Listening to short wave broadcasts gave me a strong sense of contact with the enormous variety of cultures and ways of thinking embodied in the human race in all parts of the globe. For this I built my own progression of short wave receivers and became fascinated by the ionospheric propagation of signals. [PDF]
The HF radio spectrum is divided up into bands by international treaty. My interest, however, has always centred on the international broadcast bands. Transmissions from every nation and culture provide rich, varied and challenging content around the clock. First hand geographical insight. Every shade of political philosophy. A complete and unfiltered view of all humanity.
Consequently, unfiltered, in the context of short wave listening, can mean only that stages 3 and 4 are circumvented - which is nonetheless an improvement.
A brief outline of the short wave (HF) broadcast radio bands is shown below. These may have been change since I wrote this and allocations may differ slightly between global regions. The colours for daytime propagation (lower) and night time propagation (upper) have the same meanings as on my propagation diagram.
I became keen on amateur radio while at school, passing my Radio Amateur's exam in August 1961. At first I listened to the amateur bands with interest. However, what I heard was so boring that my interest waned. This I feel was far more to do with the Draconian restrictions imposed by governments on what amateurs may talk about on air than it was to do with their personalities. I never took out an Amateur Radio licence.
An outline of the short wave (HF) amateur radio bands is shown below. These may have been change since I wrote this and allocations may differ slightly between global regions. The colours for daytime propagation (lower) and night time propagation (upper) have the same meanings as on my propagation diagram.
The 10 Metre Band: 28·0 to 29·7 MHz (1700 kHz wide, which is a little wider than the Medium Wave broadcast band). Normally a local band, but biggest and best world-wide daytime band during solar peaks.
Different parts of each amateur band are often allocated to different kinds of amateur radio transmissions. For example, one part of a band may be reserved for ordinary amplitude modulation (AM) voice transmissions, another for single side band (SSB) voice transmissions, another for Morse code transmissions and another for frequency-shift keying [radio teletype (RTTY) or data] transmissions. Certain parts of a band may be used for two or more types of transmission. Some amateur bands - or parts thereof - are shared with other kinds of users. For full details check out this web site for the original ITU Document.
3500.0-3510.0 10 international Morse (general and contests) 3510.0-3580.0 50 Morse 3500.0-3560.0 60 CW contest preferred segment 3560.0-3585.0 25 UK Novice licence 3580.0-3620.0 40 Digital modes (and CW) 3590.0-3600.0 10 Preferred packet radio frequencies 3600.0-3650.0 50 Phone contest preferred segment 3635.0-3650.0 15 Used by CIS stations for intercontinental working 3700.0-3800.0 100 Phone contest preferred segment 3730.0-3740.0 10 SSTV/fax recommended 3775.0-3800.0 5 Reserved for intercontinental phone working
My interest in the intercontinental aeronautical bands stems from my career work on flight simulators and aircraft navigation. These were concerned with LF and VHF navigation aids. However, they did invoke a curiosity about the other side of aeronautical radio, namely communications. Although the most active traffic is on the VHF air band, in-flight communications between VIP passengers and their ground offices are sometimes carried on HF. However, this is rare and mostly unstimulating. Listening to private conversations between people I do not know does not hold my interest long. Neither does the other and more major content of the HF air bands: continuously repeated weather reports.
An outline of the short wave (HF) aeronautical radio bands is shown below. These may have been changed since I wrote this and allocations may differ slightly between global regions. The colours for daytime propagation (lower) and night time propagation (upper) have the same meanings as on my propagation diagram.
They seem to divide each band into channels of 3kHz starting 1kHz in from the low frequency end of each band.
Maritime bands held the same fleeting interest. Conversations between people you don't know rapidly lose their intrigue. The same goes for those specialised weather forecasts. Signals from over-the-horizon radars, ionospheric research stations and distant galaxies could be interesting if only one had the means of interpreting them. An outline of the short wave (HF) maritime radio bands is shown below. These may have been changed since I wrote this and allocations may differ slightly between global regions. The colours for daytime propagation (lower) and night time propagation (upper) have the same meanings as on my propagation diagram.
2000-2850 kHz (850 kHz wide)
Ship-to-shore, coast guards, distress channels using SSB, CW, RTTY.
6200-6525 kHz (225 kHz wide)
Exclusive to maritime use throughout the world using USB CW RTTY.
8195-8815 kHz (620 kHz wide)
International ship calling frequency, Ship communication traffic, International emergency & distress
12330-13200 kHz (870 kHz wide)
Active throughout the day and early evening. Most signals are CW and RTTY.
18780-18900 kHz (120 kHz wide)
Shared with non-maritime users.
19680-19800 kHz (120 kHz wide)
Shared with non-maritime users.
22000-22855 kHz (855 kHz wide)
Active during daytime. Ship-to-ship communication. Coast Guards.
25010-25550 kHz (540 kHz wide)
Shared with other users. Many are low powered units like taxis, boats, factories. Vast distances can be covered on low power during the years of solar maxima.
An outline of the usage of the entire short wave or high frequency (HF) part of the radio spectrum is shown below. This 'band plan' is not totally precise or all-inclusive. Its purpose is just to give a general picture of what may be found on HF, and where. The colour coding here denotes usage: NOT propagation characteristic.
This band plan may have been changed since I wrote this in 1997 and usage allocations may differ between the different global radio regions as designated by the International Telecommunications Union. For more details on HF band plans, look at the websites of the Radio Society of Great Britain, the American Radio Relay League and the International Telecommunications Union.
I built my own receivers. My first short wave receiver was the Practical Wireless 'Short Wave 3' which I built while still at school. It was a TRF and hence not very selective.
After trying fruitlessly to revive a No 19 tank transceiver, I bought a government surplus Canadian Marconi No 9 Set. It was big and heavy. However, although it only covered 1·5 to 4·5 MHz, its stability and good performance made it ideal for attaching front-end converters to cover other bands. It did an excellent job and was still working perfectly when I gave it away years later.
During my 1962 summer vacation from college, I built a Heathkit Mohecan. This was one of the first all-transistor short wave receivers. It was a long-serving friend which was finally laid to rest in the local rubbish skip in July 1997. Still working!
These old receivers had a kind of character which is now hidden in the otherwise far superior PC-driven virtual receivers of today.