Abstract: A system and method include receiving an external reference signal and generating first temperature control commands to maintain a constant ambient temperature for a crystal oscillator using a first temperature control system. The method further includes generating second temperature control commands for a second temperature control system to establish a desired ambient temperature for the crystal oscillator according to a temperature training profile. While at least one of the first and second temperature control systems operates to change an ambient temperature, the method includes extracting a clock from the external reference signal, generating a correction signal to further generate a corrected oscillation based on a difference between the extracted clock and the crystal oscillator and training an adaptive control algorithm based on the correction signal in relation to a determined crystal oscillator response to temperature variations caused by the second temperature control system.

Abstract: An object of the invention is to provide an oven controlled crystal oscillator that prevents a reduction in characteristics due to temperature rise in the crystal vibrator and circuit elements other than the oscillating stage, and that increases energy efficiency of a heater element, to thereby facilitate temperature control.

Abstract: A lead wire led-out type crystal oscillator of constant temperature type for high stability is disclosed, which includes a heat supply body that supplies heat to a crystal resonator from which a plurality of lead wires are led out, to maintain the temperature constant. The heat supply body includes a heat conducting plate which has through-holes for the lead wires and is mounted on the circuit board, and which faces, and is directly thermally joined to, the crystal resonator and a chip resistor for heating which is mounted on the circuit board adjacent to the heat conducting plate, and is thermally joined to the heat conducting plate.

Abstract: A constant-temperature type crystal oscillator includes: a crystal unit including a case main body including a first power source terminal on an outer bottom surface thereof; a surface-mounted oscillator; a temperature control circuit including a heating resistor and a temperature sensor; and a circuit substrate including a second power source terminal. One ends of the heating resistor and the temperature sensor are electrically connected to the second power source terminal. The first power source terminal of the surface-mounted oscillator and the one ends of the heating resistor and the temperature sensor are electrically connected to the second power source terminal of the circuit substrate. The first power source terminal of the surface-mounted oscillator is directly and electrically connected to, at least, the one end of the temperature sensor via an electrically-conducting path.

Abstract: A constant-temperature type crystal oscillator includes: a crystal unit including a case main body, in which two crystal terminals and two dummy terminals are provided on an outer bottom face thereof, and a crystal element housed in the case main body; an oscillator output circuit including an oscillating stage and a buffering stage; a temperature control circuit for keeping an operational temperature of the crystal unit; and a circuit substrate, on which circuit elements of the crystal unit, the oscillator output circuit and the temperature control circuit are installed. The temperature control circuit includes: heating chip resistors; a power transistor; and a temperature sensing element. The dummy terminals are connected to a circuit terminal for dummy on the circuit substrate. The circuit terminal for dummy is connected to an electrically-conducting path, to which one terminal of the heating chip resistors is electrically connected, on the circuit substrate.

Abstract: A constant-temperature type crystal oscillator includes: a crystal unit that is installed on one principal surface of a circuit substrate, and chip resistors, which function as heating elements, and which are installed on the other principal surface of the circuit substrate so as to face a principal surface of the crystal unit, the chip resistors heating up the crystal unit to keep an operational temperature of the crystal unit constant. A heating metal film facing the principal surface of the crystal unit is provided on the one principal surface of the circuit substrate. A heat conducting material is interposed between the principal surface of the crystal unit and the heating metal film to perform thermal coupling therebetween. The heating metal film is thermally coupled to electrode terminals of the chip resistors via a plurality of electrode through holes.

Abstract: A thermostatic-chamber temperature control device includes: a heating element for heating a thermostatic chamber; a bridge circuit having a temperature sensitive element whose resistance value varies in accordance with the temperature of the heating element; a detection circuit for detecting an unbalanced voltage of the bridge circuit; a PWM signal generating circuit for generating a PWM signal corresponding to the unbalanced voltage detected by the detection circuit; and a switching element that has a current output terminal connected to the heating element and a current input terminal connected to a power supply circuit and is driven on the basis of the PWM signal generated by the PWM signal generating circuit.

Abstract: An oven controlled crystal oscillator capable of uniformly transmitting heat from the heat generator to improve the frequency-temperature characteristics. The oven controlled crystal oscillator includes a high thermal conductivity plate having high thermal conductivity and provided on one side of a substrate, where the crystal resonator is provided, in such a manner to contact the resistors, the transistor, the crystal resonator, and the temperature sensor. This structure can transmit heat from the resistors and the transistor as the heat generator to the crystal resonator and the temperature sensor rapidly with less heat loss to assure a uniform temperature inside the substrate, thereby improving the frequency-temperature characteristics.

