Abstract: An edge-guided mode microstrip device having a pair of input ports and a mon output port, with two separate ferrite substrates each having a microstrip conductor electrically connected between a respective input port and the common output port. Both microstrip conductors additionally each have a conductive or inner edge spanned by a resistive film which acts as a resistive load. The other or outside conductive edge of each of the conductors includes an exponentially tapered segment which when a predetermined biasing magnetic field is applied transversely relative to the field of the substrates, causes input microwave energy at the two input ports to travel along the respective exponentially tapered edges and combine at the common output port. Any reflective energy returning from the output port will travel along the inner edges and be absorbed in the resistive load.

Abstract: A power amplifier includes a plurality of generally identical amplifier elements connected in parallel between input and output transmission lines for phase coherent addition of the signal outputs of each amplifier element. Resistive elements are connected across normally phase identical points on the transmission lines. If the amplifier becomes electrically unbalanced, power is absorbed in the resistive elements, thus protecting the amplifier elements.

Abstract: A balance control system for multichannel audio apparatus wherein stereophonic signals are transmitted through plural audio channels of the audio apparatus. The balance control system includes a balance control network connected to the audio channels for selectively adjusting the relative amplitudes of the respective stereophonic signals transmitted therethrough with respect to each other. The balance control system further includes at least one signal delay circuit included in at least one of the audio channels for establishing relative delays among the transmitted stereophonic signals. The delay circuit is controlled simultaneously with the control of the balance control network.

Abstract: This is a seismic digital recording system for use where the seismic amplifiers are placed near the geophone locations and their outputs transmitted by common cable to the recording truck or recorded on magnetic tape at the geophone location. In such a digital recording system, it is impractical to use a high-speed, high gain-ranging amplifier of 15 or 16 bits range. In our design the gain-ranging amplifier is high-speed but employs fewer bits total range. The extra range is made up in a preamplifier which has a variable range of gain, which can be automatically set, but at slower speed. The invention involves a control system which is responsive to the output of an A/D converter which is connected to the output of the gain-ranging amplifier.

Abstract: An output circuit for balanced amplifiers connected to one terminal of each of two loudspeakers with the other terminal of each loudspeaker connected together to the arm of a double-throw switch to make contact either with a terminal connected to the first terminal of one load to short circuit that load while applying signals from the amplifiers differentially to the other load, or to connect the second terminals of each of the loudspeakers to a common signal output terminal of the amplifiers so that each load is connected across a respective amplifier output circuit.

Abstract: A power amplifier device comprised of at least two amplifying circuits, each including an input, at least one voltage amplifier stage, at least one power amplifier stage adapted for signal impedance conversion, and an output, all connected in series, and further including a signal input terminal and a signal output terminal. Plural switch means are provided for selectively interconnecting the voltage amplifier stages and the power amplifier stages of the amplifying circuits for selectively establishing a parallel connected amplifying circuit, individual amplifying circuits and a balanced transformerless connection across the signal output terminals. In the parallel connected amplifying circuit, the plural switch means are operated to connect the amplifying circuit inputs in parallel, the amplifying circuit outputs in parallel and the respective amplifier stages and the respective power amplifier stages of the amplifying circuits in parallel.

Abstract: A broad band directional coupler including a conventional attenuator is disclosed. The coupler permits detection of signals propagating simultaneously in opposite directions on a single-signal path or transmission line. Detection may occur at one or a multiplicity of ports located at arbitrary positions along the line. In the specific embodiments disclosed, the attenuators employed are symmetrical, .pi., O, T, and H attenuator networks. The invention, however, is equally applicable to .pi., O, T or H attenuator networks which are not symmetrical. The specific embodiments shown employing active devices have wide frequency responses which are flat and flat to DC. Where operation down to DC is not required and where a broad band directional coupler comprised entirely of passive elements is desired, a version of the coupler circuit employing transformers is disclosed.