US2250090A - Arrangement for tuning high frequency oscillation circuits - Google Patents

Description

- July 22, 1941. w. BUSCHBECK 2,250,090

ARRANGEMENT FOR TUNING' HIGH FREQUENCY OSCILLATION CIRCUITS Filed Oct. 5, 1959 2 Sheets-Sheet 2 ii l l I T -i, K cl W I i---- 4 'L J INVENTOR. WERNER B SCI/BECK BY ,d

' ATTORNEY.

Patented July 22, 1941 ARRANGEMENT FOR TUNING HIGH FRE- QUEN CY OSCILLATION CIRCUITS- Werner Buschbeck, Berlin, Germany, assignor to T'elefunken Gesellschaft fiir Drahtlose Telegraphic in. b. 11., Berlin, Germany, a corporation of Germany Application October 5, 1939, Serial No. 297,978 In Germany September 28, 1938 7 Claims.

For the purpose of governing wider wave ranges without utilizing additionally connectable rough adjustment means, the gliding variometer has found its way more and more into the short ances of the grid circuit certainly exist so that at acorrespondingly tuned anode circuit feed back eliects in accordance with the Huth-Kuehn principle, i. e. disturbance waves, in other words,

wave field. But such structures have the disadmay be produced owing to the fact that a neuvantage that in the case of wider wave ranges it tralizing action no longer exists within this wave is, for instance, the wattless power of the interrange. Even though the resonance resistance of mediate circuit which decreases with an increase the short coupling wave is low against that of in the wavelength owing to the pure inductive the long waves, a quantitative observation shows variation. Moreover, large inductances require 10 that in many cases the condition for the feed larger space and more structural means since the back will be fulfilled. Hence, it should be aimed coil of the variometer is in fact to be dimenat excluding in principle the self excitation at 'sioned for the maximum current appearing at the short coupling wave. This is accomplished the shortest wave and for the highest coil poaccording to a further feature of the invention tential then prevailing so that the coil will have by inserting a further inductance L5 (Fig. 4) excessive dimensions as regards the setting of the which is placed in series to the parallel condenser higher inductance values. C4. In the case of several parallel capacitances In accordance with the invention, these draweach of them is to be given obviously a respecbacks are avoided in that parts of the variometer tive series inductance. The lower limit value of have one or several capacities connected in parthe short coupling wave now is practically deterallel thereto (Fig. 1) whereby the said capacities mined by L5 and C4 so that the short coupling are placed at those variometer turns which at wave will be moved definitely out of the region short waves are still short circuited. Therefore, of the grid resonance and it may eventually even in the case of short waves the parallel capacibe brought into the region of the actual operattances are inefiective. If the inductance is ining waves. The curves 0, d, e of Fig. 3 show the creased by shifting the variometer tapping, the power curves for such cases in which the short parallel capacities have gradually impressed coupling wave is limited to about 9 In. These thereon potentials whose values increase in succurves indicate that already at the use of a single cession and thus they become ever more effecadditional capacitance the variation of the watttive. The case of a single parallel capacity will less power of the intermediate circuit can be next be considered. maintained very small as compared with the case If xmn designates a fictitious natural wave calof the simple variometer and that the required culated from capacities and inductances having maximum inductance can be reduced to a very the indices m and n, the resonance places of the great extent. It is clear that through the use of region according to Fig. 2 follow from the equaa further condenser a renewed raising etc. can tion: be brought about. More especially, it is also The minus sign underneath the square root furpossible through a suitable variable dimensioning nishes the longer coupling wave, i, e., the wave of the' stray capacity between the individual actually corresponding to the tuning. When turns of the coils to obtain an extremely flat and considering the limit condition, it is seen that stepless pattern of the power curve. the short coupling wave starting at zero ap- In many cases, for instance, for push-pull proaches the limit value given by the series constages, symmetrical variometers L3, L3 and nection of C1 and C4 and L2. corresponding symmetrically connected addi- Fig. 3 shows for a practical example the watttional capacities will obviously be employed. As less powers of the intermediate circuit for cases shown in Fig. 5, it will be advisable in this case whose additional capacitances dilier in value as to compose the parallel capacity of two parts indicated by the curves a and b.

