Q:

From collation Modern_Spanish_CI_AI (in SQL Server) to UTF-8 (in MySQL)

I am writing a PHP script to import some data from a Microsoft SQL Server database to my MySQL database. 
Collation in the SQL Server is Modern_Spanish_CI_AI (so I guess the encoding is ASCII), and in my MySQL database I'm using UTF-8 encoding and utf8_unicode_ci as collation. 
When I import the data I get wrong characters corresponding to the Spanish letter Ñ. I've tried to use the PHP functions utf8_encode($string) and mb_convert_encoding($string, "UTF-8") without any success, (I got different wrong characters but still wrong). 
Perhaps this helps:
Table's definition in SQL Server:
CREATE TABLE [dbo].[myTable] (
[myField] varchar(2) COLLATE Modern_Spanish_CI_AS NOT NULL,

Table's definition in MySQL
CREATE TABLE `myTable` (
`myField` varchar(2) COLLATE utf8_unicode_ci NOT NULL,

A:

I have no experience with SQL server, but from a cursory glance at this collation chart, Modern_Spanish_CI_AI seems to be essentially a Windows-1252 character set, probably with some Spanish sorting / comparison rules on top. 
You should be able to convert the data like this:
$utf8 = iconv("windows-1252", "utf-8", $input);

try it out.  However, when using PHP for this, the character set of the connection to each database also plays a role - if it still doesn't work, you need to show some more code.