Using my C3g and D3a triode curves, I developed the following SPICE models:

 

** D3A TRIODE ************************************************************
* Created on Sat Jan 12 09:17:53 GMT 2013 using tube.model.finder.PaintKIT
* model URL: http://www.bartola.co.uk/valves/valve-curves/d3a-triode/
* Created by Ale Moglia [email protected]
*--------------------------------------------------
.SUBCKT TRIODE_D3A 1 2 3 ; P G K ; 
+ PARAMS: CCG=6.7P CGP=3.3P CCP=1P RGI=2000
+ MU=72.1 EX=1.456 KG1=65.625 KP=534.0 KVB=300.0 VCT=0.0557 ; Vp_MAX=500.0 Ip_MAX=0.07 Vg_step=0.5
*--------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))} 
RE1 7 0 1G 
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1} 
RCP 1 3 1G ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID 
C2 2 1 {CGP} ; GRID=PLATE 
C3 1 3 {CCP} ; CATHODE-PLATE 
D3 5 3 DX ; FOR GRID CURRENT 
R1 2 5 {RGI} ; FOR GRID CURRENT 
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N) 
.ENDS 
*$

C3G triode SPICE model

 

** C3G TRIODE ************************************************************
* Created on Sat Jan 12 09:40:08 GMT 2013 using tube.model.finder.PaintKIT
* model URL: http://www.bartola.co.uk/valves/valve-curves/c3g-pentodetriode/
* Created by Ale Moglia [email protected]
*--------------------------------------------------
.SUBCKT TRIODE_C3G 1 2 3 ; P G K ; 
+ PARAMS: CCG=7P CGP=2.7P CCP=6P RGI=2000
+ MU=50.4 EX=1.428 KG1=199.6875 KP=426.0 KVB=204.0 VCT=0.5760 ; Vp_MAX=500.0 Ip_MAX=0.07 Vg_step=1.0
*--------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))} 
RE1 7 0 1G 
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1} 
RCP 1 3 1G ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID 
C2 2 1 {CGP} ; GRID=PLATE 
C3 1 3 {CCP} ; CATHODE-PLATE 
D3 5 3 DX ; FOR GRID CURRENT 
R1 2 5 {RGI} ; FOR GRID CURRENT 
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N) 
.ENDS