Tab mis-interpreted by RichTextBox

I have RTF that is being mis-interpreted.  `StringWriter` takes a `\t` and replaces it with some character that `RichTextBox` cannot deal with inside a table.

    string rtfBeforeConversion = @"{\rtf1{\trowd\cellx1150 \cellx3750 \cellx7350 Temp\intbl\cell 96 - 99.7\t\intbl\cell 97.9\t\intbl\cell \row}}";
     string rtfBrokenByConversion = @"{\rtf1{\trowd\cellx1150 \cellx3750 \cellx7350 Temp\intbl\cell 96 - 99.7 \intbl\cell 97.9 \intbl\cell \row}}";

`rtfBeforeConversion` correctly displays 3 columns with data in a `RichTextBox`.

`rtfBrokenByConversion` results in the 3rd column displaying no data (or data outside and to the right of it's column depending on the DLL being used to interpret the RTF).

Stringwriter code

     using (StringWriter sw = new StringWriter())
                 {
                     GetRTF(sw);//inserts value of rtfBeforeConversion
                     return sw.ToString();//ToString() creates rtfBrokenByConversion
                 }

How can I correct this problem?  (Note that I tried `StringBuilder` and had the same results)

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