Please, someone can tell me how to export data in a flat-file with comp-3 COBOL format?

I tried to spool in a file converting in a ebcdic character set by the CONVERT statement:

select convert (1234,'WE8EBCDIC500','US7ASCII') from dual;

but it return a string like x'F1F2F3F4' and not ina comp-3 format...

tnx!