Ubertuber resistor heat

[bbd]

How hot should the R39 5W resistor get?  Degrees F. Just test a new build with an EH 18V power supply that is putting out a bit more voltage than the suggested Dunlop 18vdc +shield -tip power supply. I can get the plate / drain / heater trimmers fairly close to the suggested voltage, but the resistor is getting what appears to be overly heated. Using a direct contact Thermapen to read the temperature. Have not plugged in an test signal yet to judge output sound due to the high R39 temperature reading. Did not what to damage anything. What is a normal temperature for the resistor and how hot is too hot?

[madbean]

I don't know the actual temp measurement on the resistor but as the doc says, under power it will be too hot to touch. It will not damage anything. The 5W rating on the resistor is almost 50% more than the minimum spec of what's required for the 300mA current draw by the tube heater.