TP-Link TL-WR703n 3G Router External Antenna Mod
Here are some helpful links:
Step 1. Drill A Hole
Step 2. Cut the two Internal Antenna PCB Traces as shown here: http://blagg.tadkom.net/2012/09/01/wr-703n-external-antenna-mod-diy/
I decided to keep the J1 resistor and C114 capacitor as they orignally were after reading some comments suggesting the signal strength would be better leaving them alone.
Step 3. Solder on Antenna Pigtail Cable. My cable was scavenged from a broken cheapie $5 USB Wifi adapter. The soldering was hard. It is just really small down there. Here is a trick: put a blob of solder on the tip of your hot iron. Now smear that melted blob OFF onto a dry sponge. Now you should be able to PICK UP a SMALLER BLOB of solder and place it where you want.
I used tape to hold down the wire. As you bend the cable, it puts a lot of tension on the two little solder points. If you do not hold down the wire somehow, your precious little solders will eventually break off. Since the tape will eventually fail, it would be far better to hold the wire down with a blob of hot glue gun stuff.
Step 4. Insulate, Assemble and Test. Make sure you insulate the two little R82 resistors under the antenna fitting metal. You do not want to short out the circuit board with the metal from the antenna screw fitting inside the case. A small piece of sturdy electrical tape under the brass nut should cover and protect R82.