OK. Here we go again: All settings identical as before EXCEPT modulation set to 30% AM. No signal input noise level 110 mV Signal-plus-noise level at 1 microvolt at 2.0 MHz at 30% modulation at 400 Hz: 900 mV. V2/V1 ratio: 8.181818 S+N/N ratio: 18.256996 db A 20 db S+N/N ratio requires an input of about 1.2 microvolts. Now for CW. Ken W7EKB