I found this on the web somewhere the curves for triode connected 813 tube.
Please help me out here, Are these curves for class C operation. If I'm reading the chart correctly, it looks like an 813 tube would require -170 volts at around 1325 vdc to keep the tube within specifications or to operate class C. I know people use these in class B service with zero bias. I know these questions will make it look as if I don't know what I'm talking about. You would be correct. Let me know what I'm missing please?
http://www.pmillett.com/file_downloads/813%20curves.gifI found this data at this site.
http://www.pmillett.com/tube_data.htmLots of good old stuff here.