When the knob is pushed “IN”, the Dynatuner will switch to full separation stereo operation when tuned to a stereo signal, and will automatically revert to mono operation (through both channels) on mono broadcasts. The normal position of this control is “IN”. It may occasionally be desirable to disable the Stereo-matic feature, and for this, the tuner can be locked in mono operation by pulling the volume control “out”. This will enable you to make monophonic recordings of stereo programs, or to eliminate spurious interference on a mono broadcast.