GB262083A - Improved arrangement for the composition of two variable electric currents of any wave form and frequency - Google Patents

Abstract

262,083. Soc. des Etablissements Ducretet. Nov. 27, 1925, [Convention date]. Thermionic heterodyne receivers; thermicnic modulating systems.-Four-electrode valves are used for the compounding of electric currents, and the resultant or output current is taken from the circuit of the inner grid or from that circuit and the plate circuit jointly. The system is shown in Fig. 7 applied to modulation in wireless transmission, and in Fig. 5 to heterodyne wireless reception. Referring to Fig. 5, the plate circuit and the circuit of the inner grid 3 are coupled by the coils 8, 9 so as to set up oscillations in the tuned circuit 7, 8. The aerial 25 is connected in the circuit of the outer grid 4. The compounded or beat current is taken from a primary coil 10 in the inner grid circuit and from a similar coil 14 in the plate circuit, the two secondary coils 11, 15 being connected in series to produce an additive or differential effect. The two primary coils 10, 14 are shunted by condensers 20, 24. Alternatively the two output coils 11, 15 may excite separate circuits. For radio telephony transmission, the coils 8, 9 are coupled as before to produce oscillations in the circuit 7, 8 and the microphonic modulation is applied to the circuit of the outer grid 4. The modulated oscillations are transferred to the aerial 26 by coupling it to a coil in the tuned grid circuit 7, 8, or by jointly coupling it to the coils connected respectively in the inner grid circuit and the plate circuit. The differential action of the two output currents may be utilized in duplex telephony for eliminating the effect of transmitted currents on the asociated receiver. The elimination of parasitic disturbances is referred to. Specification 246.434 is also referred to.