GB430408A - Improvements in and relating to combined wireless transmitters and receivers - Google Patents

Abstract

430,408. Wireless signalling. HERMES, L.W., 444, Ewell Road, Surbiton, and HERMES, L., Meadow View, Dickerage Road, Coombe Lane, Kingston Hill, both in Surrey. March 23, 1935, No. 9128. [Class 40 (v)] The first valve 7 of a combined wireless transmitter and receiver for use on short waves is coupled to the aerial system 1 ... 3 by an oscillatory circuit comprising two coils 4, 5 connected by a condenser 6 and shunted by a tuning condenser 8 the circuit being connected between the grid and anode of valve 7. When used as a transmitter the right-hand contacts of the change-over switch 9 are connected to the centre contacts to connect the anode of valve 7, which acts as the carrier frequency oscillator, through contacts 10, 16 to the anode of the second valve 20, the transmitter grid-leak 26 is connected to earth from the grid of the oscillator through contacts 11, 17 and the modulation transformer 27, fed from microphone 19, is connected through contacts 12, 18 in the grid circuit of valve 20. With these connections the valve 20 acts as a modulating valve the telephones 23, which may be shunted by the inductance 24, acting as a monitoring means and modulating choke. When functioning as a receiver the valve 7 acts as a super-regenerative detector by the substitution of a suitable grid leak 25 through contacts 14, 11 of switch 9, the anode being connected to the high tension source through contacts 13, 10 variable resistance 36, and the low frequency coupling transformer, while the secondary of the latter is connected in the grid circuit of valve 20, which acts as a low frequency amplifier, through contacts 15, 12. As a battery economizer, a dry rectifier 21 shunted by a resistance 22 rectifies a part of the output of valve 20 fed thereto through condenser 35 the D.C. output voltage being used as grid bias for the valve 20 in opposition to a steady large negative bias. Aerials. The aerial of Fig. 1 is constituted by two quarter wavelength conductors 1, 2 joined by a coupling coil 3. To render this system less directional two further quarter wavelength conductors 39, 40, Fig. 2, arranged at right angles to the conductors 1, 2, may be connected to the coil 3. For use on aircraft the conductors 1, 2 may be supported from or arranged in the trailing edge of a wing and the conductors 39, 40, if provided may be accommodated in or on the fuselage or they may project upward or downward.