The adapter should output either AC or DC at 9 volts. If the output is AC, then the minimum current is 350 milliamps. If the output is DC, then the minimum current is 175 milliamps. The DC output plug can be either polarity.
The AC adapter made by HP is the same one used for the HP 82240A Infrared Printer. Different versions of this adapter are made to accommodate the AC power in various countries: HP 82241A for USA and Canada (110v 50-60Hz), HP 82241AB for Europe (220v 50Hz), HP 82241AU for UK (240v 50Hz), HP 82241AJ for Japan (100v 50Hz), and HP 82241AG for Australia (240v 50Hz).