GB444608A - Improvements in high frequency coupling coils - Google Patents

Abstract

444,608. High-frequency transformers. HAZELTINE CORPORATION, 15, Exchange Place, Jersey City, New Jersey, U.S.A.- (Assignees of Johnson, J. K.; 2600, North Kedzie Avenue, Chicago, U.S.A.) Jan. 23, 1935, No. 2289. Convention date, Feb. 27, 1934. [Class 38 (ii)] [See also Groups XXXVI and XL] A high-frequency coupling system adapted to operate over a number of frequency bands comprises a number of secondary coils connected in series, means for short-circuiting one or more of the coils and a short-circuited winding for preventing interaction arising from local resonance in the short-circuited coil or coils. In the form shown in Fig. 2, the H.F. transformer comprises a primary winding 21 and a secondary winding in three sections 22, 23, 24 so that by switching three wave bands can be covered, the two parts 22, 23 being separated by a short-circuited turn 33 which reduces the coupling between these sections so that when operating on the short wave band with the sections 23, 24 shorted less loss results. The application of such transformers in a superheterodyne receiver is shown at 13, 15 and 17 in Fig. 1. The tapping switches 26, 39 and 51 and condensers 25, 46 and 65 are separately ganged for simultaneous control. The transformer 15 has a dead end coil 44 for capacity coupling and a primary in two sections 34, 35, the section 35 being shorted during short wave operation and bridged by a condenser 58 for long wave operation by means of a switch 55. The local oscillator transformer 17 is provided with alignment condensers 60, 61 controlled by a switch 56. Switches 55, 56 are gauged to tapping switches 26, 39 and 51.