Abstract: An antenna system is disclosed that is suitable for use in the transmission of communication signals from expendable marker buoys. The antenna system is designed such that the antenna is interiorly disposed within the buoy, which eliminates the need for antenna seals and antenna automatic extension mechanisms.The antenna is top loaded to permit the use of a relatively short vertical section. The antenna is attached to a ground plane skirt which is capacitively coupled through a dielectric form for establishing good radio frequency (RF) connection to the water surface within which the antenna system operates. The dielectric medium is provided by the outer housing of the buoy and hence the water surface becomes the effective ground plane for the antenna. In this manner, therefore, the antenna system does not require components to be extended beyond the interior of the buoy housing.

Abstract: The disclosed junction field-effect transistor (FET) has a precisely controlled gate configuration which enables either high power operation or high frequency operation or both. The FET is manufactured by steps including the growing of a first epitaxial layer having a predetermined crystallographic orientation on a substrate to form a drain. Next, a first anisotropic etch of the epitaxial layer provides "U"-shaped grooves with flat bottoms, therein through which a gate is diffused having internal side walls of uniform depth that define the source-to-drain channel. A second epitaxial layer is then grown on the surface of the first epitaxial layer and of the gate to provide a source. A second anisotropic etch exposes a portion of the gate, which also forms an etch stop, to facilitate electrical contact thereto. Current flowing through the channel is controlled in response to an input signal applied between the gate and source which adjusts the thickness of a depletion region extending into the channel.

Abstract: A gain controlled audio amplifier for each channel which includes a differential to single ended converter fed by a differential amplifier, the common emitters of which are coupled to balance and volume control circuitry for controlling the amount of current flowing in the amplifier relative to the other three amplifiers. A pair of diodes are connected in back-to-back relationship between the control electrodes of the differential amplifier and receive a signal from an enhancement circuit which controls the amount of signal being applied to the input of the differential amplifier. The enhancement circuit includes a pair of amplifier sections which are connected together so that the output voltage of one increases as the other decreases and vice versa and the decrease of output voltage in either section occurs substantially more rapidly than the increase of output voltage in the other section.

Abstract: There is disclosed a motor speed control circuit for use in battery-powered tape recorders, tape players and record players in which the motor speed is made independent of power supply voltage swings, temperature and loading. The circuit is comprised of three sections including a discriminator-comparator section, a protection circuit and an output circuit. The discriminator-comparator circuit provides that the control signal to the motor be independent of power supply variations. A tachometer signal of an AC nature is coupled into the discriminator-comparator circuit which generates a pulsed current. The number of current pulses generated over a given time interval corresponds to the frequency of the tachometer signal. These pulses are subtracted from a reference current which difference is integrated, with the integrated current difference indicating the difference in speed of the motor between the desired speed and the actual speed.