Jay, Opera16 requires audio tones in the range 1600-1700Hz when the specified program dial frequency is 73.0 kHz, at least with v1.4.9. Are you still sending at 477.0+1.55 kHz, or have you perhaps moved the tone up to +1.65 kHz? -- 73, Garry, K3SIW, EN52ta, Elgin, IL