US2270771A - High frequency oscillation generator - Google Patents

Description

Jan. 20, 1942. w. scHoNr-'ELD HIGH FREQUENCY OSCILLATION GENERATOR Filed Oct. 51, 1940 TUBE EYE;

ATTORNEY Patented Jan. 20, 1942 HIGH FREQUENY oscmLA'rIoN GENEnA'roR Wilhelm Schonfeld, Berlin, Germany, assignor to Telefunken Gesellschaft fr Drahtlose Telegraphie m. b. H., Berlin, Zehlendorf, Osteweg, Germany, a corporation of Germany `Application October 3.1, 1940, Serial No. 363,617 In Germany September 18, 1939 (ci. 25o- 17) 8 claims.

-This invention is concerned with a generator adapted to the production of high frequency oscillations, especially of the ultra short wave type.

`For generators of this kind it is often demanded that upon failure of a transmitter a spare trans` mitter should at once be connected automatically to the same antenna. VTo this end it has been suggested in the art to include a switch in the antenna lead which will switch either of the two transmitters with the antenna. The necessity for insuring safe contact by such a switch makes severe demands regarding its construction.

There may arise joints in the antenna feed whichv would entail losses of high frequency energy.

These losses should be minimized as much as possible because of the comparatively low powers which lare available in ultra short wave transmltters.

It hasfurthermore been suggested to provide two complete magnetron transmitters which work upon a common and joint energy line in coupling relation with the consumer or load, switches being provided designed to automatically render operative the spare transmitter whenever the transmitter fails. Also, this scheme involves difiiculties connected with contacts because they are. liable to lead to losses of energy. Another factor is that both transmitters must comprise tuning means which `must be variable under synchronized conditions in order that when one transmitter fails, the other one may be ready to operate on the same Wave.

r The disadvantages of the circuit organizations disclosed in the earlier art may be avoided by providing only two tubes being in permanent coupling relation with a joint and common tuningsystem (say, a Lecher-wire system or pot or trap circuit), rather than to make arrangements so as to have two independent transmitters work upon a joint consumer or load as heretofore suggested. The coupling of the standby tube or spare tube is so that the impedance of the spare tube and the coupling lines are of a value such that the feed of energy to the tuning system will not be affected. What should be aimed at in this connection is that for capacitive coupling the impedance should be as high as feasible, while for inductive coupling it should be as low as feasible, for only then will a maximum amount of energy be coupled into the tuning system. The dimensions of the circuit elements should be so chosen that for inductive coupling of the tuning system at the coupling point the unheated standby tube represents with its coupling leads a short-circuit and for capacitive coupling a no-load.

The appended drawing illustrates, in Figs. 1 and 2, two exemplified embodiments of the object of the invention. In both gures similar parts are denoted by the same reference letters.

In the circuit organization of Fig. 1, the tuning system A is in conductive coupling relation with the Lecher-wire lines L1 and L2, and this corresponds to a capacitive coupling. In this instance, if tube R1 is the transmitter tube, tube Rz with its lines should constitute a no-load at the coupling points, lest the entrance of energy into the tuning system A be made more difllcult or limpeded (couplingzzero). This is done by mak` ing the standby tube and its connections appear as a very high impedance as seen from the junction points M, N. One way of doing this is to make the end of the standby circuit (R2 in this case) away from M, N an open circuit. The same thing applies to the case where the tube Rz is the transmitter and tube R1 the standby tube.

The heating relay Hr switches the heating potential from the transmitter tube to the standby tube. This relay preferably is controlled automatically by apparatus REC as a function of the transmitter energy. Thus, in case of failure of the transmitter tube the standby tube is immediately connected. Apparatus REC may includ-e any suitable wave energy responsive circuit coupled in suitable manner to the output of the system.

Attention at this time is invited to Fred H. Kroger United States Patent No. 2,017,126, which illustrates by way of example how means may be provided at a radio station which is responsive to the failure of radiation for automatically changing over from one set of equipment to a spare set. 1

Fig. 2 shows an inductive coupling of the tuning system A. This system is coupled through coupling loops K1 and K2, respectively, with the Lecher wire line L1 and Lz. In this case the standby tube with its lines should constitute a short circuit at the coupling point. In view of the inductive coupling between K1, K2 and the Lecher wire systems, the spare tube circuit is, in effect, in series relation to the output of the working tube, and by making the standby circuit a short circuit the output of the working tube goes directly to th-e tuned circuit A without any added impedance. The end of the standby circuit (R2 in this case) should appear as an open circuit with the dimensions illustrated.

