I just gutted and redid a single 4cx250b amp. I have 1200vdc on plate ( old amp had 2400Vdc for a single 250B) 300vDC on screen and about -55v for bias. I am getting about 300-325W pep for a single 250b. I noticed that as soon as plate/screen switch is turned on, tube starts to heat up. I have a decent blower on it. Bias is only applied when amp is activated. Is it usual for tube to run hot? This is my first tetrode and i am not familar with these. Any ideas, suggestions? any and all comments are welcome.