Originally Posted by
tom775257
If your power supply is a traditional linear power supply (Transformer->bridge rectifier->smoothing cap) it certainly will not work at 400hz.
Actually, years ago working with the Naval Air Development Center in Warminster, PA we were able to certify the AC power supply of the Hewlett-Packard HP-67 calculator for use on 400 Hz aircraft power. I've got a couple of the power bricks in the closet, I believe that they are of the conventional transformer-rectifier design that you describe. In this instance, the units ran cooler on 400 Hz, perhaps because the small transformers were more efficient at the higher frequency. At 400 Hz RF issues weren't a significant player and in this case the ni-cad batteries did not overcharge or run hot.
And, I believe some electronic flight kit tablets are currently FAA authorized to charge (but not operate) off 400 Hz cockpit outlets.
Even though I've seen various chargers and power supplies used successfully on 400 Hz power over the years, the folks that say it's not authorized certainly have a valid point. If anything happens and the feds take a closer look, your Personal Electronic Device plugged into an unauthorized power source will be under the microscope.
