Multi cavity klystron used as lowpower microwave amplifier. Ece questions and answers on microwave engineering with explanation for various interview, competitive examination and entrance test. With the signal applied in the first cavity, we get weak bunches in the second cavity. The helix travelingwave tube twt, the coupledcavity twt, the forwardwave am plifier fwa, and the backwardwave amplifier and oscillator bwa and bwo are also 0type tubes, but they have nonresonant periodic structures for electron inter actions. The disadvantages of the klystron are that it is usually large and it requires high voltages e. A reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram. The losses due to circuit factors can be reduced by a judicious use of the microwave. Article pdf available in ieee transactions on microwave theory and techniques 5210. Application of multi cavity klystron this type of klystron is mostly used for the purpose of amplification of microwave length of frequencies. To read and print pdf files, download adobe acrobat reader.
Pdf optimization of micromachined reflex klystrons for operation. Oct 01, 2014 0type tube is the twocavity klystron, and it is followed by the reflex klystron. Two cavity klystron amplifier is not lownoise device. In klystron, each cavity operates independently and there is no mutual coupling. Klystron amplifier free download as powerpoint presentation. One major type is the reflex klystron, which is used primarily as an oscillator. Archived from the original pdf on september 24, 2015. The microwave energy modulates the velocities of electrons in the beam, which then enters a drift space. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. Following are the benefits or advantages of klystron.
Pdf lowfrequency klystron for accelerator applications. The following figure depicts an example of multicavity klystron amplifier. Employs a power saver feature to optimize khpa efficiency to meet your operating condition. Reflex klystron working, oscillator and applegate diagram engineering funda, microwave engineering. We know that british carefully planned all the developmental steps for their radar sets, including the use of microwaves when elsewhere the upper limit of usable frequencies was around 500 mhz. The simplest klystron tube is the twocavity klystron. Klystron amplifier vacuum tube electrical engineering. Which is impossible and not feasible to use other components for this purpose. There are two cavities known as buncher and catcher cavity. For use as an amplifier, a klystron receives microwave energy at an input cavity through which the electron beam passes. The 6229 employs a grounded anode and a negatively pulsed cathode to generate 0. This type of klystron is mostly used for the purpose of amplification of microwave length of frequencies. Reflex klystron working, oscillator and applegate diagram. After the electron gun there are two focusing electrodes used to keep the electron beam in the center around the glass envelope.
It is known by this name due to its reflex action of electron beam. In this tube there are two microwave cavity resonators, the catcher and the buncher. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. The development of reflex klystron as local oscillator. Sep 27, 2017 in this video, i have explained two cavity klystron amplifier with following points 1. Of the resulting frequency spectrum only a narrow band, which. Scribd is the worlds largest social reading and publishing site. What is a klystron amplifier, types, differences and their. These will set up a field in the third cavity, which produces more concentrated bunches and so on.
Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. Multistage depressed collector klystron allows the amplifier to use less power and produce less heat than other khpas. The klystron amplifier is capable of some of the highest power levels used in radar many hundreds of kilowatts of average power. Reflex klystron is one of the most commonly used microwave low power generators. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. The uhf region range of klystron amplifier ranges from 300 mhz3 ghz to 400 ghz. B derive an expression for the bunching parameter in the reflex klystron. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. The electronic tuning range of the reflex klystron is usually referred to as the variation in frequency between half power pointsthe points in the oscillating mode where the power output is half the maximum output in the mode. In general helix travelling wave tubes contains a electron gun and rf interaction circuit. Jan 07, 2019 a reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram. Construction a reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram.
Jensen abstract this report deals with a method of modulating a reflex klystron whereby the message to be transmitted is modulated on a subcarrier, which in turn modulates the klystron through its repeller. A 2cavity klystron amplifier has accelerating voltage volt and frequency 5 ghz and cavity gap 1 mm. Draw the schematic diagram of helix travelling wave tube. Jul 31, 2018 technical article introduction to the twocavity klystron amplifier july 31, 2018 by mark mitchell klystron amplifiers are used in a variety of industries, including satellite systems, television broadcasting, radar, particle accelerators, and in the medical field. Klystron amplification, power output, and efficiency can be greatly improved by the addition of intermediate cavities between the input and output cavities of the basic klystron.
