Unbalance effects in modulators

The various groups of output frequency-components which can be produced in rectifier modulators of the shunt (or «Cowan») and ring types are separated into those which are inherent in the operation of the modulator and those which are absent when the modulator is perfectly balanced. It is shown that in the shunt modulator only one balance control potentiometer is needed, and only one unbalance component can, in general, be brought to a real minimum by a particular adjustment; nevertheless, all the unbalance components tend to vary (and balance) together. In the ring modulator, two independent balance controls can be provided, and two (though not any two) unbalance. components can be simultaneously brought to a minimum. The effect of the signal voltage on the magnitude of unbalance output-components is examined, and shown to be zero in a modulator which is perfectly balanced in the absence of signal, and to be notice able only near the overload point even when an initial unbalance exists.