So also with the numerous bronzes, the phosphor, the delta, the aluminium and other alloys of copper; each is made in several grades to render it suitable for different kinds of treatment.
For this reason some observers use a thin strip of phosphor bronze to suspend the magnet, considering that the absence of a variable torsion more than compensates for the increased difficulty in handling the more fragile metallic suspension.
Three scanning electron beams hit the phosphor screen at slightly different angles to excite different phosphors to produce red, green and blue dots.
When the electrons strike the phosphor dots they glow to give the colors.
In 1969 the 160W blended lamp was upgraded to the new phosphor, and the 250W and 500W ratings made the change in 1970.