Assertion A: A reflex klystron is a single cavity high power generator of efficiency 90%. Reason R: The loop gain is unity with a phase shift of multiple of 2π.

 

88) Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R 

 Assertion A: A reflex klystron is a single cavity high power generator of efficiency 90%. 

Reason R: The loop gain is unity with a phase shift of multiple of 2π. 

In light of the above statements, choose the most appropriate answer from the options given below 

1. Both A and R are correct and R is the correct explanation of A [Option ID = 3181] 

2. Both A and R are correct but R is NOT the correct explanation of A [Option ID = 3182] 

3. A is correct but R is not correct [Option ID = 3183] 

4. A is not correct but R is correct [Option ID = 3184] 

Answer: 4

Solution

A reflex klystron is indeed a single-cavity microwave oscillator.

However, it is a low-power microwave source, not a high-power generator.

Its efficiency is typically around 20%–30%, sometimes up to 40%, but not 90%.

Statement 2: This is the Barkhausen criterion for sustained oscillations:

$$|A\beta| = 1$$

and

$$\angle (A\beta) = 2n\pi$$

where $n = 0,1,2,\ldots$

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