I want to add an external antenna

[natto fire]

To make a long story short, these radiowaves do not travel well through 30 inches of adobe wall very well. The max range I was getting was about 125-160 feet. I want to put an external antenna on the roof. Not sure if the power will need to be boosted too, but that can be worked in.

I took the base station apart and found that it has two pieces of metal shaped like very small allen keys soldered to the PCB. I was wondering if there was a way to solder an external connector and if so, which types could I use?

These operate at 1920-1930 MHz.

 

[pm]

I wouldn't think that this would work very well. You'll be taking a precisely tuned load - the L shaped wires on the PCB - and increasing it dramatically.

But, if I wanted to solder on a connector for 1.9GHz RF, I'd use surface-mount SMA connectors:
http://en.wikipedia.org/wiki/SMA_connector

As you mentioned, you'd likely want to boost the power/tune the output amplifier and this is likely to be tricky so that you don't ruin the input sensitivity. I've done what you are proposing - I fly model airplanes and I have played around a fair bit with RF digital/analog downlinks - and I can honestly say that I've spent a lot of time doing it, and not achieved great results... and downlinks are only a unidirectional data stream. If you know a fair bit about antennas and amplification, you will likely do better than I did... although I studied a lot of books over the years, and I'm an EE.

I'd recommend instead getting a bunch of cordless phones that plug into the telephone jack in the wall so that you have a cordless phone per room or section of the house that doesn't need to reach a central base-station but instead, only it's local dock/cradle.