Regular structure with 10 to 50kHz-scale was detected in the radio scintillation spectrum of PSR 1919+21. This regular structure may be a simple interferometric pattern formed by refractive multi-ray propagation between the pulsar and observer. It was found that the pulsar PSR 1919+21 radio emission scintillation spectrum phase changes significantly across the average profile. Within the refractive scattering scenario this phase-longitude dependence corresponds to a transversal shift of the magnetosphere emitting region of about 6 x 108 cm. The radio emission altitude is estimated to be near the light cylinder.