We present numerical calculations of spatial growth rates of multiharmonic electron cyclotron instabilities driven by a loss cone energetic distribution, in the presence of colder electrons. When the cold electron density is comparable to the hot, nonconvective instability is possible in harmonic bands below or including the cold upper hybrid frequency. When the cold electron density is larger than the hot, nonconvective instability is possible only in that band containing the cold upper hybrid frequency. Increasing the cold electron temperature in relation to the hot eventually removes all nonconvective behavior. Convective instability is still possible above the cold upper hybrid frequency.