function convertToHex(num) {
  var hex = ''; 
  for (i=0;i<num.length;i++) {
    if (num.charCodeAt(i).toString(16).toUpperCase().length < 2) {
      hex += "%0" + num.charCodeAt(i).toString(16).toUpperCase(); 
    } else {
      hex += "%" + num.charCodeAt(i).toString(16).toUpperCase(); 
    }
  }
  return hex; 
}