HF band pass filter for television tuning - has two sections using two parallel coil pairs with magnetic coupling and smoothing

摘要

The high-frequency band pass filter which operates in the UHF range has magnetic coupling and smoothing facility for each of two band pass filter circuits by changing the inductance. It is used in television circuit tuning etc. The inductance of each band pass filter circuit consists of two parallel coils (L1-3, L2-4). One coil of each pair is used for trimming, whereas the other coil of each pair is magnetically coupled to its counterpart. The magnetic coupling is adjustable. When using printed circuits the earthing conductor of each of the coupled coils is separate.