I have what you are looking for, from my G1 olden days. Basically it is a CA-PS400 "compact power adapter" plus DR-400 "DC Coupler". The output from the power adapter is 8.1V at 1.8A. I can't part with the CA-PS400, but to be honest I've never used the DR-400 component of it.
Here is another workable home built solution:
http://home.arcor.de/panacocha/astro...10d_power.html
Those in the know will know that I currently have two clone BP511 packs that could be had by anyone willing to pick them up (no mail Li-ion battery of questionable origin...). They could be used in the creation of one of these power supplies. I could probably strip out the battery component and mail the casing.
Eric