A simple explanation

If you think about it, within a small margin of error the triode curves and the pentode curves pass though the same points when Ep = Eg2 (pentode) so if your argument were true there would be no difference between triode curves and pentode curves.

The curves for triode operation have the plate and screen voltages equal at all points. As you move up and down the X axis the screen voltage changes with the plate voltage. Since the plate current is mostly governed by the screen voltage this gives "steep" curves.

For pentode operation, the plate voltage is the value on the X axis while the screen voltage is constant, so you get a different set of curves. As you move up and down the X axis the screen voltage stays constant so you get "flat" curves. At the points where the plate voltage equals the constant screen voltage the value will be the same as the triode values for the same plate voltage, minus screen current.

For ultralinear operation the plate voltage is the value on the X axis and the screen voltage is the supply voltage plus 40% of the difference between the value on the X axis and this supply voltage. As you move up and down the x axis the screen voltage changes but not by as much as it does with triode connection. Thus you get intermediate curves - not as flat as pentode, not as steep as triode.

More is learnt from one bold error than from a hundred craven equivocations - Daniel Dennett

Mark Kelly

This post is made possible by the generous support of people like you and our sponsors:

Follow Ups Full Thread

Topic - 6v6 Ultralinear plate curves? - jsn 11:46:10 09/27/05 (21)

Draw them yourself - Mark Kelly 16:58:39 09/27/05 (3)

More accurate version - Mark Kelly 05:27:56 09/28/05 (0)

Re: Draw them yourself - jsn 17:11:21 09/27/05 (1)

Close enough - Mark Kelly 20:52:36 09/27/05 (0)

Re: 6v6 Ultralinear plate curves? - Septarnebula 15:18:17 09/27/05 (3)

Re: 6v6 Ultralinear plate curves? - jsn 16:13:00 09/27/05 (2)

Re: 6v6 Ultralinear plate curves? - Septarnebula 16:51:55 09/27/05 (1)

Are you looking at curves with the screen at 180-200V? (nt) - Dave Cigna 18:13:56 09/27/05 (0)

Will be same as triode connection curves. nt - sser2 12:06:17 09/27/05 (12)

Dynamic curves of a pentode vs triode. - cheap-Jack 11:35:29 09/28/05 (0)

Re: Will be same as triode connection curves. nt - fatbottle 15:18:28 09/27/05 (0)

Nope (nt) - Pär 12:30:40 09/27/05 (9)

Why no? - sser2 15:15:21 09/27/05 (8)

See above - Mark Kelly 16:59:48 09/27/05 (7)

Common sense comes before eqns. - sser2 20:22:32 09/27/05 (6)

Common Sense? - Mark Kelly 20:54:14 09/27/05 (5)

I guess I am dumb trying to grasp how curves passing through same points could be different. - sser2 21:44:04 09/27/05 (4)

A simple explanation - Mark Kelly 05:44:23 09/28/05 (0)

Re: I guess I am dumb trying to grasp how curves passing through same points could be different. - Pär 21:51:57 09/27/05 (2)

Thanks for explanations, - sser2 11:14:15 09/28/05 (1)

OK - Mark Kelly 16:50:29 09/28/05 (0)

Follow Ups

A simple explanation - Mark Kelly 05:44:23 09/28/05 (0)

You can not post to an archived thread.