US2360694A - Voltage supply circuits - Google Patents

Description

oct. 17, 1944. R'. B, LlNCOLN 2,360,694

VOLTAGE SUPPLY C IRCUIT Filed Sept. 9. 1942 BY TTO Patented Oct. 17, 1944 UNITED STATE s PATENT OFFICE VOLTAGE SUPPLY CIRCUITS Y' Roy Lincoln, deceased, late of Newark, N. J.,

by Hazel Lincoln Lang, administratrix, New York, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application,September 9, 1942, Serial No. 457,711

` s claims. (c1. 25o-17) An object of this invention is to provide an` The ordinary series screen resistoras usedinv the prior art its not practicable for a screen grid tube used as a class .C radio frequency amplier, the excitation ,of which is modulated by being keyed, for the reason that when the space current in the vtube is reduced toa low value. under key-up conditions by the normally cuto fixed bias, the screen voltage will `rise considerably. This', in turn, necessitates a v e'ry highV value of iixed bias to -keep the anode current and dissipation within reasonable limits.` v

By this invention, the driver tube can.l obtain its anode voltage from the same series resistor that supplies the screen of the final tube, and thus reduces the xed bias necessary to obtain the proper anode current lcut-off in the amplifier.

The invention will best be understood by referring to the accompanying'A drawing, in which a circuit diagram of the invention is shown.

The keyed oscillation stage I, which maybe any suitable form' of oscillation generator for developing thedesiredoscillations, is connected to an electron discharge Vdevice 2, which is preferably of the pentode type, such as the'RCA #47. Device 2 is VVprovided with a grid 3,Y anode' 4, screen grid 5, suppressor grid 6 and cathode 1. The device 2 serves as the driver stage of a second electron discharge device 8, which acts` as a radio frequency amplifier stage andis preferably of the RCA #813 type of transmitting beam power amplilier. K j

The electron discharge device 8 includes input grid 9, screen grid I0, anode I I, beam-forming electrodes I2 and I3, and cathode I4, Resistance I6,`connected between ground and grid 3, forms a direct current return path for grid 3.

The key circuit includes a key I5, which is coupled to grid 3 by a condenser I1. A coupling condenser IB is connected in series between' anode Ilv and the yinput grid 9 of the radio frequency stage. A tuned circuit, including inductance I9 and variable condenser 20, is connected from anode 4 to the source of high voltage 2|. A grid bias resistor 22 is connected from grid 9 to a source of grid bias voltage indicated as -'-C.'

A second tuned circuit, including inductance 23 and variable condenser 24, is connected to anode II of the radio frequency stage, and to the highl voltage source 2I.` A series resistor 25 is iprovided ior supplying the proper voltage on screen I0 and is so adjusted that the normal operating anode and screen voltages appear on the` buffer 2 and the Iinal tube 8 under key-down conditions.

Y Inl the operation of the circuit of this invention when the key I5 is up, or open, the anode resistance ofthe electron discharge device 2 drops to a low value, since its bias Voltage is zero. Because of resistance 25 the anode voltage of tube 2 and the screen voltage of tube 8 drops to a lowvalue. This circuit arrangement saves an additional power supply for the anode of tube 2, the screen IIJ of tube 8, the bias supply for grid 3 Vof tube 2, and enables a relatively low value I nect to ground 30 and are provided with condensers 3l and 32. In brief, it is to be noted that tube 2 is provided with a resistor I6 connected between the grid 3 and cathode l. Consequently, in the absence of oscillations from source I, tube 2 draws current, and in the presence of in-put from source I, the plate grid of tube 2 is reduced. On'the other hand, the plate current flow through tube 8 is just the reverse for the reason that this tube is substantially cut-oil by the -C voltage impressed through resistor 22 on the grid 9. `When keyed oscillations reach the grid 9 of tube 8, plate current ow through tube 8 increases. Hence, it should be apparent that during periods'of"n`o.signa the current flow through tube 2 produces a'voltage drop in resistor 25, which serves to cutdown the'screen voltage on screengrid I0.l f; 1 Y

This invention should not be -limited`to the precise circuit application-shown, as it isto'be distinctly understood'that itis capable of being used in other circuit applications where similar circuit characteristics exist.

