|
|
|
CQ DX for an SWL Working with the long path (III) To hear far stations a solution of compromize can be found in listening for example in automn to the 20-10m bands searching emitters during the local morning (before 0800 UTC), in the afternoon (around 1200 UTC) or in the evening (around 2200 UTC). Two paths can be used : the short path (long circle), direct, where shortwaves travel in the sunlight to the far stations at relativity low altitudes (E, F1, F2-layer) or the long path (off-long circle), where shortwaves travel "backward", first to the side of the Earth plunged into darkness and at higher altitude (F-layer) to reach the remote DX stations on the sunside, reaching them "from behind". The path is much longer, for example 23000 km vs. 16000 to reach VK3, but signals are often much clearer with little QSB, because the ionosphere is less disturbed. You can receive a VK station between S4 using a dipole and over S6 using a beam. Of course an SWL cannot control this path. But in the past I have used such stratagems with OMs from South America for example calling Europe in summer by 2200 UTC and receiving a contact with VK or ZL with the rear side of their beam. A similar configuration occured by 1600 UTC with a 9K station bearing to Europe and who heard a YB in his back. I usually receive these far countries with a signal strength less than S5 using a dipole. They are not strong but readable. Even if this task can be accomplished regularly, that remains a performance using an ordinary wire antenna but also for the listener who has sometimes to stay awake long after midnight or wake up with birds !
To be complete, one must tell that the opportunity to work (to listen) or not a DX station using one path or another is quite hard to predict. First such openings are determined by the activity of the ionosphere. It it obvious for example that during a geomagnetic storm occuring at high latitudes, it will be useless trying to work or listen to northern stations (at a few exceptions). There is probably a radio blackout over 50° of latitude and no amateur will be able to transmit by shortwaves during a few hours. This event is very recognizable if you work from those latitudes because most bands from 20m and above, sometimes the lower too, are empty, without the least activity excepting a huge background QRM. As we told on the previous page, the status of the ionosphere is also determined by the MUF. I remind you that if at both the transmitting and the receiving stations the MUF is for example 21 MHz, short distance propagation (3000 km) is open between both stations up to that frequency, but not above, and the signal will be hear over the complete path. This is only using an antenna showing a low takeoff angle that you might overtakes the MUF at longer distance. At last, a strong activity of the E-layer, or a MUF below the E-layer will always reduce your chance to capture far DX. Listening to DX networks Now if you do not want searching for DX stations hours long in browzing frequencies, there is another performing solution, this is listen to DX networks. Here are some DX networks that I regularly try to work (or that I listened to in the past) : - The European DX network is working on 14.242 MHz (summer) or 7.045 MHz (winter) from 1700 UTC on week days and from 0600 UTC on weekends. Thanks to the net control who manages QSOs by list, you could hear radio amateurs stations from many far countries or from very small entities, including LX when I am QRV, Hi! - The Brasilian network (BRYLA) is regularly in QSO with YL's and works on wednesday's on 14.248 MHz from 1700 UTC too. - The Africana net is working every day on 21.355 MHz from 1300 UTC or preferably 1800 UTC allowing you to listen amateurs from rare african countries, from SU to ZS but also from other continents like CO or HH. - The 247 DX Net, a north american network is working on 14.247-14.250 MHz from 2100 UTC, a good time to capture many central american and Caribbean stations. - The Family hour network works on two different times and QRG, on 14.245 MHz from 1400 UTC and on 21.350 MHz from 1730 UTC. - At last the famous WABA network is on the air on monday's from 1700 UTC on 21.275 MHz (summer time) and will offer you one of the rare opportunities to hear Antarctic bases and stations. All them can be hear (and work) with small antennas like receive magnetic loops, verticals 6m high and dipoles 20 to 40m long, even tight at low height (4-6m only). Of course the larger antenna the better receive. If you work with a high gain directive array (beam, quad, loop), on weekends and with good ears you can hear several remote networks if you are searching rare DX entities for Asia and Pacific, including military and maritimes networks. Of course due to the time shift, most of them work when europeans are asleep. I have tried to list some of them in the following Excel sheet. Marius Rensen from HF-Fax maintains also a list of ham maritime mobiles net. All these networks are not necessary QRV the day listed. Communications always depend on the propagation and can be subject to atmospheric noise or static, interference or fading, as much perturbations that may convince an amateur to QRT until the band is clearer or open again. For an european DXer, remote networks like Pacific Island, Oceania DX Group or China DX are also more difficult to listen to if these amateurs to not bear their antenna in your direction, even though. So don't try to hear them with a small dipole and a short vertical, their signal is usually much too weak, excepted if they are in QSO with stations right in your direction. Most of the time, you need a directive array to hear them in good conditions. Listen to the CQ WW contest Another opportunity to listen to DX stations is the famous CQ WW contest organized by CQ Magazine and planned the last week-end of october (SSB) and of november (CW). There are tens of contests each year, almost one each week, including the ARRL international DX Phone contest, but the CQ WW is by far the main HF contest. In 2003 it gathered over 8000 official competitors (ten times more than the ARRL one !) who returned a log to their national association and in 2004 up to 4300 SSB logs where returned to CQ Magazine, the highest score to date. This is a contest that last 48 hours non-stop. During these weekends thousand amateurs, single or gathered in club teams, are QRV on all HF bands excepted on WARC. At daytime there is no one kHz which is not used ! Even bands segments usually free are at this occasion crowded ! This situation is still worse of low bands and mainly of 40m were stations are placed a fraction of kHz from each another, still closer than during an ordinary weekend ! This is in such situations that amateurs appreciate a performing receiver equipped with the best DSP to reject QRM generated by near stations, HI! During the CQ WW contest you have all chances to hear stations in most CQ zones (there are 40). I remember that as SWL and using a longwire antenna 40 m long, I heard 65 DX entities during a weekend (being QRV 2x 12 hours) and as amateur I worked as much. The best competitors using beams work up to 150 DX entities, including small entities like Marion island, Macao or Galapagos islands to name a few. You rarely hear them and amateurs have few opportunities to work these stations, but at this occasion there are tens of such rare DX on most bands, including on QRP frequencies. Good news for amateurs, during a CQ WW not all DX create huge pileups and you have chance to be a handful of amateurs to work them. Some pileups are easier to work than usually because all amateurs are spread on all bands and a weak signal has more chance to be hear from the operator. This situation is still better when propagation is open with a low K-index.
