BH,

You are right the Redsun RP2100 on eBay does come with
a 110 to 220 VAC Step-Up Transformer.
LIYPN Writes : "A 110V input 220V. output step-up power
transformer included for FREE to buyers in America & Japan"

LIYPN Writes : "Battery: Uses 4 D size 1.5V. battery or
4 AA size 1.5V battery (not included in this auction)

LIYPN Writes : "Re-Charge of Batteries inside the Radio Possible"
- fwiw - I Don't know if this applies to the "AA" Batteries
{Most Likely} -or- the "D" Batteries ? ? ?

TIP - Either way Plug the Radio into the AC when not in-use
to Recharge the Batteries -and- Un-Plug it from the AC to
use-it on Batteries for lower noise and better reception in
most instances.

LIYPN Writes : "MANUAL IN PDF FORMAT
WILL BE PROVIDED FOR FREE"

hope this helps ~ RHF