i have 3 zenith crts. 25vs with green label,blue and purple.they came out of the same chromacolor 2 sets. does anyone know why the different color labels? the numbers are all the same too. we jigged them up on a test chassis and noticed the purple label crt seemed to have the best quality picture. also the screen on it was darker the the other two. all tubes checked about the same on the beltron. green label looks to have a safety glass. any info?

Perhaps the colors represent lot numbers or production runs - if they follow the resistor color code, they represent consecutive lots (green =5..blue=6...purple=7)

Doug (drh4683) may know - he's a Zenith guru with lots of info. I'll also ask a retired Zenith dealer rep - I seem to recall orange labels being limited to dealer stock / replacement CRTs.

Cheers,

Are the EIA numbers the same on all 3? I would suspect all would be built by Zenith/Rauland at that point; I have seen both a Zenith bw tube and a color rebuild from that era that were Zenith labeled/Sylvania built.

all numbers are the same. as i said,the green label has a safety glass.the purple has a dark mask. very nice picture. the blue label has a light gray mask and the picture is also outstanding. never noticed these things before i started reading this forum.all tubes check within 5% of each other.the blue label is strongest.green label also has a slight green mask.the purple is in my chromacolor2 as we speak.the best tube i have checked is the empire rebuilt tube in the e-41 bryan gave me.10s across the board.and the picture!!!!!!