Abstract: This antenna includes a helically formed wire coil having a lower end that is positioned in a connector a solid dielectric material is injection molded into the coil and connector to precisely maintain the coil dimensions and support the coil. An outer cover is injection molded over the coil and dielectric material.

Abstract: An expandable chassis includes a four sided frame with a central opening to receive a plate or "shield" which is allowed to move within the frame between two predetermined positions. Protuberances on the shield contact the frame and limit its inward movement while outward movement is limited by a spring clip on the shield that snaps into an aperture in the frame. Tabs on the frame support integrally formed spring fingers on the shield which tend to force the shield outward. A membrane switch contact assembly and a speaker are respectively attached to the inside and outside surfaces of the shield. By compressing the shield partially into the frame, the chassis assembly slides into a molded plastic housing. A rubber key actuator pad on the outside of the housing has a plurality of keys each having a protrusion or "actuator" that extends partially into an actuator hole in the housing. When the key is depressed, the actuator depresses and activates one of the switches in the membrane switch contact assembly.

Abstract: An electrical connector is provided for making electrical connection to a mating connector. The connector includes a body portion that has a substantially cylindrical cavity. A contact block is located in the cavity and carries three contacts. A spring engages the contact block for applying biasing force to the contact block and contacts for providing electrical connection of the contacts to the mating connector. A peripheral resilient seal is located above the contact block and provides a seal between the contact block and a cylindrical cavity. The peripheral seal includes a bead portion that engages the mating connector for providing a water seal about the contacts.

Abstract: A trimmable circuit includes a first transistor for generating an output current and a plurality of programmable trimming networks connected to the first transistor for regulating the output current of the first transistor. The plurality of programmable trimming networks include a network for decreasing the output current of the first transistor by introducing a second transistor into the trimmable circuit to draw current away from the first transistor and a network for increasing the output current of the first transistor. The trimmable circuit further includes a voltage-divider circuit connected to the plurality of programmable trimming networks, for limiting the voltage across any trimming network during programming.

Abstract: A variable capacitance circuit includes a varactor having an anode side and a cathode side. A first variable bias voltage is applied to one of the sides and one of a plurality of voltages is applied as a second bias voltage to the other side for controlling the capacitance of the varactor. A voltage multiplier circuit connected to a voltage divider network is used for supplying the plurality of voltages. A decoder is responsive to input signals for selecting and applying one of the multiple voltage outputs. The variable capacitance circuit is used in a voltage controlled oscillator of a frequency synthesizer for providing extended frequency range.

Abstract: A tone generator for producing a plurality of output tone waveforms for a plurality of frequencies, includes an encoder for selectively generating a first waveform that has a first number of states and second waveform that has a second number of states which are less than the first number of states. A control circuit is connected to the encoder and selects the second waveform for higher frequency output tones and the first waveform for lower frequency output tones. The control circuit provides a control clock signal to the encoder for determining the frequency of the output tones. A low pass filter is connected to the encoder for filtering the output tones. The encoder includes a plurality of flip flips having outputs connected to a summer by gates that are actuated by the control circuit.

Abstract: A liquid crystal display module with self contained display decoder circuitry is attached to a radio frame with a minimum of electrical interconnections. Module assembly and attachment are both accomplished without the use of tools. Attaching the module to the frame interlocks the module to prevent accidental disassembly and places a preload force on the electrical interconnections to insure good electrical continuity. Ambient light reflection provides primary display illumination while lamps, controlled by an integral switch, provide secondary illumination.

Abstract: An R.F. switch includes a directional coupler with a main line and a quarter wavelength coupled arm. One end of the main line is connected to a first input port and the other end is connected to a first output port. The coupled arm is selectibly terminated at one end in either its characteristic impedance or a short. A PIN diode controls the termination. The second end of the coupled arm is connected to a second input port. A PIN diode switch is connected between the second end of the coupled arm and a second output port. In a first position, signals present at the input ports are combined and appear at the first output port. The directional coupler provides isolation such that the signal at the second input port is not coupled to the first input port. In the second position, the signal at the second input port is disconnected from the first output port and only connected to the second output port.

Abstract: An I.sup.2 L programmable read only memory (PROM) row driver circuit sinks current from a row of memory elements when selectively activated. The circuit operates in the read mode at very low power levels and down to 1.0 volt. The circuit has two current sinking capabilities, a low current capability for the read mode and a high current capability for the program mode. Switching between modes is accomplished merely by changing the voltage on a power supply terminal; 1-3 volts for the read mode and 9-12 volts for program.

