IMPROVED TV COLOR WHEEL CONVERTER

Posted on Feb 6, 2014

d 101-2 depend on the TV to supply a wide bandwidth video signal. Most black-and-white TVs from 1954 on contain narrowband IF strips or low-pass filters. A wide passband is a disadvantage, because it picks up the chroma signal. In a black-and-white TV, the chroma signal interferes with the monochrome signal. Today, comb filters take care of this p

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roblem. Back in 1955, comb filters are an engineering fantasy. The narrowband IF or low-pass filter has to do. Narrow & Wide IFs. Unfortunately, the resulting passband seems to attenuate chroma and burst signals that Col-R-Tel depends on. Col-R-Tel picks up its signal at the CRT cathode. Yet the signal that arrives there is often too weak to be useful. For color adapters, it`s not a fair world. Engineering ingenuity to the rescue. Col-R-Tel engineers discover that the problem actually isn`t the IF strip or low-pass filters. The real problem An inductive peaker in the final video amplifier`s plate circuit. See the schematic. After the peaker, some TVs provide an excellent chroma signal. This is the traditional Col-R-Tel connection, where the last video plate meets the CRT cathode. On other TVs, the signal there contains attenuated highs. With these TVs, the trick is to move the yellow Col-R-Tel input wire. The new connection is through a 0. 01 uF capacitor. Connect the capacitor to the plate side of the inducive peaker. The capacitor isolates Col-R-Tel from high voltage DC at the plate. Color Converter, Inc. also adds an LC series filter between the TV and the Col-R-Tel coupling capacitor. This filter reduces video smearing. Col-R-Tel`s delay line. Another Colordaptor advantage is its delay line. Installing the delay line before the final luminance amplifier takes a little extra time. But the 1. 3 uS delay lines up the color...

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