[DotNetDevelopment] Refactoring code for the class below ?

[S]

public class Converter
    {
        private string _retVal;

        public string Convert(Int32 _nInputNumber)
        {
            try
            {
                Int32 _numberToConvert = 0, baseForNumber =
13,_counter = 0;
                string _strOutput = null;

                while (_nInputNumber > 0)
                {
                    _numberToConvert = _nInputNumber % baseForNumber;
                    if (_strOutput == null)
                        _strOutput = _numberToConvert.ToString();
                    else
                        _strOutput = _strOutput +
_numberToConvert.ToString();
                    _strOutput += "|";
                    _nInputNumber = _nInputNumber / baseForNumber;
                    _counter++;
                }
                _counter--;

                string[] _separator = _strOutput.Split('|');

                Array.Reverse(_separator);
                foreach (string _InStringSeparator in _separator)
                {
                    if (_InStringSeparator != "")
                    {
                        if
(UInt64.Parse(_InStringSeparator.ToString()) == 10)
                            _retVal += "x";
                        else if
(UInt64.Parse(_InStringSeparator.ToString().Trim()) == 11)
                            _retVal += "y";
                        else if
(UInt64.Parse(_InStringSeparator.ToString().Trim()) == 12)
                            _retVal += "z";
                        else
                            _retVal +=
_InStringSeparator.ToString().Trim();
                    }

                }
            }
            catch (Exception e)
            {
                e.ToString();
            }
            return _retVal;
        }

So this is the code I have written. I was wondering if its possible to
refactor this code so I can make 3 more classes say XConverter,
YConverter & ZConverter. I dont see a need but I am not an expert in
this and would like to know what all can be refactored in this code
for other classes.
-S