Electrical properties, Fe concentration, and deep centers in semi-insulating Fe-doped GaN substrates grown by hydride vapor phase epitaxy (HVPE) were characterized by temperature-dependent Hall-effect measurements, secondary ion mass spectroscopy, and thermally stimulated current (TSC) spectroscopy, Five adjacent samples from a low-[Fe] wafer displayed very high resistivity, dominated by a center at 0,94 eV. At least six traps were observed in the samples by TSC, with trap (0.56-0.60 eV) being dominant. A metastable trap A, at similar to 0.82 eV appeared after white-light illumination at 300 K-A sample from a high-[Fe] wafer displayed a lower resistivity, dominated by a center at 0,58 eV. The largest TSC peak in this sample was trap A(1), although trap B also appeared. These TSC traps are compared with deep-level-transient- spectroscopy traps reported in conductive epitaxial and bulk HVPE-GaN.