Troubleshooting Channel Vision IR-Over-Coax

["Rob Ivy" <robivy@xxxxxxxxxxx>]

Hello everyone.  I'm looking for some assistance from those of you
running an IR-over-coax system in your home.

Here's a summary of my setup: I have Cat6 and coax home run from each
room in my house back to a rack in my laundry room.  I'm routing cable
plus modulating 2 Tivos  through a Channel Vision CVT2/8-PIA II
amplified splitter to 5 TVs.  I have a Channel Vision IR-4000 engine
attached to one of the 3 unused outputs on the splitter, and I have
Channel Vision IR-4100 receivers on 4 of the 5 TVs.  I'm using Channel
Vision IR-2105 targets plugged into the IR-4100s.  I have DC blockers
on the 2 unused outputs on the splitter, the 5th TV, and the cable
input to the splitter.  This setup is exactly as depicted in the
channel vision literature.

Here's the problem:  When any 2 of the IR-2105 targets are plugged in,
everything works just fine.  I can control my Tivos remotely from
those 2 TVs with no problems.  However, when I plug in the third
IR-2105 target, the response becomes spotty.  Some signals get through
but most don't.  When all four IR-2105s are plugged in, there is no
response whatsoever from any of the 4 locations.  I know that the DC
is passing to all the targets, because the bright blue indicator bulb
lights brightly when they receive IR, yet the IR is not making it back
to the engine.

My only thought (and I'm no expert on any of this so this is just
speculation) is that perhaps there is a limit to how much distance the
DC can travel without weakening to the point where it can no longer
carry the IR signal.   My four coax runs where the IR-4100s are
located are of approx 40ft, 50ft, 120ft, and 120ft, respectively.
Perhaps the single 12V DC input to the IR-4000 doesn't have the
horsepower necessary?  The Channel Vision instructions state that 4
IR-4100s can be run off of a single engine, and that the max distance
to the engine is 500ft, however it doesn't say if that is 500 feet in
aggregate or each individual run.

Any help/thoughts/advice is MUCH appreciated, as this is driving me
nuts.  Many thanks in advance.   -Rob