US1983848A - Short wave oscillation generator - Google Patents

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Dec. 11, 1934. w 1,983,848

SHORT WAVE OSCILLATION GENERATOR Filed Oct. 2, 1931 J INVE'NTOR cz F ERNEST WALTER snuveuzu. em

ATTORN EY Patented Dec. 11, 1934 PATENT" oFFicef;

. 1,983,848 snon'r WAVE OSCILLATION GENERATOR Ernest'Walter Brudenell Gill, Oxford, England,-

assignor to Radio Corporation of America, a

corporation of Delaware Application October h h In Great Britain Serial No. 566,441

October 8, 1930 9 Claims. (01. 250-36) J a v This invention relates to short wave oscillation generators and more particularly to valve :generators adapted to generate wave lengths of the order of about 3 metres.

In valve generators as at present employed for frequencies of the order above referred to, it

is common to employ as the only cencentrated capacity in the oscillatory circuit the self capacity between the grid and plate of the thermionic valve employed,

reduced as far as limit to the extent y the inductance of the usual 'coil or other inductance possible. to which the inductance value device employed bein There is however a if free oscillatons are to be maintained in the circuit is that the various electrical values be such that the effective resistance L is the effective inductance, R

and C the efiectivecapacity of the circuit. If, however, the circuit is of the kind in which one side of the oscillatory condenser is connected to the anode and the other side to the grid and if the valve characteristic is given by the equation:

volts) C where Anode current a. x (grid volts) +11 (plate 2=the valve magnification vand =the valve impedance, then L 8 I '6( fb) R o is the condition for' oscillation, I

If, for example, (ct-b) has a value of the order of v vL I I 1000R may be a more severe condition than There is thus a theoretical critical value of minimum inductance below which oscillations are not maintained; and if the value of inductance is reduced so :thatit comes near ical value, the oscillations to this theoretbecome very weak.

In order that the present invention may be the better understood,

a nertia ema te .and assuming the inductance'in tionof currents and L1 and L2 respectively,

' nitudes and directions of the operation ofthe invention accuracy or otherwise.

When the current in an oscillatory circuit reaches its maximum value, the energy can be regarded as substantially wholly electro-magnetic the circuit to be of valueL and the maximum current of value 1' the amount of energy maybe written inthe form /zLi Obviously," this. energy is analogous to mechanical energy in a flywheel, and'since it is that which maintains the oscillation in being during the change over from growing? todying current intensity, it is desirable that this energy be as large as possible. According to this invention, there is placed in parallel with the inductance of an oscillatory circuit employed inashort wave oscillation valve generator a circuit whose natural wave length is larger than that of the original circuit'but less than twice that of the original circuit.

The effect of providing theadditional circuit in carrying out the present invention may be regarded as that obtained by so arranging an oscillatory circuit in which the concentrated cav pacity is a valve capacity that a large portion of the oscillatory current never reaches-the valve capacity at all, so thatior a comparatively small potential variation across the valve there are obtained large oscillatory currents and very large electromagnetic flywheel effects.

Referring to the drawing, 7

Fig. 1 illustrates schematically acircuit equivalent of an arrangement inaccordance with the present invention,

Figs. 2 and 3 illustrate the theoretical distribupotentials along inductances of Fig. 1, f Fig. 4.- illustrates, diagrammatically, the mag- 'the various currents Fig. 5 shows a preferred arrangementembodying the principles of the present invention and F g.6 illustrates another embodiment in accordance with the present invention;

e circuit arrangement; in accordance with the present invention may be represented theo-' retically as shown in Figurel of the drawin wherein the capacity between C C represents the d, anode capacity of the valve, L1 the innqg eonnected between plate andgrid of of said output and input oscillatory circuits and directly connected thereto in parallel with said first mentioned inductances, said additional linear wires having inductance values respectively greater than the inductance values of said first mentioned linear wires.

5. In a short wave electron discharge device oscillation generator having an anode and a control electrode, the combination with an oscillatory circuit connected to said anode and control electrodes, said oscillatory circuit comprising an inductance and capacity in series, of a second circuit comprising an inductance and capacity in series in parallel with said oscillatory circuit, said second circuit having a natural wave length larger than that of said oscillatory circuit, but less than twice that of said oscillatory circuit.

6. An oscillation generator in accordance with claim characterized in this, that said inductance in said second circuit consists of Lecher wires.

'7. A short wave oscillation generator adapted to generate a substantially constant wave comprising two electron discharge devices connected in push-pull, each of said devices having anode and control electrodes, the corresponding anode and control electrodes of said devices being connected together by linear wires to constitute together with the inherent capacity of the devices output and input oscillatory circuits respectively, and additional linear wires having inductance values greater than the inductance of said first wires in each of said output and input oscillatory circuits inparallel with said first mentioned wires. 8. In an electron discharge device oscillation generator having input and output electrodes, the combination with an oscillatory circuit connected to said input and output electrodes, of a second circuit in parallel with said oscillatory circuit, said second circuit having a natural wave length larger than that of said oscillatory circuit, but less than twice that of said oscillatory circuit. 9. In a short wave electron discharge device oscillation generator having an anode and a control electrode, the combination with an oscillatory circuit connected to said anode and control electrode, said oscillatory circuit comprising an inductance and capacity in series, of a second circuit comprising an inductance and capacity in series in parallel with said oscillatory circuit, said inductance in said second circuit consisting of Lecher wires each of which has a length equal to A, where A is the Wave length of said oscillatory circuit.

ERNEST WALTER BRUDENELL GILL.

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