Why should I run screen resistors?

[trobbins]

In the EL34T loadline plots, the Ig2max level must be around 100mA to get to 11W if Ig2 at idle is around 4-5mA. The Vg2 value will start sliding away due to the action of the screen stopper and even at 220ohm have a noticeably influence on Ia and Ig2max, and hence Pg2 max.

Original EL34 Pg2 max design centre level was 8W.

[jazbo8]

In the EL34T loadline plots, the Ig2max level must be around 100mA to get to 11W if Ig2 at idle is around 4-5mA. The Vg2 value will start sliding away due to the action of the screen stopper and even at 220ohm have a noticeably influence on Ia and Ig2max, and hence Pg2 max.

Original EL34 Pg2 max design centre level was 8W.

The plot did not factor in Rg2 nor did it match the actual diode line of the tube, so the actual Pdg2 would be lower as you indicated, it was simply used to illustrate that perhaps YCV50's operation condition is a bit on the "hot side"...