[joebog1]

For output valve protection I still use the 10 ohm sense resistor in the cathode, but only use 1 watt carbon resistors. I cover them with good quality clear heatshrink to prevent the burnt carbon going all over the place when they do burn, plus you can "check" the colour of them in a quick check of overloads.

Under normal operation the resistors are within " limits", but when an overload happens the resistor cooks and goes open circuit disconnecting the valve itself. Its cheap, works extremely well and the smoke is a dead set giveaway that something has failed.

Joe