The 6HZ6 is a dual control pentode. G1 and
G3 are both control grids. Feed signal to
G1 and it looks like a regular pentode. Feed
signal to G3 and it looks like a cross between a
pentode and a triode. Below is a firly close
spice 3f4 model:

*Vacuum Tube dual control
..SUBCKT X6HZ6 A 3 S G K

*work in progress, not final
* Calculate contribution to cathode current
*
*the number at the right end determines sharpness of knee
Bat at 0 V=0.636*ATAN(V(A,K)/24)
*the URAMP(V(S,K)/# mostly determines peak plate current, grid line
spacing nearly constant
*the number at the right end determines slope of grid lines (plate
resistance)
Bgs gs 0 V=URAMP((V(S,K)*1.1964+V(G,K)*43.75+V(A,K)*0))
Bgss gss 0

*this next line will probably wrap. remove the and at both
*ends
V=URAMP((V(S,K)*0.0005)+(-(URAMP((SQRT(URAMP(V(K,3))^2.7)))/((((SQRT(V(A,K))^1.5)/5)^1)))*0.0405+V(A,K)/9400))*1+((URAMP(V(3,K))/((SQRT(V(A,K))*11)))*1)*1

*the exponent sets the linearity of grid line spacing, and big impact on
peak plate currrent
Bgs2 gs2 0 V=V(gs)^1.5
Bgs3 gs3 0 V=V(gss)^1.5
Bcath cc 0 V=V(gs2)*(V(at))
Ban an 0 V=V(gs2)*(V(gs3))*(V(at))
*
* Calculate anode current, grid line spacing adjust and peak plate current
*
Ba A K I=0.345E-3*V(an)
*
* Calculate screen current
*
Bscrn sc 0 V=V(gs2)*(1.0-V(at)*0.9)
Bs S K I=(URAMP(0.34E-3*V(sc)-(0.95E-3*(V(an)))))*0.29*(V(at))*0.37
*
* Grid current (approximation - does not model low va/vs)
*
Bg G K I=(URAMP(V(G,K)+1)^1.5)*50E-6
*
* Capacitances
*
Cg1 G K 5.5p
Cak A K 7.5p
Cg3 3 S 5.6p
Cg1g3 G 3 0.09p
Cg1a G A 0.02p
Cg3a 3 A 1.6p

..ENDS X6HZ6

If your newsreader does goofy things to
the equations of my original post, go to
http://home.netcom.com/~wb2jia/tubes/spice.txt
at the bottom of this page/text document.
Cut and paste as needed into your spice simulator.

You're the best Robert, thanks! :-)

Got time for a 6EJ7 triode mode, based on Serpentine's plate curves? I
tried to make it, but again, my Spice kept segfaulting :-(

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

Gregg wrote:
You're the best Robert, thanks! :-)
Thanks again.

Got time for a 6EJ7 triode mode, based on Serpentine's plate curves? I
tried to make it, but again, my Spice kept segfaulting :-(


This below looks pretty close (I did it to the pentode
curves and Sepertine's triode mode curves):

*Vacuum Tube pentode aka ef184 (assumes K tied to g3)
..SUBCKT X6EJ7 A S G K
*
* Calculate contribution to cathode current
*
*the number at the right end determines sharpness of knee
Bat at 0 V=0.636*ATAN(V(A,K)/32)
*the URAMP(V(S,K)/# mostly determines peak plate current, grid line
spacing nearly constant
*the number at the right end determines slope of grid lines (plate
resistance)
Bgs gs 0 V=URAMP(V(S,K)/42.8+V(G,K)*1.55+V(A,K)/9000)
*the exponent sets the linearity of grid line spacing, and big impact on
peak plate currrent
Bgs2 gs2 0 V=V(gs)^ 1.5
Bcath cc 0 V=V(gs2)*V(at)
*
* Calculate anode current, grid line spacing adjust and peak plate current
*
Ba A K I=7.985E-3*V(cc)
*
* Calculate screen current
*
Bscrn sc 0 V=V(gs2)*(1.1-V(at))
Bs S K I=0.20E-2*V(sc)
*
* Grid current (approximation - does not model low va/vs)
*
Bg G K I=(URAMP(V(G,K)+1)^1.5)*50E-6
*
* Capacitances
*
Cg1 G K 10p
Cak A K 3p

Cg1a G A 0.0055p

..ENDS X6EJ7

********************

Also can be found at the bottom of my updated page:
http://home.netcom.com/~wb2jia/tubes/spice.txt

Thanks muchly Robert! :-)

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca