Details
Ballast, nominal voltage drop 49 volts at 300mA. Typically intended for radios using one number 40 or 47 dial lamp.
Known uses include:
Howard 56, 221, and 271
Knight B203, B223, BA222, E10704, E10718, E10800, E10803, and E10818
Radolek R17510 and R17512
Remler 28
Sonora B, BA, BE, B44, and C22
Truetone D704