EAR-C6 Spain
This is a provisional, pirate, callsign in Spain pre 1934 licensing.
The spanish administration issues EAR callsigns from EAR1 to EAR336, after that, all the legal EAR were changed to EA as we know today, from district 0 to 9.
People initially used EAR plus letters (normally identifying name or city) in pre-licensing days.
QSL & Info courtesy of EA5BM