Mal, Stefan et al.,

You wrote:

...
Try permability osc tuning like Collins use instead of variable condensers, 
maybe even a valve osc.
...

Of course the best choice. But
1. you need an iron-dust cylindrical core, hard to find.
   (you know, ferrite is a bad choice for oscillators)
2. if you need a linear tuning range careful aligning of each winding
   is a must.
   (I remember photos from Drake, workers adjusting coils for "4-Lines")
3. without elaborate mechanics slack will be a big problem.

STEFAN, DK7FC: if you need some small "red" and/or "yellow" cores
I have an envelope and stamps - but no address ???

Otherwise try http://www.kitsandparts.com/ from USA.
Order in German, he's a "Fischkopp" like myself.

Peter, df3lp