I need a 12v 200ma power supply for a Kenwood DEM-999D (AC-3) RF demodulator. Any suggestions would be appreciated!

You can pretty much get any off the shelf AC to DC power supply that matches the power requirements you need. The only minor issue might be the plug as from what I see in pics of the Kenwood's back panel seems to indicate a very specific plug style.

It seems to need a specific plug with a positive center pin. I’ve tried several, including a different Kenwood (also 12v, 200ma and with center pin) along with a universal (with a half dozen separate plug heads) and none have yet to fit snuggly into the DC input of the DEM-999D.

I am assuming you don’t have the original power supply? But if you do, you could simply snip off the plug and solder it on to the new power supply.

Also, I might check the plug design that Sony uses on some of their Blu ray players. It appears they have the same design but just not sure of the fit.