character encoding (unicode to utf-8) conversion problem

I have run into a problem that I can't seem to find a solution to.

my users are copying and pasting from MS-Word.  My DB is Oracle with its encoding set to "UTF-8".

Using Oracle's thin driver it automatically converts to the DB's default character set.

When Java tries to encode Unicode to UTF-8 and it runs into an unknown character (typically a character that is in the High Ascii range) it substitutes it with '?' or some other wierd character.

How do I prevent this.

I tried different encodings using a simple driver like:
class UnicodeConversionTest
{
    public static void main(String[] args)
    {
   try {
     String str = new String("`test3`");
     String utfStr = new String(str.getBytes("UTF-8"), "UTF-8");
     System.out.println("Converted:" + str + " to:" + utfStr);
   } catch (Exception e) {
       e.printStackTrace(System.out);
     }
    }
}

But that didn't work.  Then I tried a more elaborate conversion:
import sun.io.CharToByteConverter;
import sun.io.ByteToCharConverter;

public class UnicodeTest {
 public UnicodeTest() {
 }

 public static void main(String[] args) {

   UnicodeTest unicodeTest1 = new UnicodeTest();

   try {
     ByteToCharConverter fromUnicode = ByteToCharConverter.getConverter("US-ASCII");
     char[] subChars = { ' ' };
     fromUnicode.setSubstitutionMode(true);
     fromUnicode.setSubstitutionChars(subChars);
     String originalStr = new String("test3");
     char[] convertedChars = fromUnicode.convertAll(originalStr.getBytes());
     String convertedStr = new String(convertedChars);
     //String convertedStr = new String(originalStr.getBytes("US-ASCII"), "US-ASCII");
     System.out.println("String:" + originalStr + " converted to:" + convertedStr);
   } catch (Exception e) {
     e.printStackTrace(System.out);
   }
 }

I tried a variation of the second code snippet that inserts into the DB - just to see the results and it was a no go.

I don't want '?' replacing the uknown chars.  I would rather strip them or replace them with ' ' but I haven't been able to get that to work (using the second bit of code)

Any ideas on what I am doing wrong?

Thanx,
CJ