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[bkenobi]

I have a circuit that has 2 FilterLinc 10A filters installed on it.  I also have 2 other unfiltered devices plugged into that circuit.  Without filters, I get zero signal strength from my XTB-IIR when plugging my XTBM on that circuit near the devices.  When I unplug all devices, I get good signal strengths (8-9.99).  When I plug in the filters with the devices, the signal drops by around 2.5 on the meter.  If I plug the filter in without the device plugged in, I actually get the same reading as without.  I guess that means that the filter is a moderate signal sucker.  I have checked the 2 unfiltered devices and they do not cause a significant change in signal strength when plugging in the meter locally to the device.

So, here's what I'm confused about.  If I go down to the main breaker panels and plug the meter into the outlet right below the panel, I get zero signal from the XTB-IIR if everything is hooked up normally.  If I kill that circuit breaker, I get a signal of 9.99.  If I unplug all devices on that circuit and turn it back on, I get the same 9.99 signal.  If I plug in one filtered device or one of the unfiltered devices, the signal drops to zero.  Does anyone have a clue what's going on here?  The outlet by the panel is on a different panel than the problem circuit.  I don't recall if the outlet and the problem circuit are on the same leg of power.  Either way, why would the signal from the XTB-IIR be attenuated so much by a signal sucker much farther away and yet not be as much of a problem when measuring near the filters?  I'm at a loss here.

[JeffVolp]

That is an interesting problem.

First, all X10 devices, including filters, do present some loading to X10 signals.  X10 transmitters present the most loading.  Even the XTB-F10 filter presents some loading, but not as much as X10’s own XPPF.

I did receive a report some time ago about an expensive surge protector severely loading down the XTB-IIR signal level.  As I recall, it placed something like 5 microfarads across the powerline.  That is an extremely heavy load at 120Khz – just a fraction of an ohm.  But even that didn't totally kill the XTB-IIR output.

The only way I can see reading absolutely no signal from the XTB-IIR is that it is not transmitting at all.  What may be happening is that something on that circuit is generating enough powerline noise that it is causing the XTB-IIR to raise its detection threshold above the incoming signal that would be repeated.  Or the signal source is just too low for the XTB-IIR to pick up when that circuit is loading it down.

Jeff

[bkenobi]

The really strange thing is that I get a signal strength with everything plugged in if the meter is close to the load but nothing if I move far away from the load and close to the XTB-IIR.  Adding filters is supposed to fix this type of problem, so I'm at a loss as to what to try next.  I guess the one thing I didn't try was turning off everything but the XTB-IIR and that circuit.  Maybe there's some strange interaction between that circuit and something else.

[westom]

Either way, why would the signal from the XTB-IIR be attenuated so much by a signal sucker much farther away and yet not be as much of a problem when measuring near the filters? 

Numerous electrical issues are at play.  For example, let's say your signal source transmits a short pulse.  Where is that pulse first seen?  At an adjacent meter?  Or at a meter at the far end?

  That pulse is first measured by a meter at the far end.  Then later by a meter adjacent to the signal source.  It makes no sense using layman speculation.  But it makes complete sense when using concepts on how electricity really works.

  In another example, a 200 watt transmitter is connected to a long wire antenna.  Touch one part of that antenna to be jolted maybe by 100 volts.  Touch another part of the same wire to feel no voltage.  Another example of how electricity works.  A 'signal sucker' at a point where voltage is zero would not 'suck' any signal.  Answer depends on how your wires are uniquely routed.

[dave w]

bkenobi:

I may have missed it, but do you have a problem other than strange readings on the XTBM? e.g. does an Appliance Module work on the circuit where the filters are? Or at the outlet where you get no signal on the XTBM?

[bkenobi]

I have not noticed any failures of any modules that i can attribute to these filters and the mystery signal killer. I realized this morning that I have another one of these filters on my TV and stereo.  That filter kills XTB-IIR to XTBM signal locally.  I wonder if there is some problem with using multiple of these smarthome units in the same setup.

Again, this strange behavior does not seem to cause any functional issues that I have seen as of yet.  I'm just trying to fix this since I noticed it and would rather fix it before it does cause an issue.

[JeffVolp]

The higher current filters are notch filters.  An out-of-tolerance component could move that notch enough off frequency so that it could present a significant load.

I test each one I assembly myself for both loading and signal rejection.  I wonder if the other manufactures are as rigorous in their testing.

Jeff

[bkenobi]

Is there something that I can do with the tools that I have to determine if a component could be replaced such that it would fix the problem?  I don't have a scope, but I have other basic tools.  It seems like it would be worth pulling one of the filters out and checking to see if there's anything going on inside.

The thing that I haven't put much weight on is the fact that one of the unfiltered devices seems to cause the same problem as the filters themselves.  That device is an old EM pinball machine.  It has a switch that kills power to the unit such that once it's flipped, it's the same as unplugging it from the wall (IOW, it's not like a modern computer power switch).  If the pinball is plugged in, the signal drops to zero just the same as the filters.  I can't see that the pinball could cause noise when turned off, could it?

[dave w]

I can't see that the pinball could cause noise when turned off, could it?

My $0.02 would be No, not if electrically it is same as unplugging. Electricity is mysterious, but not magical. 

OK another silly question: Did you get the filters before the XTBIIR? Are you sure you need (all of) them?

[bkenobi]

I don't recall if they were before or after the XTB-IIR.  I know they were after the XTBM since that's what found the problem components.  Since everything seemed to work ok, I haven't don e any tinkering recently with the filters.  As I recall, after I installed them I checked and the XTBM did pick up signal from the outlets in question.  It might be interesting to try removing the filters to see if things get notably better or worse.

[Brian H]

Not too much you could mess with inside a Filterlinc.
I looked inside three of mine and the three caps maybe 10%. Only a guess as they have no tolerance marking that I could see.
http://home.comcast.net/~gafield/family/gary/electronics/X10_Filter.pdf

I doubt Smarthome does any matching of caps and the inductors.

One BIG tip. If you do not like random surprises. Unplug the FilterLinc with a load on it.
The 2.2uf cap that is basically across the Line and Neutral and has no large value discharge resistor on it. It can have a nice charge on it if you unplugged the FilterLinc when the AC wave was near or at peek.
Want to guess how I know that? 

[JeffVolp]

The 2.2uf cap that is basically across the Line and Neutral and has no large value discharge resistor on it. It can have a nice charge on it if you unplugged the FilterLinc when the AC wave was near or at peek.
Want to guess how I know that? 

Been there, done that...  That's why mine have a 330K across that cap.  As I recall, the UL spec says the voltage across the cap must discharge to 37% of the peak value within 1 second.

Jeff

[bkenobi]

So I shouldn't lick the plug?   

[Brian H]

Mine are not recent date codes and I was hoping maybe later versions had the added resistor.
Though I still see folks in the Smarthome forums. Reporting surprise shocks or a spark when they put one down on a metal surface.

[dave w]

  It might be interesting to try removing the filters to see if things get notably better or worse.

Yeah, that's where I was going with the question. I was able to dump two filters after upgrading to the XTBIIR. Only one remains, on a nasty Panasonic microwave.  I'm sure I will need them with the next flat screen TV, or new notebook, etc. etc. but I like relieing on the XTBIIR brute force because the filters are just added loads at X10 frequencies. When / if the system becomes unreliable again,  I at least know where my biggest noise makers are (Panasonic cordless phone wall warts...hmmmm Panasonic seems to be the common element...).