Crosley 9-413B Horizontal Issue

[Penthode]

Originally Posted by Penthode

The horizontal frequency is actually 15,734.26573426573 Hz. Or rounded off 15.73 kHz

To calculate the horizontal frequency:

4,500,000 ÷ 15,750 = 285.7142857142857

Round up to 286:

4,500,000 ÷ 286 = 15,734.2657....

The reason? When over 70 years ago NTSC color was being formulated, to minimize a beat interference between the FM sound carrier at 4,500,000 Hz and the color subcarrier nominally at 3.58MHz, the original horizontal sweep frequency was shifted slightly to ensure the sound carrier was an exact integer multiple of the horizontal frequency. The sound carrier could have shifted instead but the concern was that the millions of intercarrier sound TVs would require minor realignment.

The color subcarrier therefore will be 455 times half the new horizontal frequency to minimize beating with the sound carrier:

15,734.265734426573 ÷ 2 X 455 = 3,579,545.454545455 Hz