US2193500A - High frequency apparatus - Google Patents

Description

March 12, 1940. G, L U ELM N HIGH FREQUENCY APPARATUS Filed Aug. 14, 1936 6 Sheets-Sheet 1 INVENTOR G. L. U SSELMAN ATTORNEY March 12, 1940. G, USSELMAN 2,193,500

HIGH FREQUENCY APPARATUS Filed Aug. 14, 1936 6 Sheets-Sheet 2 NEUTRAL lZ/N G CONDENSER PREJZfl/RE GAUGE INVENTOR G.L. USSELMAN ATTORN EY March 12, 1940. V

ca. L. USSELMAN HIGH FREQUENCY APPARATUS Filed Aug. 14, 1936 6 Sheets-Sheet 3 INVEFIITOR e. L. USSELMAN ATTORNEY March 12, 1940. G. L. USSELMAN HIGH FREQUENCY APPARATUS Filed Aug. 14. 1936 I NVENTOR 6 Sheets-Sheet 4 G. L. USS ELM'AN ATTORNEY March 12, G L SSELMAN HIGH FREQUENCY APPARATUS Filed Aug. 14, 1936 6 Sheets-Sheet 5 4 I. \V E i r W March 1 G. ussELMAN- 2,193,500

area FREQUENCY APPARATUS Filed Aug. 14, 1936 e Sheets-Sheet 6 INVENTOR G.L.U$ ELMAN BY ,w'zrm/ ATTORN EY Patented Mar 12, 1940 UNITED sures earner FFECE HIGH FREQUENCY APPARATUS George Lindley Usselm'an, Port Jefferson, Y., assignor to Radio Corporation of America, a corporation of Delaware Application August 14, 1936, Serial No. 36,046

6 Claims. (c1.250- ,27) r My present invention relates generally to the improvement of high frequency apparatus particularly suited for use in short wave radio transmitters.

Among the objects of my present invention are; I

To provide an improved condenser for high frequency use;

To provide an improved cooling system for vacuum tubes generally;

To provide an improved push-pull arrangement of tubes, tuning and neutralizing condensers, and;

, To provide an improved push-pull vacuum tube arrangement employing condensers and vacuum tubes, the arrangement being such as to be perfectly symmetrical reactively with respect to tubes and with respect to ground.

A further object of my presentinvention is to provide a neutralized stage for a radio trans mitter employing neutralizing leads of minimum length. Such leads are desirable for various reasons and in order to effect this object I employ condensers of the compressed air or fluid type. These condensers not only enable me to minimize the length of the neutralizing leads but they also permit optimum utilization of space with increased safety factor.

Further objects, advantages, and features of 1111! present invention will be apparent as the more detailed description thereof proceeds.

Referring to the drawings which are illustrative'only of my present invention;

Figure 1 is a top View of a push-pull stage employing a variable tuning condenser, parallel vacuum tubes, compressed air neutralizing condensers, and a fixed auxiliary tuning condenser;

Figure 2 is a view of Figure l takenalong the line 2, 2 of Figure 1;

Figure 3 is a side View of the system shown in Figure 1 andxshows, among other things, the inductance for the push-pull stage which is made up of a pair of pipes or fluid conducting tubes, Figure 3 also showing an air valve for injecting air of desired pressure into one of the neutralizing condensers and also showing the air gage. for indicating the air pressure and in turn, the

effective capacity of the neutralizing condenser. Generally, the higher the pressure, the higher the voltage the condenser will stand. Other factors for increasing the break-down voltage of the condenser are described and explained hereinafter;

Figures 4, 5, 6, and 7 are side views of concoupling I and shaft 12.

denser plates used in the system shown in Figures 1 and 3; I 'Figure'B is a rear end view looking from right to left of the system shown in Figures 1 and 3; I

Figures 9 and 10 are views similar to Figures l and 3 of a modified push-pull system employing single tubes rather than parallelled tubes;

Figure 11 is a sectional view through an improved neutralizing condenser which may be used in'connection with Figures 1 and 3 01' Figures '9 and 10;

Figures 12, 13, and 14 are views of apparatus for uni-controlling or simultaneously adjusting a pair of neutralizing condensers in a pushpull circuit.

Turning to Figure 1, the transmitter assembly is set up to include a variable condenser portion to the left, the neutralizing condenser and tube structure at the center, and 'a removable fixed N condenser portion at the right. The entire struc- 2Q ture is generally supported bytwo insulating strips 2, 4, in turn supported by legs, not shown. or to any suitable metallic or insulating supporting means.

