I got my Diamond CR8900A and mounted it, and it was pretty good out of the box on 2m. I believe it started at 1.8 SWR but as I used it, that dropped to 1.46. It was rainy today and I checked it. 1.66-1.68, which was expected with the rain out there. I figured that, after the rain stopped I would run a copper wire from the mounting bracket to a ground bolt to see if we could lower the SWR. It was fine on 2m but on 10m and 6m it was high. I used an old lamp cord for the test. I stripped the ends and clamped one end to the antenna bracket, and the other to the ground-bolt on the frame which the battery goes to. I dropped the 2m SWR reading to 1.63-1.64. Is this normal or am I grounding/bonding incorrectly? My truck is aluminum but I would have assumed at least a 0.1-.05 VSWR drop. How should I reduce the VSWR in a more potent way?