As a new HAM I'm still learning a lot.  I am weak mastering knowledge in so many areas but trying. 

I have set up my node using a Linksys WRT54G.  It is confirmed flashed and ready to roll.  I'm about to put it up on my chimney next to my dual band antenna (2m/70cm) which extends about a foot or two above the chimney crown.  I was planning on attaching the linksys on the top of my chimney mounted vertically with a box around it that is sealed (but large enough for the captured air to to insulate.  It might have a door so I can access the unit or I might just have to cut around the sealant when I need to get to it.  It shouldn't be exposed to very much sunlight in the summer so i'm not too worried about overheating since it won't be processing data all the time.

I am powering the unit via ethernet with A/C power pigtails on both ends of the ethernet Cat7 so I won't be running any extension power cord to the unit.  Two of the unused channels in the ethernet cable will run the power to power to the unit. I'll plug in the 12-volt converter at shack end of the line so I'll only have 12 volts running through the ether.  This way only the ethernet cat7 cable will connect from shack to node.

My question is about an antenna.  I understand that the two Linksys WRT54G's antennas are specifically designed for one to transmit and one to receive.  If that is the case, can I just use a duplexer to blend the signal and route it through the box (sealed penetration) and run that short single coax into a mag mount 2.4GHz antenna a top the metal chimney crown?  I am close enough to two other nodes (about a mile away and line of sight) so I believe they will communicate without a directional beam antenna. I am pretty high in NW Austin so I think my signal can be picked up pretty easily. 

Side note, if there are any node owners in the NW Austin area around Oak Knoll/Jollyville/183, content me please. I'd like to talk about the signal strength as I set this up.  I can be contacted at ham@texcode.com

(I had images to show but they wouldn't upload even when reduced to <50k jpegs)