I have a Grundig 800 shortwave radio and need an AC adapter. The one that came with it which is not the original produces a lot of ripple making the radio unusable. I have purchased a replacement power supply and it was no better. The original power supplies are not available any more. I tested the radio on a laboratory power supply and the radio works fine however this supply is large and needed for other things. I have purchased a down converter board. I plan to use a laptop power supply which puts out 19 VDC and this converter board to reduce the output to 9 VDC which is needed by the radio. I have numerous laptop power supplies so this is free and the down converter is only a few dollars. It this works out then many people can use this idea to power other things including charging cellphones. The quest is to find out if this concept will provide clean power.