These I did using AF's software
(stuff between and should be one line, also remove the
and symbols in your spice program's model editor)
**********************************

* 12u7 Spice 3F4 model low voltage space charge dual triode
..SUBCKT X12u7 P G K

Bp P K
I=(0.001972003403e-3)*uramp(V(P,K)*ln(1.0+(0.001530503245)+exp((0.038 59673121)+(0.03859673121)*((564.8225939)+(-114911.4871e-3)*V(G,K))*V(G,K)/sqrt((15.44447752)^
2+(V(P,K)-(8.343447975))^ 2)))/(0.03859673121))^(1.148627719)

CPK P K 0.0000000000004

CGK G K 0.0000000000016

CGP G P 0.0000000000015

..ends X12u7

************************************************** ******************************
* below is a 12AX7 style triode running on 80% of its normal heater
voltage, improves linearity.

* 12av6-10vh Spice 3F4 model
..SUBCKT X12av6-10vh P G K
Bp P K
I=(0.008002535364e-3)*uramp(V(P,K)*ln(1.0+(0.1781769699)+exp((4.80847 8051)+(4.808478051)*((80.28638516)+(-6220.101955e-3)*V(G,K))*V(G,K)/sqrt((71.2061203)^
2+(V(P,K)-(51.18537952))^ 2)))/(4.808478051))^(1.174758456)

Cgk G K 2.2P
Cgp G P 2P
Cpk P K 0.8P

..ends X12av6-10vh

************************************************** **********************************
*Below is a detector diode running on 2/3 normal heater voltage,
improves detector performance.

* 5896 4v on 6.3 heater not valid over 30ma; with contact potential
..SUBCKT X5896-4hv P K
Bp P K I=(1.259102866e-3)*uramp(V(P,K)+(0.6788214279))^1.5
..ends X5896-4hv

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

* 12FM6 Space charge low voltage triode
..SUBCKT X12FM6 P G K
Bp P K
I=(0.001097962853e-3)*uramp(V(P,K)*ln(1.0+(0.06123349699)+exp((0.0216 1200134)+(0.02161200134)*((23.7503614)+(-156710.2813e-3)*V(G,K))*V(G,K)/sqrt((-6.356755714)^
2+(V(P,K)-(6.569413423))^ 2)))/(0.02161200134))^(1.51472413)

CPK P K 0.0000000000004

CGK G K 0.0000000000016

CGP G P 0.0000000000017

..ends X12FM6

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