6B4G Philco by Sylvania engraved base springs hold up filaments NOS 1930”s (rare)

91ma

Gm=6400

Recommended for

(6B4G=6.3V filament)
(6B4G is electrically equivalent to 6A3, but 6A3 has UX-4 pin base and 6B4G has 8 pin octal base)
(The best sounding 6B4G are 1940”s-1950”s: Ken Rad, Tungsol, Sylvania, Raytheon)