US PATENT SUBCLASS 455 / 291
.~.~.~ Using active device (e.g., as preamplifier or reactance)

Current as of: June, 1999
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455 /   HD   TELECOMMUNICATIONS

130  DF  RECEIVER OR ANALOG MODULATED SIGNAL FREQUENCY CONVERTER {24}
269  DF  .~ With wave collector (e.g., antenna) {4}
280  DF  .~.~ With coupling to a stage of the receiver {7}
291.~.~.~ Using active device (e.g., as preamplifier or reactance)

DEFINITION

Classification: 455/291

Using active device (e.g., as preamplifier or reactance):

(under subclass 280) Subject matter wherein the coupling means includes an electron tube device, solid state device, transistor, diode, or other active device whereby the magnitude of the high frequency signal applied to the receiver may be maintained constant or other wise influenced.

(1) Note. The coupling means may act merely as a resistive impedance in the coupling circuit, or may act as an amplifier.

SEE OR SEARCH CLASS

327, Miscellaneous Active Electrical Nonlinear Devices,

Circuits, and Systems, for miscellaneous nonlinear circuits utilizing active devices.

330, Amplifiers, appropriate subclasses for amplifiers.