Current as of: June, 1999
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24.1  DF  .~> Nonreciprocal gyromagnetic type (e.g., directional phase shifters) {2}
25  DF  .~> Balanced to unbalanced circuits {1}
27  DF  .~> Interlinking long line
28 R  DF  .~> Equalizers {1}
138  DF  .~> Delay lines including a lumped parameter {2}
141  DF  .~> Delay lines including elastic bulk wave propagation means {7}
150  DF  .~> Delay lines including elastic surface wave propagation means {5}
156  DF  .~> Delay lines including long line elements {5}
32  DF  .~> With impedance matching {1}
165  DF  .~> Frequency or time domain filters and delay lines utilizing charge transfer devices
166  DF  .~> Time domain filters
167  DF  .~> Frequency domain filters utilizing only lumped parameters {10}
186  DF  .~> Electromechanical filter {5}
202  DF  .~> Wave filters including long line elements {4}
24 C  DF  .~> Capacity coupling

Unofficial Alpha Subclasses: R C


Classification: 333/24

(under the class definition) (1) Networks including significant reactive structure for effecting the transfer of oscillator energy from one circuit to another circuit and having attenuation and/or delay characteristics over a frequency range for attenuating and/or delaying in a predetermined manner, wave energy passing therethrough, and/or providing an impedance match between the network and at least one of the circuits; (2) smoothing type wave filters having shunt capacitance, or series inductance, or both usually designed to pass direct current and to reduce the effect of any undesired alternating or pulsating current, or to pass direct current and low frequency alternating current or pulsating current and to reduce the effect of any undesired higher frequency alternating or pulsating current, and (3) systems within the class definition including one or more of the networks defined in (1) or (2) above.

(1) Note. The coupling networks under the above definition usually include a shunt impedance common to the input and output circuits.

(2) Note. The systems included are single channel systems having coupling networks, and include for example echo suppression on a single channel where the echo would be due to an impedance mismatch, or the elimination of echo in a single channel system by using a delay line. Such systems are classified in the first indented subclass which provides for the network used in the system. See section I, subsection C, of the Class Definition.

(3) Note. Class 323, Electricity: Power Supply or Regulation Systems, is the miscellaneous class for systems for coupling a single source to a single load circuit using only transformers and/or impedances. Also, see (4) Note below.

(4) Note. Coupling networks using an electronic tube as a part of the network are not included in this or the indented subclass, but are classified in the appropriate class providing for the system. For examples, see the Search Class notes below.

(5) Note. See the Search Class notes below for a reference to the classification lines between coupling networks and antennas combined with such coupling networks.

SEE OR SEARCH THIS CLASS, SUBCLASS: 1+, for plural channel systems involving coupling networks.

17+, for automatically controlled systems involving coupling networks.

81, for attenuators of the resistive type.

245+, for transmission line joints within the class definition which do not modify the characteristics of the wave propagated therethrough or do not effect an impedance match between dissimilar impedance lines or networks.


178, Telegraphy, appropriate subclasses for coupling networks in combination with code signaling systems or apparatus other than telephony. See

64, for such systems for transmitting messages by induced currents utilizing an induction coil or transformer, and for such systems having an induction coil or transformer between sections of the main line.

307, Electrical Transmission or Interconnection Systems, particularly

1+, for miscellaneous superimposed current systems involving coupling networks, and subclasses 11+ and 43+ for miscellaneous plural load or plural supply systems which include coupling networks.

323, Electricity: Power Supply or Regulation Systems. See (3) Note, above. Class 323 provides for the miscellaneous transformer and impedance systems and includes structural combinations of different impedances which are electrically connected together.

323, Electricity: Power Supply or Regulation Systems, for a coupling network using tubes to control the current and/or voltage magnitude and/or for phase control where there is a single input and output and at least a part of the input energy appears in the output circuit. (See the (4) Note above) 327, Miscellaneous Active Electrical Nonlinear Devices,

261+, for a delay system using tubes; subclasses 552+ for a filter using tubes; subclass 231 for a phase shifter using tubes where the input energy is applied to an input electrode (e.g., grid) of the tube to control a local source of energy (e.g., anode supply) connected to the output electrode of the tube (See the (4) Note above)

330, Amplifiers, appropriate subclasses for various types of coupling networks involved in amplifier systems,

116, for an amplifier system with means to couple a balanced line to an unbalanced line. (See the (4) Note above)

331, Oscillators,

74+, for oscillation generators combined with a particular output coupling network.

334, Tuners, for tuners, per se. See also (4) Note above for tuners combined with other systems.

336, Inductor Devices, appropriate subclasses for the structure of transformers and inductances of the passive type.

343, Communications: Radio Wave,

743, for high frequency loop type antennas with feed coupling at spaced points on the loop; subclass 771 for slot type antennas with wave guide coupling; subclasses 814, 816 and 820+ for balanced doublet type antennas with a coupling network, subclasses 850+ for antennas in general with a coupling network or impedance in the leadin; subclass 700, (11) Note, for the classification lines between coupling networks and antennas combined with such coupling networks (see the (5) Note above).

361, Electricity: Electrical Systems and Devices, 600+, for miscellaneous combinations of different impedances which are not in circuit relationship (e.g., a variable condenser combined with a resistance with no electrical connection between them).

379, Telephonic Communications, appropriate subclasses for telephone systems having coupling networks. If the system is limited to use with speech (other than by mere name), such as including a microphone or reproducer (e.g., loudspeaker) the system is classified in Class 381, see

338+, for repeaters utilizing hybrid coil systems.

455, Telecommunications,

91+, for radio transmitters involving coupling networks and subclasses 130+ (particularly subclasses 338+) for radio receivers involving coupling networks.