07-26-2013, 10:08 PM
I also found a broken 78 tube in place of 6D6. They seem to be the same - anyone? The S is the same and the filament current at 6.3V also, which is important in Hot Chassis due to serializing the filaments. 78 has a bit more oomph - 10mA vs 8mA in 6D6.
Another thing: the ballast tube is shot. Only one out of three resistive sections conducts, the rest is open.
Of course knowing that it drops 49V at 300mA helps, but this is almost 15W dissipation. Do I really want to start dropping that on a resistor.....? Plus I need to know the exact "hot" resistances of the sections as two of them parallel the pilot lamps.
Another thing: the ballast tube is shot. Only one out of three resistive sections conducts, the rest is open.
Of course knowing that it drops 49V at 300mA helps, but this is almost 15W dissipation. Do I really want to start dropping that on a resistor.....? Plus I need to know the exact "hot" resistances of the sections as two of them parallel the pilot lamps.
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