here is what I was told to do. Works great Its from tubesrule
A lower cost, less intrusive, and better regulated solution is to use a simple bidirectional TVS diode (Transient Voltage Suppressor). This is basically two back to back zener diodes. By carefully selecting the breakdown voltage, not only do you eliminate the cold start surge, but you are now clamping the voltage on the filament to a set maximum, so regardless of what the line voltage is, or transients on it, the filament will always be protected. No modification of the chassis is required, and it can be installed in seconds!
Since we want 6.3Vrms on the filament, we need to clamp at about 8.9V maximum. In practice we actually want to clamp a bit less than this to limit the maximum rms voltage, so a standard 8.2V TVS is used. The diode is simply added across the crt filament leads at the 25Z6 socket
you also might want to check this out.
http://videokarma.org/showthread.php?t=264074