Abstract: A microwave oven having a door with a peripheral microwave seal structure which is fabricated from one or more die formed aluminum parts and solid dielectric inserts to form a resonant transmission line structure with peripheral oven wall portions, with transmission of microwave energy in the seal around the periphery of the door prevented by impedance discontinuities, and leakage of microwave energy through the seal is prevented by impedance mismatch or resonant choke action of the seal structure, and the size of a notch in a solid dielectric insert in a quarter wavelength shorted branch line of the seal is selected for different production runs of the oven to compensate for dimensional changes in different die stamped metal parts or assembled door structures due to assembly jig changes, stamping die wear or assembly procedures.

Abstract: A heat exchange system is provided having first and second heat exchangers connected to one another. A burner supplies products of combustion to the first heat exchanger. Fluid heated in the first heat exchanger is pumped to the second heat exchanger. A blower forces air over the second heat exchanger to heat the air. An electric heater is provided in heat exchange relationship with the first heat exchanger. The electric heater maintains the temperature of the fluid in the first heat exchanger above the effective dew point of the flue gas in the heat exchanger.

Abstract: A method and apparatus for fracturing and/or heating subsurface formations wherein an alternating current electric field is produced in the frequency range between 100 kilohertz and 100 meghertz between electrodes spaced apart in the formation and a radio frequency generator supplying a voltage between said lines with suitable loading structures tuned to the frequency of the generator to resonate the electrodes as a parallel wire transmission line which is terminated in an open circuit and produces a standing wave having a voltage node at the end of the line.

Abstract: Magnetographic printing apparatus having scan magnetization of the recording surface. A bubble plate is provided adjacent the recording surface upon which bubble magnetic domains are propagated in a direction perpendicular to the direction of movement of the recording medium. A row of electromagnetic recording heads on the opposite side of the recording medium from the bubble plate are energized to produce a magnetic field which, when added to the magnetic field of the bubbles, is sufficiently high to cause magnetization of selected portions of the recording medium. In a second embodiment, a belt having magnetically permeable vanes mounted thereon is positioned on the side of the recording medium opposite the electromagnets. The vanes concentrate the magnetic field from the electromagnets to a sufficiently high value to magnetize the recording medium.

Abstract: Surface acoustic wave devices are disclosed which have enhanced reflectivity gratings with conductive stripes between grooves in the substrate or conductive stripes within the grooves. For lithium niobate substrates, aluminum stripes coupled together and positioned between grooves or unconnected and positioned within the grooves are preferred. For quartz substrates, gold stripes within the grooves are used. Methods for fabricating such structures are also disclosed.

Abstract: A platinum film resistor device and method for making the same. A layer of quartz, deposited upon an insulative substrate preferably silicon, is sputter etched at high power levels to produce etch pits in the surface thereof. A layer of platinum is then deposited over the quartz layer by first sputtering platinum at high power for a relatively short period of time and then completing the layer by continuing to sputter deposit platinum at a lower power. A second layer of quartz is deposited over the layer of platinum and the second layer of quartz masked and chemically etched away in the regions where portions of the platinum layer are to be removed. The exposed platinum and a portion of the second quartz layer are then sputter etched away leaving the platinum in a predetermined configuration. The platinum is then annealed, the second quartz layer removed above the lead bonding pads, and external leads attached. The device is particularly useful in temperature measuring application.

Abstract: A variable range marker device for use with a PPI radar with digitized video displayed in non-real time. The position of the range marker is initially operator determined by rotation of a knob mechanically linked to an optically encoded disc. Optical sensors produce a digital output indicative of the disc rotation angle and range mark position as a distance from the center of the radar display screen. A counter is preset with the digital ouput at the start of each sweep and decremented once each range cell until a count of zero is reached at which time an unblanking pulse is produced. A numeric display of range is produced by dividing the number of range cells to the range mark by the range setting, scaling according to chosen units of measure, and displaying the result with a LED display, the computations being performed by a processor controlled by a permanently programmed memory. The range mark stays on target as the range scale is changed.

Abstract: A microwave oven control circuit in which the filament of a magnetron supplying microwave energy to the oven is heated to its electron emitting temperature around 1500.degree. C where it emits red spectrum radiation which is sensed by a photoconductive element through the magnetron microwave output structure to produce a control signal actuating the magnetron high voltage supply.

