GB405944A - Improvements in receiving apparatus for short waves, applicable to ordinary wirelessreceivers - Google Patents

Abstract

405,944. Valve circuits for wireless reception. GROSPAS, P. J., 701, Boulevard Emile Zola, Casablanca, Morocco. May 12, 1932, No. 13699. Void [Abridged as open to inspection under Sect. 91 of the Acts, May 16, 1932]. [Class 40 (v).] A het rodyne receiver employs local oscillations of a fixed frequency, the second detector having a tunable input circuit. Fig. 1 shows the circuit arrangement of an adapter comprising a high-frequency amplifier 2 and triode oscillator 1, the output from which is passed to the terminals of an ordinary radio receiver 6. The inductance 21 in the oscillator plate circuit is coupled to the oscillatory circuit 17, 18 19, 22, which is resonant at either of two frequencies according to the position of the switch 20. By means of switch 24, the adapter is disconnected from the receiver and the aerial circuit is then connected to the latter. The valves are indirectly heated from transformer 25. For each oscillator frequency, determined by switch 20, two wavebands can be received to give beat frequencies lying within the tuning range of the detector circuit of the receiver, in addition to the band available when the aerial is directly connected to the receiver. In a modification, two stages of frequency changing are employed in order further to increase the number of receivable bands (Fig. 3, not shown).