Abstract: An oscillator includes an oscillator circuit and a resonator that produces an output frequency. A temperature compensation circuit is coupled to the oscillator circuit. The temperature compensation circuit stabilizes the output frequency in response to changes in temperature. At least one temperature sensor and a temperature sensor signal modification circuit are coupled to the temperature compensation circuit. The temperature sensor signal modification circuit receives a temperature signal from the temperature sensor and generates a modified temperature sensor signal that is transmitted to the temperature compensation circuit.

Abstract: A package device, such as an oscillator, includes a package module, a circuit module, a plurality of conductive pins, and a plurality of conductive arms. The package module defines an airtight space therein. The circuit module is disposed in the airtight space in the package module. Each of the conductive pins extends into the airtight space in the package module. Each of the conductive arms is disposed in the airtight space, and has a first end that is connected to the circuit module, a second end that is connected to a respective one of the conductive pins, and an intermediate portion that extends between the first and second ends thereof and that has a length longer than the shortest distance between the first and second ends thereof.

Abstract: A voltage-controlled oscillator has an oscillation frequency controlled through a voltage applied across ends of a variable-capacitance element. The voltage-controlled oscillator has a frequency control bias circuit which applies to a first end of the variable-capacitance element a voltage for frequency control according to a control voltage, a first current source which generates a first current according to the control voltage, a second current source which generates a second current according to temperature, independent of the control voltage, a converting resistor which converts a current, obtained by adding together the first and second currents, into a voltage, and a temperature compensation bias circuit which applies to the second end of the variable-capacitance element a voltage for temperature compensation according to the voltage produced by the converting resistor.

Abstract: A system is provided for the regulation of temperature of a crystal oscillator, that system having a thermally conductive support disposed upon a substrate and upon which is disposed the crystal oscillator, an array of thermal vias disposed around the crystal oscillator within the substrate, at least one primary heater communicating with the support, a thermal enclosure communicating with the array of thermal vias, and a at least one secondary heater communicating with the enclosure.

Abstract: A system is provided for the regulation of temperature of a crystal oscillator, that system having a thermally conductive support disposed upon a substrate and upon which is disposed the crystal oscillator, an array of thermal vias disposed around the crystal oscillator within the substrate, at least one primary heater communicating with the support, a thermal enclosure communicating with the array of thermal vias, and a at least one secondary heater communicating with the enclosure.

Abstract: A self-refresh timer circuit for generating a timer period for controlling self-refresh operation of a semiconductor memory device comprising: a temperature-dependent voltage source for outputting a voltage having a temperature dependency based on a diode characteristic; a control current generating circuit for applying an output voltage of the temperature-dependent voltage source to a temperature detecting device having a diode characteristic and for generating a control current having a magnitude in proportion to a current flowing through the temperature detecting device; and a timer period generating circuit for generating a timer period in inverse proportion to the magnitude of the control current.

Abstract: A surface-mount crystal oscillator includes: a crystal blank; an IC chip in which at least an oscillation circuit using the crystal blank is integrated, a plurality of IC terminals are provided on one principal surface, and a plurality of mounting terminals for surface mounting are provided on the other principal surface; and a housing member joined to the one principal surface of the IC chip and formed into a recessed shape. The crystal blank is fixed to crystal connection terminals out of the IC terminals, and is hermetically encapsulated in a space formed by the IC chip and the housing member. At least a power supply terminal, an output terminal and a ground terminal out of the IC terminals are electrically connected to the mounting terminals by a through-electrode provided to penetrate through the IC chip.

Abstract: An ovenized oscillator package including at least a heater and a crystal package mounted on opposite sides of a circuit board. Vias extend through the body of the circuit board to transfer heat from the heater to the crystal package. Layers of thermally conductive material extend through the body of the circuit board and are in thermally coupled relationship with the vias for spreading heat throughout the circuit board and other elements mounted thereon.

Abstract: A constant temperature oscillator includes a crystal oscillator that is provided upright on a circuit board, an oscillation element arranged on the circuit board and configuring an oscillation circuit in conjunction with the crystal oscillator, and a temperature control element including a heating chip resistance and a thermistor, arranged on the circuit board, and configuring a temperature control circuit that keeps an operating temperature of the crystal oscillator constant, and which is provided with a heat transfer plate between the heating chip resistance and the bottom face of the oscillator container, wherein, the heat transfer plate has a notch into which the heating chip resistance is fitted, and a heat sink lies between the heat transfer plate and the heating chip resistance and closely contacts with them.

