Operation of a Multiplex Linear Amplifier at WIBF-TV in Philadelphia

In April, 1964, the Federal Communications Commission adopted new rules regarding visual to aural power ratios whereby a ratio as high as 10 to 1 was authorized. This offered some interesting possibilities for minor cost reduction in conventional transmitter manufacture, such as use of a high-power klystron in the visual stage and a low-power tetrode in the aural stage. On the other hand, the possibility of multiplexing both visual and aural signals through one klystron as a means of cost reduction appeared much more attractive in that a complete aural amplifier of any type could be eliminated.