Showing papers on "Crystal oven published in 1971"

Dual crystal resonator apparatus

Abstract: Algebraic combination of the frequencies of two or more selected modes of piezoelectric crystal resonator vibrations yields a total frequency signal output which has a substantially zero temperature coefficient of frequency.

Multiple crystal oscillator measuring apparatus

Abstract: Crystal oscillators are described for measuring an environmental characteristic such as the density of a particular gas, even though other characteristics such as temperature are changing that also affect the oscillator frequencies. The apparatus includes two oscillator assemblies with both of their crystal structures uncovered and close together to experience the same temperature and mass accretion, and with the crystal structures having the same mass accretion coefficient (change of frequency per unit increase in mass) but different temperature coefficients. The difference in crystal oscillating frequencies, which is due solely to temperature change since their mass accretion coefficients are equal, is monitored to determine their temperature. The frequency of either crystal at the thus determined temperature indicates its mass accretion. The fact that both crystals are uncovered means that they both respond rapidly to environmental changes, so that measurements can be made in a short time.

Voltage-controlled crystal oscillators

Abstract: The quartz crystal oscillator is normally thought of as a stable generator of a fixed frequency. It is possible, however, to design and construct voltage tunable quartz crystal oscillators that can be electrically tuned over a frequency range on the order of ±0.3 percent of the crystal frequency. This is accomplished with a nonlinearity between frequency and voltage on the order of 0.1 percent. Moderately good long-term frequency stability and low phase noise is exhibited by the oscillators. A reactive network including varactor diodes is used to provide a voltage variable reactance which, in combination with a quartz crystal network, forms a resonator having an antiresonant frequency that is a linear function of tuning voltage. The basic reactance network is not practically realizable. However, the application of one of Norton's network transformation theorems results in a realizable network. The oscillator described is very simple in design and provides an inexpensive solution to a large number of signal processing and measurement problems.

Quartz crystal resonator tuning control apparatus

Abstract: A quartz crystal resonator tuning plating automatic control process utilizing an automatic feedback control circuit in a process loop with the quartz crystal being metal plating tuned in an oscillator circuit. The frequency of the oscillator circuit is mixed with a reference frequency and the difference frequency is converted to dc applied to an RC circuit connected to a power amplifier for developing an exponential power output response from the power amplifier that melts and vaporizes plating metal (such as gold) in a vacuum chamber. This results in the plating rate on the quartz crystal being tuned processed tapering off from a much higher rate to a very low plating rate as the desired tuned frequency is approached. Minimum power level and shutoff controls are provided for the power amplifier in attaining desired levels of product frequency adjustment and plating cutoff.

A new type of frequency-stabilized Gunn oscillator

Abstract: A new type of frequency-stabilization method for a Gunn oscillator consisting of a high-Q single-tuned oscillator circuit is described. The frequency stability of this stabilized osciilator was 5 × 10-5over a temperature change from -10 to 60°C at 20.970 GHz. This result satisfies the requirement for a 20-GHz radio relay system.

High Quality Quartz Crystal Oscillators: Frequency Domain and Time Domain Stability

Abstract: There are several aspects of electronic circuit design which must be carefully considered in order to achieve high short-term frequency stabil i ty in quartz crystal osci l la tors . W e report an advance of more than ten decibels in the state-of-the-art for high quali ty rs 5 MHz quar tz c rys ta l osc i l la tors in the no ise frequency range of 1 to 100 Hz. The most important design fac tors were A) measurement and selection of transistors for the lowest possible f l icker of phase noise' (oscillating loop and buffer stages), B) measurement and selection of transistors and diodes for the lowest possible DC flicker noise (voltage regulators, automatic gain control) , C) massive negative feedback (DC and RF) in the RF c i rcu i t ry to s tab i l ize the RF ga in and to reduce the f l icker of phase noise of the transistors ' (automatic gain control [AGC ] amplifier, buffer amplifiers, oscil lating loop amplifier) . Because more negative feedback is used in the ACC amplifier and in the buffer amplifiers than can be used in the oscil lating loop amplifier, the resultant f l icker of phase noise performance of the osci l la tor is determined by the flicker of phase noise of the t rans is tor in the oscillating loop.

Temperature compensating circuit for an oscillator

Abstract: An automatic frequency control for a crystal tuned oscillator, comprising temperature sensitive means producing an output voltage varying in magnitude over a predetermined environmental frequency range, a crystal oscillator activated by the temperature means varying output voltage to provide a corresponding output frequency deviation over the predetermined environmental frequency range, and series diodes and capacitors or inductors to compensate for the oscillator output frequency deviation, wherein the diodes are biassed to OFF states by different amounts of voltage to disconnect the capacitors or inductors from the crystal when the temperature means output voltage is less than the biasing voltage smallest amount and further wherein the diodes are activated in turn to ON states to connect the capacitors or inductors in turn with the crystal to maintain the oscillator output frequency deviation at substantially zero value over the predetermined environmental frequency range.

Frequency stabilisation of a reflex-klystron oscillator by a superconducting cavity

Abstract: A powerful X band oscillator is reported, with a frequency stability comparable to a quartz clock of high quality. It is realised by coupling externally a standard reflex klystron 2K 25 to a high-Q factor (108) superconducting cavity. The observed frequency standard deviations in one second (10?10 in relative value) are in accordance with the theory.

Multi frequency mass spring oscillators

Abstract: A multi frequency signal generator employing a cantilever beam comb wherein each beam has a different natural vibration frequency. The beams are selectively coupled through capacitive pickups to frequency modulate a high frequency oscillator. The modulated oscillator frequency is passed through a frequency discriminator, and the amplified output of the discriminator supplies the signal generator output and also is applied to a magnetic drive circuit for sustaining the selected beam in vibration at its natural frequency.

Crystal filter with temperature compensation

Abstract: A narrow band transmission system using a crystal filter having a pass band width in the order of one hertz and operable over an ambient temperature range of 60 DEG C. The output of a crystal controlled oscillator is mixed with the incoming signal to provide a sum signal as the input to the filter. The oscillator and filter crystals have matched temperature characteristics so that the oscillator frequency and the filter center frequency vary in the same amount with change in temperature.

Frequency Stability Analysis of a Grounded-Base Voltage-Controlled Crystal Oscillator

Abstract: The frequency stability is analyzed for a voltage-controlled grounded-base crystal oscillator by matrix algebra. The validity of the resulting equation was verified by measurements on an oscillator with a 110-MHz fifth-overtone quartz crystal. Sensitivity coefficients for the oscillator are computed with the aid of a time share computer program and its sweep range is drawn by a plotting routine.