1. Introduction — What is Medium Wave DXing?

This is a guide to long distance listening (DXing) on the Medium Wave (MW) band. If you’ve never tried listening to anything other than your local radio station on Medium Wave then these pages are intended to give you an insight into the stations you could hear, and how to identify them. Also covered are the types of receivers and aerials you should use and an introduction to signal propagation. With the imminent arrival of digital broadcasting on Medium Wave, we look at how this will affect the hobby. We also take a detailed look at DXpeditions, where keen listeners go to remote and electrically quiet locations to hear the most difficult catches.

Of course once you’ve caught an interesting station you will probably want a QSL card, so we also include information that should make this task easier. Naturally a guide like this can only scratch the surface of MW DXing so it needs to act as a pointer towards more information and indeed you’ll find up to date listings of suitable books, clubs and sources of specialist equipment.

MW DXing opens up another dimension not covered by most of the shortwave (SW) bands. Although a few MW broadcasts are also available on SW the vast majority are unlikely to be heard on SW frequencies. Indeed many countries (mostly island nations) have no SW operations and only broadcast on MW which means that MW DXing is the only way of logging these elusive parts of the world. Furthermore most MW stations are local in nature and thus can give an interesting insight into what is going on locally; one can hear farm news from the US mid-west, obituaries on Jamaican radio; war reports from the former Yugoslavia, religious salvation from many stations and adventures from ship bourne broadcasters on the high seas. The choice is yours!

Good listening.

2. Who goes there?

The Medium Wave (MW) band is an internationally agreed band of frequencies primarily set aside for the purpose of broadcasting. It is also known as the AM or MF band or the Broadcast Band (BCB) in various parts of the world. Indeed there are stations using this band in every continent (except Antarctica) and to appreciate the sheer numbers of broadcasters just consider that in the USA alone there are about 5300 stations on 106 channels in the AM band. For many years the MW band has stopped at approximately 1610kHz but it has been extended to 1705kHz in North America. What sorts of signals can you hear on the MW band?

International Broadcasters

Mostly found in Europe and South East Asia, these stations are designed to target audiences in countries distant from the transmitter and studios. Good examples are high power (500kW and upwards) transmitters operated by the Voice of America, BBC and Voice of Russia. Over the years these stations have been joined by a selection of religious broadcasters such as Vatican Radio, PJB in Bonaire, TWR in Monaco and HLAZ in Korea.

Regional Broadcasters

These used to be best exemplified by the Clear Channel stations in North America. These 50000 Watt stations had the exceptional privilege of having a MW channel virtually to themselves. This was a deliberate move to ensure that the vast rural interior could get good radio reception at night when coverage of half the continental USA is typical. Although some stations still operate as de facto clear channel stations, they no longer have an automatic right to use their frequency exclusively.

Synchronised Networks

These are networks of several stations all on one frequency carrying the same programme set up specifically to provide national coverage. Such networks need care in their design and operation to avoid problems with carrier frequency synchronisation and variable delay in the distribution of audio to each transmitter. The most notable examples of synchronised networks are run by the BBC in the UK for distribution of Radio 5 Live, the news and sports network. The network operated by Virgin 1215, also in the UK, is less successful.

Local Broadcasters

By far the majority of stations on the MW band fall into this category, characterised by the co-location of the station, its studios and transmitter and its audience. Transmitter powers can range from as little as 1W to 100kW or more, depending on the coverage area and the degree of co-channel interference. Many local broadcasters in North America operate only during daylight hours in order to avoid problems with co-channel interference brought in by the night-time sky-wave.

Navigational Beacons

Radio signals are an essential means of navigating for most ships and aeroplanes and the frequencies between the Long Wave band and the MW band have been allocated for this purpose. More surprisingly, a sizeable number of aeronautical beacons operate in the MW band interspersed amongst the broadcasters. Over 100 beacons are known, of which the majority are in the former Soviet Union. Beacons are usually low power and intended to give accurate navigational information over 50-100 nautical miles range, however long distance listeners (DXers) will be able to detect the repetitive Morse code identification messages from beacons over much greater distances.

