GB303541A - Improvements relating to electrical transformers or couplers - Google Patents

Abstract

303,541. Twort, F. W. Oct. 4, 1927. Transformers.-Radio circuits are coupled together by a transformer with two or more windings so arranged that some or all of the turns or conductors of one winding are shielded by the corresponding conductors of another winding, the field of each shielded conductor having no direct access to adjacent conductors of the first winding nor to any conductor other than the corresponding conductor of the second winding. The conductors of the second winding may enclose those of the first. In a high-frequency transformer, the secondary comprises a copper tube c, Fig. 5, wound helically, in notches in longitudinal ribs b on a cylindrical former a, Fig. 6, and the primary k comprises a fine wire within part of the tube c and separated therefrom by an insulating tube or coating. The lower end of the former a carries evenly spaced contacts detachably engaged by protruding spring contacts g, Fig. 2, on a base e of the same shape as the former a, the circuit wires of the radio set being soldered to tabs h on the contacts g. The lower half c<2> of the secondary c is connected as in Fig. 6 to diametrically opposite contacts OS, ST<2> and the upper half c<1> to similar contacts IS, ST<1>. The contacts IS, OS form the terminals of the secondary and are thus connected to points at the centre of the winding the extreme ends of which are directly connected by joining the contacts g corresponding to the contacts ST<1>, ST<2>. Similarly, the primary winding comprises symmetrically arranged halves at the lower and upper end of the secondary, the extreme ends being joined together at k<1> and the ends nearest the centre of the former a being connected to diametrically opposite contacts IP, OP forming the terminals of the primary. The parts of the secondary not enclcsing the primary need not be hollow. The windings may be shielded by an axially adjustable metal cylinder within the former. In a high-frequency amplifier for short wave lengths, the primary is connected in an aerial or anode circuit, the connected terminals ST<1>, ST<2> are connected through a high resistance to the filament of the next valve, and the terminals of the secondary are connected to the grid and neutralizing condenser. In modifications, a reaction coil may be arranged in the parts of the tube c not occupied by the primary k or as a separate winding. In another modification, more than two concentric conductors are employed, the primary conductor k being hollow to enclose another winding. In other modifications, the primary may comprise a tubular conductor enclosing the secondary or the tubular conductor is replaced by a strip wound around or folded over the other conductor. Specification 288,379, [Class 40 (v), Wireless signalling &c.], is referred to.