This klystron is totally dissimilar from cavity klystron because it has a single cavity and used for modulation otherwise demodulation. Po1, po2, po3 2 a describe with the neat sketch the constructional details and principle of operation of a reflex klystron tube. The klystron is a linearbeam device that overcomes the transittime limitations of a. Reflex klystron used as a lowpower microwave oscillator 2. As to have oscillations, feedback is needed to be applied at the input which is provided by the oscillator. The heater boils off electrons when heated and the electrons are ejected from the cathode and accelerate towards the anode due to the high dc potential between the two elements. Nov 09, 2016 on this channel you can get education and knowledge for general issues and topics. It means that the high frequencies can be amplified by multi cavity klystron. Reflex klystron working free download as powerpoint presentation. Lowpower klystrons are used as oscillators in terrestrial microwave relay communications links, while highpower klystrons are used as output tubes in uhf television. Klystron working and important applications analysis of. Voltages required for operation of reflex klystron tube such as beam, heater and reflector voltage. Reflex klystron this microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency.
Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode. A collector is present at the end to collect the electrons. After the pass, they get reflected by a reflector of a negatively charged electrode. Reflex klystron is a microwave device that works on principle of velocity modulation in addition to current modulation. It is a low power tube with a single and work as an oscillator. Initially, electrons are emitted from the electron gun and the anode present in the structure provides the desired acceleration to the beam. To study the mode characteristics of the reflex klystron tube and to determine its electronic tuning range. Consider the aboveshown figure of twocavity klystron amplifier. Lowpower klystrons are used as oscillators in terrestrial microwave relay.
The electron gun emits the electron beam, which passes through the gap in the anode cavity. Diode drive cavity idler cavities output cavity collector guidefield solenoid. The expected lifetime of a tetrode in uhf service is usually shorter than a klystron ofthesamepowerlevel. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. Mar 05, 2018 reflex klystron amplifier, microwave klystron amplifier 1.
Pdf new micromachining techniques now provide us with the technology to fabricate reflex klystron oscillators with dimensions suitable for operation. There are no two identical reflex klystrons, even if they are manufactured in the same series. A comprehensive analysis of reflex klystrons is developed by considering the electrons as particles acted upon by forces which modify their motion. Special variation to the basic klystron tube is called as reflex klystron. It also utilizes a collector element at the end of the electron stream. The output frequency range of the oscillator is in the range of 1 to 25 ghz. The electron beam emitted from the cathode is accelerated by the grid and passes through the cavity anode to the repeller space between the cavity anode and the repeller electrode.
Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. Intensive work, however, has led to products that offer higher output powers and extended operating lifetime, while retaining the benefits inherent in tetrode devices. The essential elements of klystron are electron beams and cavity resonators. The schematic diagram of a reflex klystron tube is shown in fig. In this video, i have explained reflex klystron with following points1. Operation of the reflex klystron can best be understood by examining the. However, there exist variation in constructional structure and the respective applications of the two. The internal electrode arrangement of the tube is given in the drawing of fig. Although the power output of a klystron is quite sufficient for relay repeater service, this type of direct modulation is not satisfactory, because the cumulative distortion. Jul 31, 2018 the twocavity klystron utilizes an electron source heater, an anode, and a cathode like a conventional vacuum tube. Electron emitted from the cathode are accelerated and passed through the positive resonator towards negative reflector, which retards and, finally, reflects the electron. A reflex klystron is a specialized low power vacuum tube used to produce oscillations at microwave frequency. Reflex klystron works on the principle of velocity. Following equation or formula is used for reflex klystron calculator.
Lowpower klystrons are used as oscillators in terrestrial microwave relay communications links, while highpower klystrons are used as output tubes in uhf television transmitters, satellite communication, radar transmitters, and to generate the drive power for modern parti. The essential features of reflex klystron theory are i discussed in this chapter in order to provide a basis for the description of the different modes of operation. The reflex klystron makes use of velocity modulation to transform a continuous electron beam into microwave power. The main difference between two cavity reflex klystron amplifier. Construction of reflex klystron the electron gun emits the electron beam, which passes through the gap in the anode cavity. Measure the frequency, attenuation, vswr, impedance using klystron bench setup. The name of this klystron is taken due to its reflex act of electron beam. Following is the list of useful converters and calculators. Microwave engineering cavity klystron tutorialspoint. Microwave tubes klystron,magnetron,twt traveling wave tube. Three power sources are required for reflex klystron operation. The electron beam emitted from the cathode is accelerated by the grid and passes through the cavity anode to the repeller space between. The klystron power supply also provides all the other d.
What is a klystron amplifier, types, differences and their. F input signal to the buncher cavity with the help of loop coupling. Before answering this question, we need to know how the oscillations are generated. 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 maximum electronic efficiency of two cavity klystron is 58%. Single reentrant cavity as a resonator the electron beam. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. With the help of applegate diagram, explain the operation of a reflex klystron. The difference between normal klystron and reflex klystron is that reflex klystron uses single cavity. Reflex klystron devices are targetted for low power and are small in. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. The cathode emits electrons which are accelerated forward by.
