Do you use any frequency less than 10kHz?
What is the output impedance of the signal source? A low impedance from the output of an opamp or a high impedance from the collector of a transistor?

 

Do you use any frequency less than 10kHz?
What is the output impedance of the signal source? A low impedance from the output of an opamp or a high impedance from the collector of a transistor?

I use signal from signal generator in protus. Also, I use 10khz only