As for a quick check, try using rxvt instead. Lanch it with such command:rxvt -fn "your-font-with-necessary-charset-here"
I am not sure sure what this means!
-fn "font-specification-as-given-by-xfontsel" is an option for rxvt to use the specified font. You need to pick one which contains the necessary charset (in my case that was koi8-r), so specification would look something like this: "*-koi8-r*" or may be "*fixed-*-koi8-r*" or all the way up to full specification. You can get one by trying output of xlsfonts or xfontsel. Check also 'rxvt --help' or 'man rxvt' for more information on options which rxvt understands.
You may try xterm instead of rxvt (you basically just need any terminal for which you can select what font it should use, I liked rxvt the best). This will require you to modify .Xresources or .Xdefaults. Unfortunately I don't remember off the top of my head the details. I you will need I can dig up the relevant file and send it to you.
George