Abstract: A temperature-compensated crystal oscillator for surface mounting wherein an IC chip into which is integrated a temperature-compensated device having an oscillating circuit and a temperature sensor, which supplies a compensation voltage to a variable-voltage capacitor element of the oscillating circuit, and which also has IC terminals disposed along two edges comprising at least diagonally opposite corner portions of one main surface that acts as a circuit function surface is affixed with the use of bumps to an inner base surface of a main container that is concave in section, and one edge portion of a crystal piece is affixed to an inner wall step portion of the main container; wherein an active element of the oscillating circuit that acts as a heat source and a temperature sensor of the temperature-compensated device are disposed at diagonally opposite corner regions of the IC chip at the greatest distance apart.

Abstract: An apparatus for providing oscillator frequency stability is disclosed. The apparatus includes an internally ovenized oscillator module having an oscillator and an inner heater to maintain the oscillator at a first temperature during operation. The apparatus also includes a thermally conductive cover for forming a first compartment to contain the internally ovenized oscillator module along with multiple heaters. The heaters are in thermal communication with the thermally conductive cover and the substrate to form an oven to keep the internally ovenized oscillator module at a stable second temperature during operation. In addition, the apparatus includes a thermally insulative cover for forming a second compartment to contain the first compartment.

Abstract: There is provided a high-stability piezoelectric oscillator. The high-stability piezoelectric oscillator includes an oscillating circuit unit that has a piezoelectric vibrator and oscillating circuit components, an inner oven that accommodates the oscillating circuit unit, an outer oven that accommodates the inner oven, and an outer metallic case that covers the outer oven. Further, airtightness is ensured inside and outside the outer metallic case. Furthermore, at least one of the outer oven and the inner oven is airtightly sealed.

Abstract: An oscillator assembly includes an oscillator circuit that is configured to generate a frequency signal. A temperature compensation circuit is in communication with the oscillator circuit and adapted to adjust the frequency signal in response to changes in temperature. The oscillator and temperature compensation circuits are located within an oven. A heater and a temperature sensor in communication with the heater are also both located in the oven. The temperature sensor is adapted to directly control the heater in response to changes in temperature. In one embodiment, the oscillator components are mounted to a ball grid array substrate which, in turn, is mounted on a printed circuit board. In this embodiment, a resonator overlies the ball grid array substrate and a lid covers and defines an oven and enclosure for the resonator and the ball grid array substrate. The oscillator and temperature compensation circuit are defined on the ball grid array substrate.

Abstract: A surface mount type temperature-compensated crystal oscillator includes a crystal blank; an IC chip integrating an oscillation circuit using the crystal blank and a temperature compensation mechanism of compensating frequency temperature characteristics of the crystal blank; and a substantially rectangular parallelepiped container body for surface mounting having a first recess of housing the crystal blank and a second recess of housing the IC chip. Respective side surfaces corresponding to the long sides of the container body are provided with crystal inspection terminals for inspecting oscillation characteristics of the crystal blank and respective side surfaces corresponding to the short sides are provided with data writing terminals for writing temperature compensation data to the temperature compensation mechanism.

Abstract: A constant temperature crystal oscillator includes on a circuit substrate: a surface-mount crystal resonator which is provided with two crystal terminals as mount terminals and a dummy terminal on the bottom surface, and has a metal cover; an oscillation circuit element which forms an oscillation circuit together with the crystal resonator; and a temperature control element which keeps a constant operation temperature of the crystal resonator, in which the temperature control element includes at least a heating chip resistor, a power transistor for supplying electric power to the chip resistor, and a temperature sensitive resistor for detecting the operation temperature of the crystal resonator, wherein a dummy terminal on the substrate side of the circuit substrate for connection to the dummy terminal of the crystal resonator is connected to a resistor terminal on the substrate side to which the temperature sensitive resistor is connected through a conductive path.

Abstract: A lead wire led-out type crystal oscillator of constant temperature type for high stability is disclosed, which includes a heat supply body that supplies heat to a crystal resonator from which a plurality of lead wires are led out, to maintain the temperature constant. The heat supply body includes a heat conducting plate which has through-holes for the lead wires and is mounted on the circuit board, and which faces, and is directly thermally joined to, the crystal resonator and a chip resistor for heating which is mounted on the circuit board adjacent to the heat conducting plate, and is thermally joined to the heat conducting plate.

