X10 Passive Couplers

["Jeff Volp" <JeffVolp@xxxxxxx>]

When using the XTB in a house with X10 devices on both phases, a good
passive coupler should be installed to propagate the strong XTB output
signal to the other phase.  The inexpensive .1uF capacitor often recommended
is NOT a good match for the XTB.  That has a capacitive reactance of 13 ohms
at 120KHz, and is barely adequate to transfer the energy from a normal X10
transmitter.  It will also not discriminate between X10 signal and line
noise, and will couple any high frequency line noise directly across the
phases.

The XTB should be used with a series tuned circuit, using a capacitor and
inductor as a minimum.  Should you want to roll you own, a .22uF
630VDC/250VAC capacitor in series with a 8.2uH inductor, similar to the
Miller 5800 8R2, will give good performance.  However, the more elaborate
passive filters sold by X10, Leviton, and Smarthome will provide the best
performance.

Jeff