Dxers Unlimited Dxers Unlimited weekend edition for January 27-28 UTC By Arnie Coro Radio amateur CO2KK
Hi amigos radioaficionados around the world and in space! Welcome to the weekend edition of Dxers Unlimited reaching you when solar activity is still at really very low ebb… I am Arnie Coro, radio amateur CO2KK and here is item one of today’s program, solar scientists continue to scratch their heads about cycle 23’s final months…and there are conflicting news about the possibility that solar minimum is already behind us… yes , you heard it right, some recent statistical analysis could be interpreted as the first signs of a solar minimum that has already happened while some researchers still believe that we may see a rather extended tail end of cycle 23, while others insist it over by now. Another school of thought continues to underscore the very high probability that upcoming solar cycle 24 is going to be a record breaker, even capable of matching the super cycle 19 that sent the average monthly sunspot count up to two hundred and seven. For us radio hobby people, a super solar cycle, with a very high average sunspot count will also mean many solar flares and geomagnetic storms too !!! Now, we must just wait and see what’s going to happen during the next year and a half or so, when it would be possible to have a fairly good knowledge of the early phase of cycle 24… Item two: The most popular amateur radio band around the world continues to be two meters, spanning in some parts of the world from 144 to 146 megaHertz, while in other areas amateurs are assigned two more megahertz, so the band in those parts of the world goes from 144 to 148 megaHertz as it happens in North America. Two meters is very popular because with very simple equipment and low cost antenna systems, radio amateurs are able to communicate locally and even at longer distances when propagation conditions are good and they may even use amateur satellites that have two meters uplinks or downlinks. But the two meters band is not only a good place for FM voice mode communications. Amateur operators can make very good use of existing satellites, and also enjoy very sophisticated communications modes, like sending signals of high power transmitters to the Moon, using it as a passive reflector as part of an Earth – Moon – Earth or EME link. I have made several two way amateur radio contacts using the Earth –Moon - Earth or EME mode while running at CO2KK, my ham radio station not too much power output and a pair of small size Yagi antennas. But, fully equipped EME capable stations use huge antenna arrays, high power transmitters of up to the maximum legal power authorized to amateur operators and extremely low noise signal preamplifiers… EME is one of the more than 79 ways that you can enjoy our wonderful hobby… yours and mine: RADIO !!! Amigos, Dxers Unlimited’s weekend edition will continue in just a few seconds… I am Arnie Coro in Havana, stay tuned or connected to our server: …….. Si amigos, you are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited, and as always its my pleasure to share with you this on the air and on the web time devoted to this wonderful hobby “RADIO” here is our next item, the most popular section of the show “ASK ARNIE “answering listeners questions as fast as they come in via e-mail sent to [EMAIL PROTECTED] Today’s number one question: came from the USA, from Southern California, listener Adonis asks if he can adapt an FM band Yagi antenna that is sold at a popular electronics retailer outlet near his home, so that the antenna will work on the 2 meters amateur band… And amigo Adonis, the answer is YES… it can be done, and as a matter of fact, you will end up with a very nice looking 2 meters band antenna, at a much lower cost than if you try to homebrew one by buying materials at a hardware store. The typical FM band 5 or 6 elements YAGI antenna has a boom length that provides more than enough space for a 6 to 7 element 2 meter band Yagi, and the length of the elements allow you to cut them to the segment of two meters where you want to operate. After buying the commercial FM broadcast band YAGI, you must proceed to carefully measure each element and write down the result of the measurement. You will find that as in any typical Yagi parasitic array, the elements lengths go from the longest one, the reflector, that will be very near a half wavelength at the operating frequency, to the shortest one , the last director, that will be much shorter than a half wavelength. The FM band Yagi will probably be cut for a frequency around 100 megaHertz, because that is roughly the center of the FM broadcast band that spans from 88 to 108 megaHertz, and that means that the longest element of your commercially built Yagi will be very near 1. 5 meters long, that is almost 5 feet long. The second step required for converting a commercial FM band Yagi for the amateur 2 meters band is to decide to which segment of two meters you want new antenna to be optimized. For example you may enjoy talking to friends on repeaters located in the upper two megahertz of the 2 meters band, from 146 to 148 megaHertz, so you may want then to optimize your YAGI for a center frequency of 147 megaHertz, which is not exactly the optimum way of doing it, but that in actual practice works quite well. The third step is to use any of the available freeware programs that calculate YAGI VHF antennas, and run it with the 147 megaHertz center frequency design target. Those programs generate several outputs: they will give you the length of each element; how the elements are spaced along the antenna’s support boom and