There are posts now for external antennas on the WMR100 and WMR200. Why not the WMR80? I did this with my WMR80A and if made a world of difference -- it picks up all sensors from any room in the house now. It's quite easy to do and will of course void your warranty. For some background, see these two related posts: "External Antenna for WMR100" and "WMR200 External Antenna".
Here's how:
- Remove the batteries.
- Remove six screws (accessible from the back) holding the two halves of the case together.
- Carefully separate the two halves of the case. There are several wires running between the two halves, so be gentle.
- Lay the front half face down on a flat surface. The wires are long enough that you can lay the back half down next to the front half.
- Un-solder the built-in antenna (the two bare wires that are coiled at the ends) and remove it from the housing. You may have to pull gently with needle-nose pliers where the antenna is glued to the case.
- Solder a length of insulated wire (anything from 18 to 24 gauge works well for this) to the bottom antenna connection and run it down the side of the case and along the bottom (see photo). I used insulated wire to keep it from shorting to any metal or circuitry that might be along the bottom. Make sure the end of the wire is not in contact with anything metallic or any circuitry.
- Drill a 1/16th inch hole in the top of the case as shown in the photo. Keep the drill going and drill a hole in the thin plastic rib just below the top of the case (see photo).
- Cut an 18" length of #14 solid insulated wire. Strip enough insulation so you can insert it down through the top of the case, all the way to the upper antenna terminal and solder in place (see photo).
- Fit the case halves back together. You may need to adjust how the antenna wires are bent/routed if there is interference.
- Install and tighten the six screws and re-install the batteries.
It might help a little to trim the external wire in 1/4" increments -- but probably no more than an inch at the most. This was not necessary on my unit.
It should also be quite easy to make a modification similar to what gadgetguy did with his WMR100 -- installing an antenna connector instead. See the "External Antenna for WMR100" post for details.
