Abstract: An improved heterojunction bipolar transistor power amplifier circuit providing an efficient and linear amplifier comprising: a first heterojunction bipolar transistor (HBT) having a base emitter voltage; a power supply; a power supply resistor connected to the power supply causing DC current to flow through the first HBT which develops a resultant voltage equal to the base emitter voltage of the first HBT; at least two manifold base resistors; at least two output HBTs, each of which receive the resultant voltage through its corresponding manifold base resistor; a RF signal input; at least two segmented capacitors, each coupled in parallel to receive the RF signal input and to the input of each corresponding output HBT; the segmented capacitors having a common input connected to the RF signal input and having individual outputs that are DC isolated from each other and which are connected to each output HBT; a RF output signal obtained from the parallel connection of the output HBTs; and provided that each HBT

Abstract: An improved heterojunction bipolar transistor power amplifier circuit providing an efficient and linear amplifier comprising: a first heterojunction bipolar transistor (HBT) having a base emitter voltage; a power supply; a power supply resistor connected to the power supply causing DC current to flow through the first HBT which develops a resultant voltage equal to the base emitter voltage of the first HBT; at least two manifold base resistors; at least two output HBTs, each of which receive the resultant voltage through its corresponding manifold base resistor; a RF signal input; at least two segmented capacitors, each coupled in parallel to receive the RF signal input and to the input of each corresponding output HBT; the segmented capacitors having a common input connected to the RF signal input and having individual outputs that are DC isolated from each other and which are connected to each output HBT; a RF output signal obtained from the parallel connection of the output HBTs; and provided that each HBT

Abstract: High accuracy is achieved by employing, in conventional DAC architectures, very accurate current sources. To create these high-accuracy current sources, the outputs of several smaller, less accurate, nominally equal current sources are summed. A procedure is taught for selecting the number of current sources to achieve an arbitrary degree of accuracy with a desired level of confidence. Assuming the current sources are taken from a population whose output currents deviate from a design value according to a normal distribution, the minimum number of constituent current sources, n, required to provide an accurate total current is given by the formula n=(Z.sigma./E).sup.2, where Z is a number which corresponds to the probability that the output will fall within an error band E (i.e., a predetermined accuracy level) with a predetermined level of confidence, .sigma. is the standard deviation of the population.

Abstract: A rear pivot mount for the rear axle assembly of heavy vehicles is disclosed and includes a housing, a spindle member attached to the rear axle assembly and disposed within the housing, a sleeve member circumferentially disposed about the spindle member and attached to the housing of the rear pivot mount. The sleeve member is spaced radially from the spindle member to form a first and a second cavity therebetween. A bearing member is positioned in each cavity to allow the spindle member to move or pivot with respect to the housing of the rear pivot mount. A retaining member is attached to the spindle member and is in contact with a bearing member to maintain the bearing members in position. A cover member is attached to the housing to provide a sealed cavity around the spindle member, sleeve member and bearing members.

Abstract: The horizontally rotatable upper section of a mobile crane is swingable in opposite directions by a speed reducer which is driven by a selectively operable reversible variable speed hydraulic motor. A fail-safe spring-loaded hydraulic brake located on the speed reducer operates, when needed, to slow or stop or prevent rotation of the upper section. A hydraulic control system which supplies pressurized hydraulic fluid to operate the motor and the brake includes a pedal-operated master brake cylinder for selectively applying the brake when the motor is in operation. The brake comprises a cylinder housing, an outer brake piston axially movable through a hole in the housing, and an inner brake piston axially movable in a bore in the outer brake piston. Each piston has an extended position and a retracted position.

Abstract: A drive axle assembly including a housing structure having a fixed spindle, a nonrotatable spacer ring disposed about the spindle and a drive hub rotatably mounted on the spindle by bearings, one of which abuts the spacer ring. The spacer ring has a brake apply fluid inlet to an interior passage which opens to a first sealed annular cavity between the spacer ring and the hub. The exterior of the spacer ring defines in conjunction with the drive hub a second low pressure cavity therebetween enclosed by a radial face seal having a rotating portion disposed in the hub and a nonrotating portion disposed in the spacer ring. Lubricating and cooling fluid is pumped through the second cavity to cool the face seal and continues through passages in the drive hub to provide a nearly continuous flow to the drive and brake components in the hub assembly.