If you're trying to control the TM751's appliance outlet from the IR543, then you're out of luck. The TM751 has exactly zero capability to __RECEIVE__ powerline X-10 signals. It does of course receive RF X-10 and that will control the TM751's built-in appliance outlet. If you just have to have a transceiver with an appliance outlet that can be operated from powerline X-10 signals, then get an RR501. It will do everything the TM751 can and then some.

John Galvin