Radio Havana Cuba Dxers Unlimited Dxers Unlimited’s mid week edition October 2 -3 -2007 By Arnie Coro Radio amateur CO2KK
Hi amigos, welcome to our mid week edition , coming to you Tuesdays and Wednesdays UTC days. I am Arnie Coro , radio amateur CO2KK your host here in Havana, and as always it is my pleasure to share with you about seventeen minutes of on the air and on the web time. Here is now item one of today’s program: The Headline : Back to Zero , yes back to zero sunspot count after a very short break , when a single small sunspot was seen… according to a recent analysis by a group of well known solar scientists, cycle 23 actual minimum has required no less than three revisions, and it has certainly extended beyond all forecasts. Another relevant piece of information about this solar cycle is that the number of consecutive days without sunspots has so far extended into two series of great significance, when compared with other previous solar cycles. For short wave listeners and amateur radio operators, as well as for professional users of the HF spectrum, cycle’s 23 extended minimum has already had a very significant negative impact, including, in the case of amateur radio, rather low scores during the latest contests !!! Item two: Less time on the air, or more time using the highly efficient digital modes, like the PSK31 keyboard to keyboard brainchild of G3PLX Peter Martinez that with just 10 Watts transmitter output and even a very simple antenna is capable of providing nice two way amateur radio contacts. Yes less time on the air is one option for ham radio operators at this present stage of the solar cycle, that can then be devoted to more home construction of radios, one of the 81 wonderful ways of enjoying our wonderful hobby. At a recent edition of Dxers Unlimited, I talked about new approaches to the design and construction of simple short wave receivers, that have already proven to be quite feasible for the average home builder… The Wheatstone Bridge Regenerative Receiver Circuit is now available in both a vacuum tubes and a solid state devices versions .. The solid state version provides amazing performance according to my breadboard prototype tests, and it is also quite amazing that this receiver works from a single 1.5 volts battery and requires a current of less than one milliampere to provide full output into the headphones. The circuit is very simple, and easy to reproduce without requiring the use of a printed circuit board… as a matter of fact you can assemble it using the now classic small islands technique, that is gaining favor among homebrewers of ham radio gear… Si amigos, yes my friends, oui mes amis… HF propagation conditions may be very poor, band openings above 20 megaHertz rare or non existent, but the radio hobby has so many different aspects that can be enjoyed , among them homebrewing receivers that have a very special sound when you use them… because I can assure you that a radio that you assemble has a unique sound to your ears… build your first homebrew radio and when it starts bringing in stations, even if the first one is the local AM broadcast band super power 50 kiloWatts transmitter , you will agree with me that your homebrew radio has that very special sound too… Stay right here on this same frequency or world wide web connection … Dxers Unlimited’s mid week edition will continue in just a few seconds amigos … …… This is Radio Havana Cuba, the name of the show is Dxers Unlimited and here is item three of the show… ASK ARNIE, la numero uno, the number one most popular section of the program… The question that I will be answering today here came from Australia, more precisely from Perth, where amigo Ian picks up RHC’s 9550 kiloHertz frequency during the two yearly equinoctial periods with what he describes as “amazing reception”… Amigo Ian wants to know more about the best antennas for picking up very distant stations, that may be reaching his receiver at very low angles above the horizon. Well Ian, low take off or receiving angle antennas are difficult to install at urban locations, and the only type of antenna that provides really low take off and receiving angles above the horizon suited for an urban area is unfortunately prone to picking up a lot of man made noise, something that will make reception a lot more difficult. During solar cycle 21 , I had installed a vertical antenna for the 20 meters amateur band that was about 120 electrical degrees high, and had six elevated radials . The antenna itself was installed on my rooftop, but the bottom of it was elevated about three meters from the reinforced concrete roof. The six radials worked as the elevated ground plane, and this antenna provided wonderful DX contacts around the world while using less than 100 Watts. The zero decimal thirty three wavelength vertical with elevated ground plane sent out and received signals at very low angles above the horizon , and it worked so well that several of the local ham radio Dxers visited me just to see the antenna, as during pile ups, I often made