Abstract: A piezoelectric resonator storage case, includes a piezoelectric resonator stored therein, and a resonator container for storing a metal case. Here, the piezoelectric resonator includes: a piezoelectric resonator body having the metal case and a piezoelectric resonator element which is sealed in the metal case in an air tight manner; and two lead terminals protruding from a bottom of the piezoelectric resonator body.

Abstract: A double oven crystal oscillator (DOCXO) is disclosed which is highly stable by incorporating means to reduce the effects of ambient pressure changes on the frequency of the oscillator. The oscillator crystal is mounted in a temperature controlled inner oven to reduce the effects on the frequency stability of the oscillator. The oscillator circuitry and all circuitry associated with the inner oven is mounted in good thermal contact with the inner oven. A Faraday shield at ground potential is placed over the oscillator circuitry to minimize the effects of stray capacitance between the oscillator components and the case wall of the inner oven. The effects of minor deformations in the case walls within the oscillator caused by ambient pressure changes and other factors causing pressure changes are thereby greatly minimized.

Abstract: A method provides a temperature controlled frequency source. The method reduces the effects of temperature variations on an operating frequency of the temperature controlled frequency source by temperature compensating the temperature controlled frequency source.

Abstract: Disclosed is an oscillator that relies on redundancy of similar resonators integrated on chip in order to fulfill the requirement of one single quartz resonator. The immediate benefit of that approach compared to quartz technology is the monolithic integration of the reference signal function, implying smaller devices as well as cost and power savings.

Abstract: Design means is provided to prevent electronic parts used in a high-stability piezoelectric oscillator from deterioration due to aging by heat when the high-temperature side of the working temperature range is as high as 85° C. A high-stability piezoelectric oscillator, which is provided with a first constant temperature oven having housed therein a piezoelectric resonator and electronic parts for oscillation, a second constant temperature oven having housed herein said first constant temperature oven, and temperature control means for controlling the temperature of each constant temperature oven, and in which the temperature of said first constant temperature oven is set lower than the temperature of said second constant temperature oven, is characterized in that a heat source is disposed near said piezoelectric resonator.

Abstract: A microwave oscillator having a hollow conductor, an oscillation generator which is mounted on a heatsink and projects into the hollow conductor, and a printed circuit board having electronic components for supplying direct voltage to the oscillation generator. The printed circuit board or a metallic coating on, in, or under this printed circuit board forms one wall of the hollow conductor, and the oscillator including its heatsink is located in the printed circuit board.

Abstract: A downhole crystal-based clock that is substantially insensitive to the factors that cause frequency deviation. The clock may be maintained at a predetermined temperature using a temperature sensing device and a heating device, where the predetermined temperature corresponds to the temperature at which the crystal experiences only slight frequency deviation as a function of temperature. A microprocessor may monitor the clock and compensate for long-term aging effects of the crystal according to a predetermined algorithm. The predetermined algorithm may represent long-term aging effects of the crystal which were derived by comparing the crystal clock to a more accurate clock (e.g., an atomic clock) prior to placing the clock downhole. In this manner, the crystal-based clock may be substantially free from the factors that cause frequency, and therefore time variations.

Abstract: To provide a highly stable crystal oscillator having increased thermal efficiency. The highly stable crystal oscillator comprises; a thermostat mainframe which maintains the temperature of a crystal resonator including a resonator container for sealing a crystal piece constant, an oscillating element which constitutes an oscillation circuit together with said crystal resonator, a temperature control element which controls the temperature inside of said thermostat mainframe, and a circuit board mounted with said thermostat mainframe, said oscillating element, and said temperature control element.

Abstract: A PLL (Phase-Locked Loop)-controlled oscillator has a temperature-compensated crystal oscillator having a quartz crystal unit, an oscillating circuit connected to the crystal unit, and a temperature compensating mechanism for generating a temperature compensating voltage for compensating for frequency vs. temperature characteristics of the crystal unit, and a voltage-controlled oscillator having an LC oscillating circuit, for being controlled by a PLL using the temperature-compensated crystal oscillator as a reference signal source. The temperature-compensated crystal oscillator has circuit components except for the crystal unit, the circuit components and the voltage-controlled oscillator being integrated in a one-chip IC. The one-chip IC and the crystal unit are integrally combined with each other in the PLL-controlled oscillator.

