Heater voltages

[timmy]

I once read an article that stated that heater voltages should be what is listed for a specific tube if to high or to low damages or lowers the life of the tube ok it makes sense so with a 7jp4 at 6.3v is good but I find that most of the Motorola vt71 sets the heater voltage runs kind of high at least mine do 6.8-7.2v how can I get these voltages down where they should be. There is a resistor in the string that the crt is part of and all these resistors are what is listed in the schematics so these voltages should be where they supposed to be. I think these elevated voltages will prematurely ruin the 7jp4. I don’t know but maybe Motorola designed them to run the heater higher then it really should.