I've modded a regular 'Rubber duck' antenna for my wt-2 - see below
I just dremmeled about 2 mm off the end, The thread seems to hold. I'm using this with a 120 degree 12 Dbi sector antenna. So far, good results, but not really tested this combination to the full. I wqas going to use it at an event this weekend, but the location meant that I was based at th ebottonm of a slope, and I couldn't get the antenna high enough. Over flat ground though I'm hoping for 300-400 m range.
regards
Gareth Jones