[Moon-net] filaments

[Keith Naylor]

Running the heaters for some time at a voltage below the manufacturers
rating will poison the cathode !
Net result is a bang when you apply EHT and usually lower emission.
If you intend to "burn" the tube in do it at nominal heater voltage.
In all cases with big tubes you should have some form of current limiting
as you apply the heater voltage to the tube.

73' Keith G4FUF