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NotTaR of Television Sets : Notes on cable and broadcast frequencies
 Copyright © 1994-2007, Samuel M. Goldwasser. All Rights Reserved. Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied: 1. This notice is included in its entirety at the beginning. 2. There is no charge except to cover the costs of copying. I may be contacted via the Sci.Electronics.Repair FAQ (www.repairfaq.org) Email Links Page.

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Notes on cable and broadcast frequencies

(The following is from: (kruskal@watson.ibm.com (Vincent Kruskal).)

RF band: To get the band, subtract 1.25 from picture carrier (low end) and add 4.75 (high end).

Color subcarrier: Add 3.58... to picture carrier.

Sound carrier: Add 4.5 to picture carrier.

HRC: Harmonically Related Carrier. Makes both second- and third-order beats invisible by making them fall directly on the picture carrier of other channels. That is, multiplying the picture carrier by two or three will yield exactly another picture carrier.

IRC: Incrementally Related Carrier, add 1.25 to HRC frequency. A General Instruments (Jerrold) catalog said that IRC makes third-order (more important than second-order) beats invisible by making them fall directly on the picture carrier of other channels. But it is not true that multiplying an IRC picture carrier by two or three yields another IRC picture carrier. This contradiction has not been resolved. The reason third-order harmonics are more important is that oscillators and amplifiers tend to generate odd-order harmonics far more than even-order ones.

Broadcast frequency: Add 1.25 to HRC frequency except for channels 5 and 6. For them, subtract 0.75. But these are just nominal frequencies. The FCC actually has three channel designations for each number as in 5, 5- and 5+. The minus channels are 10 kHz below the nominal value and the plus channels are 10 kHz above. For example: