RCA 9T246 linearity

[old_tv_nut]

Apologies for a quick jump off topic -

Originally Posted by Penthode

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The CTC5 convergence compared to later color sets is also plagued with control interaction. I believe this was somewhat minimized in later designs by including clamping diodes in the convergence circuitry.

The diode clamping circuits in later sets keep the center DC convergence constant when the dynamic parabola waveform amplitudes are adjusted. (The sawtooth does't affect the center DC.) In the CTC-5, the points of constant DC adjustment when adjusting the parabolas are at the square root of 1/3 the distance from center to edge of raster (or about 0.577). This is why it is best to ignore the shift in center DC while adjusting the parabolas (and sawtooths) to make the center horizontal RGB lines parallel although not coinciding, and then re-adjust the static (DC) to get the whole line converged.