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how to measure the Q-factor of oscillators

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nauwaf

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if any body Knows how to measure the Q-factor of an oscillator, please help me.
i have a DRO operating at 6.3GHz. i am not asking how to measure the Q-factor of the dielectric resonator i want the Q-factor of the whole oscillator.
thanks
 

teteamigo

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A spectrum analyser and measure the one half power to central frequency.

Q=central frequency/bandwidth


Bandwith in the sense of 2*(fcentral-f at half power)

f=frequency
 

biff44

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I do not think so. If you had a mesfet oscillator vs a bipolar oscillator, that method would yield a 20 dB different "Q factor", irregardless of the actual loaded Q.

The best way to measure the loaded Q of the entire oscillator would be to injection lock it to a signal and see how far you can pull it. The ammount of frequency pulling is inversely proportional to Q.
 

nauwaf

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thank you
i just got it so i cant measure it but i can have a feel of it by the pull push method. by varying the load and the power supply. thanks
 

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