Instead of using the uniform warm plasma dispersion relation with an inverse Fourier transform to form the mode conversion‐tunneling equation, the equation is developed directly from the Vlasov equation and Maxwell’s equations. The plasma is assumed uniform parallel to B0. The expansion parameters are the Larmor orbit and the scale length, keeping terms to order &rgr;2LandL−1= (1/&ohgr;c)(d&ohgr;c/dx). For the special case with &ohgr;≃2&ohgr;cin a single species plasma, the asymptotic form of the mode conversion‐tunneling equation is unchanged, but localized third and first derivative terms appear even as absorption vanishes.