also you will be able to see the actual theoretical horizontal and vertical radiation patterns. Your fourth step requires the use of a measuring tape and a hacksaw, to cut the elements to the required lengths, following the data provided by the YAGI antenna calculating software. Fifth step, requires using an electric drill to carefully locate and drill the holes where the elements will be fixed to the boom, that will not be the same ones used for fitting the elements to the original FM Yagi antenna The sixth and almost last step requires a decision on your part, it you want to operate using horizontal or vertical polarization. Using horizontal polarization as needed for operating on CW and single side band modes at the lower edge of two meters needs no change to be done to the boom, but if you want to use vertical polarization, as required for FM voice and packet radio modes, then you must drill new holes so that the antenna may be installed for vertical polarization, in other words the support clamp will be at 90 degrees from the original position used for receiving FM broadcast band horizontally polarized signals.. The last step is to adjust the antenna for minimum standing wave ratio, and for doing this you will need a VHF standing wave ratio meter, and the help of an experienced radio amateur that has adjusted Yagi antennas before… Take good notes of what you do, write them down, so that in the future you will be able to adjust other antennas all by yourself… Amigo Adonis, I am sure that you will be able to find at a local radio club someone willing to help you with your antenna conversion project… And don’t forget that a YAGI with 5, 6 or 7 elements is a highly directional antenna that requires the use of an antenna rotor if you want to have around the compass coverage!!! ……. QSL , QSL , QSL on the air from Havana to the many Dxers Unlimited listeners around the world that have written during the past several weeks reporting good reception of our 6180 kiloHertz English language program heard between 05 and 07 UTC. The antenna we are using on 6i80 kiloHertz is our new Central North America curtain array, it is technically speaking according to ITU definitions an HR 4, 4 , 0.8 system, that meaning that it has 4 sets of dipoles set in four rows and four columns a configuration that provides close to 20 decibels of effective antenna gain over a half wave dipole placed at the center of the array. The new antenna is also getting reports from other parts of the world too, where listeners that wake up very early in the morning are picking up the last hour of the English program between 06 and 07 UTC. If you are picking up Radio Havana Cuba on 6180 kiloHertz in English from 00 to 05 UTC,you are listening to the same antenna and transmitter combination too. Item six: For more than fifty years I have been fascinated with my father’s 14teenth birthday present… a regenerative radio receiver kit that he was sure I was going to be able to assemble without any help, as dad told my uncle Armando during the birthday party.. that little radio, assembled breadboard fashion is still working after half a century have passed, and it has also served as the prototype for many other clones that I have helped to build all along these years. The latest version of my BIRTHDAY Regenerative is a bit more sophisticated than the original one, and works beautifully with the sets of plug in coils that its proud owner my now almost twelve year old grandson has built so far… As batteries are hard to come by locally and very expensive, this version of Arnie’s Birthday Regenerative uses a very safe 24 volts DC supply to power Arnie Coro the Fourth wonderful new toy!!!! If you want to learn more about my BIRTHDAY Regenerative receiver, just drop me an e-mail to [EMAIL PROTECTED] or a postcard to Arnie Coro, Radio Havana Cuba, Havana , Cuba asking me to send you the Birthday Regenerative receiver information package… And now, as always at the end of the show, here is Arnie Coro’s Dxers Unlimited, HF plus low band VHF propagation update and forecast…Let’s begin with the actual sunspot count that on Friday was 11,solar flux was near 80 units and the A index Saturday morning local time in Havana, that is at around 13 hours UTC was a nice and low ONE…, with the maximum useable frequency curve going as high as 33 megaHertz over parts of Africa, a good indication of the not too bad propagation we are enjoying despite the very low solar activity. The BAD news is that we may soon see yet another geomagnetic disturbance as the solar wind is bringing in a much higher than usual proton count that is expected to increase by Monday unleashing a possible geomagneti storm at high latitudes… Keep time available for DXing from about an hour before your local sunset to three or four hours after sunset, and enjoy a second propagation peak starting at around two hours before sunrise, and extending no more than an hour after sunrise… And don’t forget to send me your comments about this program, signal reports QSL requests and radio hobby related questions to [EMAIL PROTECTED], or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, and Havana, Cuba ---[Start Commercial]--------------------- Preorder your WRTH 2007: http://www.hard-core-dx.com/redirect2.php?id=wrth2007 ---[End Commercial]----------------------- ________________________________________ Hard-Core-DX mailing list Hard-Core-DX@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/hard-core-dx http://www.hard-core-dx.com/ _______________________________________________ THE INFORMATION IN THIS ARTICLE IS FREE. 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