How can a 6xxx tube work on 12 volts???
It can’t. Typically, if you have 6 and 12 volt tubes mixed in one circuit, everything runs at 6 volts (see previous question). You could also have a 12V heater circuit with a center tap, so that 6V tubes can be run off each half of the 12V winding, between one of the outer legs and the center taps (this was common in tube-based TVs). Finally, you can string two 6V tubes’ heaters in series to run them off 12V. -Miles • Is there a standard scheme for hookup wire colors? From the ARRL handbook: BLA – grounds, grounded elements, returns BRO – heaters/filaments, off ground RED – power supply B+ ORA – screen grids (and base 2 of transistors) YEL – cathodes (and transistor emitters) GRN – control grids, diode plates (and base 1 of transistors) BLU – plates (and transistor collectors) VIO – power supply, minus leads GRA – AC power line leads WHI – bias supply, B or C minus, AGC -Miles • Is there a standard scheme for power transformer wire colors? From Orr’s Radio Handbook: Primary leads —–
