This GPU served my B36TC during avionics work, testing, gear swings, and generally playing around while the aircraft is in the hangar. An avionics tech on our local field built it from a then-new medical grade 28V TDK switching power supply I had from work. I've been very happy to use it from time to time.
28 V DC (re-verified)
26 A (750 W)
120 V input
Power supply is a TDK / Kepco RCW28-26K, made in Japan.
Case is the usual Pelican.
It's an upgrade from the CSOBeech unit:
https://www.csobeech.com/DIY-GPU.htmlAsking $450 shipped (US only).