Elimination of coupling problems in multistage magnetic amplifiers

When two or more magnetic amplifiers are cascaded, it is generally found that the over-all characteristic cannot be accurately predicted from the individual stages. The cascaded gain is less than the product of the separate gains. There may be abrupt changes in the slope of the cascaded control characteristic, and sometimes “snap-action” occurs. The over-all transfer function has a time constant lag term for each stage and perhaps additional time constants introduced by the interstage coupling network, for example, where filtering is employed.