Radio
Amateur
DX is...

A Shorthand Introduction to an Epidemic Form of Madness 

Things you should be familiar with Callsign Allocations - Frequency Allocations - Beam Headings - Propagation

How would you judge a language translator who is forced to look up in a dictionary every two words of his text, because he is simply not  familiar enough with the vocabulary of the foreign language? The same applies to a DXer who is not in possession of his basic tools, the DX vocabulary, so to speak.

Callsign Allocations. One of these tools or prerequisites is to be (near-)perfectly knowledgeable, preferably by heart (!), as to which prefix (the first part of a callsign: e. g. "W4" in "W4BPD") - and sometimes also suffix (the second part of a callsign:  e. g. "XO" in "FT5XO") - represents a certain country or entity. An experienced and serious DXer rarely needs a reference book, a list, or a logging program to tell which country, region etc the callsigns belong to. There are only a relatively few cases where the callsign of a station does not give a clue as to where it is located (example: if you hear E51GGT, you cannot say by reference to his callsign whether he is in North Cook or South Cook, which are different DXCC entities). To make yourself familiar with the world of prefixes and suffixes, browse through the appropriate websites (see the Look-it-up-in-the-WEB box below).

Frequency Allocations. You will remember: knowledge of the frequency allocations of the amateur-radio service had been part of your licence examination. Radio amateurs should know rather precisely where they are allowed to communicate in a certain mode. In reality, however, things even turn out to be a bit more complicated. The International Amateur Radio Union (IARU) has divided the world into three regions. Region I: Europe, Africa, the former USSR countries, Middle East (excluding Iran) and Mongolia; Region II: North, Central and South America including Hawaii, Johnston and Midway Islands, and Region III: the rest of Asia and Oceania. These regions felt obliged to define their own bandplans, on the basis of the worldwide general frequency allocations of the International Telecommunication Union  (ITU) in Geneva. These bandplans are as a rule supplemented by special national regulations. For your daily DX-work see the band-plan publications of the IARU and of your national radio organisation (see the Look-it-up-in-the-WEB box below).

Beam Headings  - the paths to the DX locations you have to point your directive antenna for maximum gain - are another example of what a serious DXer should know, preferably by heart, at least with an accuracy of - say -  +/-10.  (It goes without saying, that beam headings do not play any role if you use non- or omnidirectional antennas.) Beam headings (in degrees), also known as QTF, to a spot you want to contact depend on where you are located and have to be calculated or taken from an azimuthal map. Some antenna rotators have an azimuthal map integrated in their indicator/control units, which is fine if you have enough geographical knowledge as to be sure where the location of your DX exactly is. If this is not the case, the superb DX-atlasses mentioned below are a better tool.

Even if you do not want to become an expert in spherical geometry, you should know that the wave your antenna radiates, with certain very specific exceptions, follows the so-called great-circles around the earth. These lines run through your location and those of your QSO-counterpart. Communication from one to the other location is theoretically possible in two directions ("headings"): one which usually results in a relatively short distance - therefore called the short path (SP) - the other one in a relatively long distance: the long path (LP). As the LP-direction is the opposite heading, it is easily calculated by just adding 180 degrees to the SP-direction (LP=SP+180). Long-path propagation is not always possible but, if conditions allow, sometimes considerably better than short-path propagation - depending on the state of the ionosphere. You can find out by trial and error and by relying on a (hopefully: long!) experience, but also - very reliably so - by using one of the propagation-forecast programmes (see below).

Propagation. At least for long-haul DX, propagation plays an enormous, if not a decisive role. Before you start your DX-session, you should inform yourself how DX-conditions look like:  What is the status of the solar flux (SFI) or relative sunspot number (R)? What do the A- and K-indices look like? If you are making use of a so-called DX cluster (see Toolbox 2), this information will be delivered automatically and in regular intervals by WWV and/or WCY. As a rough estimate, an A-index >25 and/or K-index of >4 indicate bad or less-than-average DX-conditions on most shortwave frequencies.

A perfect propagation indicator is offered by the International Beacon Project of  the Northern California DX Foundation (NCDXF). They have 18 beacons installed in nearly every corner of the world, each of which transmits successively with 100 watts, 10 watts, 1 watt, and 1 milliwatt  after a precise timetable on 14100, 18110, 21150, 24930, and 28200 kHz. The beacons use non-directional antennas; so you have a good estimate of how strong your signal will at least be in the region of the beacon. The only disadvantage, maybe: the beacons are transmitting in telegraphy... Good to have learned the code or to learn the code now...

If you intend to make sort of an exact multiband-prediction for a forthcoming DXpedition you would like to contact or undertake yourself, you better use one of the PC propagation calculators, the probably best one being the fantastic W6ELProp by W6EL. Have a look below at the frequency map delivered by this programme - for a certain date, a certain time, a solar flux of 85 (number of sunspots: 25), and a K-index of 2 - for the geographical coordinates of DJ2PJ:

Look it up in the WEB...                                                         Toolbox1

Callsign Allocations

Table of Allocation (ITU):

Table of Allocation (ARRL): 

AC6V's Mega Prefix List:

www.itu.int/online/mms/glad/cga_callsign.sh

www.arrl.org/international-call-sign-series

www.ac6v.com/prefixes.htm

Frequency Allocations

IARU Regions and Zones: 

IARU Region 1 -3  band plans

www.iaru.org/regions.html   

www.iaru.org/bandplans.html

Beam Headings

 DX-Atlasses: 

www.dxatlas.com

www.hamatlas.eu/index.php?setlang=ENG&lang=ENG

Propagation

Solar Ham page by VE3EN:

Space Weather DKWCY:   

Live Magnetometer:

Aurora:

solarcycle24.com

www.dk0wcy.de 

dk0wcy.de/magnetogram

www.aurora-service.eu

 

Initially published: 2005

Last revision: 6th February 2017

2017 by Hans-Dieter Teichmann

Impressum/Editor's Note