What is claimed is:

l. In combination, a source of modulated high frequency voltage, a first tube having an anode, a cathode, a grid and a screen grid, a second tube having an anode,.a cathode, a grid anda screen grid, a coupling between said modulated high frequency voltage and the grid cathode circuit' of said first tube, circuits coupling the anode and cathode of the first tube to the grid and cathode of the second tube, a resistance connectedacross the grid and cathode of the first tube serving to permit flow of current through saidfirst" tube in the absence of excitation from said source ofvr said modulated high frequency voltage, a source of potential for maintaining the grid of the second tube negative with respect to the cathodeof the second tube, a source of anode potential for said tubes, and a resistor connected to said source of anode potential'and-to the screen grids of both of said tubes. f

2. In combination, a source of keyed high frequency voltage, a first tube having. an anode, a.

cathode, a grid and a screen grid, a second tube having an anode, a cathode, a grid and a screen.

grid, a coupling between said source of high frequency voltage and the grid cathode circuit of said first tube, circuits coupling the anode and cathode of the rst tube to the .grid and cathode of the second tube, aresistance connected across` the grid and cathode of thefirsttube serving to permit' flow of current throughsaid rst tube in the absence of excitation from said source of keyed high frequency voltage, a source of potential for maintaining the grid of the second grids of both of said tubes, and an input circuit coupled to the grid and cathode of said first tube for applying modulated high frequency voltages thereto.

5. In combination, a source of keyed high frequency oscillation voltage with a coupling circuit connected thereto, a pair of cascade electron discharge devices, each havingfanode, grid, cathode and screen grid electrodes forming a keyed oscillation circuit, and a radio frequency amplifier circuit respectively, said coupling circuit connected to'thegrid cathode circuit of the electron discharge device which forms the keyed oscillation circuit, a source of vvoltage for supplying voltage to said'electron discharge devices, a series resistor connectedto said source of voltage and to the anode vcathode circuit of at least one of saidl electron discharge devices and forming a part of a voltage divider, and the other electron tube negativevwith respectto the cathode of the second tube, a source of anode. potential for said tubes, and a resistor connected to said source of. anode potential andto the. screen grids of both.,

of said tubes.

3. In combination, a source. of keyedhigh` frequency voltage, a first tubey having an anode, a cathode, agrid and a screen grid, asecond tube.I

having an anode, a cathode,a grid anda screen grid, a coupling between said source of keyedhigh frequency voltage and the grid'cathode circuit of said first tube, parallel Atuned. circuits coupling, the anode and cathode ofthe first tube tothe.

grid and Ycathode of the second tube, aresistance. connected across the grid, and cathode of thefirst tube serving to permitA flow `of current through sadrst tube in theabsence of excitation from said source ofrkeyed high frequency voltage, a source of potential for maintaining thel grid of the second tube negative withrespect toy the cathode of thesecond tube, a source of anode, potential forsaid tubes, and a resistor connected to said source of anode potential andf.to the,

screen grids of both of said tubes.Y

4. In combination, a first tube having anl anode, a cathode, a grid and ascreen grid, a..

second tube having. an anode,a cathode, afgrid and a screen grid, circuits coupling the anode and cathode ofthe first tube to the gridand cathode of the second tube, .ag resistance con.

nected across the grid and cathode of the first.

tube. serving to permit flow of currentIV through said first tube in the absence, of excitation,` a sourceY of potential for. maintaining. the grid'of the second tube negative with respect to. the. cathode of the second tube, a source of anode potential for said tubes, a resistor connectedto said source ofanode potentialandto ,the screen discharge device forming the other part of said voltage divider'.

6. A' radio transmitting circuit, a source of' high.

frequency voltage,` ay keyed' oscillation circuit coupled to said=source of high frequencyvoltageA including an electron discharge device having anode, grid, cathode and screen grid electrodes, a-grid-leak` bias arrangement for connection to the input gridof said electron discharge device, a radio frequency amplifier circuit including an electron discharge device having a screen grid andinputelectrodes -coupled to the anode'of said' rst'electron discharge device, and having output electrodes, asource ofvoltage supply connectedI highfrequency voltage, aV keying circuit for said transmitter coupled to saidi source of high frequency voltage, said circuit including. an electron discharge device having anode, grid, cathodev and screenv grid electrodes, a grid leakj connected to the input grid of said electron discharge device,

' a radio frequency amplifier circuit including an electron discharge device having anode grid, cathode andscreen ,grid electrodes, a source of voltage supply, a resistor connectedin series with said source ofV voltage supply and the-anode ofiv atleast one ofv said electronr discharge devices,

the screen grid electrodes of both of the electronl discharge devicesfbeing connected with the source of voltage supply so. that the first mentioned electron discharge ldevice obtains its anode voltage from saidresistor, which supplies. the screen grid voltagel to said radiofrequency amplifierY device having, anode, grid, cathode and screen.

grid electrodes, a source of voltagesupply, aresistor connected in series-,with said source of', voltage vsupply and the anode of at least one, of.

said electron discharge devices, a Variable resistor connected in series between said screen grid of said second electron discharge device and said rst mentioned resistor, the screen grid electrode of the rst mentioned electron discharge device being connected with the source of voltage supply and said first mentioned resistor so that it obtains anode voltage from said first mentioned resistor and the rst mentioned electron discharge device which serves as part of the Voltage divider for said second mentioned electron discharge device.

HAZEL LINCOLN LANG,

Admmstratri of the Estate of Roy B. Lincoln,

Deceased. Y

Images