US2007875A - Transmitter arrangement - Google Patents

Description

y 1935. H. o. ROOSENSTEIN 2,007,875

TRANSMITTER ARRANGEMENT Filed Feb. 4, 1952 2 Sheets-Shae; 1

INVENTOR HAN5 O ROOSENSTElN BY l+ ZWW ATTORNEY July 9, 1935. H. o. ROOSENSTEIN 2,007,375

7 TRANSMITTER ARRANGEMENT Filed Feb. 4, 1932 2 Sheets-Sheet 2 m o a I 5,

INVENTOR R HANS O- ROOSENSTEN BY ZM ATTORN EY Patented July 9 1935 PATENTY FI-CE corporation of Germany Application Februaryl i, 1932;, serial No. 596,904. InGermany January 30, 1931 3 Claims." (01. 179-171 The object of thistinventionis an improved circuit arrangement for a wireless transmitten.

his well knownin the art to connectthe grid electrode of an. oscillator 'tube by means 5 of a leak-resistancdwith .the cathode, that is,

with apoint having "ainegative potential relative to the cathode. According'to the present inventionthegrid leak-resistance'of an oscillator tube the'plate voltage of which is varied by a modulating device (Heising modulating arrangement) is connected to a, point having a positive potential relative to the cathode. Experiments have shown that the operationof such a 'transmittercircuit is of a different character andfar more efficient than: the operation of transmitter circuits in which the grid leak-resistance is'connected to a point of negative potential or to the cathode itself. l

.The novel features of my inventionhave been pointed outwith particularity in the claims appendedhereto. l l

. Thenature of the invention and the mode of operating the same will bebetter understood'b'y the following detailed description thereof and therefrom when' "read *in connection with the drawings, in which:

Figure 1 shows diagrammatically a circuit arrangement in which the novel features of the present invention have been incorporated; while,

Figure 2 shows a group of curves illustrating graphically the relation between currents in different portionsof the circuits of Figure 1.

An embodiment of the circuit in which the invention is incorporated is shown in Figure l. The figure shows a transmitter circuit in which use is made of a self-controlled oscillator tube I. The anode 2 of the oscillation generator l is regeneratively coupled inductively and capacitively to the grid 7 of tube l by the inductances H and. I2 and capacity l3 to produce sustained oscillations, the frequency of which is determined by the values of said inductances'and capacity. The grid anode cathode circuits are completed by way of a radio frequency choking inductance l5 and biasing meansto be described more in detail hereinafter. The voltage of the anode 2 of the oscillator tube l is varied in accordance with the modulating voltages supplied to the anode 2 in the usual way by means of a modulator 4 having its anode B and cathode El connected in parallel with the anode 2 and cathode 3 of the oscillator tube I. A low frequency choke coil 8 is disposed between the common plate voltage supply I U and anodes 2 and 6. 55 A radio frequency choking inductance l6 prevents radio frequency oscillations from being appliedtothe output circuit of the modulator tube 4. Modulatingpotentialsmay be applied to the input electrode ll of tube 4 from any source not shown; byway of the transformer T. A load circuit as, for example, an antenna 2i), may be coupled'by an inductance it to an oscillation circuit ill, l3, l2, etc. Difiiculties areencountered due to the fact that. there are discontinuities in the oscillating diagram of such an arrangement. q

Figure 2 shows the oscillating diagram of a transmitterof the type above referred to. In the diagram grid currents Ig have been plotted as a function of the grid voltage (of an oscil lator tube). For certain given anode voltages as for instance 300 v.,250 v., 150 v. and v. corresponding values of the electron current flowing to the grid electrode at different valuesyof the grid voltagehave been measured and represented by dotted line curves'in Fig. 2. In the same waythe values of the anode currentsrare plottedat constant anode voltages as a function of the gridlvoltage in continuous lines in'Fig. 2. As will be seen, when. the negative grid voltage exceeds a certain value, the oscillations suddenly break-off. The grid voltages at which this breaking off occurs for the different values of the anode voltage are represented by the dot-dashed lines in the diagram of Fig. 2. These lines separate in the diagram the conditions at which oscillations are built-up from conditions at which oscillations are not obtained.

