vacuum tube 5U4GB model

[jrshedden]

Hi,

I think the 5U4GB rectifier model may need some editing. I would like to verify my observations and see if there are prefered methods to correct it. Other rectifier tubes may have the same issues. I put the model here for reference:

.SUBCKT 5U4GB__VACUUM_TUBE__1 A1 A2 K

.mergenodes A1 A2
* 5U4GB EWB rectifier model
* The following parameters are not modelled:
*   (1) Filament and filament warmup time
*   (2) Reverse voltage breakdown
*   (3) Saturation
*   (4) Interelectrode capacitance
* Please note that this model is provided "as is" and
* no warranty is provided in respect of its suitability
* for any application.
* 5U4GB maximum ratings:
*   PIV     1550V
*   Max in  550V RMS
*   Ia pk   1000mA repetitive  (4600mA transient)
*             .----- Anode
*             | .--- Cathode
*             | |
*SUBCKT 5U4GB A K
BGP  A  K  i = 7.55E-4*(pwr(V(A,K),1.5)+pwrs(V(A,K),1.5))/2

.ENDS 5U4GB

• Both anodes are not modeled, so trying to use both of them from a grounded center tap secondary (simulated by two AC sources) will not simulate. The sources show in parallel so the two anodes must be shorted. l searched for the '.mergenodes' but imagine that makes A1 and A2 the same as A thereafter. It would seem like we should be able to model the tube correctly.
• The proper work around seemed to be to place two 5U4GB's, but it seems the spice model isn't mapped to the schematic pins properly and doesn't simulate. The pins on the schematic symbol are P1,P2,H2,K_H1.

It's not an emergency, but might be a good example of how to properly fix these issues. Would something like this work?:

.SUBCKT 5U4GB__VACUUM_TUBE__1 P1 P2 H2 K_H1

BGP  P1  K_H1  i = 7.55E-4*(pwr(V(A,K),1.5)+pwrs(V(A,K),1.5))/2

BGP  P2  H2  i = 7.55E-4*(pwr(V(A,K),1.5)+pwrs(V(A,K),1.5))/2

 .ENDS 5U4GB

Thanks in Advance for any comments!

Jim S.

[hmiraquesa]

Hi, 

Is this component not working as expected? or the issue is that the anodes are not on the spice model.

Also, you have the chance to copy and modify the components or just modify it. Maybe it is related to make the component generic for all purpose.

Regards.

[jrshedden]

Hi miraquesa,

Thanks for the interest. I'm attaching two schematics. 5U4GBtypcal is how I would expect to use that tube. When it didn't work, I tried simplified attempts to understand what is wrong. The model equations seem to match others I see on the Internet. I imagine the problem must have to do with pin mapping. The model says it doesn't simulate the heaters and I have other tubes modeled with no heater current and they simulate. I think the heater is the cathode on this tube, so that might be a consideration. I was thinking that the model should actually be able truly simulate the tube function. I don't know why the anodes (plates) are tied together.

Thanks for the reply!