The dryer units work, but this is not the best place to put a coupler. The problem with passive couplers is when you start out with 3V signals and then send it down the line it just keeps getting weaker. Every path to neutral that it finds drains a little of the signal strength. Then you add a passive coupler to the mix and it does allow the signal to pass to the other phase, but at the same time it gives it all the additional paths to dissipate. This extra dissipation causes the second phase to increase strength at the expense of the strength of the first phase. In a lot of homes there is still sufficient signal left to operate the X10 module, but it's always on the edge. So we don't bother with passive couplers on any installs, and I do not recommend them to anyone that wants their automation system to be reliable unless they are really budget constrained. The coupler repeater takes what ever signal is left on the sending leg, looks it up and resends it out on both legs at 5-6 volts, which compensates for a lot of other problems like noise. The passive couplers work and are fine sometimes but the margin a coupler repeater gives you is just worth the extra expense.

Bill
www.homeautomationnet.com