The fact that the short coupling wave begins theoretically at zero, is in many cases an undesirable condition. At any short waves lying be- C4' and C4", each of which being symmetrical with respect to ground and whose center is placed across a resistor at ground or at the direct potential. In this way a close coupling can be low the shortest operating wave natural resonobtained between the upper and the lower part of the oscillatory circuit whereby asymmetrical conditions which may eventually be present, for instance, those of the coupling of the load will be compensated for. Furthermore, with this resistor a damping or an eventual tendency to disturbance waves and the avoidance of static charges may be achieved.

It may eventually also be of advantage to represent the inductances and capacitances shown in the circuit diagrams l to 5 by open lines and short circuited lines such as shown by Way of exampl in Fig. 6. Such a structure offers an especially convenient possibility of supplying the cooling water at places at which the high frequency is grounded so that additional losses in high frequency due to the cooling water are avoided. Fig. 6 shows the variometer by the coaxial line L2 having the sliding tapping A. The inductance results from the magnetic field between the inner and outer conductors, and by means of the tapping A this field is confined to the portion of the coaxial line L2 to the left of the slider, i. e., between the slider and the anode end of the inductance. The line L2 is tapped at a suitable place by a transversal line W which consists of two different parts L5 and having different wave resistances. The part L acts in this case as inductance and C4 acts as capacity. Such an arrangement has the particular advantage that stray capacities and stray inductances are entirely avoided such as is generally known when using coaxial lines as tuning elements of oscillatory circuits. The cooling water may be supplied at K and passed off at K.

The invention is not limited to its application for the tuning of short wave transmitters but can be employed whenever at variations of the induction capacitive variations are to be carried out at the same time.

What is claimed is:

1. An amplifier system including a vacuum tub having in its anode circuit inductance and parallel capacity, and a fixed capacity fixedly connected in parallel to a portion only of said inductance, a relatively small inductance placed in series with said lastfixed capacity, and tapping means directly connected between the end of said first inductance removed from said anode and. an intermediate point on said first inductance for shortening out of said circuit an adjustable portion of said first inductance, said adjustable portion'including a part of that portion acrosswhich said fixed capacity is fixedly connected. I r

2. An amplifier system including a vacuum tube having inductance and parallel capacity in its output, and atleast one other capacity permanently connected in parallel to a portion only of said inductance, and tapping means on said inductance extending between one end of said inductance and the tapping point thereon for directly short circuiting an adjustable portion of said inductance, said adjustable portion including a part of that portion across Which said other capacity is permanently connected.

3. An amplifier system including a vacuum tube having in its anode circuit inductance and parallel capacity and a fixed capacity fixedly connected between the end of said inductance removed from said anode and an intermediate point, and tapping means on said inductance for directly shorting out of said circuit an adjust able portion of said inductance between said end removed from said anode and the tapping point.

4. A transmitter including a vacuum tube having in its anode circuit inductance and parallel capacity, and a plurality of other capacities fixedly connected directly between the end of said inductance removed from said anode and different intermediate points on said inductance, and means for shorting out a portion of said inductance extending from said one end of said inductance to any point on said inductance, whereby as more and more inductance is effectively connected in said circuit more and more capacity in shunt to portions of said inductance is also effectively connected in said circuit.

5. An amplifier system including a vacuum tube having inductance and parallel capacity in its output, and a fixed capacity fixedly connected directly across a portion only of said inductance,

and a single control in the form of a shortcircuiting member extending between one end of said inductance and an intermediate point thereon for varying simultaneously both the inductance and the effect of said last capacity in parallel to a portion of said inductance.

6. A push-pull amplifier system comprising a pair of electrode structures each including a grid, an anode, and a cathode, an inductance and a parallel capacity connected between the anode and cathode of each of said structures, a capacity individual to each inductance and fixedly connected across a portion of each inductance, and tapping means connected between the cathode terminals of each of said inductances and a point on each of said inductances for directly short circuiting a desired portion of said inductances.

'7. An amplifier having an anode and a cathode, an output circuit therefor comprising fixed capacity connected between said anode and said cathode and in parallel relation with said fixed capacity, a path composed of an inductance having one end connected to the anode side of the capacity and an adjustable tap thereon connected to the other side of the capacity, and another path including fixed capacity connected between said cathode and a fixed point on said inductance intermediate the ends thereof.

WERNER, BUSCHBECK.

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