10-02-2012, 11:31 PM
I have heard of UX171As being used as power output tubes in 1920s battery sets, usually installed after the fact, but not as a detector. The 199 is wrong, with or without an adapter, and there isn't much advantage to using one that I can think of since they have a 3 volt filament I think. MU-6 sounds like an old military tube designation, but then again there was no rhyme or reason to how a company labeled their tubes in those days.
Regards
Arran
Regards
Arran