06-11-2016, 06:55 PM
I don't have a ruler, but... Point D looks about +340V (so swing of 160V above the operating point, 180V). Posted net C looks about -50V, so about 230V below the operating point.
The fact that these aren't equal says that here would be some distortion (there would be anyway, because the curves deviate massively from the tangents for a grid swing as much as this).
But crudely, the change in Va is 160V + 230V = 390V, yes I see what you mean, not quite the 447V in the text.
If the manufacturers had given curves about 0.25V apart, it would have probably been more meaningful... No way would this valve cope with 2V p-p swing on its grid! But they didn't, so we have to use them, and extend by straight lines.
The fact that these aren't equal says that here would be some distortion (there would be anyway, because the curves deviate massively from the tangents for a grid swing as much as this).
But crudely, the change in Va is 160V + 230V = 390V, yes I see what you mean, not quite the 447V in the text.
If the manufacturers had given curves about 0.25V apart, it would have probably been more meaningful... No way would this valve cope with 2V p-p swing on its grid! But they didn't, so we have to use them, and extend by straight lines.
