I picked up a fairly new weather radio from Oregon Scientific (Model WR102) at a consignment outfitter recently. Unfortunately, due to my location, I couldn't get any signal using just the onboard antenna. I decided to rectify this situation, and make a detachable antenna for when I needed better signal. Sorry for the picture quality my camera kinda sucks and I can't afford to get a new one at the moment.
Step 1: Materials and Tools
For this project, you won't really need very much.
Small phillips head screwdriver
Soldering iron and solder (if desired, I did not use mine)
several feet of very narrow-gauge wire(I used about 24 gauge)
Crimp-on releasable connectors
External antenna (I salvaged mine from a clock radio)
Step 2: Crack open the casing
To open up the case, you need to remove four screws. Two are just outside the battery compartment, and two are on the inside. While you're doing this, make sure not to lose the thin gasket that waterproofs the batteries. Set these screws aside, and try not to lose them. Then gently pry the case open. It may catch a bit, but just keep at it
Step 3: Unscrew the existing antenna
For this step, you will need to get access to the small built-in antenna. To do so, you need to unscrew three small screws in the upper pcb of the radio, and then unscrew the antenna from the case. Hold on to the very small screw that held the two together. This is where a magnetized screwdriver comes in handy.
Step 4: Drill the hole for the antenna
I forgot to take photos for this step while I was doing it, but you need to drill a very narrow hole through the casing between the existing antenna and the headphone jack. This will be sealed with superglue later. Go very gently, as you don't want to go through too fast and damage the internals.
Step 5: Attach the new antenna wire
Now, you're going to thread the wiring you will be using for the antenna through the hole in the casing made in the previous step. Then, strip about 3/4" off the end, and wrap it around the screw that was holding the antenna in place. Now replace the screw in the same manner that it was in previously. You could also simply solder the wire onto the main board, but i'm not very skilled at soldering and didn't want to try it.
Step 6: Reassemble everything!
You're almost done! Just reassemble the whole thing, losing about half the screws in the process. Then put a small dab of superglue on the outside of the case where the wire comes out, so as to waterproof it.
Step 7: You're done!
Now that you've got the wire coming out, you can just leave it like that, or put some detachable crimped connectors on it to extend your range even further. I forgot to document that portion. Either way, enjoy your crystal-clear connection!