If you get this error: "Invalid utf8 character string" when you are using iconv you should convert from utf-8 to utf-8 to.
$htmc = iconv("ISO-8859-9", "UTF-8//TRANSLIT//IGNORE", $htmc);
$htmc = iconv("UTF-8", "UTF-8//TRANSLIT//IGNORE", $htmc);
Dont forget: //TRANSLIT comes before //IGNORE