Dissimilar triodes in parallel.

LT spice, Curve Captor, PSUDII and whatever other sims you can think of.

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dave slagle
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Dissimilar triodes in parallel.

Post by dave slagle »

a guy on the asylum was interested in putting a 300B in parallel with a KT-90.

I know it sounds like the beginning of a bad joke, but I think he should try it just for kicks. (he posted about it a year or so ago and was shot down by those who "know")

I did a few crude sims and NAZ asked for the files. Rather than bury them with the rest of my asylum dreck, I though I'd open up the discussion here. I'd actually prefer the discussion to continue at the asylum but I use this forum as an easy way to host the needed files.

The KT90 model needs to be added to your triodenh file (where the rest of your models are) and then you need to select the 300B model you want. I used a version I traced in the same way I did the KT90. Please note, I don't bother with the capacitances on any of my models.

All props go to stephie for being the great teacher that she is.

* KT90 LTSpice model
.subckt KT90 P G K
Bp P K I=(0.01798272846m)*uramp(V(P,K)*ln(1.0+(-0.1903672493)+exp((0.1218980633)+(0.1218980633)*((104.4846442)+(27.71095382m)*V(G,K))*V(G,K)/sqrt((-1.365059137)**2+(V(P,K)-(-19.04749222))**2)))/(0.1218980633))**(1.412945234)
.ends KT90

* WE300b-2 LTSpice model
.subckt WE300b-2 P G K
Bp P K I=(0.1247974139m)*uramp(V(P,K)*ln(1.0+(-0.1272915694)+exp((15.16823755)+(15.16823755)*((4.15073619)+(1.520093533m)*V(G,K))*V(G,K)/sqrt((49.69832898)**2+(V(P,K)-(-2.804610879))**2)))/(15.16823755))**(1.499346998)
.ends WE300b-2
Attachments
t_curves_match_dissimilar.asc
(1.31 KiB) Downloaded 348 times
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izzy wizzy
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Post by izzy wizzy »

I really enjoyed your contribution in that thread. Blinded em wiv science :)

cheers,

Stephen
dave slagle
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Post by dave slagle »

I'm sure it will eventually get back to me that I think it is a good idea when my only opinion on the matter is "if the guy wants to try it.... let him"

dave
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Maturin
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Post by Maturin »

Dave, love your attitude. Couldn't agree more. The people who have always been the greatest impediment to the advancement of any field of knowledge are always the experts who think they already know everything...there's no substitute for "try it, see wha' happens!!"

The Hubble Telescope has revealed all sorts of galaxies and what-not that aren't following "the rules" of astronomy; I can think of all sorts of reasons why it might be quite handy to parallel dissimilar tubes....

Now I'll try to download your .asc and see what it looks like...I expect to see a curve that would be just what one would expect: halfway between a triode and a tetrode! :)
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