@collector:
The reception qualities are outstanding. I didn't succeed in making it NOT receive (it works even in a metal can!). This is probably due to its large antenna which is integrated in the longer part of the strap (see image below). The antenna has a core made of several thin sheets of amorphous metal. The antenna coil is wound around the core at the narrow part in the middle. All this is covered with heat shrink tube. The capacitor required to complete the resonant circuit is under the black epoxy blob.
The antenna in the strap is a bit vulnerable, but still today you can get new straps for about 35EUR. They're mounted to the case with 2 screws.
On interest, I can provide detailed photos of a disassembled antenna (I have one at home that I cut out of a worn-out strap).
About the case material: It's base metal with 5 different coatings.
The cheapest and least durable was the one on the photo above (matt chrome, model 26/0010, flat crystal). Plus:
- polished "titan look" PVD coating (26/0011, curved crystal)
- matt "titan look" PVD (26/0012, flat crystal),
- matt black PVD (26/0013, curved crystal IIRC),
- polished black PVD (26/0014, curved crystal).
Junghans advertised the coatings as "anti allergic".
They came with 4 different straps.
I'm still looking for a mint 26/0011 with original strap for a reasonable price