Joe,
The battery requirement is 4 "D" cell as are the rechargeable batteries.
I am not a electronics tech so I really do not understand all of your questions and comments.
But the tech at Marconi indicated that there was a 1 amp diode in the charging circuit. He said 1125 MA would blow the diode.
The adapter I have is from an old battery charging station. Those were I believe double "A" Four charged at once. I can buy the adapter from Marconi for $11.00 plus shipping, or I can buy one here at my electronics store for $14.00 with multiple connector ends.

The tech also warned me about the polarity. He told me the center of the conn. was neg and the outer side was positive.
So I went and got my meter and could not read voltage on any of the ac adapters. So I cannot tell the polarity of the adapter. Does the adapter need a load to output voltage. I was checking with my meter set on DC volts and the positive and negative sign were jumping back and forth.
Let me know Joe. I sure do appreciate your answer and Ann's Cheers!!! Thanks