a recording from 2011 of
RR's morse signal (rb)
this communication sheet
from Rotterdam airport dates from 1979 (Rudy van Dalen)
in 1982, Rudy van Dalen received this interesting letter
Ary Boender made a nice picture of the transmitting station in
2015
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Callsigns:
RR
Frequencies Morse Telegraphy:
404.5