normal values of gm for a little-signal vacuum tube are 1 to 10 millisiemens. It is probably the 3 'constants' of a vacuum tube, the other two becoming its get μ and plate resistance Rp or Ra. The Van der Bijl equation https://socialdummies.com/story3000370/the-single-best-strategy-to-use-for-edgetech-industries-eti