The term is actually "Weichlot-Verbindung."
Without a doubt, Merkel didn't make their tubes (or assemble them??) as the order form on page 29 of the Autumn 2009 DGJ notes that the tubes/assembled tubes for the 12/9.3X53 were ordered from none other than "L. Kelber" on 3.29.1928 and were delivered on 4.4.1928. Surely he didn't perform all the work in about a week? But L. Kelber is none other than tube maker Louis Kelber of Trubenbachstrasse 1, Suhl. He was a specialist in his field. This shows that in a pinch, and maybe the norm, that a larger concern still sourced the talented craftsmen of Suhl.
And also note at the top of the page Merkel sourced Wilhelm Kelber for the 12(70mm)? tubes during the same period(3.19.1928) and he delivered on 4.11.1928?
Kind Regards,
Raimey
rse
