We received dozens of replies–thank you so much!
Many readers immediately identified the tune as some sort of utility station placeholder for Point To Point communications. Turns out, they were correct.
Many thanks to Dean Bianco who was the first reader to solve the mystery.
Dean discovered that the interval signal was for the Voice Mirror of the PTT Habana, Cuba.
Dean verified it via Rainer Brannolte ‘s excellent website, UtilityRadio.com.
Here’s the audio clip from Rainer’s website:
Here’s a link to the PTT Habana Cuba page which also includes two other audio clips of the PTT service.
Rainer even includes a scan of his verification letter:
This morning, I received a number of responses from readers confirming PTT Habana–thank you so much!
Not only have we helped Brian ID the station, but now there’s also one less UNID audio sample on the Shortwave Radio Audio Archive.
Now I need to find some more shortwave archive mysteries to solve!