Abstract: A compact heating and cooling system in which air ducts are connected to a heat exchanger system through which a coolant fluid from a condensing unit or a heating fluid from a compact water heater is selectively directed by a control circuit so that the system may be mounted outside a building to be heated and/or cooled.

Abstract: A position and force measuring system for determining the coordinates and force applied to a point on a rigid plate or surface fixed to a rigid foundation by means of a flexible support mechanism and at least three spaced apart sensors. The sensors each deliver an output signal which is proportional to the applied force and the coordinates of the force. The output signals are fed into a processor which computes the force and the coordinates at which the force is applied.

Abstract: A surface acoustic wave device having substantially all of the surface wave energy produced at an input transducer coupled to the output utilization means. Plural reflecting means upon the surface of a piezoelectric substrate reflect surface waves produced by the input transducer in plural directions. The passband characteristics of the device are determined by the interaction of the transfer properties of each of the reflecters as well as those of the input and output transducers. Devices are described having extremely low insertion loss and wide bandwidth with low sidelobes and steep passband skirts.

Abstract: A microwave magnetron having an anode assembly formed of a plurality of vanes contacting an anode cylinder and extending inwardly toward a central region containing an electron source in which the anode vanes have notches adjacent the anode cylinder into which retaining rings have been deformed to maintain the vanes in a spaced peripheral location in firm metallic contact with the anode cylinder and with the assembly brazed together by heating the assembly with a plurality of straps contacting alternate vanes adjacent their inner ends to form a unitary electrically conductive anode resonator.

Abstract: A four frequency laser gyroscope system having parallel processing of path length control and detection signals. Two output signal beams each containing components of two of the four waves circulating in the laser cavity are shone upon separate detector diodes. The output signals from the diodes contain both high and low frequency components which are separated in a crossover circuit. The low frequency component is processed to control the optical path length while the high frequency component is processed to produce a digital signal representing the amount of rotation of the laser gyroscope cavity.

Abstract: An X-ray generator comprising a shielded housing having insulatingly mounted therein an X-ray tube provided with a predetermined focal spot area on a sloped target surface which is radially aligned with an X-ray transmissive window in the housing, the window having a preferred configuration for reducing preferential absorption of X-rays in a divergent beam emanating from the focal spot area of the target.

Abstract: An air classifier system for separating mixed materials and comprising the combination of a horizontal drum or tunnel having a feed screw therein at one end of which mixed materials are deposited for movement toward the discharge end of the drum, and means for directing a flow of air through the drum at relatively high velocity for entraining and removing light materials from the drum while permitting heavy materials to be independently moved out of the drum by the screw.

Abstract: A radar system with improved display brightness in high ambient lighting conditions and with simplified deflection and video amplifiers. The incoming radar return signals are digitized and stored in shift registers with the timing to write the data into the shift registers dependent upon the radar range setting. After the digitized radar return signals have been read into the shift registers, they are read out to the display in a constant time period independent of the range setting. The radar system may be used at closer ranges than was previously possible.

Abstract: A microwave oven system in which a magnetron supplies microwave energy to a microwave oven through an isolator structure comprising a three-port circulator having a microwave energy absorbing load coupled to the third port, with the temperature of said load being sensed by a first switch actuated at a first temperature level to maintain a flow of air across the load continuously between operating cycles of the oven and by a second thermally operated switch actuated at a higher temperature to disable the power supply for the magnetron.

Abstract: An electron tube connector assembly including a printed circuit disc having aperture means for engaging a plurality of terminal members of an electron tube, and having printed circuit conductor means for electrically connecting at least one of the terminal members to a wire lead external of the tube.

Abstract: A microwave oven having a door formed from metal structural elements which are welded together and coated with a nonconductive coating. Solid dielectric portions of the microwave seal choke are inserted into the choke regions of the door seal, and slotted portions of one of the steel structural elements are then deformed to form the choke and to lock the solid dielectric portions in place.

Abstract: An improved color display system employing a beam penetration type cathode-ray tube with rapid color switching. The screen electrode is separated from the accelerating electrodes without the use of an isolating mesh so that the voltage applied to the screen electrode is switched across only a relatively small capacitance. The invention may be used in conjunction with either magnetic or electrostatic deflection beam penetration cathode-ray tubes as well as either magnetic or electrostatic focus tubes. Such display systems may be used for radar type random access or scanned raster type displays.