Abstract: 1. In an undesired signal canceller, a main signal transmission channel having an output terminal, a plurality of auxiliary signal transmission channels having output terminals, means for cross coupling each of said auxiliary channels separately to said main signal transmission channel, means for generating error signals representing the relative amplitude and phase of each undesired signal in the auxiliary channels cross-coupled with undesired signals in the main channel, compensating cross feed networks capable of adjustment for minimizing cross coupling at said main channel output terminal, and means responsive to said error signals for adjusting said cross feed networks in order to minimize cross coupling.