The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. When used as an amplifier, the weak microwave signal to be amplified is applied to the buncher cavity through a coaxial cable or waveguide, and the amplified signal is extracted from the catcher cavity. A klystron is used either as an amplifier in the microwave region or as an oscillator. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. The klystron amplifier is a device used to amplify microwave frequency signals that reach high stages of power gain by applying the principles of the vacuum tube as well as the electron bunching concept. Question bank department of electronics and communication. Klystron tube article about klystron tube by the free. The reflex klystron contains a reflector plate, referred to as the. Microwave engineering reflex klystron tutorialspoint. A reflex klystron is an obsolete type in which the electron beam was reflected back.
This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. Amplification of such twocavity klystron is low and hence multicavity klystrons are used. Why is pulse modulation required in reflex klystron. Typical operational problems with a klystron input drive power is too low and klystron is not saturated although this is required if the tube is included in a feedback loop reduced output power, efficiency, and increased output power amplitude jitter wrong cathode filament current wrong perveance. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. The multi cavity klystron consist of a glass envelope in which there is an electron gun composed of heater and cathode. The main difference between two cavity reflex klystron amplifier and reflex klystron is that the. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. When used as an amplifier, the weak microwave signal to be amplified is applied to.
Due to dc voltage in the cavity circuit, rf noise is generated in the cavity. Reflex klystron is also known as a sutton klystron. Mar 24, 2016 microwave frequencies are millimeter waves so we need to generate them through amplifiers or oscillators,in this video we will learn generation of microwave frequencies using reflex klystron. An equivalent circuit of the internal cavity reflex klystronamplifier. Important question and answers on reflex klystron with. The twocavity klystron is a widely used microwave amplifier operated by the. The general construction of the reflex klystron oscillator and a two. Inspire your inbox sign up for daily fun facts about this day in history, updates, and special offers. Now understand the concept of reflex klystron in microwave engineering in details through following questions and answers. The experimental results of microwave amplification by the reflex klystron 2k25 have been reported.
What are the high frequency limitations of conventional tubes. In a velocitymodulated linear beamtype device, such as a klystron or a travelingwave beam tube, stored potential beam energy affects both the bunching process and the process of dc to re energy. Modern semiconductor technology has effectively replaced the reflex klystron in most applications. For this article, however, we will focus on another popular type. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. Department of electronics and communication subject microwave engineeringeec 603 unitiii 1. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable.
Cw products xband, klystrons microwave power products. The 6229 is a cavity resonatortype magnetron used in the nike i missile guidance unit. Microwave engineering cavity klystron tutorialspoint. Microwave engineering ece questions and answers page 2. On this channel you can get education and knowledge for general issues and topics. At present, klystron and twt amplifiers can deliver a peak power output up to 30 mw megawatts with a beam voltage on the order of 100 kv at the frequency of 10 ghz. Introduction to the twocavity klystron amplifier technical.
Find the gap transit angle and the optimum length of drift space. Reflex klystron telecommunications engineering mechanics. State the characteristics of the twocavity klystron amplifier. Explain with suitable sketch the operation of twocavity klystron amplifier. An equivalent circuit of the 2k25 amplifier was develop. The main difference between two cavity reflex klystron amplifier. Gen iv klystron high power amplifier cband highly efficient provides up to 2. Reflex klystron free download as powerpoint presentation. Experiment4 study of the characteristics of the klystron tube. It means that the high frequencies can be amplified by multi cavity klystron. The reflex klystron makes use of velocity modulation to transform a continuous electron beam into. Klystron multi cavity klystron, reflex klystron, working. Klystrons can be used in the uhf region 300 mhz to 3 ghz up to 400 ghz.
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