Radio Havana Cuba Dxers Unlimited Dxers Unlimited’s mid week edition for 28-29 August 2007 By Arnie Coro Radio amateur CO2KK
Hi amigos radioaficionados around the world and orbiting the Earth … welcome to the mid week edition of Dxers Unlimited. I am Arnaldo, Arnie, Coro, your host here at this twice weekly radio hobby program that will be on the air for the next sixteen minutes… Here is item one: Still no signs of the expected jump in solar activity that will signal the start up of cycle 24…. Scientists keep watching the Sun in search for reverse polarity sunspots …. Item two: Imagine a low cost amateur radio repeater well above the Earth’s stratosphere…It is perfectly possible to assemble one such high altitude repeater from readily available components and put it as the payload of a high altitude balloon… Here is a very recent example of that unique way of providing over the horizon VHF and UHF communications, at least for the lifetime of the balloon.. The news comes from Finland and it explains that after what was considered to be a successful maiden flight two weeks ago, there will be another IIlmari balloon flight next weekend. The flight is scheduled for 06 UTC on Sunday, September 2nd, 2007, from Sappee, Finland, grid square locator (KP21GJ). The high altitude Ilmari balloon should be workable from many parts of north-eastern Europe, if it goes as high up as the previous flight (30 km), yes you heard it right, the Finnish radio amateurs were able to make their experimental high altitude repeater go up 30 kilometers , thus giving it a really wide coverage area. They do recommend potential users of the Illmari high altitude balloon repeater to keep the effective radiated power at low levels, saying that even 1 watt is plenty for working Ilmari's 2m/70cm ssb/cw transponder! The balloon will have APRS(-IS) callsigns that probably will be assigned as OH2SIX-11 and/or -12. A URL site with the information about the Illmari high altitude balloon repeater experiment is available at http://wiki.ham.fi/Ilmari-2007b providing detailed operating instructions and another site with the URL http://www.kolumbus.fi/michael.fletcher/ilmari.htm has or pictures and information from the maiden flight. Many amateur radio clubs around the world have done similar experiments with high altitude balloons carrying not only amateur radio repeaters, but also equipped with TV cameras transmitting back to Earth via 70 centimeters band Amateur Television . A possible future high altitude repeater may form part of tests of a unique solar powered aircraft, capable of staying up for long periods while flying at altitudes of around 20 to 22 kilometers above the Earth. These “robot” solar powered planes use highly efficient electric motors and large size propellers capable of providing enough lift even at such high altitudes where the air has a very low density. The electric robot planes can lift smaller payloads, but present day technology makes possible designing and building very compact and lightweight repeaters with 2 meters band input and 70 centimeter band output frequencies… Stay with us as Dxers Unlimited’s mid week edition will continue in just a few seconds, after a station ID… I am Arnie Coro in Havana. ……. You are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited, and YES, we do verify reception reports, and also answer your radio hobby questions sent to [EMAIL PROTECTED] or VIA AIR MAIL to Arnie Coro , Radio Havana Cuba Havana, Cuba Here is now our next item of today’s show, our technical topics section of Dxers Unlimited, that will be telling you about my most recent version of the universal linear power supply for solid state equipment… Last week I was finally able to find time to spend at the workshop and give the finishing touches to a project that had been waiting for a long time. The universal linear power supply for solid state equipment, that uses readily available components, is easy to homebrew, and has built in protection against short circuits and over voltages. This power supply has a variable output range that goes from 0 volts to 30 volts DC, and several fixed voltage outputs set at 4.5, 6. 9. 12, 13.8 18 And 24 volts DC, all at a current maximum of 2 amperes, more than enough for low power electronics experiments. The 2 ampere maximum capacity will eventually be upgraded to 5 amperes, when another project left halfway to completion is finished… that is winding a new transformer for the universal linear power supply. This supply is an excellent addition to the workbench, as it is capable also of measuring the current used by the circuit under power, giving you a good idea of how the new designs are evolving. The current meter is calibrated in three scales that go 0 to 30 miliampers, 0 to 300 miliamperes and 0 to 3 amperes, that will have to be modified when the new transformer is installed. The power supply already in use is kept operating full time when I am working in my electronic workshop, providing power to the 2 meters band handie talkie that I keep on the local Havana metropolitan area repeater on 145.190. I normally use the 9 volts DC output to provide power to the YAESU FT2008 FM 2 meter band handie talkie, that works quite well within the voltage range of 7.2 to 12 volts DC. All the other outputs of the power supply are free, and can be used to power other equipment or for test purposes. In order to have a very smooth well filtered direct current output , I used the 5000 microfarads per ampere rule, so the power supply has three five thousand microfarads at 35 volts DC working volt electrolytic capacitors, that will soon be replaced with a single 22,000 microfarads at 50 volts