Daryl. There are a few ways of improving X-10 signal strength. The first is to eliminate electrical appliances creating noise on your AC power line that conflicts with X-10 signals. The worst offenders are older TV's and surge supressors. You might try unplugging electrical appliances one at a time and see if it helps. There are more precise ways of doing this but you need test equipment. If you have identified an offending appliance, you can purchase individual plug-in noise blocker modules. The only thing these modules do is filter electrical noise at the same frequency as the X-10 signals.
If you have done this and it didn't help, you probably have a electrical phase problem, meaning your X-10 transmitter is on one electrical phase and the X-10 receiver is on the other. The way to test this is to turn on any 220 volt appliance in your home (e.g., oven or dryer) and then try your X-10 stuff. If your signal is improved, it is because your 220 volt appliance is bridging the two electrical phases. The solution for this is to purchase an X-10 signal bridge. There are two types though. One is amplified and one is not. The amplified version is much better because when it picks up the X-10 signal on one phase, it not only "bridges" it to the other phase, it amplifies the signal substantially. The amplified signal is so strong that it will overcome line noise in many cases. I highly recommend the amplified signal bridge over the non-amplified version.
We offer both of these product so just send us an e-mail and we can provide you with more information.
RCI Automation[Link: ourworld.compuserve.com]