The variable condenser section is provided with a shaft 6 which rotates the variable condenser plates 8 through the medium of a flexible The flexible coupling I!) is preferably made of the insulating type whereby shaft 6 may be grounded and whereby 3D shaft l2' is;permitted to float. In this way, the tendency for parasitic oscillation generation is reduced. The rotatable plates 8 are generally supported together with a shaft 22 by means of an insulating strip 14 containing the bearing I6. The general shape of the plates 8 is shown in Figure 2 as is also the shape of the fixed plates i8, 20, the latter being supported upon the metal strips 22, 24, in turn, mounted upon the insulating strips 2, 4 respectively.

The central section consists of two metallic blocks 25, 28 supported upon the metal strips 22.

' 24. The metal blocks 25, 28 generally house and otherwise support vaccum tubes 3t, 32, 34, and 36, it being noted that tubes 35 and 32 are connected in parallel as are alsov tubes -34 and 36. Fnese pairs of tubes are connected to the stator plates 18 and 2B, in turn connected to the op-I posite sides of a push-pull circuit, The neutralizing condensers 38, All are also connected respectively to the blocks 26, 23 but are cross-connected to the pairs of tubesiifi 32 and '34, 36 for neutralization purposes as is known in the art.

The grids of tubes as, 32 are connected to-. gether' by fiat metallic ribbon 40' and through lead 42 to the central electrode of neutralizin condenser 413. Similarly, the grids of tubes 34, 36 are connected together by metal ribbon 42 and through lead 44 to the central electrode of neutralizing condenser 38. As shown in Figure 3, the side view of the arrangement, the grids are also connected to the input leads 46, 48 through the conductors 44, 42.

For the longer wavelengths, a fixed condenser section is provided which, as shown in Figures 1 and 3, include condenser plates 50, 52, 54, and 5B. Condenser plate 50, with alternate condenser plates 54 and condenser plate 56 are connected to the metal strip 24, in turn connected to the anodes of tubes 3 35 through the metal block 28. Similarly, condenser plate 52, the other alternate plate 54, and condenser plate 58 are supported by and electrically connected to a metal strip 22. The number of condenser plates may be varied so as to give the desired capacity. The end plates 56, 52 as shown in Figure 3 and as shown in greater detail in Figures 4 and 5 re spectively, are so shaped as to minimize unbalanced capacity to tubes 26 and 28. By way of xplanation, due to differences in separation between the tube grids and the condenser plates, the plate 50 offers a greater capacitive reactance to the grid of tube 32 per unit area, than does plate 52 with respect to the grid of tube 36. A0-

. cordingly, if condenser plate 50 were made the same size as condenser plate 54 then its capacity to the grid of tube 32 would be such as to unbalance the push-pull arrangement of tubes, neutralizing condensers, and tuning condensers. Similarly, condenser plate 52 should be made of some intermediate size but may be made larger than condenser plate 50 or otherwise, if made too large condenser plate 52 would tend to unbalance the system by its efiect on the grid of tube 35.

For a somewhat similar reason two end plates 56, 58 are provided which eliminates unbalance to ground.

The shape of the intermediate plates 54 is shownin Figure 6 and the shape of the end plates 58, 56 is shown in Figure 7.

A rear end view of the condenser assembly is shown in Figured.

The inductance in shunt with the condenser system which includes the variable and fixed sections as shown in Figure 1, consists of the tubular piping (iii, 62. (Figure 3). Only a section of the pipe 530, 62 is shown but it is to be understood that it extends between and is electrically connected to a pair of inlet and outlet orifices such as 64, 66 for block 28. In Figure 3, the inlet and outlet orifices 64, 56 are drawn with broken lines. The pipes til, t?! are connected at their midpointsto an inlet rubber water pipe, not shown, and an outlet rubber water pipe, not shown, it being understood that there is a shortcircuiting connection of low impedance across the pipes E9, 52 where the rubber pipes are connected. This shortcircuiting strap is slidable along the pipes 6t, '52 which extend parallel. That is to say, the pipes 62 for block 28 and similar pipes 693, 62 for block 2% extend parallel to one another and the short-circuiting strap forms the connection across both pairs of pipes 62, 62, forming effectively U-shaped inductance loop. If desired, the inductance system may be coiled as shown in the patent to H. E. Hall- ,be removed by disconnecting the straps 68, H! by which it is attached to the frame members 22, 24.

