US1778730A - High-frequency signaling system - Google Patents

Description

Filed. Feb. 24 1925 u-H A v3 VENTOR LH LM R GE TORNEY Patented Oct. 21, 1930 UNITED s'r'rss PA ENT OFFICE WILHELM RUN'GE, OFBERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT FUR DRAHT- LOSE TELEGBAPHIE M. B. H. T-IALLESCHES, 0F BERLIN, GERMANY nren-rnnounncy sreivntrne SYSTEM Application filed February 24, 1925,'Seria1 No. 11,023, and. in Germany March 22, 1924.

In order to obtain receiving arrangements of as high a sensitivity as feasible, it is usual to use regeneratively coupled electron tubes for the purpose of reducing damping. The most sensitive reception is realized, if the re generative coupling is adjusted so close that the electron tube operates just a slight distance from the point where oscillations set in. It is therefore desirable to work with variable regenerative coupling. Then it is possible to adjust the regenerative coupling to the requisite tuning, depending upon the particular type of tube used, as well as other operating conditions such as heating, grid-, and anode-potentials, in order to insure optimum conditions under any particular circumstances.

For practical reasons of a technical nature, however, it is necessaryto prevent self-excitation in the receiver since generation of oscillations and radiation by the antenna cause disturbances in neighboring receivers.

The present invention indicates a method adapted to prevent disturbances by the generation of oscillations in the receiving system while at the same time it uses a regenerative coupling scheme which is so strong that the reduction of damping is suflicient to realize optimum signal strength. The idea underlying the invention consists in that, by the use of special oscillation circuits, it is rendered feasible for the electron tubes to start oscillating in the presence of certain regenerative coupling, but at a wavelength that is substantially different from the incoming or reception wavelength.

This fundamental idea of the invention, that is, the generation of a different wave length from the reception wave length, up a predetermined coupling limit in regene tion being exceeded, can be carried into practice in various ways. The different possibilities of connection, according to the invention, depend, inter alia, also upon the purpose in view. equipment adapted to picking up broadcasting stations, there is often provided regenerative coupling positively dependent upon and connected with the tuning means, the regenerative coupling being so chosen that In the customer 7 receiving adequate reduction in damping is attained,

while radiation by the antenna is prevented.

However, the theory of this arrangement is predicated upon the assumption that the oscillating power of all tubes which may be used is the same. In thorium and oxide tubes characterized by low temperature heating it has been found that their oscillating power grows vth increasing heating. It can thus be seen at nothing is gained by providing ing in the change or variation of oscillation power with the heating, no matter what type of tube is dealt with, the following arrangement can be utilized which is based upon the present invention.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended'clahn.

My invention itself, however, both as to its organization and method of operation will best be understood by reference to the follow ing description taken in connection with the accompanying drawing, in which:

I igure 1 illustrates diagrammatically a preferred embodiment of my invention;

"Figure 2 is similar to Figure 1 esicept that simplified tuning means are provided;

Figure 3 illustratesoiagrammatically another embodiment of my invention in which the regeneration is adapted to be varied; and,

Figure 4 illustrates diagrammatically the invention in another'form.

Referring to the drawing, Fig. 1, the waves coining in from the antenna circuit A aresupplied thru coupling coils 10 and 11 to the oscillation circuit B tuned to the incoming frequency by variable condenser 12 and are then impressed upon the tube 4 by way of the grid condenser 3. In the grid circuit there is connected a second oscillation circuit C which consists of inductance 13 and condenser ll and which is tuned to a wave differing from the receiving wave, say, to a shorter wave length. By constant regenerative coupling by means of the coil 6 which is inserted in the anode circuit of the electron tube 4 and inductance 13, this circuit is undamped. The plate circuit of tube 4 is back-coupled to the oscillation circuit B by coils 2 and 11. This regenerative coupling can be controlled, for the case here given by way of example, in a joint and positive manner with the tuning of circuit B.

The constant regenerative coupling is then so adjusted that, when the ability of the tube to oscillate is exceeded, the wave length to which circuit C is tuned is generated while the controlled regenerative coupling of the receiving circuit is so adjusted that, in order to start oscillations of the frequency to which circuit B is tuned, a somewhat greater capability to oscillate is required. As this capability to oscillate increases in the tube, as will be seen, the short wave length will always be generated first. The receiving or incoming wave will never come into action. Since the antenna is coupled with the receiving circuit B and not with the circuit C tuned to the short wave length, it follows that the shortwave oscillations will be radiated by the aerial in but a feeble degree.

Tests made on dili'erent arrangements have shown that the connection scheme is entirely safe to operate. If the auxiliary regenerative coupling is suitably adjusted, practically the same sound intensity is obtainable with this apparatus as with an equipment of the usual regenerative coupling kind. To be sure, optimum adjustment is insured only for a certain frequency, if the regenerative coupling and the tuning of the auxiliary circuit shall remain unchanged. If the equipment is to have the same sensitivity for different frequencies, a recommendable plan is to make the regenerative coupling or the tuningof the auxi iary circuit C variable so that the limit of oscillation of the auxiliary oscillation can be shifted. A scheme in which the auxiliary circuit tuned is shown in Figure 2 wherein condenser 14 is made variable. The circuit of Figure 3 covers the case where the regenerative coupling is made variable. This is accomplished by means of varying the coupling between the coils 6 and 13. In order to realize simplicity in the working of the equipment, tne change in regenerative coupling or the tuning of the auxiliary circuit 0 could be accomplished jointly and positively with the adjustment of the receiving tuning of circuit B as shown in Figs. 4 and 3, respectively.

The connection, as shown in Figure 1, can, of course, be modified in various ways; for

instance, it would be just as readily possible to insert the auxiliary oscillation circuit in the anode circuit instead of in the grid circuit, and to establish regenerative coupling relations with the grid circuit as show in Fig. 4.

Having described several ways of practising my invention, I am entitled to all modifications thereof as fall fairly within the scope of the following claim In a signal receiving arrangement, an energy absorption circuit, a space discharge device circuit coupled thereto, said space discharge circuit having regeneratively coupled input and output circuits, an undamped auxiliary circuit comprising a parallel resonance circuit in said input circuit tuned to a frequency substantially greater than the reception frequency and means for coupling said parallel resonance circuit to said output circuit so that oscillations of said greater frequency will be generated should said space discharge device be thrown into an oscillatory state.

VILHELM RUNGE.

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