Clandestines, Pirates and Jammers

Most signals described so far are more or less permanent features in the MW landscape. However, there are several more transient types of signals which can be heard, the most prominent of which are pirates and clandestine operations. Pirates are stations operating openly with out official licences from any country. They range from one time hobby pirates operating from someone’s bedroom to fully financed operations broadcasting from ships at sea. The heyday of the seaborne pirate seems to be gone since the likes of Radio Caroline, Voice of Peace and Radio New York International have passed into the history books. Just one radio ship is currently operational, in the Mediterranean.

Clandestine stations are usually politically motivated broadcasters often supported by a covert government operation. Operations are complex since stations can pretend to be what they are not and there is always the possibility of the double bluff! These stations come and go, reflecting political changes in their ‘host’ country. Currently the bulk of known clandestines are operating in the Middle East. Long serving examples include National Radio of the Saharan Democratic Republic (since 1975) and the Voice of Iraqi Kurdistan (since 1965).

Clandestine stations, as well as official broadcasters, are often the target of jamming if the government in the area targeted by the broadcaster feels threatened by the message being carried. Jamming usually takes the form of a powerful transmitter broadcasting irritating noise and interference on the same frequency as the station beaming into the country. Jamming on MW has fallen dramatically since the late 1980s and now is confined mainly to the Middle East and the Korean peninsula.

Long Wave Stations

Though the Long Wave (LW) band (148.5 — 283.5kHz) is not strictly part of the MW Band, many listeners have common interest in the two bands. Long Wave is only used by broadcasters in Europe, North Africa, Mongolia and the Asian part of the former Soviet Union. Elsewhere in the world these frequencies are used mainly by navigational beacons similar to those found between 283.5 and 525kHz. One exception is in the USA where 160-190kHz is also used by experimenters who are allowed just 1W of power to tiny antenna!

Recently, Long Wave has been undergoing something of a revival in Europe. There are currently two projects to build commercial radio stations broadcasting into the UK from The Netherlands and the Isle of Man respectively. For more information about Long Wave, check our page of Longwave Links.

3. Getting Started: You dont have to be rich — or even awake!

Let’s take a brief look at what’s needed to become a MW DXer and how you get started. Firstly, it is important to realise that the MW DXer can start listening with very cheap and simple equipment; any domestic radio will tune the MW band and it’s quite easy to hear 50 — 100 different stations at night using just an internal antenna. However, it is probably preferable to use a better quality domestic radio, or a good car radio to get started. With this type of equipment, stations from up to 1500km away will be regularly heard at night. If radio conditions are favourable and you listen at the right time, reception of some stations over 3000km away should be possible. In this way you can have a go at DXing the MW band before committing yourself to any more sophisticated (or expensive) equipment.

On the other hand, if you are already an active shortwave listener, all that is needed to get going on MW is a change of waveband. Indeed many SW listeners tend to overlook the fact that their radios can usually tune the MW band and that their outdoor antennas are often effective in picking up distant MW signals. For the SW listener who has grown tired of the megawatt international stations, a fresh challenge can be found on the MW band.

Round The Clock

It is possible to DX on the MW band 24hrs a day (provided you don’t need to sleep!) but the band has two distinctly different ‘personalities’ according to the time of day. During daylight hours MW radio signals are absorbed in the lower layers of the ionosphere and only ‘ground-wave’ signals propagate; these signals radiate away from the transmitter rather like ripples in a pond and allow reception at distances up to about 500 km. Daytime is a good time to listen for low power local radio stations since very few distant signals are audible and therefore interference is at a minimum.

