The 801 Adaptor have 2 sockets for BW tubes.
Here is the connection pinout. I hope will be useful for somebody else.
_Mueter___Big__Small_Color___
1 | 3 | 6 | Brown
2 | 4 | 7 | Red
3 | N.C. | N.C. |
4 | 1 | 3 | Yellow
5 | 8 | N.C. | Green
6 | N.C. | N.C. |
7 | 7 | 2 | Grey
8 | 2 | 1 | White
9 | N.C. | 4 | Black
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