MAX distance of homebrew serial IR? Alternate power source??

[VDR U. <use...@gm...>]

Hi.  I built a homebrew serial IR using the schematics from the lirc
website.  The computer I run VDR on sat right behind the tv so the
serial IR cable was only 2-3 feet long.  I recently rearranged and
moved the computer about 40ft away.  I basically cut the serial IR
cable in half and patched in the extra 40ft using stranded phone wire.
 I discovered that the remote no longer worked.  To test, I removed
the 40ft worth of patched in wire and the remote worked again.

I'm assuming the problem is the distance and either the signal is too
weak to make it to the serial port, or the serial port is too far away
from the IR+circuit to power it.  Is there any way I can test this
theory, or does anyone know what the problem is if my assumption is
wrong?  Additionally, does anyone know how I can fix this?  An
alternate power source maybe?  I have a gigabit switch about a foot
away and can rig up a power source using a pin off an rj45 ethernet
connector if that would work?

Any help is greatly appreciated.

Derek