At night the ionosphere tends to reflect, rather than absorb, MW signals and thus energy radiated upwards from a transmitter is refracted back down to earth at some point far away from the transmitter. These are known as skywave signals. It is quite possible for night time signals to under go multiple hops with alternate reflections occurring in the ionosphere and off the earth’s surface. This mechanism allows reception to take place many thousands of km away from a transmitter. For example Radio Globo in Rio de Janeiro, Brazil is regularly heard in Europe, its signal having to cross 9500km of ocean on the way. You will of course notice that night time sky-wave propagation fills your radio dial up with hundreds of powerful signals, so how is it possible to hear the weak DX signals?

Over the years international broadcasting organisations have agreed a band plan arrangement on the MW band which requires all stations in an area to operate on fixed frequency channels. This has been arranged to maximise the number of broadcasters who can operate and to minimise the degree of interference affecting the listener. Fortunately for the DXer, international agreement is not perfect and as a result different MW band plans are operated in different continents; most European, African and Asian stations use channels that are exact multiples of 9kHz, whereas in the Americas channels are assigned as multiples of 10kHz. This means that, in Europe for instance, by tuning between the 9kHz channels reception of trans-Atlantic stations becomes possible. For example;

* 1008kHz (112 x 9kHz) Radio 10 Gold, Flevo, Holland

* 1010kHz (101 x 10kHz) WINS New York, USA

* 1017kHz (113 x 9kHz) SWF Baden Baden, Germany

This particular example also illustrates the value of knowing a station’s timetable. Although reception of WINS is technically possible as soon as a path of darkness exists between New York and Europe, NOS is a pretty powerful signal and will cause interference. However NOS signs off for the night at the unusually early time of 2230 UTC, and knowing this it is possible to tune a virtually interference free signal from WINS before midnight.

Stations on split frequencies are usually the easiest to hear over long distances since they suffer less co-channel interference. Obviously in any part of the world reception conditions vary and different stations are heard. In order to gauge what you are likely to hear or what you are going to have real difficulty catching it is worth joining a local club that includes MW in its remit; even better would be joining a specialist MW club. You will have access to lots of information on MW listening and in particular you’ll be able to see what other enthusiasts are hearing.

DXing in Your Sleep!

The easiest way to identify MW DXers is if they fall asleep during the day. Since the fundamental characteristics of the ionosphere favour long distance MW radio reception at night this hobby will be the province of the shift worker, the insomniac or the outright fanatic. There is one solution and that is to DX in your sleep!

All you need apart from the standard antenna and receiver is a tape recorder and a timer and a fairly methodical approach to listening. Neither the tape recorder nor timer should be expensive and indeed I don’t know any serious DXer (SW or MW) who doesn’t already use a recorder. Depending on your selection of equipment there are two ways of DXing in your sleep.

If you have an ordinary radio and a separate cassette recorder you’ll need to buy a mains timer unit (get one with a digital display since these can be set precisely to the minute) which will cost about Ј15 — Ј20 (US$20-40). With such a timer connected in series with the mains lead of the recorder you are able to make a recording at any time of the day or night when you’re not around. Just make sure that your radio is tuned to the frequency of the station you want to hear. Unfortunately such remote control is trickier for really tough DXing, since in these circumstance you will want to be making continuous adjustments to your receiver or antennas to improve reception. However, for less marginal conditions this technique is very valuable particularly for night after night monitoring of one frequency. In this case it would be impossible for me to be awake every night and I soon would get put off by the DX-less nights. Indeed taping for an hour each night allows me to quickly find the nights that are particularly good for DX (just 5-10% say) and to then examine the tape more closely for DX signals. In this way I’ve heard several North American and a couple of Latin American stations that I would not have otherwise heard.

If you have a receiver with a built in programmable timer (e.g. SONY 2001D) you do not necessarily need a separate mains timer. It might be possible to activate the cassette recorder from the radio or if this is not directly practical an external unit called a VOX or voice activated switch might be the answer. This piece of equipment connects in the audio lead from radio to cassette and detects when audio starts i.e. when the internal timer has turned on the radio. It then switches on the recorder for as long as sound is present. So if you have the equipment but have not tried this before why not give it a go.

