Shortwave Interval Signals
See https://sites.google.com/site/g3xbmqrp3/hf/interval .
For a touch of pure nostalgia try the link above. Like many, my first experience with short wave was as an SWL, listening on a simple receiver to some of these broadcasters. Many were trying to indoctrinate me whereas all I was really interested in was a QSL card! I recall some great gifts from China! I heard some impressive DX back in the 1960s.
Of course radio amateur DXing came later and radio amateurs ran considerably less power. These days I regularly copy stations running less than 5W from the other side of the planet, but I can still recall the thrill of hearing a 5kW broadcaster in the Windward Islands and copying Radio Australia on a crystal set – all the way from Australia too!
Thanks for the link(s), Roger, just had a pleasant few minutes remembering hours and hours of listening to these stations. I remember doing the language course Svenska po Radio on Radio Sweden, and had not heard that interval signal from them for over 50 years. On the other links I look forward to hearing Radio Hilversum (the Happy Station), Radio Bucharest, Radio Tirana etc. that got me into trouble when applying for security clearance in the RAF many years ago!
73, Colin