The reflex klystron oscillator is a lowpower, lowefficiency microwave oscillator, illustrated schematically in figure 118. The reflex klystron contains a reflector plate, referred to as the. Timedomain particleincell modeling of delayed feedback klystron oscillators article pdf available in ieee transactions on electron devices 616. Reflex klystron telecommunications engineering mechanics. Dhanalakshmi college of engineering department of ece. In the case of electronic tuning circuit, the control can be brought about by using a waveguide or microwave cavity or varactor diode or yig sphere. Multi cavity klystron two cavity klystronused as lowpower.
Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable. All operated at 250 v resonator voltage, with an electronic tuning range of 30 mhz and 150 mw output power. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. This problem of tuning is responsible, to a large extent, for the fact that of all forms of klystrons, by far the most common is the reflex klystron which utilizes only one resonant cavity. Reflex klystron reduced power from the bunches, in reflex klystron, reduces the reflex klystron of the cavity oscillations and causes a decrease in output power. What is the operating frequency and power output of a reflex klystron. The analysis is similar to earlier explanations of electron bunching in a fieldfree drift space and predicts a similar current distribution when bunching takes place in a reflecting field. May 02, 2020 microwave engineering lab viva question bank, engineering edurev notes is made by best teachers of. To study the mode characteristics of the reflex klystron tube and to determine its electronic tuning range. The tuning range of klystron lies between 5 ghz at 2w to 30 ghz at 10 mw. Pdf complex dynamics of a doublecavity delayed feedback. There are often several regions of reflector voltage where the reflex klystron will oscillate. This is most widely used in applications where variable frequency is desired as. The cavity operates in its fundamental mode and tunes smoothly over the wavelength band.
Early in 1940 british had taken the decision to build radiolocalization sets operating around 10 cm. From each mode and the band of frequencies over which the circuit can be. After the focusing electrodes there is a cavity resonator which encircles the glass envelope. Coates 200720 the actual value of m depends on how effectively the two inductors are magnetically coupled, which among other factors depends on the spacing between the inductors, the number of turns on each inductor, the dimensions of each coil and the material of the common core. It is a lowpower device used primarily for two purposes.
Electronic tuning and output power of a reflex klystron. Klystron oscillator reflex klystron traveling wave tube magnetron. Experiment4 study of the characteristics of the klystron tube. A sutton tube, or reflex klystron, is a type of vacuum tube used to generate microwaves. Electronic tuning is also possible, by adjustment of the repeller voltage. The development of reflex klystron as local oscillator. Such mechanical tuning of reflex klystron oscillator may give a frequency variation which ranges in practice from 20 mhz at x band to 4 ghz at 200 ghz. The reflex klystron is a single cavity variable frequency microwave generator of low power and low efficiency. Klausst 72fvm 36betwixt 22 reflex klystron, volker muehlhaus 21asdf44 the process is referred to as modulation. 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. It is possible to produce oscillations in a klystron device which has only one cavity, through which electrons pass twice. Oscillators are used to generate coherent sinusoidal waveforms which may be used to transmit information or energy. By the way, the idea of factory installed and adjusted cavities was accepted also by.
The 2k28 reflex klystron has a lead protruding through the top of the glass envelope which is used to connect the reflector voltage to the tube. This is the reflex klystron oscillator, which will now be described. The main difference between two cavity reflex klystron amplifier. From each mode and the band of frequencies over which the circuit can be tuned. The work was advanced by the spacechargewave propagation theory of hahn and ramo l in 1939 and con. This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam. Some modifications and additions have been made in the interest of flexibility and ease of adjustment.
What is the range of frequency variation of reflex klystron in the xband by the above two methods. As shown in the given diagram it is composed of heater, cathode, focusing electrodes and repeller anode. This wave shape is useful for changing sweeping the. Comparing the mechanism of reflex klystron and barkhausenkurz oscillators, we found them principally to be the same. The tuning range is about 8 mhz at x band and 80 mhz for submillimeter klystrons. 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. The sutton tube, the first reflex klystron oscillator.
What is mechanical tuning and electronic tuning in a reflex klystron. Important question and answers on reflex klystron with. Just how this is accomplished may be seen by considering fig. The amount the frequency can be varied above or below the center frequency is limited by the halfpower points of the mode, as shown in figure 212. Electronic tuning does not change the center frequency of the cavity, but does vary the frequency within the mode of operation.
