Vacuum tube oscillator

It has often been the practice in conductance work to ground certain parts of the bridge network for the purpose of improving the sharpness of the sound minimum in the detector at the balance point unless this is done with care it is liable to introduce errors because of the existence of leakage currents to earth. The telephone earpiece must, however, be at ground potential, otherwise the capacity between the telephone coils and the observer will result in a leakage of current. Other sources of leakage are introduced by the use of vacuum-tube oscillator and amplifier, and by various unbalanced capacities to earth, etc. 

Stratonoviclr first studied the influence of external fluctuations via a vacuum tube oscillator. He noticed a phenomenological behavior reminiscent of that of physical systems far from equilibrium. His pioneer work showed that the use of electric circuits is a simple means of shedding light on general problems, thereby stimulating further experimental work of this kind. 

Although the Nemst method is subject to many minor sources of error Nernst s results on the dielectric constant of liquids are very close to those obtained by later and more precise measurements. The Wheatstone bridge method lias been used by Smyth and associates.6 In principle their bridge is essentially that shown in Fig. 2. However, a vacuum tube oscillator replaces the induction coil, and precision in locating the balance is attained with the aid of vacuum tube amplification. As in precise conductance measurements care must be exercised to avoid errors due to capacity effects between the different arms of the bridge, and to earth. This may be accomplished by appropriately designed electrostatic screening, ... 

Laddertron A microwave vacuum tube oscillator with a slow-wave structure coupled to a single-cavity resonator. 

Mi etron A microwave vacuum tube oscillator in which microwaves in a number of cavity resonators interact with bunched electrons in motion rotating or rectihnearly. The basic electron motion is formed by the appUed accelerating electric fields and the DC magnetic fields. 

A family of vacuum-tube MMW sources is based on the propagation of an electron beam through a so-called slow-wave or periodic structure. Radiation propagates on the slow-wave structure at the speed of the electron beam, allowing the beam and radiation field to interact. Devices in this category are the traveling-wave tube (TWT), the backward-wave oscillator (BWO) and the extended interaction oscillator (EIO) klystron. TWTs are characterized by wide bandwidths and intermediate power output. These devices operate well at frequencies up to 100 GHz. BWOs, so called because the radiation within the vacuum tube travels in a direction opposite to that of the electron beam, have very wide bandwidths and low output powers. These sources operate at frequencies up to 1.3 THz and are extensively used in THZ spectroscopic applications [10] [11] [12]. The EIO is a high-power, narrow band tube that has an output power of 1 kW at 95 GHz and about 100 W at 230 GHz. It is available in both oscillator and amplifier, CW and pulsed versions. This source has been extensively used in MMW radar applications with some success [13]. 

Development of Dosimeter Materials. - 4.2.1 Quantitative ESR and Intensity Standards of Mn1+ and CuS04.5H20. An ESR spectrometer consists of vacuum tube amplifier and a Klystron oscillator with thermal noise and frequency drift. Hence, an inherent standard of Mn2+ was used in ESR dating of carbonate stalactites,8 and patented as a standard in ESR radiation dosimetry in 1980.102 The standard sample of MgO with Mn2+ is frequently used for calibration of -factor and the magnetic field as well as for radiation dosimetry.103... 

The difference between the magnetron and other vacuum tubes is that the electron flow passes along a spiral this route is created by an external magnetic field B (Fig. 3.4). The electron cloud produces resonance cavities several times in its trip to the anode. These cavities work as Helmholtz resonators and produce oscillations of fixed frequency, determined by the cavity dimensions small cavities produce higher frequencies, large cavities smaller frequencies. The antenna in the right zone collects the oscillations. 

In the early days of nonlinear dynamics, say from about 1920 to 1950, there was a great deal of research on nonlinear oscillations. The work was initially motivated by the development of radio and vacuum tube technology, and later it took on a mathematical life of its own. It was found that many oscillating circuits could be modeled by second-order differential equations of the form... 

Power amplification is produced by four tetrode vacuum tubes connected in pushpull-parallel as a Class AB2 amplifier. Control of the master audio oscillator signal amplitude is provided by a potentiometer on the master control panel. The output voltage of the equipment may be reduced to zero even when full voltage is applied to the plates of the power tetrodes. 

Cancellation of these common forms of coupling between the input and output circuits of vacuum tube amplifiers prevents self-oscillation and the generation of spurious products. 

Excitation The input signal (typically to the grid of a power vacuum tube) that controls the operation of the stage, usually an amplifier or oscillator. 

Usually a traveling wave tube means a forward wave tube. In the vacuum tube, the electron beam and forward waves interact with each other. There is a vacuum tube in which the electron beam interacts with backward waves. This type of tube is termed the backward wave tube. The backward wave tube is inherently highly regenerative (built-in positive feedback) therefore, it is usually an oscillator. Such an oscillator is termed a backward wave oscillator (BWO). The BWO has a traveling wave structure inside, but usually it is not called a traveling wave tube. Details of a BWO are presented in Chap. 6.4.3. The oscillation frequency of a BWO is dominated by the electron speed, which is determined by the anode voltage. Therefore, a BWO is a microwave frequency voltage controlled oscillator (VCO). 

Klystron A microwave vacuum tube amplifier or oscillator that contains buncher cavity or cavities, drift space, and a catcher cavity, among other components. 

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