LORAN Sandur :
In this recording from 1974, you will hear net control station NMS Shetlands working with TFR Sandur in minute 4'30 (rb)
this PPC dates from 1974 (rb)
here is a letter from the files of Rudy van Dalen (1987)
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Callsigns:
TFR
Frequencies Voice:
3607
4857.5
6779
7512.5
7715
10337.5
13423
Frequencies Radioteletype:
100