The operating principle of the inereal klystron is clearly described by the following figures. Like twocavity klystron, a reflex klystron utilizes the phenomenon of velocity and current modulation to produce oscillations. A cloud of thermionic electrons is generated by heating a filament inside a vacuum tube. Microwave frequencies are millimeter waves so we need to generate them through amplifiers or oscillators,in this video we will learn generation of microwave. 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. Reflex klystron calculator converters and calculators. The reflex klystron is also called as sutton tube invented by robert sutton. Reflex klystron is a klystron with a singlecavity which acts as an oscillator by using a reflector electrode next to the cavity to deliver positive feedback through the electron beam. Optimization of micromachined reflex klystrons for operation at terahertz frequencies. Various fundamental principle are used for the analysis and design purpose with the application of field measurement techniques. As to have oscillations, feedback is needed to be applied at the input. The cavity resonator must be flexible on at least one wall due to the tolerances of the tube manufacturer. A reflex klystron consists of an electron gun, a cavity with a pair.
Summary this prospectus describes the design and electrical properties of the t e le f u n k e n reflex klystron tk 6 that can be employed as frequency modulator or local oscillator in narrowband radio link systems and radar links operating in the frequency range from 6. Reflex klystron vacuum tube manufactured goods free. The analysis is similar to earlier explanations of electron bunching in a fieldfree drift space and predicts a similar current distribution when bunching takes. A reflex klystron is an obsolete type in which the electron beam was reflected back.
Bunching process in reflex klystron pdf squarespace. Experiment4 study of the characteristics of the klystron tube. It is assumed that oscillations already exist in the tube and they are sustained by its operation. Oct 01, 2014 0type tube is the twocavity klystron, and it is followed by the reflex klystron. Reflex klystron amplifier, microwave klystron amplifier. The whole set up is as shown in the following figure. Klystron multi cavity klystron, reflex klystron, working. Tech regular degree examination, november 2017 scheme. The electrons while passing through the anode cavity, gain some. The maximum electronic efficiency of reflexive klystron is 22. A reflex klystron consists of a single cavity that performs the action of both buncher and catcher cavity.
Electrons emitted from the cathode are accelerated and passed through the positive resonator towards negative reflector, which retards and finally reflects the. These electrons move at a uniform speed towards the anode until they are attracted by it. A second type of reflex klystron, known as the 2k28, uses an external cavity. Klystron working and important applications analysis of 5. Microwave engineering reflex klystron tutorialspoint. To study the characteristics of the reflex klystron tube and to determine the its electronic tuning range. Sutton used a crt electron gun to generate a focused electron beam. One is a lowpower microwave oscillator reflex klystron and the second is a lowpower microwave amplifier two cavity klystron or multi cavity klystron.
Caryotakis, performance of a 150mw sband klystron, aip conf. In a reflex klystron, the electron beam is passed through the only cavity present in the klystron. Introduction to the twocavity klystron amplifier technical. In general efficiency of reflex klystron is about 30%. Explain the principle of operation of a reflex klystron oscillator and derive an expression for the bunching parameter. Each reflex klystron, therefore, has its own calibration protocol. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids.
With the help of applegate diagram illustrate the phenomenon of bunching. The reflex klystron has been the most used source of microwave power in laboratory applications. Klystron, including the reflex and multicavity klystron. Reflex klystrons can be tuned mechanically to adjust the cavity size. Change the reflector voltages and read the current and frequency for each reflector voltage and plot the graph as shown in fig. The reflex klystron amplifier is used as an oscillator in a modulator in microwave transmitters and radar receivers. The development of reflex klystron as local oscillator. Typicallifetimesof8,000to15,000hourshavebeenreported. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. Reflex klystron devices are targetted for low power and are small in sizes. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through. Contents introduction construction working reflex klystron oscillator applications 3.
Explain and perform the gunn diode characteristics using microwave bench setup co3. When switch on the circuit, the electrons starts emitting from the cathode. Electron beams are produced from a source and the cavity klystrons are employed to amplify the signals. Jan 31, 2019 the 3k27 reflex klystron, with a fullrange tuner, is capable of covering the entire frequency range of 770 to 1150 megacycles by rotation of a single knob, and with an average power output of about 1 12 watts. Klystron historical background, applications, and the stateoftheart 2. Optimization of micromachined relex klystrons for operation. Reflex klystron is also known as a sutton klystron. History the fundamental principle behind the klystron, velocity modulation, has an interesting history. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical engineers russell and sigurd varian, which is used as an amplifier for high radio frequencies, from uhf up into the microwave range. 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. Which is impossible and not feasible to use other components for this purpose.
A schematic diagram of a reflex klystron is shown in fig. Reflex klystron is one of the most commonly used microwave low power generators. Pdf optimization of micromachined reflex klystrons for operation. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. Important question and answers on reflex klystron with. To study the characteristics of reflex klystron labappara. The multi cavity klystron consist of a glass envelope in which there is an electron gun composed of heater and cathode. Reflex klystron free download as powerpoint presentation. Aug 19, 2020 there are two configurations for a lowpowered klystron. Reflex klystron working, oscillator and applegate diagram.
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