[Biggles]

We found the solution to missing glass mount whips (usually the whole whip and pad) was to make sure the glass was absolutely clean with solvent spray before sticking it on and then apply a good bead of RTV silicon compound round the edge of the outer pad. The inside had to be clean too otherwise after a while the inner matching box used to come off and dangle on the coax. We also used to use glass mount VHF and UHF antennas. These had a little adjusting trimmer on the matching box to tune for minimum SWR, but I was never convinced that the whip did much, the matching box coil/capacitor combination probably radiating as much signal as the outer bit. The flexible whips we used on vehicle roof mounts (to avoid damage from vehicles squeezing under low roofs) used to unscrew themselves by rotating at certain vehicle speeds if you didn't apply some loctite to the threads.
Alan.