A further insulating spacer 72?, similar to I4 is provided as shown in Figures 1 and It should be noted in connection with Figure 2 that the rotor plates are cut out of a single piece of metal. This form of rotor platewith two sectors mechanically and electrically connected together and as associated with the stator plates 'as shown in Figure l, eliminates objectionable sliding contacts. Sliding contact is objectionable not only when tuning but also when a tuned condition has been reached and the condenser arrangement shown eliminates these objections.

, Figures 9 and 10 are respectively, top and side views of'a modified push-pull system which is generally similar to Figures 1 and 3. in Figures 9 and 10 only a single tube is mounted on each side of the push-pull system. As shown in Figures 9 and 10, the tubes lfmiilfi and the neutralizing condensers H34, H36 are alternately arranged at the corners of a rectangle or a square. The arrangement shown in Figures 9 and 10 offers the advantage that the length of the circuit connection between the grid of It will be understood, however, that the areas of the respective plates 56,52 and the plate 54 adjacent may be differently proportioned from those shown in Figs. 1 and 3, due to the fact that the tubes [0% and I Q2 respectively are not necessarily directly opposed to. one another. The cooling water openings M, 68 of Figure 10 are shown connected to the doubly wound copper coils I083, I It. Rubber hose inlet and outlet pipes H H4 are also provided for each half of the coil, it being understood that each half of the coil of Figure 10 goes to either block 26 or block 28.. That is to say, the watercircling through the hose H2 would go to eitherblock 26 or block '28 and the water circling through the rubber hose connection H4 and the other half of thecoil system Hi8, Hli' would alsocircle tothe other block, such as, 28 and 26 respectively. Also, as

shown in Figure 10, a metal disc orv inductance.

tuner H5 is provided which. is rotated by means of shaft H8 for additional tuning adjustment.

Returning to Figure 9, an insulating strip I23 is suitably mounted on the neutralizing condensers IM, 1%. This insulating strip I29 supports the grid excitation and neutralizing connections.

The neutralizing condensers referred to hereinabove are described more fully in the copending application of C. W. Hansell, G. L. Usselman,

and C. W. Latimer, Serial No. 27,678, filed June 1935. .That is to say, for high voltage operation I prefer to use the condensers as shown in this ccpending patent application. For opera" tion at still higher voltages modifications such as shown in Figure 11 are found desirable. In

Figure 11 I have shown a neutralizing condenser which has general application, it being provided with an air inlet l2ll, a pressure gage I24, and

However,

It is to be understood, of course,

For example, the neutralizing con" an outer electrode or wall I26 which in Figures 1, 3, 9, and 10 is replaced by the metallic blocks 26, 28. The inner electrode structure I23 is adjustable and constructed as described in the copending application referred to. However, to prevent corona creepage along the conical insulator I38 an annular corona shield I40 at the base of the insulating cone IE8 is provided in order to shield the screw heads I42 for fasten ing the cone i353 to the base I26. Also, a circular doughnut-shaped corona shield M4 is provided at the upper end or apex of the insulating cone I38 which ring shaped corona shield is supported by means of metal arms I46. It has been found that by the provision of the shields M and I48 the condenser may be subjected to voltages twice as great as compared to the voltages at which, without the shields, flash-over or arcing takes place between points I42 and I48.

A further feature of my present invention resides in the uni-control of the neutralizing condensers shown in Figures 1 and 3 and Figures 9 and 10.

Figures 12 and 13 are top and side views ,of uni-control mechanism for simultaneously ad J'usting the neutralizing condensers I04, I86 which correspond with condensers 33, 4!! shown in Figures l and 3. Referring to Figure 11 when hexagonal nut I50 is rotated the capacity of the neutralizing condenser is altered, as explained more fully in the copending application of Hansell, Usselman, and Latimer referred to hereinab-ove. The neutralizing condensers 33, 40 of Figures 3., 3, l2, and 13 are provided with these hexagonal adjusting nuts I55 as shown more clearly in Figure 13. A hexagonal cup, or socket, 152 fits over each nut I50 and each socket is pinned to a shaft I54. Shafts I54 are preferably made of insulating material. At the upper end of each shaft, as shown in Figures 12 and 13, there is a 90 worm gear I55 engaging the separated worm driving gears I58 and lfill. Gears 158, Hill, 164 are pinned or otherwise fastened to the metal drive shaft I66 which is rotated by inserting a screw driver in either of its slotted ends I68, 110. A pair of stops I12, I14 are provided which engage a further stop I16. Stop I16 is in the form of a nut threaded to shaft I65 and limits the movement of the shaft so as to prevent undesired extreme movements of the inner electrode of the neutralizing condensers shown in greater detail in Figure 11. In order to effect this result the nut I16 is keyed so that it may move axially along the shaft I56 but is prevented by the keying means, not shown, from rotating with the shaft. Also in order to effect this result, it should be clear that the socket IE2 is so dimensioned as to permit the nut ifi l to move up and down within the socket !52 but not rotate within the socket. In other words, the socket I50 and nut I52 rotate together although they are relatively slidable along the axis of rotation.

