ABC Network Color - not from some affiliates

[old_tv_nut]

Existing monochrome transmitters had much looser tolerances for frequency response.

FCC monochorme response limits allowed a response of +/-2 dB at 1.25 MHz, +2/-3 dB at 2 MHz, +2/-6 at 3 MHz, +2 / -12 at 3.5 MHz, and +2 / - infinity above 3.5 MHz.

The RETMA monochrome lower limit was -3.6 dB at 3.6 MHz.

The FCC limit for color transmitters was +/- 2 dB throughout.

In addition, color tranmsission required attention to differential phase and differential gain (the variations of subcarrier phase and amplitude depending on the luminance level). Getting these within the barely tolerable +/-2 dB and +/-10 degrees required a transmitter with distortion of a few percent or less. Many monochrome transmitters were terrible in this regard, as the effect would be unnoticeable in black and white.