A televisual curiosity

[ppppenguin]

Hi David,

Not quite clear about the details of this arrangement but if a blank raster on the Decca was used as the source of the 'flying spot', then phosphor lag would have been a problem... more a 'flying streak'...

Steve

I think that just about sums up the problem, I seem to remember that a coloured filter was meant to be used to limit this problem - I dont remember if I actually had one fitted though. David.

Don't think a coloured filter helps. If the different colour components that make up a white phosphor had significantly different time constants you'd see coloured smears on moving pictures.

Perhaps you were thinking of the dual colour radar CRTs (P7 phosphor?) that had a short persistance blue and long yellow. This gave very good radar displays but was hopeless for TV. I think some who built TVs using these CRTs used a blue filter to get rid of the yellow smear on moving pictures.