Observatoire Neuchatel :

 

listen to the sound - only the phase modulated second pulses, no ID (rb, 2009)
here a screenshot of the signal from a spectrum receiver, showing RBU (66,66 kHz), HBG (75 kHz), and DCF77 (77,5 kHz) (rb, 2009)

in 1964, the 5 MHz outlet was still active, and was QSLed by Maarten van Delft. Maybe this letter from DIZ Nauen helped identifying?
this letter verifies the time signal transmitted via the swiss broadcasting station (Willi Passmann, 1977)
here a QSL card from Radio-Suisse, the transmitter operator (rb, 1982)
this beautiful card is from the operating agency (Mauro Giroletti, 2009)

visit the official web-site

 

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Callsigns:
HBG
HBN

 

Frequencies Morse Telegraphy:
75
5000