4. The Identification Question: Dont make assumptions

If you tune in to your local radio station it soon reveals it identity through a number of clues; its strength, frequency, programme style and most importantly its on air ID (callsign, jingle etc.) which is easily heard since there is no interference. We now need to ask what happens when you are trying to decipher a weak, fading signal from a distant station that may well be using an unfamiliar language. The fundamental question is, at what point is a station identified and how should a station that is not fully identified be described.

The process of identifying stations should be viewed as a broad spectrum of probability. At one end is the completely unidentified station, an example of which is the open or blank carrier with no modulation — although you may have quite a good idea about its identity such a signal really is unidentified. At the other end of the spectrum is the positively (100% probability) identified (e.g. ‘. the powerful missionary outreach station, the Atlantic Beacon 50000 Watts at 15-70, broadcasting from the beautiful Turks and Caicos Islands in the West Indies. ‘ leaves little doubt about this station’s identity!).

Many DX stations fall somewhere between these two extremes; for example you may hear only part of a callsign perhaps in a poorly understood language, or maybe in the midst of heavy interference or jamming. Or perhaps no identification is heard but certain characteristics of the signal or programme content point in the direction of one particular station. Generally speaking, the longer you listen to a station, on one date or over many days, the more clues there are to help achieve successful identification. If you can’t ID a station keep listening!

The factors which contribute to the identification of a station are almost without limit. Among them are time of reception, frequency, quality of signal, and programming style. The latter is usually one of the most important clues since valuable information can be gleaned from the languages used and music played, as well as from advertising, weather reports, time checks and so on. It should be appreciated that one’s ability to identify a station depends mostly on the ability to interpret what is being heard. And, rather like a detective investigating a crime, it takes experience as a DXer to reach a correct conclusion based upon the limited clues available. Even the most experienced DXer will not be able to identify everything heard, so there needs to be some way of indicating how certain (or uncertain) a particular identification is. Hence the following shorthand expressions have developed as a solution to this problem.

Implies that the listener is 100% certain of a station’s identity since a full announcement by the station was clearly heard.

When a station is listed as presumed it means that the listener has had sufficient clues to the station’s identity to be almost (90-99% probability) certain of its true identity. About all that is missing is a formal ID announcement.

This term usually describes a situation where the listener is fairly certain that a particular station is being heard — indeed that the probability is substantially greater than 50%, typically from 75%-90%. It is important, however, to note that a tentative logging is not just a pure guess since there still have to be a number of clues pointing in the right direction.

Anything short of tentative is called ‘unidentified’ and the DXer should resist the temptation to classify loggings as tentative if there is insufficient evidence. When there is any doubt about a logging, it is wise to err on the side of caution and list it as unidentified; however it may be worth indicating which station you think it might have been if you have an idea.

At this point a word of caution is probably in order with regards to station listings. All DXers use lists of one sort or another to help them in their hobby (e.g. WRTH, club bulletins etc.) but it is dangerous to rely on a list (even the most up to date) as the sole means of identifying a station. That is not to say that lists should not be part of a DXers ‘tools of the trade’, but just that caution should be exercised in their use.

Lists are invaluable to help narrow down the range of possibilities when it comes to indentifying a mystery station; they can also guide a listener to the right place on the dial to possibly hear a particular station, but they cannot actually identify a station — only the station itself can do that.

Over reliance on lists and a bit of related ‘wishful thinking’ results in the practice known as ‘list logging’ which can be sometimes observed as anomalous loggings reported in the DX logs of some magazines and club bulletins.

5. DXpeditions: Giving up home comforts in pursuit of rare signals

DXpeditions are the solution for urban DXers trapped in a noisy environment, lacking the real estate for erecting long aerials and yearning after a DX-fix. The solution is to find an electrically quiet environment (preferably near the sea) where aerials can be installed without threatening life (human or fauna). And some DXers go to extreme lengths to obtain these requirements, for example the Scandinavians who frequent Lemmenjoki in the Finnish Arctic Circle and suffer the extremes of weather conditions.

