The functionality of the proposed transistor relies on the ability to tune the energy levels of the gate such that one of its states is resonant with the input and output states, resulting in coherent excitation transfer, while the other state of the gate is non-resonant and is used to block the transfer. A system that offers sufficient flexibility to realize this level of control is the Heisenberg XXZ spin- chain in a longitudinal magnetic field. We thus consider a chain of N spin- particles described by the XXZ model Hamiltonian (ħ=1)