These typical UPS systems from APC, et al. obviously can run a computer
because they become an inverter when the AC input drops out. I don't
believe that the output then is a pure sine wave. Perhaps it is a square
wave or modified sine wave? In any case, what types of equipment should
they not be used with? Can they, for instance, power a Ham Radio
transceiver? Thank you.

Cordially,
west