Thanks for the insight on the 6C19. I am considering a few uses for the tube, among them as the lower part of a hybrid cascode. When hunting maximum swing from a given B+, a low plate Z triode is just what the Doctor ordered. The ability to set the upper grid line of the faux pentode circuit *ANYWHERE* by moving the MOSFET's gate voltage is a very useful property. It keeps the load line out of the sub-Ec2 knee very well.

The additional demands of the E-Linear circuit on the drivers stage set-up require a very flexible front end. See Merlin v2 in the projects folder. Or the buffer linestage...it is all sorts of handy.

That these 6C19's are available for less than $1 each delivered and can stand the idle current a 10k plate load offers with a 500V B+ can deliver is another 'Plus'. A proper radiator for the MOSFET is not as easy.

I have seen the plate curves from the Klausmobile site, and find that they look at least as linear as a 12B4. The 500R plate R when resistively loaded for 6-7 dB of gain is quite good too. Forget the need for a second buffer stage. 5k and 300V and you're 'Off to the Races'...:)
cheers,
Douglas