US1906904A - Adjustable condenser - Google Patents

Description

rL.. A. GEBl-ARD ADJUSTABLE CONDENSER Filed. Feb.

May 2, 1933.

I N VEN TOR.

V.. E N A) M T 1-- 1- 1-IQITT2----!! m a Q A/w QM e Q @w 4 .n 1 @w n. L x :li: w i Cum k \l l r O ,if k P -:-:-i-:--- wm SQ. Q um v RNW VPatented May 2, 1933 UNITED STATES PATENT OFFICE LOUIS A. GECBHARD, 0F WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO WIRED RADIO, INC., OF NEW YORK, N. Y., A CORPORATION 0F DELAWARE .ADJUSTABLE CONDENSER Application filed February 1l, 1929.. Serial No. 339,144.

My -invention relates to adjustable condensei's'in general and more particularly to condensers employed in high frequency electiical signaling systems.

An object of my `invention is to provide an adjustable condenser wherein the capacity is controlled easily and accurately within' desired limits.

Another object of my invention is to provide an adjustable condenser capable of withstanding high voltages.

Still another object of my invention is to provide an adjustable condenser wherein eX- traneous electrostatic elds are eliminated from the condenser when such condenser is employed` in high power, high frequencyv transmitters.

Other and further objects of my invention are to provide certain structural features whereby the efciency of an adjustable condenser for high frequency, high power transmitters is increased.

'A better understanding of my invention can be had from the specification following and from the accompanying drawing, wherein:

Figure l illustrates a front elevation in part section of the adjustable condenser of my invention; Fig. 2 illustrates a side elevation in part section of the adjustable condenserof my invention; and Fig. 3 shows a. view in section of `the upper plate structure taken on the lines 3 3 of Fig. l.

Adjustable condensers employed in high power and high frequency transmitters must be of the design capable of withstanding very highlvoltages.. Such condensers must be adjustable over V,wide limits of capacity. lin addition, the insulation of the condenser must be such as to withstand the strain of very high frequencies. The metallic capacity plates must be of low resistance and capable of carrying large values of current without appreciable loss. A further desirable feature is that the condenser be shielded from extraneous electrostatic fields which are present in high power transmitters operating at high frequencies. My application, Serial No.

327 ,990, filed December 22, 1928, shows a con.

denser similar to that described herein; the

' shows a front elevation in part section of the adjustable condenser of my invention. Adjustable plate structures 1l and 12 are electrically connected together and in combination constitute one capacity plate of the condenser. Plate structures'll and l2 are of suitable metal such as brass or aluminum.

A convenient form of construction for plate structure 11 is shown in Fig. l. Two vertical end members 7 of approximately rectangular section have their outer corners well rounded and on their inner faces are recessed to form a shoulderlportion as shown in F ig. 3. A bore 10 is provided in each end member to receive actuating shaft 15. A plate 8 is bent in the shape of an inverted U forming two vertical sheets closed on top by a curved portion which is the base of the The edges of each sheet lit into the shoulder recesses of end members 7 and are riveted or bolted thereto. rl`he interior of the Ll betweenend members 7 is therefore hollow and open below. The lower plate structure 12 may consist of a sheet folded about a forni such that it will take the form similar to that of the upper plate and having its bottom closed by base member ll. There is a connection between the lower plate and the upper due to the resiliency between the two plates. The sheets constituting plate structures 11 and 12 may conveniently approximate a parallel relationship.

Plate structure 12 is of slightly larger dimensions than plate structure 11, the foi-mer adapted to slide over the latter. The slidingmovement of structure 12 over the surface of structure 11 is accomplished by the action of a threaded shaft l5 engaging with a threaded bore in tube 5. Tube 5 is secured to plate structure 12 by means of a pin or screw 6. 'll'ube 5 moves vertically through bore l() in plate structure ll. Shaft 15 rests in suitable bearings provided in member 14. Member 14 supports gear mechanism 18, 19, 20, 21 and shafts 16 and 22. Shaft 15a. operates ina manner similar to the operation of shaft 15 and serves to divide the lifting vforce 100 in Fig. 1.

1 means of bevel gears between different portions of plate structure 12. Shafts 15 and 15a are turned by 18, 19, 20, 21and shafts 16 and 22. Supporting member 14 and plate structure 11 are held together in spaced relationship'by tubular member andvbolt 17. The adjustable plate structures 11 and 12, together with the adjusting mechanism are supported by insulating members 26. Insulating members 26 may be in turn supported by the main framework of the transmitter. To prevent complete separation of plate structures 11 and `12 some type of stop is necessary. To restrict the movement of plate structure 12 within desired limits I provide a rod 1 extending the height of platestructure 12 on the interior thereof.

