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.
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.
|The 120 metre Tropical Broadcast Band|
2300-2498 kHz (198 kHz wide)
|On the boundary between Medium Wave and Lower HF characteristics. Used for domestic broadcasting from sunset to sunrise in tropical areas where medium wave is too crackley. Band's minimum to maximum frequency ratio: 1·086956522|
|The 90 metre Tropical Broadcast Band|
3200-3400 kHz (200 kHz wide)
|Tropical domestic (similar to above). Minimum to maximum frequency ratio: 1·0625|
|The 75 metre Tropical Broadcast Band|
3900-4000 kHz (100 kHz wide)
|Used in Europe & Africa (longer reach). Minimum to maximum frequency ratio: 1·025641026|
|The 60 metre Tropical Broadcast Band|
4750-4995 kHz (245 kHz wide)
|The best band for tropical domestic broadcasting. Minimum to maximum frequency ratio: 1·051578947|
|The 49 metre International Broadcast Band|
5950-6200 kHz (250 kHz wide)
|Packed from late afternoon to an hour after local sunrise. Some weak signals in winter daytimes. Minimum to maximum frequency ratio: 1·042016807|
|The 39 metre International Broadcast Band|
7100- 7300 kHz (200 kHz wide)
|Europe & Asia (Also available to amateurs in Region 2). Most crowded band on the short wave. Minimum to maximum frequency ratio: 1·028169014|
|The 31 metre International Broadcast Band|
9500- 9900 kHz (400 kHz wide)
|World's most heavily used international broadcast band. A transitional band; best during evening & night, but some stations can be heard during daytime - especially in winter. Stations to the West fade-in during the late afternoon progressing across to the east by early evening until a couple of hours or so after local sunrise. Minimum to maximum frequency ratio: 1·042105263|
|The 25 metre International Broadcast Band|
11650-11975 kHz (325 kHz wide)
|Provides stable 24 hours a day world-wide transmission paths for broadcasters with very powerful transmitters. Minimum to maximum frequency ratio: 1·027896996|
|The 22 metre International Broadcast Band|
13600-13800 kHz (200 kHz wide)
|Similar to the above, but favours the afternoon when lots of powerful competing stations can be heard. Minimum to maximum frequency ratio: 1·014705882|
|The 19 metre International Broadcast Band|
15510-15600 kHz (90 kHz wide)
|Offers good transmission across the night hemisphere. Also good across the daytime hemisphere for several years each side of solar maxima. Minimum to maximum frequency ratio: 1·005802708|
|The 16 metre International Broadcast Band|
17550-17900 kHz (350 kHz wide)
|Highly directional: stations from the east receivable from morning and early afternoon, swinging round to stations from the west by late afternoon and early evening. Minimum to maximum frequency ratio: 1·01994302|
|The 13 metre International Broadcast Band|
21450-21850 kHz (400 kHz wide)
|International broadcasters use this band only a couple of years or so each side of a solar maximum when it provides a superb transmission path across the daylight hemisphere. Abandoned the rest of the time. Minimum to maximum frequency ratio: 1·018648019|
|The 11 metre International Broadcast Band|
25670-26100 kHz (430 kHz wide)
|International broadcasters don't seem to make good use of this band, even when it is open world-wide during solar maxima. Transmissions can reach world-wide on very little power during solar maxima. Minimum to maximum frequency ratio: 1·016751071|
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.
|160 Metre Band (also called 'Top Band'): 1·81 to 1·85 MHz (40 kHz wide). Normally local, but long distance possible during autumn & winter nights.|
|80 Metre Band: 3·5 to 3·8 MHz (300 kHz wide). Local during day, long distance at night all year round.|
|40 Metre Band: 7·0 to 7·1 MHz (100 kHz wide). World-wide at night. <1000 miles during day.|
7·000 to 7·045 MHz allocated to CW
7·045 to 7·100 MHz allocated to LSB
|30 Metre Band: 10·10 to 10·15 MHz (only 50 kHz wide). A 'transitional' band, ie it straddles the boundary between the 'night time only' and '24-hour'.|
|20 Metre Band: 14·00 to 14·35 MHz (350 kHz wide). World-wide day/early evening. 24-hour during solar peaks.
14·000 to 14·070 CW
14·070 to 14·100 USB
14·100 to 14·112 CW
14·112 to 14·350 USB
|17 Metre Band: 18·068 to 18·168 MHz (100 kHz wide). World-wide, less crowded than other bands.|
|15 Metre Band: 21·00-21·45 MHz (450 kHz wide). Out-performs 20 metre band during solar peaks.|
|12 Metre Band: 24·89 to 24·99 MHz (100 kHz wide). Allocated in 1979. Daytime during solar peaks.|
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.
|515-540 kHz (25 kHz wide)||Long Wave band used for long range navigational aids.|
|2850-3150 kHz (300 kHz wide)||Aeronautical weather stations: 2863 kHz Auckland, Hong Kong, Honolulu, Tokyo; 2881 kHz Brasilia, Buenos Aires, Lima; 2998 kHz Prague, Tel Aviv|
|3400-3500 kHz (100 kHz wide)||Aeronautical weather stations:|
3413 kHz Shannon (Ireland)
3485 kHz New York, Gander (Newfoundland)
|4650-4750 kHz (100 kHz wide)||Aeronautical weather stations.|
|5450-5730 kHz (280 kHz wide)||Weather stations: 5499 Antanarivo (Madagascar), Brazzaville, Johannesburg, Nairobi; 5561 Bahrain, Beirut, Cairo, Istambul, Tehran; 5601 Brasilia, Buenos Aires, Lima; 5640 Shannon (Ireland). Also aircraft flying international routes. Most activity across evening and night hemisphere.|
|6525-6765 kHz (240 kHz wide)||Weather stations: 6580 Prague, Tel Aviv; 6604 Gander (Newfoundland), New York; 6676 Bangkok, Bombay, Calcutta, Karachi, Singapore, Sydney; 6679 Auckland, Hong Kong, Honolulu, Tokyo. Plus aircraft in flight, airports, flight operations centres.|
|8815-9040 kHz (225 kHz wide)||Weather stations: 8828 Auckland, Hong Kong, Honolulu, Tokyo; 8957 Shannon (Ireland)|
|10005-10100 kHz (95 kHz wide)||Mainly used by planes in flight. Weather stations: 10051 Gander (Newfoundland), New York; 10057 Antanarivo (Madagascar), Brazzaville, Johannesburg, Nairobi; 10087 Brasilia, Buenos Aires, Lima.|
|11175-11400 kHz (225 kHz wide)||Weather stations: 11378 Prague, Tel Aviv; 11387 Bangkok, Bombay, Calcutta, Karachi, Singapore, Sydney.|
|13200-13360 kHz (160 kHz wide)||Weather stations: 13261 Antanarivo (Madagascar), Brazzaville, Johannesburg, Nairobi; 13264 Shannon (Ireland); 13279 Brasilia, Buenos Aires, Lima; 13282 Auckland, Hong Kong, Honolulu, Tokyo.|
|15010-15100 kHz (95 kHz wide)|
|17900-18030 kHz (130 kHz wide)|
|21870-22000 kHz (130 kHz wide)|
|23200-23350 kHz (150 kHz wide)|
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.
The Complete HF Band Plan
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.