Make sure that you have the shoulder washer when you install the antenna, it is that plastic washer. That was the only problem that I had when I installed mine.
Yeah I found a diagram online that showed it being used and it was included with the part that I bought so I threw it on there. Sounds like I made the right choice.
I'm also using a Comet mount but I think mine is a HD-5. I also completely scraped all the paint off where the mount is on the hatch. Just before installing the mount, I applied a thin layer of dielectric grease over the bare metal then installed the mount. After the set screws are tight, I then applied a thicker layer of dielectric grease over the remaining bare metal and the mount so hopefully it won't rust. I haven't tuned my setup yet (I need to, just haven't had time) but the reception is really clear however, I don't know how it sounds on the other end. I'm curious how it looks on a SWR meter as well so I may hit one of you up for a tuning session.
I'm not sure how precise or accurate my setup is... but it's all sitting there and seems to work fine so far. I am still a noob when it comes to this stuff so I might have it all wrong, who knows. After a little tuning it should work fine for the trails.
Speaking of which, we should try to plan a run sometime soon. Maybe head a little south to Monticello Canyon?