US1920194A - Frequency multiplier - Google Patents

Description

Allg. l, 1933. I F. GER-[H 1,920,194

` FREQUENCY MULTIPLIER Filed Nov. 5, 1929 *gmJ-Lfl-J-LL 5 Patented Aug. 1, 1933 Partnr orinar.

FREQUENCY MULTIPLIER Felix Gerth, Berlin-Tempelhof, Germany, ari signor to C. Lorenz Aktiengesellschaft, Berlin- Tempelhcf, Germany Application November 5, 1929, Serial No. 404,891, and in Germany November 17, 1928 1 Claim.

In order to permit the reception of broadcast radio performances over larger areas With the type of radio receiver in common use, it has been suggested that programs be broadcast from a number of stations on the same Wave length. In using this system a central station transmits a standard or primary frequency to the stations which are to broadcast on a common frequency, and at each transmitting stationthe standard frequency is uniformly multiplied to the common carrier frequency. A standard frequency may also be supplied from a central station to different broadcasting stations operating on different wave lengths. In this case a multiplica.- tion of the standard frequency will, of course, be different at each station. With the known methods endeavors Were made to choose the frequency transmitted from the central station to the various separate transmitting stations as high as possible, in order to get along at the local transmitting station with as low a multiplication as possible. When the control frequency is transmitted on cable lines, however, the multiplying factor must be chosen rather high, as one is forced by the limiting frequency of the cable to employ a primary or basic frequency of a low period. Thorough investigations have shown that it is more favorable not to carry out the multiplication at the local transmitting station in one step as in the former methods, but in several steps. For this purpose it is necessary according to the present invention to arrange ahead of the multiplying device an amplifying device and behind the said multiplying device a suitable device for the removal of any disturbances, which will take care that merely the desired multiplied frequency proceeds to the following circuit.

To the device for removing any disturbances are connected several similar devices for amplifying, multiplying and removing the disturbances, in a cascade-like manner.

An embodiment of the arrangement according to the invention is illustrated by Way of example in the drawing.

Figure l represents diagrammatically the arrangement of the various steps.

Figures 2 and 3 are diagrammatic views amplifying device, and

Figure 4 shows diagrammatically the operation of the tube.

Referring to Figure 1 it illustrates purely diagrammatically the arrangement of the different steps. At the left side, for instance, a frequency of the r of 2500 cycles is supplied by means of a cable.

vbe explained here.

(Cl. Z-36.)

Naturally the device according to the invention is not limited to the transmission of frequencies by means of cables. The cable is connected With the input circuit of an amplifying device V1. To the output circuit of the amplifying device is connected the stage Sti, consisting according to this invention of an amplifying device, a device for multiplying the frequency and a device for removing any disturbances. The frequency multiplied is supplied to an additional stage Stz, designed in the same manner. Between the second stage and the transmitting apparatus S inserted a further multiplying stage Sta.

The ratio of multiplication of the various steps could be about 1: 9 for the first step, 1: ,'l for the secondstep and the third step, so that there Will result a total factor of multiplication of 1: 9 7 'I or about l: 450. With the control frequency of 25Go cycles mentioned the Wave length radiated would then be approximately 270 metres. During the tests made the ratio l: 15 has proved the maximum ratio of multiplication of a single step.'

The arrangement of the individual stages is more fullyy explained in Figures 2 and 3. Figure 2 shows a system of multiplication which operates with frequency changers, While the arrangement shown in Figure 3 effects the multiplication by means of electronic tubes, whose action will be explained hereinafter. The starting frequency of the stage is supplied to the grid of an amplifying tube R1. In the anode circuit of the tube or valve is arranged an aperiodic circuit formed of the inductance L1. The amplified oscillations are supplied by means of an inductance coupled to the inductance L2 to the input circuit of the multiplying circuit formed by the inductances L3, L4 and the capacities C1 and C2, in which multiplying circuit a saturated iron frequency changer F is arranged in `lrnovvn manner. The principle of causing impulses is known per se and need not In order to carry through a further faultless multiplication in the various steps it is necessary to arrange behind the multiplying circuit a device for removing any disturbances, which Will merely permit the desired frequency to pass.

