Quote:
Originally Posted by old_coot88
Back in the day, in the sales & service arena at least, striving for perfect H linearity was never even a consideration. Even factory field reps (in our experience at least) never alluded to it. Just dip the cathode current for maximum life of the output tube, period. When dipped, there was no noticible non-linearity, even on the crosshatch pattern during setup.
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The difference in horizontal linearity between 195 mA (greatest horizontal efficiency) and 215 mA (best horizontal linearity) is hard to see with a crosshatch test pattern. It is easier to see with a test pattern consisting of 256 alternating vertical white and black stripes. The white vertical stripes in the transition region are slightly thinner, slightly brighter, and slightly closer together when 195 mA is used, whereas when 215 mA is used, all vertical white stripes are the same brightest, thickness, and spacing. Also, I am referring to the 215 mA setting that is clockwise of the minimum setting of 195 mA.
Here is an excerpt from the manual that comes with the Seco HC-8, a device for measuring horizontal output tube cathode current during TV operation. It also implies that the optimal setting for color TVs is not absolute minimum cathode current. The best cathode current is “near minimum”.