Because DXpeditions are often in remote, electrically quiet conditions, a mains power supply may not be available, with the nearest power pole some distance away (hence the need for battery-operated receivers and tape recorders). Other non-existent luxuries like hot water, telephone (& Internet) connections and nearby shops make planning important. In such circumstances the Dxer’s ingenuity is challenged as everything from cooking meals to charging batteries to staying clean and staying in touch becomes a consideration.

Sleep deprivation, bad weather, lengthy journeys and all the other ‘negatives’ are usually more than offset by the quality of the reception, the chance to experiment with aerials, receivers, splitters etc and above all by the comradeships formed. Days are spent collecting firewood, the odd aerial maintenance chore, recounting the previous night’s experiences, tales of ‘the one that got away’ or sleep (MW DX is best at night so the candle often gets burned at both ends and in the middle too!).

And a successful DXpedition usually doesn’t end when you’ve arrived home. There will be numerous reception reports to write and magazine articles to prepare (having a lap-top on the DXpedition is a great idea!).

Some famous DX-sites and links to articles follow:

Choosing A Site

There are numerous factors to consider when looking for a site. Ideally, it should be in a remote area, away from nearby power lines, miles from the nearest MW/LW transmitter, close to the sea, having a comfortable place to stay and large enough for long aerials.

Remote areas usually mean farmland. Ideally flat ground with the odd tree to assist erecting aerials. The presence of fences can be handy though a note should be taken that even with all-wooden posts, the chemical treatments to prevent the posts rotting away (eg. tanalising) leaves them conductive (albeit with a relatively high resistance but a concern nonetheless). If youre going to use a fence, either insulate the wire wherever it touches the posts, or run a separate wire along the top.

In New Zealand, the preponderance of electric fence units can ruin an otherwise promising site. A quick check with an AM radio listening for tell-tale clicking is a good test. Electric fences are usually their noisiest during a dry period and a good rain fall lowers the level of noise by improving their ground conductivity and washing insulators tracking high voltage across dusty paths. Electric fences are generally only found on stock farms so other rural land uses like extensive horticulture may offer a lower noise level than in a dairying area.

Overhead power lines, particularly high voltage varieties should also be avoided. If the choice is between a quiet, battery-powered DXpedition and an ‘all the comforts of home’ mains-run version, Id take the former any day! Noisy power lines also benefit from a good rain to clean insulators etc. Underground power supplies are a good deal quieter as there is no exposure to the elements to cause noise (and they’re fairly deep as those poles are quite long!).

And the further away from MW & LW transmitters the better as well. Even with directional aerials, locals will be a pest though youre invariably going to be better off than DXing from home. Other possible sources of RF interference like non-directional beacons (marine and aeronautical NDBs), GPS stations and the like should be checked too.

A site close to the sea is also a benefit. Absorption of signals by ground attenuation is more pronounced the further inland you go. So saying, my Beverage site at Waianakarua is 7km from the coast and reception there is very good. Id tend to exclude anything more than 10 — 15km from the sea.

My favourite months for DXpeditions are around the Autumnal and Vernal equinox, which are late March and late September respectively in the Southern Hemisphere, the opposite in the Northern Hemisphere). Reception from near-polar paths is best around these times though good signals on mid-latitude paths also occur in January/February and October/November.

If youre into long-term planning, the lowest point of the solar cycle is also the time to chase signals. That means 2006 through 2008 will be prime DXpedition years and Ill certainly be looking forward to then!

6. Equipment: The tools of the trade

O.K, so it’s a pretty essential piece of equipment, but what do you need to make all the effort you’ve put into antennas, finding a location, extra equipment, time off work and away from loved ones worth the while? A receiver that will maximise your chances of hearing those weak, distant signals.

