Who Has a Col-R-Tel?

[Dave A]

Old tv nut may be on to something here. Col-R-Tel had to use some unknown tube to set the standard for the Wratten filters they chose for the production release. With all of the possible sets that this could have been hung on, what CRT...and phosphor...was the standard?

With my 12KP4 in there, the blues as I noted are distinctly turquoise...a greenish contamination possibly from the sulfides OTN describes. Reds are vivid and greens are a bit yellowish. I have no idea why my pix put the blue back to where it should be other than that it is the sensitivity of the CCD in the camera.

James Hawes website offers a clue to the green that does not include phosphor varieties;

"The station doesn't transmit the third chroma signal, G-Y. This is the chroma signal that eventually produces green. (and this is why all color sets use green as the non-adjustable starting point for adjustments. Note by Dave A.) Most TV sets recover G-Y by adding samples of the B-Y and R-Y signals. Because Col-R-Tel only processes one color at a time, it can't add two signals. Instead, like some conventional sets, Col-R-Tel generates a third subcarrier to recover G-Y. On vector diagrams, the G-Y vector appears at about 7:00. In vector terminology, that's -106 or so from the B-Y signal. Without the advantage of a resistive matrix, Col-R-Tel creates green by phase shifting negative R-Y. Negative R-Y (roughly greenish cyan) resides on the 270-degree axis. That's 6 o'clock. Col-R-Tel's 64-degree shift should produce a yellowish green. With the hue control, the viewer can adjust this color. Not bad."

So is this a product of the phosphor or the circuitry?

And we have yet to hear from Pete D on the obscure effects of chroma matrix settings vs. the CT-100 vs. modern cameras vs. old RCA TK-40 iconoscope color cameras vs. plasma phosphors.

I suspect these designers were just throwing darts and we are lucky that they work at all.

Dave A