Quotation marks and other special characters

I’m not able to use ”alt codes” to insert special characters when using
Emacs 25.1.1 on Windows 10 Pro 64-bit.

E.g. if I press Alt+0147 in order to insert an opening double quote (”),
Emacs just displays C-u 147- in the mode line. This keyboard shortcut works
fine in other applications such as Notepad.

Any ideas how to solve this?


Best regards,
Carl Winbäck