Obtaining Characteristic Curves for a Specific Screen Voltage

[aumamps]

Greetings!
There are two ways of going about this and both ways are confusing as hell for me.
One way, is by apparently using the Three Halves law.
I have had trouble understanding how current correlates to the voltage when using the power factor law.
I am attaching a screen shot of a chart that shows this correlation, however when I do the math its very arbitrary.

Here is an example out of Richard Kuehnels book on designing power stages.

Can anyone break this equation down for me?

For the project I have been working on, I already know what I need (350 screen voltage on a P-P 6550C design) but I'm a real perfectionist and enjoy having visuals to tool around with.


Thank You

[wpaulvogel]

The anode characteristic curves are available for 6550 with screen voltage of 250 volts and 310 volts. It’s important to estimate/plot the anode characteristic for 350 volts but it’s impossible to know that when the amp is loaded at different levels during testing and playing that the screen voltage is going to be 100 % stable at 350 volts. Most likely it’s going to idle at 350 and sag down to whatever. KT88’s screens draw 60mA at full power. I understand you want to get a good estimate to draw out load lines, calculate output transformer impedance and set out plate voltage but real world conditions are going to be nearly impossible to estimate without notes from a test mule amp.

[aumamps]

True,
But I'd still like to understand the math involved in these equations.

I don't play sudoku or crosswords. This is my newfound hobby

[aumamps]

I'm not sure how to delete a post,

So I'll just share that I found this handy conversion chart and explanation in RDH4!