These results are extract from CQ Amateur Radio website. Note that we find almost the same stations in CW mode. During this event, the fastest single operators are able to work up to 8655 stations (about 3 QSOs per minute in SSB) as much as multi-operator teams or DX-peditions ! Difficult to break their record ! This contest deserves your attention, that you are SWL or licensed amateur. This is like suddenly world-wide, all amateurs woke up and work on the air for the greatest pleasure of the ham communtity. Usually there are interesting openings on 20, 15 and 10m bands. In fact most licensed amateurs take advantage of this fall week-end not only to win the contest, what becomes very hard, but first of all to complete their DXCC palmares. This is at such occasions that you can confirm new entities located over 8 to 10000 km away and closer countries in new bands. If theoretically all DX stations can transmit in all HF bands (at the exception of some licenses that do not permit to work on specific band segments), even during contests it is much more easy to hear DX stations in the 20, 15 and 10 m bands. You have few occasion to hear these remote stations on the lower bands from 160-40 m that require performing and often large antennas. But they are exceptions. Some DX will be hear loud and clear as if they work from the adjacent room. For example, some KL, VE7 or JA amateurs arrive booming in Europe with a signal 59+ but they use half-length or full length beam on 80m or 40 m and 1 kW ! So reserve this chase to advanced amateurs who calculate their chance to get a QSO with near-real-time propagation data. But I don't say that far countries never worked on lower bands - many amateurs won their 5BDXCC on the low bands too -, they are however not numerous, all the less than few of them can be heard 10000 km away with small antennas. So, as SWL the type of antenna and its size (the height above ground is not very important for listening purposes) are the greatest constraints that you have to manage if you want a performing installation, able to capture the weakest signals. We will take time to go further in this question in other pages dealing with antennas.
Chasing DXMen Before closing this long list of DX opportunities, you can also search for amateurs calling "CQ DX CQ Delta-X-Ray" or calling for a specific continent, ocean or country (CQ Pacific, Asia, Japan...) and be in alert to catch all QSOs just "behind" them. Of course amateurs using special prefixes are still more interesting as they attract still more amateurs. In thr past for example, with the help of TU2IG I was able to record in summer at around 2100 UTC, when the propagation was not disturbed by the Sun activity, dozen of JA stations, an opportunity to increase my score for the japanese awards. Another time the Belgian operator OP1A allowed me to hear many South America stations. At last with the help of 4S7AB who worked on the 17 m band around 1900 UTC I heard many US amateurs who helped me to increase my score for the US county award. Listen to DX-peditions is very exciting if you can hear them. From statistics, we can say that working on all HF bands and several modes with 8 operators for example such teams can easy work 40 CQ zones and about 150 DX entities in a week whereas an SWL working alone needs over 3 months of active listenings to achieve such a score.
For sure such a solution has some limits. An european amateur using a 2-element quad and 1 kW PEP will reach VK and JA stations with ease even if the band is so-called closed for all other amateurs working barefoot with only 100 watts PEP. This DXer is probably not the best example to follow if you like hamradio, and in all cases if you hear him you will surely not hear his contacts... Working with clusters and packet radio To be sure to pick up (almost) all amateurs stations "passing near" and put all chances on your side to hear DX or special call signs, it is very useful to read for example news about current QSOs and DX-peditions, the ones to come, and to log their period of activity in your logger calendar in order to be alerted once they will be QRV. Your national ham radio magazine as well as 425 DX Network or DX Central can provide you such an information and much more too. But this information is rarely available in real-time. Can you, just now, tell me what DX-pedition or far DX should be actually in QSO on the 15m band, in SSB mode, and what is his QSL info ? You will maybe arg that it is difficult to answer such a question without buying numbers of ham magazines, the last callbook or without browsing the Internet or using tools connected to HF bands... But I have to refute your arguments; there is a very simple solution. To fill this gap there are clusters and packet linkings established through hamradio equipments. Born in the late 1980s, this technology is today used by most amateurs worldwide who can't no more ignore this tool when they work on the air as it provides them a very useful assistance. If you are connected to Internet, preferably with a DSL connection, or if you own a VHF mobile transceiver (nothing larger) and a TNC (a sort of modem able to process digital signals coming by shortwaves), you can access online to huge databases of QSOs and hams related information saved on remote servers. Clusters allow you to talk to other amateurs for free, to sked QSOs or to request information to the ham community if necessary. If you are interested in packet radio I suggest you to read the next document that I have written about this technique. To read : Clusters and Packet Radio With all these techniques and tricks at your disposal, you can no more say that you have no information about the latest DX-pedition to date or about the last conditions of propagation (WWV) ! With all these tools in hand you should be able to work at your best on bands and break through all pileups, hearing practically all DX if you like that.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