I think u1 may have to do with getting the reflex klystron started. To study the characteristics of the reflex klystron tube and to determine the its electronic tuning range equipments klystron power supply, klystron with mount, isolator, frequency meter, variable attenuator, xband detector, bnctobnc cable and oscilloscope theory reflex klystron is one of the most commonly used microwave low power generators. Reflex klystron the analysis of a reflex klystron is similar to that. The theory of the twocavity klystron can be applied to the nalysis of the reflex klystron with slight modification. It is mounted in a metal envelope having a glass window through which the output power passes. The reflex klystron also known as a sutton tube after one of its inventors, robert sutton was a low power klystron tube with a single cavity, which functioned as an oscillator. Caryotakis, performance of a 150mw sband klystron, aip conf. The selfoscillation and stationary oscillation conditions are analyzed theoretically.
Therefore, two cavity klystrons are generally used for fixedfrequency applications. Reflex klystron oscillator operation application of. Us2944183a us636261a us63626157a us2944183a us 2944183 a us2944183 a us 2944183a us 636261 a us636261 a us 636261a us 63626157 a us63626157 a us 63626157a us 2944183 a us2944183 a us 2944183a authority us united states prior art keywords cavity coupling secondary iris resonator prior art date 19570125 legal status the legal status is an assumption and is not a legal. Sylvanias reflex klystron is designed to operate at wavelengths be tween 67 cm. Reflex klystron used as a lowpower microwave oscillator 2. At birmingham a group of scientist leaded by professor mark oliphant was working since 1939 on power transmitting klystrons, based upon information and prototypes of the velocity modulated. It was used as a local oscillator in some radar receivers and a modulator in microwave transmitters the 1950s and 1960s, but is now obsolete, replaced by semiconductor microwave devices.
All these components are enclosed in a glass envelope. Normally we use separate components in devices such as radio transmitters and receivers but as frequencies increase the two components merge into one structure and become a. Coates 200720 sweep oscillators a sweep waveform is another name for a sawtooth wave. In order to generate microwave frequencies we need amplifiers or oscillators,in this video we will learn how a reflex klystron oscillator works in generation of microwave frequencies. As reflex klystrons are oscillators thus find applications in local oscillators receivers, radar receivers, radio receivers. A comprehensive analysis of reflex klystrons is developed by considering the electrons as particles acted upon by forces which modify their motion.
A klystron is a vacuum tube that can be used either as a generator or as an amplifier of power, at microwave frequencies klystron types there are two basic configurations of klystron tubes 1. However the resonant frequency can be tuned externally either by mechanical or by electrical means. Klystron oscillators are used mainly in parametric amplifiers and in radio beacons with wavelengths in the centimeter or millimeter range. As power oscillator 5 50 ghz if used as a klystron amplifier. Klystron multi cavity klystron, reflex klystron, working. This tube is called a reflex klystron because it repels the input supply or performs the opposite function of a klystron. The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity but here the similarity ends. Wiring with a repeller klystron, and an example given low power repeller klystron tube repeller klystrons are often used in older radar sets as local oscillators or as oscillators in measurement sets. The microwave oscillations are coupled out by means of an inductive pickup loop and fed through the short section of coaxial line shown on the lefthand side of the cavity. To understand the operation of a reflex klystron i think you need to start with a basic understanding of a tuned circuit made up from a capacitor c and inductor l. The present description refers to xbnd 2k25 reflex klystron oscillators, but most of the components can be used with other tubes employing the same operating voltages. A schematic diagram of the reflex klystron is shown in fig. Klystron article about klystron by the free dictionary. History the fundamental principle behind the klystron, velocity modulation, has an interesting history.
Cavities used in a twocavity klystron have high q values with narrow bandwidths, and thus, individual tuning is awkward. In the case of gunn oscillators, the oscillation frequency primarily depends on the middle active layer of the gunn diode. Here we will discuss oscillators based on semiconductor devices. The paper describes a reflex klystron oscillator, tunable over the wavelength range of 89 mm, which is suitable both for use in a superheterodyne receiver and as a source for laboratory measurements. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids.
The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity, but here the similarity ends. Klystrons are used as amplifiers at microwave and radio frequencies to produce both lowpower reference signals for superheterodyne radar receivers and to produce highpower carrier waves for communications and the driving force for modern particle accelerator s klystron amplifiers have the advantage over the. Us2944183a internal cavity reflex klystron tuned by a. 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 complex dynamics of a model doublecavity delayed feedback klystron oscillator is considered.
719 562 1372 1181 1411 1278 794 49 732 1143 694 1004 352 1075 656 1607 1028 1399 1198 1246 1334 557 669 585 1450 944 14 121 141 864 1297 57 1066 1154 1015 1491 1107 82 162 445