Improvements in or relating to multi-range high frequency systems

摘要

562,512. Transformers. JOHNSON LABORATORIES, Inc. Dec. 30, 1942, No.' 18538. Convention date, Jan. 5, 1942. [Class 38 (ii)] [Also in Group XL] A multi-range high frequency tunable resonant circuit having an inductive winding coupled thereto and with the windings concentrically arranged is associated with a switch so that on the lower wave range the larger inductance L1 is included in the tuned circuit and the other L2 comprises a coupling coil, while on the higher wave range the inductances are connected in parallel while a tapping T1 on the inductance L2 provides the inductive coupling. Fig. 3 shows the arrangement of windings and the ferro-magnetic core F. Fig. 1 shows the application to an oscillator using separate condensers C1, C2 for the two wave-ranges. In a modification, Figs. 4 and 5 (not shown), the inductive winding is included in an aerial circuit and the resonant circuit forms an input coupling. Alternatively, the circuit may be used as an interstage coupling in which the resonant circuit forms the secondary winding and the inductive coupling the primary winding.