At the places of pure Watt tension in the device for removing any disturbances the circuit for removing such disturbances, formed of the inductance L5 and the capacity C3 is connected, which may preferably consist of a large capacity and small inductance, in order to obtain asY good a removal of disturbances as possible. It is superfluous to refer inparticular to the remaining I connection of the input inductance Le, the output inductance L9 and the inductances L7, Ls of the oscillatory circuit, further the capacities C4 and C5, which are also situated in the circuit. The neXt stage is then connected to the inductance L9.

In order to ensure a aultless operation of the arrangement shown, it is necessary to neutralize the ampliying devices in known manner. As in this instance very high frequencies are concerned, particular importance must be attached to a good neutralization. In addition the several parts must be shielded towards each other, as such is indicated by dash and dotted lines in the drawing. The shield A1 comprises the ainn plifying device and the device for multiplying the frequency. The next circuit is protected by the shield or screen A2, in order to permit of the circuit for removing any disturbances, consisting of the capacity C3 and the inductance L5, being specially vencased (A3). Special care must be exercised in order to effect the screening or shield A3 for L5 andr C3. The circuit following the circuit for removing any disturbances is surrounded by the shield A4. v

The screening can be eiected, exactly as represented in the illustration, if transmission coils with an interposed shield areused.

In contradistinction to the described arrangement with iron core frequency changers the embodiment shown in Figure 3 oiers special advantages, since the impulse energy required there, must be rather high in order to obtain the saturation of the iron, While in the tube arrangemen represented it is possible to operate on energies, which only amount to one hundredth part of the energy requisite for the iron core frequency changers. Besides, there are Vencountered diiiim culties in the constructional design of the iron core frequency changers, since they are very small. To the amplifying tube R2 is connected v the impulse tube Rz in the anode circuit, which contains the inductance L10. The grid circuit, containing the coupling inductance L11, will receive at -land an extremely high negative grid tension from a battery connected across these points. The source of tension is preferably bridged by means of a capacity C6. In the anode circuit of the tube is situated a circuit tuned to that frequency at a ninefold multiplication, which circuit is formed of the capacity C7 and the inductance L12. The mode of operation oi the tube is shown in Figure 4. On account of the extremely high grid tension, which in a practical inode of execution will amount up to several 100 volts, the working point of the tube or valve is shifted or displaced in such a manner, that only short tension impulses will occur in the grid circuit.

The hatched portion of the curve of the grid tension in said illustration will clearly show the mode of action. To the circuit tuned to the ninth frequency is connected the device for removing any disturbances in the same manner as in the arrangement ill strated in f.'1i-3^ii.re 2. The encasing of the individual parts towards each other is efiected with the multiplication of the frequency also by means of tubes in the same manner, as represented in Figure 2.

In order to give a practical example the following Will serve: Ii the starting energy in the Jrst step is about 100 watt, there will remain available yet after the excitation of the impulses and the sifting or screening about 5 watt only, which are again ampliiied to 1Go watt and supplied to an additional step. To the third step is `connected the main amplifying device V2 which will increase to about 200 watt, while the transniitting apparatus may possess an output of 3 kilowatt.

I claim:

A frequency multiplying arrangement coinn prising a device to which a transmitted primary frequency is supplied characterized in this that said device comprises a pluraiity of stages connected in cascade and each stage including an aniplier, a frequency multiplier requiring a minimum amount of energy for its operation, conn nected to the output circuit of the ampliner and a disturbance remover coupled to the output circuit of the multiplier and suppressing substantially all frequencies except a harmonic oi' the frequency impressed on the input oi the multiplier.

FELIX GERTI-I.`

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