There are numerous figures and specifications provided by manufacturers and test panels which will point you in the right direction towards a DX dream-machine. If were to purchase a receiver for the prime intention of MW DX, the factors I’d be most interested in are:

In the crowded MW band where stations are separated by as little as 1kHz, the ability of the receiver to discriminate between adjacent stations and to provide loggable audio is essential. What’s more the width of the filter’s skirt is as important as its quoted width and is often determined by the type of material the filter is manufactured from. For example, ceramic filters have very wide skirts allowing interference to ingress whereas mechanical or crystal filters provide very sharp skirts. Look for a receiver with a filter of around 2.5kHz at -6dB and a skirt width of less than 5kHz at -60dB (the narrower the -60dB figure in relation to the -6db the better — don’t worry too much what that means, just use it as a point of comparison between receivers). If you’re tossing up options at purchase time, between a VHF converter, external speaker or a sharper filter, take the latter!

Some receivers aren’t designed to apply all of their features to MW and sensitivity is often affected by internal attenuation to prevent strong local signals over-loading the receiver. In many receivers the attenuation can be readily set to zero by a front-panel control, or a simple software fix. In others, (e.g. Kenwood R-5000) it’s a soldering iron job which, given the complexity of modern receivers, not all will be keen to tackle.

Generally useful devices that may be handy for giving a weak signal that extra nudge. Pre-amps that do not degrade the signal-to-noise ratio are extremely useful, though often they have been disabled on MW or require a user software fix to be enabled. Check to see if they will work on the MW band or can be adapted to do so.

Some may consider having a receiver with 400 memories as more than sufficient, though for the MW DXer, the ability to program in every MW DX channel in the best mode, with the optimum filter setting etc. is a real bonus. This allows swift tuning between channels which in a strong opening is very handy for analysing the best frequency(s) to monitor.

And there’s little point in erecting long antennas, spending heaps on coax, preamplifiers, tuners, baluns etc, if the weak signals you’re chasing can’t be heard under the receivers internal noise! A simple test to see how noisy a receiver is, remove the antenna and turn the volume right up — should be very quiet, a low-level background noise, ideally the noise level would be near zero and you would hardly notice the volume had been increased. I’m fortunate to have an ultra-quiet 25 year old Drake SPR-4 that has allowed reception of weak signals at loggable levels, which have been buried on colleagues’ receivers.

Modern receivers with all their synthesisers, microprocessors and fluorescent displays can produce a fair amount of internal noise. This can effect the use of indoor loop antennas near the receiver, as they’ll pick up the noise radiated from the electronics. Another simple test is to hold a transistor radio about 50 cm from the set and see how much hash it picks up.

Operating Voltage/Current Consumption

If battery operation is required (for example when running mobile or on DXpeditions) the amount of power drawn by a receiver will dictate how long a battery will last (and if you can start the car after a nights DX!). The Drake R-8A uses 2 amps when running (i.e. 30 hours operation on a fully charged car battery) though the drop in voltage will see the set turning itself off well before the 30 hours are up and 1 amp switched off on the front panel. The consequences of high battery drain mean that you’ll need to be prepared for long stints at the dials by bringing extra batteries or charging between uses. Most receivers are designed to work off 12 or 13.8 volts DC though the AOR 7030+ prefers 15 volts for optimum performance, although it functions very well at 12 volts.

Antenna Switches

Most receivers come equipped with the facility for 1 x 50 ohm input and 1 x 600 ohm input antenna with front-panel switching. Id prefer to see at least 3 x 50 ohm inputs to allow ready access to a range of antennas. Strangely, the AOR7030+ doesnt have an antenna switch so an external device is necessary.

If you’re looking for a new receiver, there are a number of models currently available that are hailed by DXers as good MW DX machines. Sadly Im not in the position of having personally used all of these sets, with the exception of the Drake SPR-4 (which Ive owned for 15 years), R-8, R-8A and AOR-7030+, though general consensus would be to seriously consider the following: