Higher Line Voltage- Cheap Solution

Cliff,
Yes. As an example: a good quality film capacitor of several microfarad (or more) wired in series with the filament string can be used to replace the bad portion of a resistance type (3) wire line cord found in the early AC/DC sets. Some calculation or experimentation will be required to find the right value of capacitor needed for a given AC voltage drop. Keep in mind that the early sets used 0.3 Amp tubes (filament current). Starting around 1940, the 0.15 Amp, higher voltage type tubes came into use. 

Don't forget to wire in a shunt if you want to use a 50L6 as a sub for a 25L6 tube in your AC/DC set. Try using a 330 Ohm 10W resistor wired across pins (2) and (7) at the tube socket or in a plug-in adapter made from an old octal tube base and socket. I suppose an appropriately sized film capacitor could be used for the shunt also. A quick calculation suggests the required capacitor to be 8uF. 

Note: No DC operation of the radio will be permissible with series or shunt capacitor replacements!

73, Rod  WB6FBF

Just use a Cap in series to lower voltage.???

I might have posted this before but:
 You can easily compensate for higher line voltage in the old series filament radios by replacing:
 The 25L6 output with a 50L6.
 The 35C5 with a 50C5, etc.
 Just verify the filament current is the same. 
The same holds true for series fil. TV sets.