In this report we discuss the effects of additional electrodes, fabricated near the center electrode of a magnetostatic wave (MSW) straightedge resonator, on the frequency shifts of the MSW oscillator. By switching the pin diodes in the additional electrode circuits on and off, the resonant frequency can be shifted without changing the external magnetic field and the circuit parameters of a feedback load circuit. We constructed oscillators using this technique and could observe shifts of oscillatory peaks as predicted by our equivalent circuit model. Some interesting features of additional frequency shifts are also discussed.