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Capacitors:  A Hazard in the Making
 
 
Unlike today's modern radios where voltages rarely get above 30 to 50 volts, Vintage radios that utilize vacuum tubes operate quite differently.  The only area that has the actual input voltage of either 6 or 12 volts dc is the tube heater circuit.  The remaining stages of the radio, rf, if, detector and amplifier circits all operate on high voltage, e.g.  250 to 450 volts ac.  In some circuits capacitors have working voltages of 1600 to 3000 volts, but on the average run 350 to 500 volts.
These capacitors were made primarily of 2 or more foil strips with a wax paper insulating strip between each one, rolled tightly into a tube configuration and coated in beeswax.  A wire connection at each end connected to each of the foil strips.  There is no electrical connection between the two terminals.  However . . .
 
High voltage capacitors in vintage tube equipment tend to dry out and deteriorate if the equipment is not used for an extended period of time.
This deterioration takes the form of reduced capacitance and greatly increased leakage current.  In some cases, the capacitor will become a virtual short circuit.
If equipment with capacitors in this state is used, the high current drawn could damage the rest of the components and cause the capacitors to over-heat and possibly explode.
 
Are You Willing to Risk the Possibility of a Fire in your Classic Ride?
 
 
 
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