> Hey for fun I was thinking of taking some transistors, octal coil holders 
It's probably simpler if you use FETs.
   and plastic
covers to make a 'solid state tube'.  The heat sinks would
 look like Seleium recitfiers  fins... :) 
     I've seen that as replacement for rectifiers and RF Power tubes... 
 
I seem to rememebr seeing references to little PCBs you could fit over
the pis nf defective 01As (between the valve and the holder) that
contained an FET and a few other bits and let you keep 1920's radios in
operation.
-tony