In the past several years the use of neutron monitors for Pu concentration monitoring has been expanded in the Chemical Processing Department. Most of these monitors have been quite successful, and considerable effort is being made to improve the operation of both existing and future monitoring systems. One of the major improvements has been the development and use of a transistorized pre-amplifier or impedance matching circuits. This unit solves several problems associated with the use of boron trifluoride (BF3) neutron detectors in process monitoring; e.g., vacuum tube pre-amp failure because heat is not being conducted away.