One end of rod 1 is threaded and engages in base member 4. The upper end of rod 1 is provided with a head 1a.. A block 2 of suitable material is secured to the interior wall of plate structure 11 by means of screws 3. The head 1a of rod 1 passes through part 2 fora limited distance but is prevented from disengagement therefrom. The other capacity plate of the condenser is supplied by plate member 30, shown in section. Plate member 30 comprises a partly flattened metallic cylinder or compartment the walls of which are held in spaced relationship with respect 'to plate structures 11 and 12 and insulated therefrom. Plate member 30 may be in the form of a box entirely enclosing plate structures 11 and 12. It is desirable to arrange this box so that it will have sides approximately parallel to plate structures 11 and 12. Plate member 30 is supported on insulating members 25 which are in turn supported from the main framework of the transmitter. The socket for retaining the anode of a liquid cooled thermionic tube may be positioned in the space 31 and supported member 40. The anode of the tube would be, in this instance, connected electrically to plate member 30. Certain details of the stop employed for restricting the downward movement of plate structure 12 are more fully illustrated in Fig. 2 of the accompanying drawing. Reference characters corres ndto those employed in Fig. 1. Plate ructures 11 and 12 are illustrated with broken away sections to more clearly `show this feature. The effective capacity area of plate structures 11 and 12 is adjustable by means of sliding plate structure 12 over plate structure 11. The sliding movement is obtained by the threaded stud and bore shown A part 2, such as a block of insulating material or metal, is secured to the inner walls of plate structure 11 by means of screws 3. y

-A vertical bore partly through member 2 serves as a guide for rod 1. Near the lower edge of part 2, the diameter of the bore is reduced, from approximately that of the terials are employed, both electrically head 1a to that of the body of rod 1.l This prevents head la from entirely disengaging from part 2 and since rod 1 is secured to the base 4 of plate structure 12, prevents excessive downward movement of plate structure 12. y

Many advantages appear from the arrangement employed in the adjustable condenser system of my invention. The structure is such asto provide a highly efficient condenser for use in electricallyv balanced circuit arrangements of high requency transmitting systems. A maximum air insulation area is provided and the insulating material employed is placed in such positions where the electrostatic fields are of minimum intensity. The losses experienced when insulating mad an mechanically, make the arrangement of my invention superior to types o high power, high frequency adjustable condensers heretofore employed. Any number of plate structures similar to members 1l, 12 and 30 lmay be employed. Any number of plates either electrically connected in common or insulated from each other may be adjustably controlled by a common mechanical means. I realize that many modifications of my invention are possible and it is to be understood that my invention shall not be limited by the foregoing specification or by the accompanying drawing but only by the scope of the appended claims.

lVhat I claim as new and desire t'o secure by Letters Patent of the United States is as follows:

1. An adjustable condenser comprising in combination a plurality of plate structures having faces substantially mutually parallel and adapted to telescope the one over the other, a threaded rod in one of said plate structures engaging with a threaded bore provided in another of said plate structures for adjusting the relative position of said plate structures, a traveling rod member associated with said first named plate structure movable through a restricted bore therein for restricting the relative movement of said plate structures, and a stationary outer conductive plate structure having faces substantially parallel to faces of said first mentioned plate structures, said outer plate structure being maintained in spaced and insulated relationship from said first mentioned plate structures.

2. An adjustable condenser comprising in combination a plurality of plate structures electrically connected together and slidably positione one over the other, Ireans for causing the sliding movement of said plate structures with respect to each other, means for restricting such sliding movement to prevent disengagement of said plate structure and a stationary outer plate structure spaciall) aaoaeoa positioned and electrically insulated from said first mentioned plate structures.

3. An adjustable condenser comprising in combination a plurality of conductive plate structures slidably positioned one over the other, means for actuating the sliding movement of said plate structures with respect to each other, said means comprising a threaded rod in one of said plate structures coacting with a threaded bore contained in another of said plate structures, means for restricting such sliding movement to prevent disengagement of said plate structures, and an outer. stationary plate structure maintamed 1n spaced relationship with respect to said first mentioned plate structures and having faces substantially parallel to faces of said first mentioned late structures. u

4. An adjustable condenser comprismg 1n combination a plurality of conductive plate structures slidably positioned one over the other, means for actuating the sliding movement of said plate structures with respect to each other in balanced relationship, said means comprising a plurality of rotatable rods cooperatively actuated and attached to one of said plate structures and having a threaded portion coacting with threaded bores in another of said plate structures, means for restricting such sliding movement to prevent disengagement of said plate structures, and an outer stationary plate structure maintained in spaced relationship with respect to said first mentioned plate structures and having faces substantially parallel to faces of said first mentioned plate structures.

5. In a condenser system, a pair of plate structures having faces substantially mutually parallel and adapted to telescope the one over the other, one of said plate structures comprising two supporting members and a conducting sheet comprising a pair of parallel fiat portions each attached to and join'ng said supporting members, a threaded rod in one of said plate structures engaging with a threaded bore provided in the other of said plate structures for adjusting the relative position of said plate structures, a traveling rod member associated with said plate structures movable through a restricted bore therein for restricting the relative movement of said plates, and a stationary outer conductive plate structure having faces substantially parallel to faces of said first mentioned plate structures, said outer plate structure being maintained in spaced and insulated relationship from said first mentioned plate structures.

6. In a condenser system, a pair of plate structures having faces substantially mutually parallel and adapted to telescope the one over the other, one of said plate structures comprising two supporting members, a llshaped plate member closed at the end opposite said otherplate structure and open at the end adjacent thereto, said U-shaped member having its parallel sides attached to and joining said supporting members, a threaded rod in one of said plate structures engaging with a threaded bore provided in the other of said plate structures for adjusting the relative structures. l

LUUIS A. GEBHARD.

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