Talk:Porta-Color

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I have removed the following statement...

"As a result, color sets were much larger and more expensive than B&W; while portable B&W sets were widely available for around $200, color sets were all packaged in large consoles and generally cost $500."

as it is basically incorrect. The larger size and higher price of a color TV has almost nothing to do with the need to increase beam current. It is due to the high cost of the shadow-mask CRT (and associated convergence circuitry); the additional circuitry needed to extract the color information; and the need for the receiver to be of higher overall quality than a B&W set, to minimize flaws that would be more-obvious and disturbing in a color image (poor linearity, incorrect black level, etc). WilliamSommerwerck (talk) 00:50, 7 April 2010 (UTC)[reply]

One of the reasons GE was able to sell the original Portacolor for about $180 was that the set used a GE invention, the Compactron. These were vacuum tubes with three or more "tubes" in each envelope. This was not in and of itself new; there had been dual tubes before, with the second tube either identical to the first, or a diode (for detection). The Compactrons, however, often had three different tubes. The selection of tube types was designed to optimize the chassis layout of the Portacolor chassis.

The article also neglects to mention that the CRT had a coarse "stripe pitch" that made for a rather "grainy" picture at close viewing distances. WilliamSommerwerck (talk) 01:02, 7 April 2010 (UTC)[reply]

In the "Porta-Color" section, the article currently states that "a contemporary shadow mask design might have 25% of the screen surface covered by phosphor, but in the Porta-Color layout this was improved to about 50%. This doubled the brightness of the system with no other changes."

Anyone who has examined a color CRT with a decent magnifier should know that the deposited phosphor dots or stripes are nearly or actually contiguous. Perhaps the author meant to say "might have 25% of the screen surface covered by each phosphor", but then the subsequent "improved to about 50%" part of the sentence would make no sense—the tube in a Porta-Color set is still a three-color, three-phosphor RGB device. I suspect that phosphor coverage is being confused with what is explained in the preceding "Shadow masks" section: "the vast majority of the beam energy, typically 85%, is lost "lighting up" the mask itself as the beam passes over the opaque sections between the holes". Still, even in the least efficient shadow mask picture tubes, the areas of the three phosphors that are actually struck by electrons and glow should total well over 50% of the screen area.

Will someone with a more solid knowledge of the actual numbers than mine kindly clean up this mess? AVarchaeologist (talk) 03:57, 15 September 2013 (UTC)[reply]

The whole section outlining the CRT used in the Porta-Color sets is wildly wrong. The only difference between GE's shadow-mask tube and that of RCA's is that the guns in the GE tube were in-line, rather than the delta arrangement of RCA tubes. This allowed GE to circumvent RCA'a patents, and it also simplified the convergence arrangements for GE, since the in-line system required convergence in only one plane instead of two. Convergence was implemented by simple adjustable permanent magnets. The in-line system referred to, which I am going to change, applies to much later striped phosphor shadow mask systems, which came about in efforts to circumvent Sony's Trinitron Aperture Grille striped phosphor system. Freddy011 (talk) 21:49, 25 September 2016 (UTC)[reply]