Oh, well. Sometimes I'm an idiot.
We had some sunny days recently, which left me with enough motivation to install this Beacon. Only to discover, that the SWR is beyond anything I'd call reasonable. I assumed it was, as usual, the metal construction of the roof that caused it. Adjusting the matching circuit didn't help. I was clueless for some minutes until it struck me. To make sure the matching circuit in the foot of the antenna won't become lose due to vibrations of the antenna (introduced by the wind) I've filled the coil with epoxy. Thus, making sure it's permanently attached to the socket. I should have thought about the fact that the material, a coil is wound on, even if it's a non conductive material, affects the inductance. So, well, yeah. The Epoxy filling affected the matching circuit enough to make it unusable.
Well. Do it again, Sam. Looks like I've to build and install a new coil.
Greezings,
Zazzle