[turretslug]

There was a very substantial US military presence in the-then West Germany post-war and overseas allowance was good- could there have been a significant number of the quality table radios etc. offered by a number of German manufacturers and equipped largely or solely with Rimlock valves that came back to the US with their owners, subsequently resulting in a worthwhile US requirement for Rimlock spares? I had always assumed that this would have been a drop-in-the-ocean market but registering US designations for European valve types may have been part of trading red-tape even for small quantities.

Another thing that has long struck me about the Rimlock series of valves is that they seem to be outliers compared to their Mullard/Philips predecessors and successors in terms of their typically low heater-current requirements and relative socket complexity. Both of these are more typical of German-origin valves of the late '30s/early '40s and Rimlocks have a certain resemblance to larger Telefunken valves such as the LS50 power pentode with its 8 symmetrically-disposed pins in a glass button base and a keyed glass envelope. Could it be that Rimlocks represented technology-acquisition of a Telefunken-originated and wartime-development valve series that seemed too good to pass up?

Edit: I was slightly surprised to see an EK41 listed- that really would have been a nod towards US practice, away from the European triode-hexode/heptode trend- but cross-referencing 6CK5 suggests the more familiar EL41?