US3339146A - Fast rise and fall time rf burst amplifier - Google Patents

Description

1967 A. A. GORSKI ETAL 3,339,146

FAST RISE AND FALL TIME RF BURST AMPLIFIER Filed July 29, 1964 I 4 I us 1 I5OKV Alexander A. Gorski Joseph S. Wulunos,

INVENTORS.

By M J,

MM w W 6. M

United States Patent Ofifice 3,339,146 Patented Aug. 29, 1967 3,339,146 FAST RISE AND FALL TIME RF BURST AMPLIFIER Alexander A. Gorski, River-ton, N.J., and Joseph S.

Walunas, Philadelphia, Pa., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army Filed July 29, 1964, Ser. No. 386,100 12 Claims. (Cl. 328-232) ABSTRACT OF THE DISCLOSURE First and second triodes connected to a load such as the modulating anode of a klystron. Feed-back transformers connected to the grids of the triodes to provide fast turn on rates. The first triode is connected in series with the load, is in an on state during RF burst inputs, and is in anoif state when there is no input. The second triode is connected in parallel to the load, is in an off state during RF burst inputs, and is in an on state when there is no input.

There is present in radar systems a need for providing a dependable system for pulsing the modulating anode of a klystron positive with respect to the cathode. This must be done so as to have the :full voltage swing with rise and fall times (in the order of 4 microseconds) with a Wide range of pulse widths to 500 microseconds). A practical device is needed to drive high resistance loads shunted by relatively large capacitance with no ringing or droo-p.

It is therefore an object of this invention to provide a pulsing system suitable for use in radar systems.

Another object of the present invention is to provide a dependable system for pulsing the modulating anode of a kylstron.

These and other objects and advantages of the present invention will become apparent from the following detailed description and from the accompanying drawing, in which the single figure is a schematic circuit diagram according to the invention.

A RF burst (from a source not shown) of signal voltages is fed to terminals 1 and 2. Terminals 1 and 2 are connected across primary winding 5 of transformer 4 and across primary winding 3 of transformer 6. (Capacitor is used to resonate secondary winding 8 at RF.) The voltage across center tapped secondary winding 8 is rectified by rectifiers 11 and 12. Capacitor 14 is connected in circuit to provide proper filtering action. The output of the rectifiers is applied to terminals 21 and 22.

Control element 24 is a vacuum tube having input and output circuits which have sides defined by circuit connections to the tubes anode 26, grid 27 and cathode 28. Anode 26 is connected directly to ground. Grid 27 is connected to terminal 21. Cathode 28 of tube 24 is connected to primary winding 30 of transformer 31. Secondary winding 32 of transformer 31 is connected in parallel with a rectifier 34. A series circuit comprising rectifier 36, the parallel combination of winding 32 and rectifier 34, and resistor 38 is connected across terminals 21 and 22. A capacitor 40 is connected to one side of winding 30 and to a junction between resistor 38 and secondary winding 32. A source of bias voltage 42 is connected to said one side of winding 30 and terminal 22. A voltage divider 44 having a slider arm is connected across battery 42.

A triode 50 having anode 51, grid 52 and cathode 53 has its cathode connected to a junction 55. The grid of tube 50 is connected to slider arm 46 of voltage divider 44.

Secondary winding 61 of isolating transformer 6 is connected to an input circuit of a triode 62 by way of diode 109. A resistor 63 is connected across cathode of diode 109 and junction 110. Battery 68 connects the output circuit of tube 62 to terminals 70 and 71.

Control element is a vacuum tube having input and output circuits which have sides defined by circuit connections to the tubes anode 81, grid 82 and cathode 83. Tube 80 is shown having its anode 81 connected to junction 55, its grid 82 connected to terminal 70, and its cathode 83 connected to one side of primary winding 78 of transformer 76. Secondary winding 75 of transformer 76 is connected to terminals 70 and 71 by way of capacitor 74. A battery is connected to terminals 70 and 71 by Way of resistor 91. Resistor 92 is connected between junction 55 and junction 56. Junction 56 is connected to output terminal 93.

Output terminals 93 and 94 may have a high resistance load 98 shunted by a relatively large capacitance 96. The voltage across output terminals 93 and 94 may also be supplied to a modulating anode 101 and cathode 103 circuit of a kylstron 105 either with or without the load elements 96 and 98. The kylstron has anode element 106 and has a collector element 108 connected to a ground circuit. A 150 kv. D.C. source 114 having output terminals 115 and 116 is connected between output terminal 94 and ground to provide power for the system and the klystron.

The invention performs in the following manner. A RF burst of a predetermined pulse width (variable over a wide range) is fed simultaneously to primaries 3 and 5 of isolating transformers 4 and 6.

The RF burst is rectified on the secondary side of transformer 4 by rectifiers 11 and 12. This full wave rectified pulse triggers tube 24, and due to the regenerative action of the blocking oscillator transformer 31, a high positive voltage spike is placed on the grid of tube 24. The voltage level of the spike and pulse Width of the spike is controlled by the design of the transformer 31. This voltage spike will enable the tube 24 to act as a high current source and produce a rapid rise time (on the order of 4 microseconds) for a kv. travel. After this initial 4 microseconds spike, caused by transformer 31, the input pulse takes over and the level of the input pulse determines whether there is a rising, falling or a preferably flat pulse fed to the Mod-Anode circuit of the klystron.

