The document discusses the reflex klystron, a single cavity microwave oscillator. It consists of an electron gun, a cavity with grids, and a repeller plate. Electrons emitted from the cathode are accelerated through the cavity, undergo velocity modulation, and are repelled back through the cavity. This produces electron bunching and microwave oscillations. Applications include radar receivers, local oscillators, signal sources, and parametric amplifiers.

1. REFLEX KLYSTRON
Presented by: Presented to:
Kamal Jeet Mr Rohit Giri
B.tech(ECE) 3rd yr Dept. of (ECE)

2. CONTENTS
 Introduction
 Construction
 Working
 Reflex Klystron oscillator
 Applications

3. Reflex Klystron
 Microwave Tubes – klystron, reflex klystron, magnetron
and TWT
 Reflex klystron is single cavity variable frequency
microwave oscillator
 Reflex Klystron that works on reflections and oscillations
in a single cavity

4. Construction
 A reflex klystron consists of an electron gun, a cavity with a pair of grids
and a repeller plate
 Accelerating grid are present which insists the electron to travel in linear beam

5. Reflex Klystron oscillator

6. Working
 The cathode emits electrons which are accelerated forward by an
accelerating grid with a positive voltage on it and focused into a narrow
beam
 The electrons pass through the cavity and undergo velocity modulation,
which produces electron bunching and the beam is repelled back by a
repeller plate kept at a negative potential with respect to the cathode.
 On return, the electron beam once again enters the same grids which act
as a buncher

7. Working

8. Working
 er crosses the anode cavity but has no extra velocity and it repels back after
reaching the Repeller electrode, with the same velocity
 let's say ee which has started earlier than reference electron, reaches the Repeller
first, but returns slowly, reaching at the same time
 late electron el, which starts later than both er and ee, however, it moves with
greater velocity while returning back, reaching at the same time
 Now, these three electrons, namely er, ee and el reach the gap at the same time,
forming an electron bunch.

9. Applications
1. Radar receivers
2. Local oscillator in microwave receivers
3. Signal source in microwave generator of variable frequency
4. Portable microwave links
5. Pump oscillator in parametric amplifier

10. References
 https://www.tutorialspoint.com/microwave_engineering/microwave_engin
eering_reflex_klystron.htm
 https://en.wikipedia.org/wiki/Klystron
 http://www.edgefxkits.com/blog/klystron-amplifier-types-and-
applications/
 http://blog.oureducation.in/what-and-how-of-microwave-communication-reflex-
klystron/
 http://www.edgefxkits.com/blog/klystron-amplifier-types-and-applications/