A grid leak R of the size of 100% ohms shunted by a capacity C (Fig. l) was first used. Assuming a grid current of 10 m. a. the potential drop in this resistance causes a negative grid bias of -10 v., of 20 v. at 20 m. a., of 30 v. at 30 m. a. grid current. This relation between the negative biasing potential applied tothe grid l and the grid current in R is shown by the heavy straight line OP. This line shows the grid voltage which at different grid currents is built-up. Oscillations for grid voltages lying'between points Q and P are produced only when more than 220 volts are applied to anode 2. It can be taken from the diagram that at an anode potential of 300 v., a grid current 39 m. a. and a grid potential of -39 v., and an out-put current of 233 m. a. will result; all these values correspond to the point of intersection of the line OP with the grid current curve for plate potential 300 v. For plate voltages below 220 v. the resulting grid potential lie in the region below the breakingoff line and oscillations therefore are not builtup. At least permanent oscillations are not built-up, and the transmitter may change very rapidly from the not oscillating state to the oscillating state, which even though not always perceptible to the ear in the case of short wave transmitters, results. in discontinuities. of the modulating characteristics.

If in accordance with this invention a constant positive grid bias supply is used in series with the resistance R, for instance, a source 22,

the grid potential resulting from the combined.

effect of the source 22 and resistance. R is. rep.- resented by the heavy straight line AB, which in this case lies entirely within the region of permanent oscillations of the diagram.

Although due to the modulating device the plate voltage of the oscillator tube may droppractically to zero, the permanent oscillations do not break-01f and no discontinuities in the modulating characteristics can be noticed.

I claim:

1. Transmitting means comprising, a thermionic oscillation generator including a tube having an envelope enclosing an anode, a cathode and a grid electrode, a pair of inductancesconnectedbetween said anode and grid electrode, a source of potential having its negative terminal connected to said cathode, a resistance connecting the positive terminal of said source to -a point between said first named inductances, a load circuit coupled to one of said first named inductances whereby sustained oscillations are impressed on said load circuit, and means: for modulating said oscillations comprising a thermionic modulator tubehaving its anode coupled by way of a choking inductance to the anode of said osillator' tube and its control electrode energized by modulating potential.

2. Transmitting means comprising, a thermionic oscillation generator including a tube having an envelope including an anode, a cathode and a grid electrode, inductances connected between said anode and grid electrodega source oi potential having itsnegative terminall connected to said cathode, a. resistance and a capacity in parallel connecting the positive terminal of said source to a point on said first named inductances, a load circuit coupled to one of said first named inductances, means for energizing the anode of said tube whereby sustained oscillations are impressed on said load circuit, and means for modulating said oscillations comprising; a thermionic modulator tube having its anode coupled to the anode of said oscillator tube and its control electrode energized by modulating potentials.

3;. In signalling means, a thermionic oscillation generator tube having an anode, a cathode and a grid electrode, an oscillation circuit including an inductance connected between said anode and grid. electrode, a. circuit connected between a point on said oscillation circuit and the cathode ofsaid' tube, a source of potential connected betweenthe cathode of said tube and the anode of said. tube to energize said anode to produce oscillations in said oscillation circuits, means for modulating the oscillations produced including a thermionic: tube having its inputelectrodes: coupled tea source of modulating potentials and its output electrodes. connected to said first. named source: andtolthe anode of said oscillation generator tube, and means; for insuringv the production of continuous oscillations in said oscillation generatorirrespective of decreasesv of potentiall on the anode of said' oscillation generator. resulting from changes in said; modulating potentials including,.asource of direct current potential in series: with. a resistance shunted by a capacity interposed in. said circuit; connected between said pointott said oscillation circuit andthe cathode at said; tube, said source of potential having its negatiive terminal connected; to the cathode of; said tube and, its; positive: terminal connectedv to. said point on said oscillation circuit, whereby the pa.- tcntialof said control grid: is determined in part by'potential drop. in said resistance-due: to current flowing in the grid circuit of the oscillation genrerator, and in, part by said last, named. source: of direct; current potential.

HANS OTTO RQQSENSTEIN;

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