Remembering Radio Interval Signals

Long before the days of multichannel Television and the INTERNET we had multichannel radio.
Although AM or Medium Wave as it used to be referred to, had plenty of stations,
it was the short wave bands that offered the Pandora's box.
This is was what initiated my interest in Broadcasting.

If you’re not familiar with short wave, it's defined as broadcasts between the frequencies 3.2 to 21.850 MHz (Medium Wave being transmission being 535 to 1700 kHz)
The Short Wave spectrum is sub divided into various meter bands, all having different propagation properties.
On certain bands you are able to listen to stations just several hundreds of miles away, and others you can expect to receive broadcasts from countries many thousands of miles away, the properties of these bands will alter after dark, normally resulting in an increased capture area.
The majority of these broadcaster are the external services of a country’s domestic service.
I would listen to the news in Moscow one minute, then tune to a music show on Radio RSA: The Voice of South Africa in Johannesburg then maybe see if i could receive 'ABC' Radio Australia in Melbourne.
In these days of satellite and Internet it's no big deal, but as a 13 year old boy growing up in the 1970s I found it fascinating.
One of my earliest programme memories was listening to "The Short Wave Merry Go Round" presented by the two Bobs on SBC (The Swiss broadcasting corporation)

You had to know where and when these stations were on the air, for this, the latest copy of the World Radio and TV handbook was extremely important.

Short Wave Broadcast Bands

120 metres

75 metres
60 metres
49 metres
41 metres
31 metres
25 metres
21 metres
19 metres
16 metres
13 metres

     3200 - 3400 kHz
     3950 - 4000 kHz
     4750 - 5060 kHz
     5850 - 6200 kHz
     7100 - 7350 kHz
     9400 - 9900 kHz
    11600 - 12050 kHz
    13570 - 13870 kHz
    15100 - 15800 kHz
     17480 - 17900 kHz
     21450 - 21850 kHz

Propagation or the ionosphere had to be in your favour, you couldn’t always guarantee receiving your favourite station.
But if all was good you’d be ready to search for your station of choice.
In 1973, I received a birthday present of an ‘Astrad 17 Poratable Radio’ (or Astrad F8-TR17-B202 to be exact) which offered 5 shortwave bands. It was advertised in my reggualr copy of ‘Everyday Electronics’
Manufactured at the Minsk Radio Works; Minsk Russia,: it was described as the state of the art receiver. Incorporating 17 transistors and 11 diodes. It was the height of technology .. believe me.
But with no digital display finding the exact position of the station on the dial could be a challenge.
So in between programming the broadcaster would help the listener by transmitting a repeating unique 'interval signal’.
Over time you’d become quite expert in identifying the station.
I had long time forgotten about these little ditties and recently came across some of these online and it brought back memories.

So if you were a short wave DXer, as we used to be called, how many of these haunting little melodies do you remember ?