如何将php mb_convert_encoding（）转换为C＃等价物

I have tried rather unsuccessfully , to convert the following php code to C# and require help please.

php code is

$string="012014Te$ting#501834502014060007400";
$salt = "Cli3ntH@sah";
$utfString=mb_convert_encoding($string.$salt,ÄSCII");
$hashTag=sha1($utfString,true);
$Hash = base64_encode($hashTag);

with C# code

    byte[] ascii = Encoding.ASCII.GetBytes(objtohash);
    byte[] utf8 = Encoding.Convert(Encoding.ASCII, Encoding.UTF8, ascii);
    byte[] hashBytes2 = sha1.ComputeHash(utf8);
    var Hash  = Convert.ToBase64String(hashBytes2);

also tried this, where objtohash = $string.$salt (i.e. concatenated)

var sha1 = new System.Security.Cryptography.SHA1Managed();
//convert to ascii byte array
byte[] AScii = EncodeAscii(objtohash);
//Hash it
byte[] hashBytes = sha1.ComputeHash(AScii);
//convert it to base 64
var Hash = Convert.ToBase64String(hashBytes);

I have tried several other ways as per SO, but I cannot get the same hashed value as the php sample.Hopefully someone can do it and hopefully give explanation as to why.

Thanks

The syntax error was finger trouble.

The answer it turns out, ..basically by trying any and all combinations of what i could find by googling is:

        var objtohashArry = Encoding.ASCII.GetBytes(objtohash);
        var HashSharresult = SHA1.Create().ComputeHash(objtohashArry);
        var requestHash = Convert.ToBase64String(HashSharresult);
        RequestHash = requestHash;