contact with the rare DX station before the owner of the best 20 meters 4 element Yagi antenna in town. He was scratching his head how could CO2KK could beat him breaking a pile up, when he had installed a huge 4 element full size 20 meters Yagi… and I had to spend quite some time to explain to him that he would need at least a 120 feet or about 36 meters high tower, in order to achieve the low take off angle that my elevated ground plane was providing. Fortunately at my city location, the noise level is rather low, because as I have explained here several times, the man made noise , man made interference is mostly vertically polarized, so a vertical antenna picks up a lot more local noise than a horizontally polarized antenna… Amigo Ian, I have already sent to you the sketch of the elevated ground plane antenna for 20 meters, which is the most popular DX band among radio amateurs. You will also see in the drawings a table of dimensions for the 17, 15, 12 and 10 meters band. An elevated ground plane antenna for the lower frequency amateur bands like 30, 40 and 80 meters will be difficult to build and install, and that’s why I didn’t include information about them. Now another question , this one came from Canada , where the short wave listening hobby is , according to my analysis, a mostly winter time activity for many Canadians… although as my good friend Bob Chandler , radio amateur VE3SRE from Toronto has told me, the summer time ham radio contests, like the one held during Canada Day national celebration are also very popular… The question came from Quebec City, where amigo Robert lives. He wants to know about amateur radio satellites, and how easy or how difficult it is to operate using them. Well amigo Robert, ham radio satellite activities , in my opinion, have gone down significantly after the failure of several of the most popular birds, as the satellite enthusiasts call them. As a matter of fact, the failure of RS10 and RS12 , followed by Oscar 40 has left out of the picture both the simple station operators and those who spent a lot of time and resources to install a complex Earth station to work the Oscar 40 satellite. At this moment the amateur satellites that are available provide very short time windows to communicate, due to the fact that they are all in the so called Sun synchronous orbits, at rather low altitudes, and they don’t have , as far as I know, HF bands inputs or outputs… So amigo Robert, we must wait and see if a new ham satellite project in the works can finnally be completed , and a Molnya elliptical orbit satellite can be launched … As regards to your question about why there are not stationary ham radio satellites, like the ones used for telecommunications and relaying TV signals, the answer is a very simple one amigo: they cost a lot of money, and so far it has proven impossible for any of the amateur satellite organizations to collect enough resources to even think of starting such a project. Another possible approach would had been to find a geostationary orbit satellite to which an amateur radio transponder could be attached, but , again, so far, this has proven to be impossible… You can still have fun with a dual band 70 centimeters and two meters FM transceiver and a simple hand held antenna by communicating with the low earth orbit ham satellites that are now in operation , but your fun will have a very limited time , because even on the best passes, the time available to communicate is limited to fifteen minutes or less. And now amigos, just before going QRT, here is Arnie Coro’s Dxers Unlimited HF plus low band VHF propagation update and forecast… Solar flux continues at very low levels, with the actual flux measurements not going over 67 or 68 units… and do remember that the lowest registered microwave solar flux was 64 units… Sunspots are non existent… sunspot count again zero after a brief spell when a very small sunspot emerged and then vannished… Expect daytime maximum useable frequencies not to exceed 20 megaHertz for 90 percent of the time, and barely moving above 21 megaHertz for very short periods on the best possible propagation paths, that again will be North to South, and vice versa, with the East to West path showing the worst propagation , as expected during extended periods of very low solar activity. Trans equatorial DX season still in progress, with options opening for 6 meters band ham radio operators for nice contacts from the South of the US, Mexico and the Caribbean, to Brazil, Argentina, Uruguay, Paraguay and Bolivia, and slightly less chances of contacts on six meters via TE scatter to Chile and Peru. Join me next Saturday and Sunday UTC for the weekend edition of Dxers Unlimited, and don’t forget to send your signal reports, QSL requests and comments about the program to [EMAIL PROTECTED] or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, 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 [email protected] 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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