The dependence of short-circuit photo-current on the voltage applied to the source-gate (or drain-gate) junction Vg was studied. One should consider the fact that the photo-current begins to drop with voltage exceeding certain threshold value. Thus the 6H-SiC JFET behaves uncommonly. Moreover Isd ~Vg dependence shows a drop Isd to zero at a condition that there is a non-pinched-off part of the channel. For a comparison parallel investigations were conducted with two industrial Si JFETs with a structure similar to that of 6H-SiC JFET under study. The results obtained for Si JFETs are trivial for photocurrent and Isd. We believe that the effects observed in 6H-SiC JFET should be attributed to the Wannier-Stark localization regime.