I put a RP-SMA pigtail in a Netgear WGT-634U.  On an AP that's about 300 feet away (but with suburban obstacles), iwconfig reports my link quality/noise margin as 10.  That's with a 5 or 7 db antenna.  Without the antenna, the margin is 6, and with 14db antenna, assuming I aimed it right, the margin is 12.

These just see too low.  Is it more likely that I did a bad job stripping the pigtail wire and soldering, or that there are too many obstacles?