a short recording, giving
the id of OMA (rb, 1974)
Maarten van Delft received this interesting letter back in 1963
nice QSL card from 1971 (Wilfried Westrupp)
special QSL card for 50 kHz (Patrick Robic, 1995)
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Callsigns:
OLB5
OLD2
OMA
Frequencies Morse Telegraphy:
50
2500
3170
18985