I received this Tram 300 antenna as part of a package deal with a radio I bought from Walmart and it has a nice rubber cushion to protect your vehicle paint. I was thinking I might like to try it on top of my astro van because it is shorter than my Wilson Lill Will or my K40, but I was wondering if anyone ever tried putting a spring between the base and the whip? I would like that extra protection from low hanging objects like canopy's. It might play havoc with the swr but was wondering if it could be adjusted out. Anyone ever try it before I waste my money on a spring?