Why Did NBC Use Trinitrons?

[etype2]

Yes I misstated. One of the constant complaints of the RCA system was the very dim color. One had to turn the lights down and draw the drapes in homes to see the image clearly. Another problem, color fringing on black and white programs and blurred images with color. This is why the Chromatron (and other systems such as the Apple tube by Philco) were proposed.

Chromatic Laboratory a subsidiary of Paramount Pictures Corporation built several prototype Chromatron chassis's which were encoded to accept one or three gun Chromatron tubes. Chromatic pitched the virtues of the design to all the manufactures. That is what I meant and should have said.

Citation: THE PDF CHROMATRON-A SINGLE OR MULTI-GUN TRI-COLOR CATHODE-RAY TUBE by Robert Dressler from the PROCEEDINGS OF THE I.R.E. VOL.41, NO. 7, JULY, 1953.

“Described in this paper is a single gun and three gun version of a simple color cathode-ray tube developed by Chromatic Television Laboratories, Inc., based on the ideas of Dr. Ernest O. Lawrence of the University of California. Both types utilize post deflection focusing (PDF) and acceleration as will be discussed in the body of this paper. The principles described are quite general and may be applied to other cathode-ray tube and camera tube designs. The single and three gun types discussed below will operate with any of the presently proposed color television transmission systems.”

[zenith2134]

The HF video response rolloff that old_tv_nut mentioned, may be a reason why none of my vintage Trinitrons have a sharpness control? Since the sharpness control alters the high frequency of the video signal.
Just wondering.

[old_tv_nut]

Originally Posted by zenith2134

The HF video response rolloff that old_tv_nut mentioned, may be a reason why none of my vintage Trinitrons have a sharpness control? Since the sharpness control alters the high frequency of the video signal.
Just wondering.

A sharpness control could still act on the mid frequencies - deleting it is mainly a cost saving. However, there is another technical point - the typical sharpness control was a simple RC circuit that can affect the amplitude of overshoots (following an edge), but not the pre-shoots. In a set with no sharpness control, usually the IF response would provide some pre-shoot and a fixed RC circuit would provide a matching amount of overshoot. A really good sharpness control would involve a short delay line to produce both preshoots and post (over) shoots, and the control would vary the amplitude of both equally. This sort of control was provided on professional monitors and was labeled "aperture," as it compensated for the finite aperture of the electron guns in the camera and CRT. Later, when analog ICs were used in consumer sets, it was possible to get a symmetrical pre/post shoot of adjustable but equal amplitude.

For example, see US patent 4,296,435
http://patft.uspto.gov/netacgi/nph-P...tl&RS=IN/Bretl