Sorry, I misunderstood your question Daryl. I understand that the 501 transceiver will switch its built-in appliance module on and off via both X-10 RF signals, and power line X-10 signals. The 751 transceiver will only switch its built-in appliance module on/off via RF X-10 signals. What is interesting however is that you said you tried an appliance module and it made the bulb flash when turned off, but you don't get the same effect from the built-in appliance module on your transceiver. I really can't explain that because I thought the electronics were the same.

Robert
RCI Automation