Vacuum Tube SPICE Models

[Koonw]

"Ix(U1late)" trace is not limited in your plot, try to use same Limit range in all expressions. Say if Limit(140m, ... , 0) then use same range for any other added expression.

Which bracket do you use: [] or ()? I use (). It appears to me you have a space in Limit function: Limit(1 30m, ...., 0)? You can paste the expression here if you wish.

No need to include "Ix(U1late)" in all expressions of the trace plots other than the "Ix(U1late)" plot itself. I can plot one myself later to confirm you try again.

 

[Koonw]

You have plotted the same trace "Ix(U1late)" twice, one with and one without Limit, remove the one without the Limit..

 

[dgta]

Koonw, did you (or anyone else) try the 6AG7_GE model in post 2532 in LTSpice? I get a missing node error. Thx

 

[Koonw]

I tried 6AG7_GE is fine. You probably have one or more unknown spice directive, maybe you mislabel a net name as spice directive?

 

[dgta]

This is the simple circuit. Do you see anything wrong?

 

[Koonw]

I added this spice directives it works.

.options GminSteps=0
.options NoOpIter
.options SrcSteps=100

 

[dgta]

Still doesn't work for me. Here is the screen shot with the added directives.

I was running the same basic circuit with the same exact directives today with several other tubes, no problem at all. It only refused to run with 6AG7_GE.
Is the model correct for LTSpice as posted or is it for PSpice?

 

[Koonw]

Try if any problem with the copy from me. The error message appears unrelated to the model.

 

[dgta]

Thanks. It was the model indeed. It took me a while to figure it out but something got corrupted when I copied the model from post #2532. I don't know what or how it happened, but I re-copied it and it works fine now. It looked the same, I didn't go through it letter by letter. I must have accidentally touched a keyboard key while cut-and-pasting it. I appreciate your help.

 

[Koonw]

intersting, the Y axis changed to mV

Oh I realise we need to be more specific about the exact unit. 11mA is more exact instead of 11m which it treated as 11mV, so it should be as below:

Limit(11mA,(263V-V1)/24.812K,0)

 

[EL8]

Thanks Koown, as your advise, assign the Y axis to mA it worked very beautiful.

 

[woodo]

Is there a link to published I-V curves for the 6DQ5 in triode operation?

 

[Sorento]

some measured curves here on this forum:
26DQ5 curves pin out

 

[woodo]

Cool thx @sorento. Similar shape and pattern to the Ayumi model in triode mode though difficult to judge the voltage and current levels.

 

[Ray Waters]

Ayumi provided a separate triode strapped model for the 6DQ5, to be used with the built-in LTspice triode symbol.

*
* Generic triode model: 6DQ5T
* Copyright 2003--2008 by Ayumi Nakabayashi, All rights reserved.
* Version 3.10, Generated on Sat Mar  8 22:39:49 2008
*             Plate
*             | Grid
*             | | Cathode
*             | | |
.SUBCKT 6DQ5T A G K
BGG   GG   0 V=V(G,K)+0.99999998
BM1   M1   0 V=(0.097911417*(URAMP(V(A,K))+1e-10))**-0.59116807
BM2   M2   0 V=(0.71730246*(URAMP(V(GG)+URAMP(V(A,K))/2.8872786)+1e-10))**2.0911681
BP    P    0 V=0.0034387228*(URAMP(V(GG)+URAMP(V(A,K))/4.0251899)+1e-10)**1.5
BIK   IK   0 V=U(V(GG))*V(P)+(1-U(V(GG)))*0.001983081*V(M1)*V(M2)
BIG   IG   0 V=0.0017193614*URAMP(V(G,K))**1.5*(URAMP(V(G,K))/(URAMP(V(A,K))+URAMP(V(G,K)))*1.2+0.4)
BIAK  A    K I=URAMP(V(IK,IG)-URAMP(V(IK,IG)-(0.0030773802*URAMP(V(A,K))**1.5)))+1e-10*V(A,K)
BIGK  G    K I=V(IG)
* CAPS
CGA   G    A 9.5p
CGK   G    K 13.5p
CAK   A    K 10.5p
.ENDS

 

[woodo]

Thx Ray. Will investigate. I missed that one.

 

[woodo]

I am looking for a circuit to model the ultralinear curves for a pentode/tetrode. Does anyone know how this is done? Jazbo8 and Jackinnj were discussing a few years back but links to pics are dead now.

 

[Koonw]

Below is the latest discussions on Triode, Pentode and Ultra linear curve plots, the results are assumed more accurate:

Vacuum Tube SPICE Models
Vacuum Tube SPICE Models
Here is pseudo ultra-linear model for PP for SE Amp. There are Composite PP curve model as well on this forum, maybe need a little correction. I see if I can locate them.
Vacuum Tube SPICE Models

 

[Koonw]

Push Pull Load Lines - revisited - Intact Audio
The above site has a composite curve for Pentode and I added UL mode, but you can run any other mode by changing UL=0 pentode, UL=1 triode, UL=0.43 UL, of course you can too plot single ended UL curve.

 

[woodo]

Much appreciated. Really good work there.