I ran an LTSpice simulation on the attached common-emitter amplifier. The ac voltage gain
is 10 with input signals between 28mV peak and 148 mV peak.

When I bread boarded the circuit, the ac voltage gain varied depending on the input
signal which ranged between 28mV peak and 148 mV peak. Why would the gain
vary?

Thanks,

David

 

You are compressing the signal peaks at higher signal levels which makes the gain appear lower.
Check the bias voltages.
You need to bias the circuit at a lower emitter and collector voltage (lower values for R5 and R2) to allow more signal output amplitude (dynamic range).
Ideally you want to bias the collector voltage about midway between the supply voltage and the emitter voltage with an emitter voltage of 2-4V or so.

 

This might help -

http://www.guitarscience.net/calcs/ce.htm

https://www.electronics-tutorials.ws/amplifier/amp_2.html

Regards, Dana

 

See

 

You are compressing the signal peaks at higher signal levels which makes the gain appear lower.
Check the bias voltages.
You need to bias the circuit at a lower emitter and collector voltage (lower values for R5 and R2) to allow more signal output amplitude (dynamic range).
Ideally you want to bias the collector voltage about midway between the supply voltage and the emitter voltage with an emitter voltage of 2-4V or so.

Thank You

 

This might help -

http://www.guitarscience.net/calcs/ce.htm

https://www.electronics-tutorials.ws/amplifier/amp_2.html

Regards, Dana

Thank You

This might help -

http://www.guitarscience.net/calcs/ce.htm

https://www.electronics-tutorials.ws/amplifier/amp_2.html

Regards, Dana

 

See
View attachment 152477

Thank You