(under the class definition) Subject matter wherein a variable tuned circuit or circuits consists of at least two or more windings which are so constructed or located that the
windings are mutually coupled together by the magnetic field or the electric and magnetic fields created by and existing between the windings, with means being present in the circuit or circuits to vary the electrical and/or magnetic coupling existing between the windings so as to cause or effect a change in the mean resonant frequency and thus vary the tuning of the circuit or circuits.
(1) Note. The two or more mutual inductance coupled windings may be in effect two coils connected in series or a single winding folded upon itself as, for example, a variometer.
SEE OR SEARCH THIS CLASS, SUBCLASS:
59+, for tuned transformer substitution circuits.
65+, for tuners in which both the inductor and capacitor are variable.
71+, for tuners which are tuned by a variable inductor. SEE OR SEARCH CLASS
323, Electricity: Power Supply or Regulation Systems,
247, 301, 305, 328, and 355 for transformer systems.
330, Amplifiers,
154, 165+, 188+, and 195+ for amplifiers having transformer coupling.
333, Wave Transmission Lines and Networks,
167+, for coupling networks of the wave filter type which are adapted to pass or reject only a single frequency or band of frequencies particularly indented subclasses 177+ for transformer coupled filters.
336, Inductor Devices, appropriate subclass for transformers which are not designed to be frequency responsive.
343, Communications: Radio Wave Antennas,
850+, for antennae with coupling network or impedance in the lead-in.
361, Electricity: Electrical Systems and Devices
268+, for transformers or inductors combined with a switch, condenser or lock. 379, Telephonic Communications,
443, for induction coils combined with the structure of telephone instruments.
