A Question about PAL television sets

[Robert Grant]

A true PAL set did not need a hue knob because of the phase alteration by line (hence the name PAL).

The phase of the R-Y color information changes with each horizontal scan line. Every line where R-Y is transmitted is followed by a line where Y-R is transmitted. Since the B-Y is transmitted as such on every line, the "hue wheel" essentially is clockwise on half of the lines and counterclockwise on the other half the lines. Any phase error that would turn red toward orange in one line is cancelled out by the adjacent lines (in which red would be skewed toward magenta). A delay line memory is usually used to mix adjacent lines to avert flickering colors.

Pretty clever, eh? They managed to correct the one most frequently heard complaint about NTSC. It would haunt them in later years, because the alternating phase can cause trouble when doing the special video effects that became common in the 1980's.

FWIW, I'm almost sure that PAL sets had some passive component inside the cabinet to assure that the phase of the internal oscillator was reasonably close to the color burst reference on the back porch. As mentioned above, if the phase is too far off, color saturation could fall off.

It may have been in the form of a trimmer pot, or different tap points on the resistors in the oscillator circuit.