@mcchaos Google for "Frag Jan Zuerst" or go to https://www.die-wuestens.de/eindex.htm and click on "Catalogue" in a top left. He has all kind of "wrird" or unusual electronic stuff, including tubes.
Not affiliated with him, not even bought one thing ever.
But he's been there for some years and was mentioned in the german "Funkamateur" magazine several times.
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