This mode of connecting the standby tube increases the operating safety of transmitters comprising sensitive tubes to twice what it is ordinarily, while yet the circuit means required are little elaborate. Mechanical switches in the radio frequency part and the energy losses associated therewith are avoided. Moreover, as already pointed out only one tuning system is provided, and this facilitates the switching in of the standby tube.

What is claimed is:

1. In combination, a first vacuum tube oscillation generator, a second vacuum tube oscillation generator of the same frequency, a single utilization circuit permanently coupled to the outputs of said two generators, an energizing circuit adapted to be operatively connected to only one of said generators at a time, and means responsive to failure of one of said generators for automatically connecting said energizing circuit to the spare oscillation generator, the connections from both of said generators to said utilization circuit being so. arranged and having such length relative, to the Wavelength as determinedA by the character of said coupling that the spare generator does not affect the. constants of said utilization circuit.

2. ApparatusA inA accordance with claim 1, characterized in thisthat the length of the connections from the generators to the common junction pointsto the utilization circuitare each one-half the length of the communication wave, the spare generator presenting a very high impedance to the utilization circuit as seen from said junction points.

3. In combination, a first vacuum tube oscillation generator, a second vacuum tube oscillation generator of the same frequency as said first generator, a single utilization circuit permanently inductively coupled to the outputs of said two generators, any energizing circuit adapted to be operatively connected to only one of said generators at a time, and means responsive to failure of one of saidgenerators for automatically connecting said energizing circuit to the spare oscillationgenerator, the effective lengths of the coupling connections from the generators to the common junction points to the utilization circuit being each three-quarters of the length of the communication Wave, the spare generator presenting a very low impedance to the utilization` circuit as seen frornsaid junctionpoints.

4. In combination, a first source of ultra high frequency waves, a second source of ultra high frequency Waves of the same frequency, a transmission line, a utilization circuit coupled to said line, an energizing circuit for effectively energizing only one of said sources at a time, and separate means permanently coupling each of said sources to the same location on said line, said separate means being so arranged and having such effective lengths relative to the length of the communication wave corresponding to said same frequency that when one of said sources is energized the other does not affect the constants of said transmission line.

5. In combination, two electron discharge device sources of radio frequency oscillations of the same frequency, a transmission line, a utilization circuit coupled to said line, a switch for energizing the laments of only one of said electron discharge devices at a time, and separate means permanently coupling each of said sources to the same location onl said line, said separate means including connections of substantially equal predetermined length relative to the length of the communication wave corresponding to said same frequency and being so arranged that when the lament of one of said sources is energized the other source does not affect the constants of said transmission line.

6. In combination, two electron discharge device sourcesofradio frequency oscillations of thesame frequency, a transmission line, a utilization circuit coupled to said line, a switch for energizing the laments of only one of said electron` discharge devices at ak time, separate connections eX- tending` from said sources to said line, and means permanently coupling inductively said line to each of said sources at substantially the same location onv said line, said connections being of substantially equal predetermined length relative to the length of the Wave produced by said sourcesand being soiarranged that when the lamentof one of said sources is energized the other source and its associated connection presents a short circuit at said location on said line.

'7. A system in accordance with claim 4, including means.- responsive to failure of oneof said sources to function satisfactorily for automatically connecting said energizing circuit to the spare source. i

8. In combination, a first vacuum tube oscillation generator, a second vacuum tube oscillation generator of thesame frequency as said rst gener-ator, a` single utilization circuit permanently conductivelyr coupled to the outputs of said two generators, an energizing circuit adapted to be operatively connected to only one ofV said generators at a time, and means responsive to failure of one of said generators for automatically connecting saidenergizing circuit to the spare oscillation generatontheeffective lengths of the cou.

pling connections from the generators to the common junction points to the utilization circuit being each one-half ofthe length of the wave,

produced by said oscillation,V generators, the spare generator presenting a very high impedance to the utilization circuit as seen from said junction points.

WILHELM SCHONFELD.

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