CT3AA 1952 Madeira Island
This station is listed as 3CO in the June 1928 "Flying Horse Callbook," under the heading Madeira--EP. The "P3CO" call was actually 3CO before prefixes were authorized by international law. The station used the indicative "ep" or "p" in his calling sequence to identify his "country".
QSL from the estate of W9ABB /
W9HK
Info courtesy of W5KNE