The economic advantages of wide-band multi-channel transmission either by radio or high-frequency cable links were appreciated early in the war, and systems of this type were developed on a wide scale. The simultaneous amplification of the channel signals without introducing noticeable distortion or mutual interference presented highly specialized problems which were solved economically in the majority of cases only by the use of negative feedback. The most outstanding contribution to amplifier design during the period 1939????????1945 was the analysis by H. W. Bode of feedback amplifier networks which established the design procedure on a firm logical basis. No appreciable improvement took place in valves for wide-band amplifiers up to 50 Mc/s, and it would appear that a near-maximum amplifier performance is now being obtained with existing valves so that the next major development might be expected in the thermionic field. Many different types of amplifier were developed during the war period, usually to meet urgent specific demands, and a representative selection is described briefly in the paper. The examples range from a highly stable (60-db feedback) 100-mW repeater for speech channels on a coaxial cable, to a transmitter amplifier capable of feeding up to 12 simultaneous 40-watt telegraph signals in the frequency band 3????????8 or 8????????15 Mc/s direct into a rhombic aerial.
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机译：在战争初期，人们就认识到通过无线电或高频电缆链路进行宽带多信道传输的经济优势，这种类型的系统得到了广泛的开发。在不引入明显失真或相互干扰的情况下同时放大通道信号带来了高度专业化的问题，在大多数情况下，仅通过使用负反馈即可经济地解决这些问题。 1939年至1945年期间，对放大器设计的最杰出贡献是H. W. Bode对反馈放大器网络的分析，该放大器在牢固的逻辑基础上建立了设计程序。高达50 Mc / s的宽带放大器用阀没有任何明显的改进，现在看来，使用现有的阀可获得近乎最大的放大器性能，因此有望在热电子领域进行下一个重大发展。在战争期间，通常是为了满足紧急的特定需求而开发了许多不同类型的放大器，并且在本文中简要介绍了代表性的选择。示例包括从同轴电缆上用于语音通道的高度稳定的（60 dB反馈）100 mW中继器，到能够在3 ????频段内同时馈送多达12个40瓦电报信号的发射机放大器。 8或8？15 Mc / s直接进入菱形天线。
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