First Color CRT Sizes (before truth in advertising)

[bhegges]

What sizes of early color picture tubes were available? This 1966 buyers guide: http://www.bretl.com/tvarticles/docu...uyersGuide.pdf references 19", 21" (round), 23" and 25" screens. I didn't think that the true 25" (25v tubes) came out until the early 1970s. Interesting though it looks like the Deceptive Advertising as to Sizes of Viewable Pictures rule came out in 1966: https://archives.federalregister.gov...343.pdf#page=2, I assume its this rule that changed the tube numbering to start with the real viewable number followed by a "V", such as 23VAXP22 for what use to be a 25XP22.

• 15 Round - 15GP22 (First color tube, briefly used)
• 19 Round - 19VP22 (briefly used)
• 21 Round - 21AXP22, 21FJP22, etc (the 21", 265 sqin, tubes as described in the buyers guide)
• 11 Rectangle - 11SP22, etc (Porta-Color & clone color sets)
• 19 Rectangle - 19EYP22, etc (the 19", 180 sqin tubes as described in the buyers guide)
• 22 Rectangle - 22EP22 (briefly used in 1957 sets, poor convergence, then withdrawn from the market)
• 23 Rectangle - 23EGP22 (First "working" rectangle color tube, assume the same size as subsequent 25 tubes)
• 25 Rectangle - 25AP22, 25GP22, etc (the 25", 295 sqin tubes as described in the buyers guide)

That leaves a question around what tube was used in the 1966 buyers guide reference to 23" 274 sqin screens? Would this have been a 25 tube but with smaller bezel or simply smaller cabinet and less generous marketing dimensions?

[Electronic M]

I have a 1968 consumer reports TV issue where they claimed that was the first year for the revised CRT sizes.
All 66 and 67 sets I've owned still had the old CRT designations used since the beginning of time.
When they switched to the viewable area designations the first letter in the tube number was always V...I had a CTC-20 roundy with it's original 19V something CRT that was literally a renumbered 21FJP.
Most tubes lost 2" when the law went into effect.
The first real 25" tubes came out in 1970.
Before the switch 22JP23 CRTs were a thing.

[bhegges]

I haven't came across a 22JP22 set yet. Maybe this was the 23" sets referenced in the 1966 buyers guide. Some more RCA resources below, note the 22 was absent in the 1965 listing but present by 1967.

• RCA 1965 color tubes listed are the 15 (round), 19, 21 (round), and 25: http://www.bretl.com/tvarticles/docu...eguide1965.pdf
• RCA 1967 tube guide shows an expanded list of rectangle tubes 15, 19, 22, and 25: http://www.bretl.com/tvarticles/docu...HiLite0867.pdf

[jr_tech]

Were pre rule Canadian advertised sizes slightly less deceptive?
jr

[trinescope]

Looking through the Buyers Guide, the 23" (or 274 square inch) screen size is the infamous 23EGP22. It was based on an existing "23 inch" monochrome tube and has a different overall screen shape than the RCA designed rectangular color CRTs. The aspect ratio of RCAs tubes was more like 5:4 instead of the standard 4:3 associated with NTSC, they also had a bit more curvature at the edges compared to the 23EGP22.

The 1970 25V and 19V types were different from the earlier types, they had a true 4:3 aspect ratio, sharper corners, and a flatter faceplate.

[Electronic M]

Originally Posted by jr_tech

Were pre rule Canadian advertised sizes slightly less deceptive?
jr

I don't know if Canada ever applied the same type of laws. At least into the 70s they still did it the old way we had since the 40s. I've seen Canadian ads where they were selling mid 70s American 25V Zenith CCIIs to the cannucks as 27" sets years before an honest 27" viewable color tube had been developed.

[nasadowsk]

When my parents got a colortrak 2000 in the 80s (I think it was a 2k, didn’t those ise I/Q demod?), the box said one size for the US, another for Canada. My brother joked how they measured it in Canadian inches…

[old_tv_nut]

Originally Posted by trinescope

Looking through the Buyers Guide, the 23" (or 274 square inch) screen size is the infamous 23EGP22. It was based on an existing "23 inch" monochrome tube and has a different overall screen shape than the RCA designed rectangular color CRTs. The aspect ratio of RCAs tubes was more like 5:4 instead of the standard 4:3 associated with NTSC, they also had a bit more curvature at the edges compared to the 23EGP22.

The 1970 25V and 19V types were different from the earlier types, they had a true 4:3 aspect ratio, sharper corners, and a flatter faceplate.

The narrower aspect ratio, cropping the left and right a bit, allowed longer horizontal retrace time, which reduces the peak pulse amplitude in the horizontal output. Not a terribly crucial thing for tube or hybrid sets, but very helpful in designing transistor horizontal outputs when the industry was just barely capable of making transistors with the required breakdown voltage.