Hello,



For those who need it, here are two (or four, depending on your view) 3f4
spice models for the 71A direct heated triode. One version without filament
and one with filament. The filament version has an extra pin for the
filament (pin f), the other end of the filament is pin k (I was too lazy to
call them f1 and f2). I have used these models in Circuitmaker 2000 and
especially the ones based on Norman Koren's model are good.



I hope that they are any useful.



With kind regards,

Simon van de Laak



*71A direct heated triode 5V 0.25A version without filament pkg:UX4 1,2,3
..SUBCKT 71A a g k
* Data from the RCA datasheet for use with 3f4 spice
* Made by Simon van de Laak, august 2005
* Although made with care, this model is provided "as is" and
* I give no warranty for its use in any application.
* Please feel free to use it and improve it.
*best model:
Bout a k i=(1/5699.167193)*((v(a,
k)/35.3634889)*ln(1+exp(35.3634889*((1/3.060930456)+v(g, k)/v(a,
k)))))^1.635475676
*simple model:
*Bout a k i = ((uramp((v(a, k)/3.72062)+v(g, k)))^1.5)/4582.72
Cgk g k 3.7e-12
Cga g a 7.4e-12
Cak a k 2.1e-12
..ends 71A


*71A direct heated triode 5V 0.25A version with filament pkg:UX4 1,2,3,4
..SUBCKT 71Adht a g k f
* Data from the RCA datasheet for use with 3f4 spice
* Made by Simon van de Laak, august 2005
* Although made with care, this model is provided "as is" and
* I give no warranty for its use in any application.
* Please feel free to use it and improve it.
*best model:
Bout a kp i=(1/5699.167193)*((v(a,
kp)/35.3634889)*ln(1+exp(35.3634889*((1/3.060930456)+v(g, k)/v(a,
kp)))))^1.635475676
*simple model:
*Bout a kp i = ((uramp((v(a, kp)/3.72062)+v(g, kp)))^1.5)/4582.72
Cgk g kp 3.7e-12
Cga g a 7.4e-12
Cak a kp 2.1e-12
Bheat1 f kp i=(v(f, kp))/10
Bheat2 kp k i=(v(kp, k))/10
..ends 71Adht