Hear are some results after ~ 450 hours using a used JJ E88cc tube, at ~5.85 filament volts.
The AC line voltage varies slightly, which I can adjust, so there is only a slight DC voltage variations,
but not enough to cause a problem. I can adjust the line voltage for exactly 5.58 filament volts at
measurement times. Military Grade Mills RL's A and B values remain stable since the dissipation
is only ~0,7 watt dissipation vs 24 watt rating.
Filament 5.85 volts 5.85 volts
B+ voltage 142 volts 141.7 volts
Plate A voltage 71.8 volts 72.2 volts
Plate B voltage 63.8 volts 63.7 volts
Will continue to add hours, and will check in later.
cheers
steve
9-28-2024 ~600 hours
Fil voltage 5.85 volts
B+ 141.2 volts
Plate A Voltage 72.9 volts
Plate B Voltage 64.3 volts
Voltage changed slightly but within 2%. Will continue.
steve