Abstract: [Object of the invention] To provide designing means that prevents deterioration through thermal aging of an electronic part used in high-stability piezoelectric oscillators and the like when the high end of the usage temperature is 85 deg C. [Means for solving the problem] In a high-stability piezoelectric oscillator equipped with: a first isothermic oven housing a piezoelectric vibrator and an electronic part; a second isothermic oven; a case; and the like, a high-stability piezoelectric oscillator wherein a temperature of the first isothermic oven is set to be lower than a temperature of a second isothermic oven using a Peltier element or the like.

Abstract: A self-calibrating integrated circuit includes a processor having at least one analog function used with the processor; one or more sensors adapted to sense one or more environmental parameters of the at least one analog function; and a solid state memory being configured to store the one or more environmental parameters of the at least one analog function.

Abstract: An oven controlled crystal oscillator has an onboard processor containing an algorithm used to generate a frequency compensating signal based on a predetermined relationship and a monitored current consumption of a heater.

Abstract: The present invention is for a thermally controlled package for oscillators, particularly evacuated miniature surface acoustical wave oscillators (EMSO) devices. In a preferred embodiment the surface acoustical wave device is bonded directly to a heated substrate. The package is evacuated to improve temperature characteristics. A temperature heater, sensor, and control controller are utilized to maintain the internal package temperature above ambient. In one embodiment there is an additional substrate layer that house components that are not sensitive to temperature with interconnects electrically connecting the heated substrate and the additional substrates.

Abstract: A system and method for programming a digitally tunable oscillator is provided. A desired output frequency is received. A tuning effect of a set of digital tuning words on a crystal resonant frequency is determined, and valid parameters of an algorithm for translating and tuning the crystal resonant frequency to a value within an error tolerance of the desired frequency, based on the determined tuning effect are calculated. Valid parameters are preferably calculated based on an intermediate tuning value, sorted by ascending divide parameter of the algorithm, and then evaluated in sorted order for ability of a tuning effect to null frequency error to within the error tolerance. The valid set of calculated parameters are then programmed into a nonvolatile memory. The oscillator control parameters may remain unprogrammed until all necessary parameters are defined.

Abstract: An ovenized oscillator has two ovens. One of the ovens is heated by a heater and the other is cooled by a thermoelectric module. The ovenized oscillator has an inner oven with an oscillator located inside. A thermoelectric heat pump cools the inner oven. An outer oven contains the inner oven and the thermoelectric heat pump. A heater heats the outer oven. The ovenized oscillator is operated with the inner oven temperature being lower than the outer oven temperature to improve component life and reduce crystal aging.

Abstract: A miniature ovenized crystal oscillator has a ceramic case that has a cavity, a bottom and a ledge that extends into the cavity. The case has several circuit lines. A substrate is located in the cavity and is supported by the ledge. The substrate has a top and bottom surface and several circuit lines. A crystal is mounted to the bottom surface of the substrate and is connected to the substrate circuit lines. A signal conditioning circuit is mounted to the top surface of the substrate and is connected to the substrate circuit lines. The case circuit lines are connected to the substrate circuit lines by a conductive epoxy. A heater is mounted to the bottom of the ceramic case. A thermal adhesive is located between the heater and the crystal. The thermal adhesive thermally links the crystal and the heater.

Abstract: An apparatus and method for stabilizing the frequency of a piezoelectric crystal resonator, especially useful in common emergency positioning radio beacons. A temperature compensated crystal oscillator circuit (TCXO) is mounted on one surface of a thin substrate. The TCXO includes a piezoelectric device such as a quartz resonator and a capacitor thermistor compensation network to reduce the frequency fluctuations of the crystal through variations in temperature. A heating circuit is mounted to the opposing surface of the substrate, thereby providing a thermal connection between the two circuits. The heating circuit includes a temperature sensor for sensing changes in ambient temperatures and a heater control amplifier for adjusting the power of a heating element. The substrate with the two circuits disposed thereon is suspended within a hermetically sealed enclosure by a plurality of support pins.

Abstract: A thermal control circuit for an integrated power transistor includes a current generator controlled by a turn on signal, a sensing resistance in series with the power transistor, and a current limiter acting when the voltage drop on the sensing resistance overcomes a certain value. The circuit also includes a current amplifier coupled to the output node of the controlled current generator for outputting a drive current that is injected onto a control node of the power transistor. A soft thermal shut down circuit is provided having a conduction state which is enhanced as the temperature increases for reducing the drive current. The circuit controls the voltage on the power transistor in a more effective manner because the current amplifier has a variable gain controlled by the state of conduction of the soft thermal shut down circuit.

