Different points of view exist on the mechanism of neon optogalvanio effect in a hollow cathod tube. We have carried out eleotrodeless RF optogalvanio experiments to investigate such mechanism. Experimental results show that there exists no anomalous signal in the RF optogalvanio signal at the same pressure. The small peak on the tail still exsists and has no relation to the cathode. Bipolar diffusion effect is cited to discuss the peak s coourrence.