RCA CT-100 Color Television Design

Posted on Feb 6, 2014

If you haven`t already read my CT-100 restoration article, I suggest that you start there. It chronicles how I found a CT-100 and restored it to working condition. This article discusses what`s under the hood. After noting some hardware highlights, we`ll discuss how the CT-100 decodes color, framing that in the context of the NTSC standard. The a

RCA CT-100 Color Television Design
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rticle concludes with a library of key CT-100 documents, including the factory service manual and the NTSC specification. The CT-100 television is a complicated critter. It uses 37 tubes, including the 15GP22 tri-color picture tube. This diagram from the RCA service manual shows the layout of tubes and controls. The photo shows my chassis during restoration. Here`s a diagram of the CT-100`s front and side controls. The previous chassis layout diagram shows additional service adjusters on the top and rear of the chassis. You might be a little surprised to hear that the CT-100 contains solid-state components. It actually uses five of them: two selenium rectifiers for the low-voltage power supply and three crystal diodes for the RF mixer, audio detector, and video detector. My 1940s televisions use tubes for all of those functions. Had the CT-100 followed suit, its tube-count would have topped forty! The CT-100`s 15GP22 picture tube is both rare and complex. Few were produced in the first place, and of the few survivors, many have lost vacuum, relegating them to the netherworld of duds. It is not possible to substitute any other tube without making modifications that would destroy the authenticity of the CT-100. The 15GP22 had a short service life, and at this writing (November, 2010) nobody in the world has a commercial process for rebuilding it. Here`s a page from its data sheet : In many picture tubes, the envelope is a...

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