I have a Raptor G2 400 size helo and I'm in the process of upgrading my helo to brushless with lipo battery. My stock receiver trashed a while back, and i purchased an ExceedRC wk-701 PCM receiver (7 channel). Yet, it does not work with my tx. Why is that? Also, I heard the tx is PPM vice PCM. Is there any way to change to tx to pcm so my receiver can work?? Pls help!