figure 14 is a top plan view of a system for simultaneously adjusting the neutralizing condensers of the arrangement such as shown, for example, in Figures 9 and 10. Because the condensers are staggered or he on opposite sides of the shaft the gearing 2E0, 262 is similarly staggered because of corresponding changes in the condenser structure. For this reason, too, the pitch on the sets of gears 25!), is reversed. The mechanism is otherwise similar to that described in connection with Figures 12 and 13 and consequently, further detailed description is believed to be unnecessary in view of what has tion of said rotor plate system from all other portions 'of said apparatus, means for adjusting said rotor plate system with respect to said stator plates, a pair of electron discharge tubes, each tube having its anode connected substantially directly through connections of low direct current and alternating current resistance and impedance to one of said stator plates respectively, and fixed condenser system connected in shunt to said anodes, said fixed condenser system comprising end plates unequally spaced from said anodes, said end plates being of different size in orderto maintain capacitive symmetry of said tubes with respect to each other.

2. A push pull system comprising a variable condenser having complementary stator plates disposed in co-planar pairs and a cooperating adjustable rotor system comprising plates interleaved with said stator plates, a push-pull elec tron discharge tube system the tubes of which have their anodes substantially directly connectedv each to a particular group of said stator plates, a fixed condenser connected in shunt with said variable condenser and comprising a plurality of interleaved stator plates whereof each plate is of an effective area which is a function of its distance away from the electrical center of said discharge tube system, said function being suitably determined for balancing the electrical characteristics of said tubes, a pair of neutralizing condensers each having one of its electrodes substantially directly connected to a particular group of said stator plates, and means for simultaneously varying the capacities of said neutralizing condensers.

3. Apparatus of the character described comprising in combination a pair of electron discharge tubes having their anodes disposed in a push-pull arrangement, a tuning condenser systern connected across said anodes and including two groups of stator plates and a group of rotor plates, certain of the stator plates of one group being co-planar with respect to corresponding stator plates of the other group, means including an insulation member for supporting said rotor plates in interleaved relation to the coplanar stator plates, means including conductive supports each for electrically interconnecting the stator plates of a particular group, and for maintaining certain of the same in interleaved relation to certain of the stator plates of the other group, and means providing insulation of all the stator plates of one group from those of the other group, said apparatus being further characterized in that a stator plate of one group is disposed adjacent the anodes of said discharge tubes, said stator plate being of reduced size relative to the stator plate of the other group which is nearest thereto.

4. Apparatus according to claim 3 and further characterized in that two of the stator plates, one in each group are of progressively diminished areas relative to others of the interleaved plates, the plate of smallest area being disposed nearest the anodes of said discharge tubes.

5. Apparatus according to claim 3 and having two substantially identical stator plates, one in each group, disposed in a common plane and furthest removed of all the plates from said discharge tubes.

6. A resonant circuit arrangement for a pushpull system comprising a capacitor having a plurality 01 pairs of co-planar stator plates, and movable plates interleaved therewith, a set of additional plates electrically connected to those of the co-planar stator plates which are disposed v on one side of a plane separating complementary stator plates of each pair, a second set of additional plates electrically connected with those of the co-planar stator plates which are disposed on the opposite side of said plane, the plates of said first and second sets being interleaved, and a pair of discharge tubes disposed in push-pull relationship and in unsymmetric proximity to opposing ones of said additional plates, certain of said additional plates being of sufiiciently reduced area with respect to others thereof so that electrostatic compensation for said unsymmetric 10 proximity is provided.

GEORGE LINDLEY USSELMANl

Images