Abstract: The component, located inside a corresponding package, is associated with a first heat sensor, located in proximity to the component inside the package, together with a second heat sensor. A thermal conditioning element is controlled in such a way as to keep the temperature of the first sensor at a level identified by a reference signal (rifv). The second sensor is associated with the package in such a way as to generate a second temperature signal indicating the external temperature, and the aforesaid reference signal (rifv;) is modified as a function of the said second temperature signal, providing effective temperature control of the component.

Abstract: A temperature compensated crystal oscillator using an AT cut crystal produces a reference frequency. The temperature compensated crystal oscillator is located inside a temperature controlled oven. The temperature controlled oven provides a stable temperature to the temperature compensated crystal oscillator such that deviations from the reference frequency are reduced.

Abstract: A crystal oscillator consists of an outer housing (1), a circuit board (2) and an inner case (6). The resonator in a separate casing (9) is mounted on the bottom of an inner case. The inner case (6) looks like an inverted open box and is made of material that is an excellent heat conductor. The bottom of the inner case (6) is tightly adjoined to the central part (3) of the circuit board (2). All the thermostatically controlled elements of the oscillator are located in the central part (3) of the circuit board (2). The central part of the circuit board is separated from the peripheral part by means of through cuts (4), both parts being connected at the ends of the cuts with narrow bridging strips (5). Heating elements (10) and a main temperature detector (11) are attached to the side walls of inner case (6), which has heat-conducting rods that pass through the central part (3) of the circuit board (2) in close proximity to each bridging strip (5).

Abstract: The present invention is a stabilized oscillator system comprising an oven controlled crystal oscillator positioned inside an insulated housing. Within the insulated housing, there is a cold plate in thermal contact with the oven controlled crystal oscillator and a thermo-electric cooler in contact with the cold plate. A heat sink external to the insulated housing is in thermal contact with the thermo-electric cooler. The thermo-electric cooler pumps heat into or out of the oven controlled crystal oscillator through the cold plate and into or out of the heat sink. The thermo-electric cooler is controlled as part of a feedback loop which attempts to stabilize the output frequency of the oven controlled crystal oscillator.

Abstract: A heater control system for ovenized oscillators that is capable of changing the relative influence of multiple temperature sensors in order to keep a uniform temperature profile across the oscillator enclosure. A resonator is located near a heater in an enclosure. Several temperature sensors are located in proximity to the resonator for sensing temperature. One of the sensors is closer to the heater and another sensor is closer to an outer wall of the enclosure. A control circuit is connected between the sensors and the heater to provide a control signal to the heater, in response to the sensors. An adjustment circuit is connected to each of the sensors, for adjusting the relative influence that each sensor has on the control circuit.

Abstract: A low profile integrated oscillator operable to provide an oscillator signal includes a substrate having a cavity and a via passing through the substrate. A crystal or other resonator is disposed in the cavity and stabilizes the oscillator signal. An electrical circuit means is mounted to the substrate and electrically connects to the via to condition the oscillator signal. A cover seals the resonator in the cavity. A connector electrically connects the resonator to the via. A heater is mounted to the substrate to elevate the oscillator temperature and a temperature sensor is mounted to the substrate to monitor and control the oscillator temperature. The substrate is surrounded by an insulation and mounted within a housing. The housing has a connection means for connecting to an external electrical circuit.

Abstract: A crystal resonator assembly is described wherein a piezo-electric resonator is mounted over a heat conducting substrate and one or more heat generating elements are located on the substrate. The heating elements provide heat both by conduction and radiation and by virtue of the use of a heat conducting substrate enable a uniform and efficient heating of the crystal resonator to a desired oven temperature.

Abstract: An emergency positioning indication radio buoy used in case of emergency by being thrown into the sea from a ship. This radio buoy comprises a transmitting unit for generating a high frequency signal of a predetermined frequency, a battery for supplying the power to the transmitting unit, a switch which is normally breaking the power supply circuit from the battery to the transmitting unit and operates automatically or is operated by hand to make the circuit when the buoy is used, and an antenna for radiating the high frequency signal from the transmitting unit into the air, and is characterized by that at least the crystal resonator of said transmitter unit is put in a heat insulating container which is enclosed with a vacuum or a heat insulating material and that an antifreezing solution, oil or other appropriate material is filled in the heat insulating container.