Abstract: An RF interconnect between a printed circuit board and a coaxial connector mounted in a housing is self-aligning along all three major axes. The coaxial connector has a pin connected to its inner conductor that extends beyond the edge of the outer conductor. The outer conductor has an external circumferential groove. The interconnect includes two terminals wherein the first terminal includes a substantially "M" shaped wire formed conductor having five functional segments: two flexible attaching segments near the ends of the wire, two substantially parallel pin contact segments, and a joining segment connecting the pin contact segments. The coaxial connector pin is inserted between the parallel pin contact segments of the wire formed conductor and a clamping force is generated on the pin by the joining segment. The second terminal includes a flat flexible conductor that has a "U" shaped lug at one end and a snap ring at the other end which is inserted into the groove of the coaxial connector.

Abstract: In a multiple state data signal, a first and second state are equated to logic states while a third state is designated as a read state. The read state and one of the two logic states are alternately generated so that each logic state is immediately preceeded by a read signal which may be utilized to tell the peripheral that a valid bit of data follows.

Abstract: A portable radio housing has a shield that provides electromagnetic isolation between logic and radio boards operating on close frequencies. The radio board is positioned in a conductive frame having fours sides surrounding a central opening. A tab on the frame is connected to a power module on the radio board to sink heat from the power module. A middle shield having sides with integral spring fingers at calculated intervals is attached to the frame over the rear surface of the radio board. A logic board and rear shield are attached to the frame over the middle shield. A connector protrudes through an opening in the middle shield and interconnects the logic and radio boards. A front shield, also having sides with integral spring fingers, is attached to the frame over the front surface of the radio board. The front shield has an integral speaker baffle and tabs for holding a connector. An outer housing and keypad/display module enclose the frame.

Abstract: This microphone includes a microphone element, speaker and antenna all internal to the microphone housing. These components are carried by a chassis that is fastened to the microphone body at its lower end which also provides the effective attachment point for the microphone cable. The speaker is mounted in the chassis at an angle having its face slight upwardly incline to project sound towards the top of the microphone. An antenna element includes walls on either side of the speaker for reflecting sound upwardly. The antenna element has apertures in its top portion to allow for the passage of sound therethrough. The microphone element is also in a position for picking up sound through the top of the microphone.

Abstract: A flexible printed circuit board assembly having an integrated circuit die bonded directly thereto. A first layer of the flexible printed circuit board assembly includes a plurality of conductive paths and geometrical patterns on each of its surfaces. The conductive patterns include pads for mounting the integrated circuit die and connecting the wires from the integrated circuit. Additional intermediate layers of the flexible printed circuit board assembly, having an aggregate thickness greater than the height of the integrated circuit die and associated leads bonded thereto, surround the integrated circuit die. The top layer of the flexible printed circuit board provides for total encapsulation of the integrated circuit die for protection thereof. In the preferred embodiment that portion of the top layer which covers the integrated circuit die is opaque to prevent the passage of ultraviolet light which might otherwise cause damage to the integrated circuit.

Abstract: An electrically variable three terminal monomorphic piezoelectric capacitor is manufactured with thick or thin film hybrid microelectronic circuit technology. A first capacitor plate and a ridge, which substantially surrounds and extends above the first capacitor plate, are formed on the surface of a substrate. A monomorphic piezoelectric wafer having a control plate and a second capacitor plate on opposing surfaces is bonded to the upper surface of the ridge. During bonding, a force is applied at the center of the wafer which fixes a permanent bow in the wafer in the direction of the first capacitor plate. A four terminal monomorphic embodiment and three and four terminal bimorphic embodiments are also described.

Abstract: An LED and battery powered driver circuit provide efficient operation to conserve battery energy and maintain the intensity of light emitted from the LED at a substantially constant level despite changes in the battery voltage due to charging and discharging. A pulsed voltage output of a switching power supply is capacitively coupled to the LED. The voltage amplitude of the output pulses is maintained substantially constant by a duty cycle modulator which is connected in a feedback path of the switching power supply. A diode or a transistor circuit is provided to discharge the capacitor between voltage pulses.

Abstract: An I.sup.2 L programmable read only memory (PROM) output circuit has a selectable dual non-inverting input differential amplifier with each non-inverting input connected to a different column of memory elements. In the read mode the circuit operates at very low power levels and down to 1 volt. To program the memory elements, the circuit includes two selectable programming current sources which self extinguish as soon as the memory element being programmed changes from its unprogrammed to its programmed state. Switching between the read and program modes is accomplished merely by changing the voltage on the B+ terminal; 1-3 volts for read and 9-12 volts for program.

Abstract: An alphanumeric entry system which is provided with an electronic lock-out feature. The keypad entry system of the present invention comprises an alphanumeric keypad having function keys and display, a microprocessor, and an electronically programmable read-only memory device. The display consists of a series of system related menus as well as an alphanumeric display area. One of the system related menus corresponds to a locking feature, which may be activated by a general purpose function key. In the locking mode, the radio keypad toggles between a locked and unlocked condition as controlled by the function keys in accordance with a predefined sequence. The alphanumeric entry system of the present invention is particularly advantageous for use with portable two-way communications equipment which operate in a plurality of radio systems.