Quote:
Originally Posted by Zenith6S321
Do you find that you have to reduce the high frequency IF response in order to slow the rise time to limit the overshoot?
Dave
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No, I believe it is essential to make the response as close as possible to the factory specification. It may be that way it is currently aligned, the carrier is too low on the "Nyquist" slope to compensate for perhaps the higher video frequencies ("lower IF") rolloff. You can check this as I would suspect the white line will disappear when fine tuning the video carrier up the slope.
I believe the CTC2B chassis with 5 IF stages and the response going down to 21.65MHz AND the sharp transition makes it even tougher to get it right. But it can be done with the right equipment and some practice.
I recall Wayne suggested that is why the later "haystack" IF response became popular: it would get rid of the "galloping ghosts" when fine tuning and perhaps help prevent the white line. But I like the extended IF response design because I imagine if aligned right the picture will be better on a 21CT55 than on the the later CTC4's CTC5's and upward.
Terry