|
Hi! to All,
Follow-up answers from RACS on various inquiries:
Photo of CRT during aluminization operation:
The tube was indeed vertically mounted, screen at the top.
For John/Jeyurkon: P4 phosphors with/without Cadmium.
RACS comments that "you have one hell of an eyesight" to perceive such minute variations in P4 White qualities.
Just curious (me) what is the nature of your vision deficiency, Daltonism for instance?
To come back to the topic:
- Sure we still have Cadmium phosphors, for instance Yellow phosphors used in monochrome computer monitors are Cadmium based.
As for vintage P4 Cadmium phosphors, NOS inventories aren't kept for no good reason...
For Vintagecollect:
RACS confirms they routinely rebuild video projector CRTs.
Please supply data on your specific Red tube:
Tube type, maker, screen size, EHT (if known), base type...
For Terry Cheek:
Ah! the 15G, the Holy Grail of CRTs!
RACS is not ready yet, although would like to do this in the future. The ETF (Thanks! Steve) supplied a 15G gun assy from a broken tube for preliminary assesment. To go any further, RACS will need a complete dud tube, still under vacuum, if possible, and maybe more than one.
I had long discussions with RACS about the 15G's major plague, i.e. the leaking glass/metal junction. They have good experience in this domain, having encountered the same problem on other tubes they were asked to rebuild. We didn't go in depth about the details of resealing, but i understood that in general terms Frit glass is applied around the rim of the leaky glass/metal junction then hardened by baking. Afterwards, the CRT is evacuated, etc.
My friend John Folsom Jr is doing pioneering work in this domain along with Pete Deksnis and Bob Galanter. One tough questions remains on both sides of the Atlantic: as no CRT rebuilder can make a new tricolor screen, are the 15G phosphors still usable on a tube which has gone to air, usually for decades.
just FYI, a new gun, any gun, on which a new cathode has been installed and activated, is instantly destroyed by contact with air, even if brand new and never used. Are phosphors as vulnerable? no one knows until a rebuild is attempted.
To finish on a more positive note, RACS is also interested in rebuilding "easier" tubes than the 15G such as 21xxP22, the 21" roundies which ruled supreme for a decade between 1955-1965. Providing the tubes are still under vacuum, no major theoretical stumbling block is anticipated as RACS has the expertise to rebuild B&W and Color electrons guns in-house
Best Regards
jhalphen
Paris/France
|