Academy of Science, Praha (OMA):
a short recording from 2.5 MHz, giving the id of 'OMA' (rb, 1974)
nice QSL card from 1971 (rb)
special QSL card for 50 kHz (Patrick Robic, 1995)
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Callsigns:
OLB5
OLD2
OMA
Frequencies Morse Telegraphy:
50
2500
3170
10985
.