DC working voltage capacitor, so that it can be used when the new higher current rating transformer is installed. Having such a wide voltage range, fully measured and short circuit an over voltage protected power supply is something I recommend to all electronic hobbysts and radio amateurs that like to homebrew and repair solid state equipment. ….. And now la NUMERO UNO… ASK ARNIE, the most popular section of Dxers Unlimited, closely followed by the HF plus los band VHF propagation update and forecast and the technical topics section of the program… Today’s ASK ARNIE question came from Surinam, where listener Dersi wants to know if it is worthwhile to buy broken down radio receivers from a local dealer that is selling them at very low prices. Well amigo, if the price is low, you have almost nothing to loose and a lot to gain… In many instances broken down solid state receivers can be fixed by someone willing to spend more time than the time usually spent by a dealer’s repair technician… Especially lower priced radios are usually just tossed away instead of spending expensive labor in attempting to fix them… But beware that you may find the cause of the breakdown sometimes by just opening up the receiver’s case… For example, just recently a neighbor gave me an old transistor radio, so old in fact that it uses germanium transistors… He had taken it to the repair shop and they told him that the set was beyond repair… It took just ten minutes, using classical signal injection techniques to find out that the first audio amplifier transistor was not operating… Putting in a new transistor, that wasn’t new at all, because I had recycled it from energy saving fluorescent light lamp…Although the transistor from the lamp has more gain than the one it replaced, the only minor chage required was to increase the value of the emitter resistor. A quick realignment using the workbench signal generator and the digital multimeter, brought the little transisor radio back to several more years of useful life !!! ……… Si amigos, short wave listening, tuning in to stations from 3 to 30 megaHertz is one of the most popular aspects of the radio hobby , you can tune in to the many users of that frequency range, from international short wave broadcast stations , to aircraft long range communications , time and frequency standard stations, as well as the several million active amateur radio stations worldwide. But nowadays one of the things that really worries me about short wave listening is that many newcomers to this hobby are making their entry using very poor radio receivers, in fact so badly designed and built radios that many people simply drop any further efforts to “listen to the world” as many sales promotions for those receivers say… My advise is that if your present radio receiver is a very low cost one, and you are experiencing difficulties when tuning in stations, think about the possibilities of buying a better receiver, that will obviously is going to be more expensive, several times more expensive than the cheap little radio , but that will be able to provide much better reception with good frequency indication in the form of a digital frequency display , and equipped with an input connector for installing an external antenna system. You will feel the difference immediately and start tuning the HF bands much more frequently with much better results,,, …… Human powered radios....using radios that obtain their electricity from a person winding a clockwork , hand cranking a generator or pedalling a stationary bicycle connected to a generator recently made number 78,of the now more than 81 ways you and I enjoy our hobby. Yes amigos, Walt , ae Canadian listener from Nova Scotia has convinced me that human powered radios open up yet another way of enjoying our hobby in a unique way... Now those who criticize us radio hobbysts as potato couch guys, will be surprised to learn that we can share two wonderful hobbies at the same time... exercising with a stationary bike and generating our own electricity to power the radios. After receiving Walt's e-mail, I attempted to couple a small generator to a bicycle that I had kept in the garage for several years, and all I can say is that IT WORKS !!! The small direct current generator that was originally intended to power the headlight and a small taillight for the bicycle, provided enough power to make a small transistor radio work quite well, after I added a big ten thousand microfarad capacitor in parallel with the generator output. Please note that this generator was not charging a battery, but feeding directly the radio with its direct current output that was very near 6 volts when I pedalling at slightly below my long range biking cruising speed... ...... And now as always at the end of the program, here is our exclusive and not copyrighted Arnie Coro’s Dxers Unlimited HF plus low band VHF propagation upate and forecast…Solar activity will continue at very low levels, solar flux around the 70 units baseline, and the daytime maximum useable frequencies are still well below the figures I expect them to go in about 2 more weeks when we enter into the autumn equinox period of much better short wave propagation. Remember to send your signal reports and comments to [EMAIL PROTECTED], and VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba, Hope to have you listening to the weekend edition of Dxers Unlimited Saturday and Sunday amigos… ---[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. It may be copied, distributed and/or modified under the conditions set down in the Design Science License published by Michael Stutz at http://www.gnu.org/licenses/dsl.html