Tube 80 is normally conducting, however, when tube 62 is fired by the input pulse, battery 68 Will apply a reverse bias to the grid 82 of tube 80; therefore cutting off tube 80. At the trailing edge of the input pulse, tube 62 starts to cut off and the voltage level of anode 66 will start rising, finally triggering tube 80 to a conducting condition. Transformer 76 serves a similar blocking oscillator function as transformer 31.

Tube 80 now conducts heavily causing a voltage to develop across resistor 92 which triggers tube 50. Tube 50 will now discharge the grid of tube 24; therefore cutting tube 24 off in a very short time. This will result in a rapid discharge of the Mod-Anode of the klystron; therefore yielding extremely fast fall times.

While the invention has been described with reference to a preferred embodiment thereof, it will be apparent that various modifications and other embodiments thereof will occur to those skilled in the art within the scope of the invention. Accordingly, we desire the scope of our invention to be limited only by the appended claims.

We claim:

1. In combination first and second control elements having input and output circuits; a source of signal voltages connected to the input circuits of said first and second control elements by first and second circuit means respectrvely; a source of DC supply voltage having first and second output terminals, wherein said first output terminal is connected to one side of said output circuit of the first control element by way of a third circuit means; a load circuit having first and second load terminals; fourth circuit means connecting another'side of the output circuit of said first control element to the first load terminal; fifth circuit means connecting one side of the output circuit of said second control element to said first load terminal; said first terminal of said source of DC supply voltage being connected to the second load terminal; and means connecting another side of the output circuit of the second control element to said second output terminal of the source of DC voltage.

2. A device as set forth in claim 1, wherein said fourth circuit means is a resistor.

3. A device as set forth in claim 2, wherein said fifth circuit means is the primary winding of a transformer; said transformer having a secondary winding connected across the input circuit of the second control element.

4. A device as set forth in claim 3 further comprising a third control element having an output circuit connected across the input circuit of said second control element and an input circuit connected across said resistor.

5. A device as set forth in claim 4, wherein said first, second and third control elements are triodes.

6. A device as set forth in claim 5, wherein said third circuit means is the primary winding of a transformer; said transformer having a secondary winding connected across the input circuit of the first control element.

7. A device as set forth in claim 6, wherein said second circuit means is a full wave rectifier.

8. A device as set forth in claim 7, wherein said first circuit means is an amplifier.

9. A device as set forth in claim 8, wherein said load circuit is a modulating anode and cathode circuit of a klystron.

10. A pulser comprising first triode means having first anode, cathode and grid elements; a source of signal voltages connected across said first grid and cathode elements; a resistor; a second triode means having second anode, cathode and grid elements; means connecting said signal voltages across the second cathode and grid elements; a series circuit comprising the second cathode and anode of said second triode means, the resistor, said first cathode and said first anode; a source of DC power having positive and negative terminals; a load circuit having first and second load terminals; connections between the negative terminal, the first load terminal and the cathode of the second triode means; means connecting the positive terminal of the source of power to the anode of the first triode; and connection means connecting the second load terminal to a junction between the resistor and said first cathode.

11. A pulser as set forth in claim 10 further comprising a third triode means having third anode, cathode and grid elements; said third anode being connected to the first grid of the first triode means; said third cathode being connected to said second anode of the second triode means; and said third grid being connected to said second load terminal.

12. A pulser as set forth in claim 11 further comprising a klystron having a modulating anode and a cathode; said load circuit comprising the modulating anode connected to the second load terminal and the cathode connected to the first load terminal.

References Cited UNITED STATES PATENTS 2,948,855 8/ 1960 Swanson et a1 328-67 3,098,980 7/1963 Dodington 3327 3,167,717 1/l965 Jones et a1. 328-61 3,257,619 6/1966 Fackler et a1. 328-65 JAMES W. LAWRENCE, Primary Examiner.

V. LAFRANCHI, Assistant Examiner.

Claims (1)

1. IN COMBINATION FIRST AND SECOND CONTROL ELEMENTS HAVING INPUT AND OUTPUT CIRCUITS; A SOURCE OF SIGNAL VOLTAGES CONNTECTED TO THE INPUT CIRCUITS OF SAID FIRST AND SECOND CONTROL ELEMENTS BY FIRST AND SECOND CIRCUIT MEANS RESPECTIVELY; A SOURCE OF DC SUPPLY VOLTAGE HAVING FIRST AND SECOND OUTPUT TERMINALS, WHEREIN SAID FIRST OUTPUT TERMINAL IS CONNECTED TO ONE SIDE OF SAID OUTPUT CIRCUIT OF THE FIRST CONTROL ELEMENT BY WAY OF A THIRD CIRCUIT MEANS; A LOAD CIRCUIT HAVING A FIRST AND SECOND LOAD TERMINALS; FOURTH CIRCUIT MEANS CONNECTING ANOTHER SIDE OF THE OUTPUT CIRCUIT OF SAID FIRST CONTROL ELEMENT TO THE FIRST LOAD TERMINAL; FIFTH CIRCUIT MEANS CONNECTING ONE SIDE OF THE OUTPUT CIRCUIT OF SAID SECOND CONTROL ELEMENT TO SAID FIRST LOAD TERMINAL; SAID FIRST TERMINAL OF SAID SOURCE OF DC SUPPLY VOLTAGE BEING CONNECTED TO THE SECOND LOAD TERMINAL; AND MEANS CONNECTING ANOTHER SIDE OF THE OUTPUT CIRCUIT OF THE SECOND CONTROL ELEMENT TO SAID SECOND OUTPUT TERMINAL OF THE SOURCE OF DC VOLTAGE.

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