XTB-II and UPB Bridge


Senior Member
I am thinking of installing an XTB-II for my legacy X-10 stuff because the XTB-II put the X-10 signal on both AC power legs at the same time. I am also thinking of installing a UPB passive coupler to act as a hard wired bridge for Insteon signals.

Since the UPB bridge will also bridge X-10 signals I am wondering if there are any issues with installing it next to the XTB-II? The UPB bridge would effectively be a shunt across the output of the XTB-II and I can't figure out if that is good, bad or just not an issue?
A 2-wire passive coupler between the phases should have no significant effect on the XTB-II output. It drives both phases with the same 120KHz signal. The 40V UPB signals are in the 4KHz to 40KHz range, so the coupling networks in the XTB-II will not pass much of that signal.

It is possible that UPB signals can appear as noise to the XTB-II, and corrupt an incomming X10 message transmitted at the same time. This is something that should be considered in a combined system if you send X10 signals back from remote transmitters.

What if I use the Smarthome model 4816H SignaLinc phase coupler? It looks like it will be better tuned for X-10 and Insteon than the UPB coupler is.

The UPB noise issue would not apply here as I am not using UPB. I was just looking at UPB couplers because they are reported to work well for Insteon too.
What if I use the Smarthome model 4816H SignaLinc phase coupler?

While I haven't used that myself, its specs look good. It may be the best choice in a passive coupler.

The XTB-II coupling networks are optimized for X10, but they will still pass some energy at 135KHz. It passively couples about half the voltage from phase to phase at 120KHz. It might couple about 1/4 of the Insteon signal across the phases. An additional passive coupler may not be necessary. Certainly not for X10 if you enable its repeater function.

So how about this...

An XTB-II plus 2 duplex outlets on oppsite legs. I put Insteon appliance modules in each outlet (Since all Insteon devices are repeaters). The Insteon module on the signal source side will repeat what it hears and about 1/4 of that will pass through the XTB-II to the other module which will repeat it on the other leg at full strength.

Not sure if this ends up being better than 2 SignaLincs in outlets right next to each other (but on opposite legs). I'm just assuming the transition from AC to RF and then RF back to AC must count as a couple of extra hops?

Also what would be the negative effect of having additional passive couplers? another one down at a subpanel someplace?
Additional passive couplers downstream shouldn't be necessary if the XTB-II is the source, but it will help distribute signals from remote transmitters.

Your idea on the Insteon modules sounds like it should work.