  Early electron tunneling experiments with the Tl2Ba2CaCu2O8 measured \Delta =
16-28 meV, while bulk optical experiments measured \Delta = 43-45 meV. We
report new tunneling measurements of Tl2Ba2CaCu2O8 single crystals and c-axis
oriented thin films, where the measured \Delta values on both sample types
cover the range of 24-50 meV, with more than 70% of the junctions displaying
\Delta > 30 meV. This work resolves the inconsistency between previously
published results of tunneling and optical experiments. New tunneling
conductances reveal improved superconducting gap region characteristics
consistent with d-wave symmetry. The tunneling spectra also display features
similar to the dip feature observed in Bi2Sr2CaCu2O8. We discuss our results in
context of experiments reported previously on related materials.
