Sao Tome Aero :
no recording available...
look at this verification by PPC from Lars Lundström (1978)
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Callsigns:
S9Y *
Frequencies Voice:
5493
5680
6535
6537
6586
8826
8873
8903
13294
13304
Frequencies Morse Telegraphy:
4592
5748
10132.5
Frequencies Radioteletype:
7642
10132
11580
Systems used:
50 Bd