Here are a couple of plots taken from my 2016 talk at Golborne on Valves. They show the anode current vs anode voltage with the G1 and G2 voltages set to a fixed value.
Both are taken using an EF91, one configured as a tetrode with G3 connected to the anode and the second configured as a pentode with G3 connected to the cathode.
The full text of the talk is in this thread
https://www.vintage-radio.net/forum/...d.php?t=130544
Keith