What I do is take the power transformer from a 12 volt Buick radio and install it. Then, I switch the heater leads on four of the tubes to make two pairs in series, and feed the 12 volts to each pair. The 6V6 I replace with a 12V6. I think you can buy 12 volt versions of all the tubes from Antique Electronics Supply. You would have to check on that. Also, I replace the vibrator with a 12 volt solid state unit.
The old Buick/Olds radios are not as popular as the truck radios and they usually can be picked up for much less. They don't have to be complete or look nice either.
