GB157405A - Improvements in wireless telephone transmitters - Google Patents

Abstract

157,405. Ges. f³r Drahtlose Telegraphie. Dec. 11, 1919, [Convention date]. Void [Published under Sect, 91 of the Act]. Thermionic modulating systems; thermionic oscillation generators.-In a wireless telephone valve transmitter, the degree of the grid coupling or of the anode coupling or of both couplings is influenced by a modulating valve controlled by the micropnone currents so that the anode current varies in rhythm with the speech oscillations. In the arrangement shown in Fig. 1, the anode and grid couplings of the main generator valve 4 consist of adjustable inductances 6, 8, the antenna consisting of the oscillating circuit 9, 10, 11, 12 and the direct current supply being connected at 1, 2. The modulating valve 14 influenced by the microphone 13 is connected in parallel with the grid coupling coil, and the contact 8 so adjusted that the anode current follows exactly the rhythm of the resistance variations of the valve 14. The valve influenced by the microphone may alternatively be arranged in parallel with the anode coupling coil of the valve 4 or these two arrangements may be combined as shown in Fig. 4 with the two coupling coils of the microphone circuit 20 arranged either in series or in opposition, preferably the latter. In Fig. 5 the modulating valve 21 is shown arranged between the anode and grid of the main valve 4. The coupling elements, Fig. 6, are dissimilar and comprise an inductance and a capacity. In a further arrangement, similar to that shown in Fig. 1, the oscillatory circuit may be directly connected to the point 7, the coupling between the coils 6 and 8 being then purely inductive.