As a result of suggestions on another thread, I confirmed the X10 Transmit Buffer works well with a CM15A. I set up a ping-pong test with a CM15A macro programmed to echo F2 whenever it received F1. The initial command was sent from the Ocelot via an unbuffered PSC05. The CM15A was at the other end of the house, and was tested both unbuffered, and running through the XTB. I monitored the X10 level with an ESM1 at an outlet near the Ocelot. The breaker panel is about in the middle of these runs.
The PSC05 transmission lit 7 bars on the ESM, or just over 2.5V. The echo from the unbuffered CM15A lit one bar, or about 100mV. Feeding the CM15A through the XTB increased its level to 3 bars, or not quite 1V. So the increase was substantial. The Ocelot command was recognized by the CM15A every time in both unbuffered and buffered configurations.
I was unsuccessful doing this test with a CM11A. The communication link would not work with XP or W98, and I was unable to download a test program. Unfortunately, the old W95 computer that was used with the CM11A is no longer in service. But, the CM15A tests should be similar.
Jeff