html_entity_decode( $orig , ENT_NOQUOTES, "KOI8-R" ) not working

[ms.buggy]

How I should convert hmlt-entitys to koi8-r characters?

According to manual, I think this is correct:

$decoded = html_entity_decode( $orig , ENT_NOQUOTES, "KOI8-R" );

If I try to write data into excel, there stands "decode cannot yet handle MBCS!" -error. And according to phpinfo() server has php5 installed. If I set charset to UFT-8, it works without errors, but ofcource right characters cannot be found..  And when I'll try to write a csv, prosessing stops on this line.

So what have I done wrong? Have I used html_entity_decode -sentence right?

Any help apprichiated!