I do not yet know the vintage of this grid bias battery.  I only presume that it is from the late 1920s.

I would very much like to see photographs of similar G.E.C. 'B' Batteries.

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The sockets are simply brass tubing with an INSIDE diameter of 1/8".  The mounting is simply a piece of fiberglass printed circuit board material. 

The light green block is my fixture for cutting the brass tubing with a very fine jewelers hack saw.
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