Antenna curiosities

[gusm]

I've installed a CB in my 1995 Mercedes Benz E300D. I would have loved to mount a permanent antenna but other than drilling a hole in my car somewhere this is not an option. This is my work car that I put 1200 miles per week on but still; I just don't want to drill a hole in it.
My problem is with magnetic antenna's. I have bought two of them one is a 5' whip from Radio Shack w/5" magnetic base; the other is a short rubberized antenna about 16" high on a 3" magnetic base. Neither of these antenna's will let me transmit. I can receive; all-be-it noisy but I can not transmit at all. Although the Uniden 510xl lights up like a Christmas tree when I key the mic.
I suspect a grounding issue; but I just can't get my head around the fact that the body wouldn't already be grounded. I was wondering what your take on this problem might be.

Thanks,
gus

[Cobra]

Is your CB new? Has it ever been keyed without the antenna hooked up? Worse case scenario, blown finals (transistors).

Check the SWR's. An SWR of less than 2:1 is best. Anything over will indicate a problem in the antenna system.

Check the ground. Make sure the CB is grounded well on bare metal.