I have a byte array that I'm encoding to a string:

Private Function GetKey() As String
    Dim ba() As Byte = {&H47, &H43, &H44, &H53, &H79, &H73, &H74, &H65, &H6D, &H73, &H89, &HA, &H1, &H32, &H31, &H36}

    Dim strReturn As String = Encoding.ASCII.GetString(ba)

    Return strReturn
End Function

Then I write that to a file via IO.File.AppendAllText. If I open that file in 010 Editor (to view the binary data) it displays as this:

47 43 44 53 79 73 74 65 6D 73 3F 0A 01 32 31 36

The original byte array contained 89 at position 11, and the encoded string contains 3F. If I change my encoding to Encoding.Default.GetString, it gives me:

47 43 44 53 79 73 74 65 6D 73 E2 80 B0 0A 01 32 31 36

Any help would be much appreciated!