the diameter of the stud portion -of said anode connector axially juxtaposed in contact with said anode connector, iirst and second coaxial cylindrical conductors connected respectively to the cathode and grid connectors of said tube, said second conductor being intermediate said extension and said first conductor and connected near one end to said grid connector and having at its other end a substantially open-circuited termination, and a third conducting cylinder intermediate said extension and said second conductor and slidably connected at one end to said extension, said one end of said third cylinder being enclosed by said second cylinder and defining with the disk portion of said anode connector an annular channel surrounding said extension, and means connected to said third cylinder for moving said third cylinder axially relative to said extension thereby controlling the axial dimension of said annular channel.

6. An electronic oscillator comprising an electron tube having an anode, cathode and grid,

electrodes, and external connectors therefor, iirst, second and third coaxial cylindrical conductors, said first and second conductors forming a resonant circuit between the anode and grid electrodes, said second and third conductors forming a resonant circuit between the grid and cathode electrodes, said first and third conductors forming a resonant circuit between said anode and cathode electrodes, an auxiliary cylindrical conductor positioned in stationary connection with said anode connector and providing an axial extension therefor, said iirst cylindrical conductor being in axially slidableconnection with the outer surface of said auxiliary conductor, and means connected to said rst cylinder for tuning said oscillator by causing movement of said first cylinder relative to said auxiliary conductor whereby the configuration of the oscillating field in the neighborhood of said slidable connection may be varied.

7. An oscillator comprising, in combination, an electron tube having an anode, cathode, grid, and external connectors therefor, and a tunable circuit structure. said structure comprising iirst, second, third and fourth coaxial conductive cylinders of differing diameters. said first cylinder being electrically co ,y ected to the cathode connector of said tubeaid second cylinder being in stationary connection with the anode connector f said tube and forming an extension therefonsaid third cylinder being in axially slidable con ection with the outer surface of said second cylinder, said fourth cylinder being intermediate said rst and third cylinders and connected near one end to the grid connector of said tube and having at its other end a substantially open-circuited termination, and means connected to said third cylinder'for causing axial motion thereof relative to said second cylinder whereby the configuration of the oscillating field in the neighborhood of said slidable connection may be varied and the frequency of the oscillator varied in accordance with the axial position of said third cylinder.

8. Apparatus for tuning an oscillator of the type which includes a lighthouse type electron tube having an external disk and stud connector for its anode and iirst and second coaxial conductive cylinders respectivelyconnected to the cathode and grid connectors of said tube, said apparatus comprising a conductive cylindrical extension for said stud having a diameter slightly larger than the diameter of said stud axially juxtaposed in contact therewith, and a third conducting cylinder intermediate said extension and said second cylinder slidably connected at one end to said extension, said one end of said third cylinder and said disk deiining an annular channel of variable axial `dimension surrounding said extension.

9. Apparatus for tuning an oscillator of the type which includes a lighthouse type electron tube having an external disk and stud connectorl for its anode, and rst and second concentric conductive cylinders respectively connected to the cathode and grid connectors of said tube. sald apparatus comprising. an auxiliary cylindrical conductor positioned coaxially with said iirst and second cylinders and electrically connected at one end to said anode stud and forming an axial extension therefor, a third conductive cylinder having a diameter intermediate said cylindrical conductor and said second cylinder mounted concentrically with said cylindrical conductor and electrically connected at one end to said cylindrical conductor. said third cylinder being in axially slidable connection with REFERENCES CITED the outer surface of said auxiliary conductor and The following references are of record n the being formed at said one end to define in coopme of this patent: eration with said disk an annular channel sur'- rounding said conductor in the region of said 5 UNITED STATES PATENTS anode connector of said tube, and means secured Number Name Date to said third cylinder for adjusting the axial po- 2,404,113 Wagner July 16, 1946 sition of said third cylinder relative to said con- 2,408,355 Turner Sept. 24, 1946 ductor whereby the axial dimension of said 2,408,927 Gurewitsch Oct. 8, 1946 channel may be varied. 10 2,429,811 Guan-era Oct. 28, 1947 HOWARD L. scHULTz. OTHER REFERENCES HAROLD G. COOPER. Electronics, vol. 19, No. 2, February 1946, pp.

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