The conditions for oscillation in Reflex Klystron

hi microwavers :D

so i was studying the reflex klystron and i came through something i cannot understand ....

it is said that the condition of oscillation is Y+Ye=0

or G+Ge≤0

where Y is the total admittance of the cavity and Ye is the electronic admittance

anybody knows why is that the condition for oscillation .... i know that the oscillation condition for any oscillator is : βA=1 .... but couldnt relate this to that ...

There are two general ways to analyze oscillators, loop and one port. The one port method looks for negative resistive portion of the impedance. This is what the two equations you mentioned are about.

can u give me more details about that plz ?

Do a web search for "negative resistance oscillator" and you will get the details.

http://people.deas.harvard.edu/~jone...vanderpol.html is one example of what you will find.

G+Ge<0 "as far as i could remember"
this means that u overcome the losses of the circuit , as far as i could remember u draw the diagram of the Y and u draw a horizontal line of Ge then the part to the left of the line is the region of possible oscillation