Wobulator gives you 2 signals - one (about 20..50Hz) saw-like to drive scope X-axis and second is the higher frequency with f changing like that saw signal. When you drive with that output the amplifier input you can see at scope the amplifier characteristic. The picture I send you was the amplifier with demodulator at output. If not demodulated what you see is X-axis symmetrical.
Many years ago I have heared from someone the sentence: Day without wobulation is the lost day 