Radio Havana Cuba Dxers Unlimited Dxers Unlimited's mid week edition for 10-11 April 2007
Hi amigos radio-aficionados around the world and also those of you orbiting the Earth, because, yes, there are amateur radio operators in space at this moment you are listening to Dxers Unlimited, and whenever they have some spare time, they do make some nice two meters band two way contacts with hams around the world. There are radio amateurs almost everywhere, as you can quickly find out by operating on one the short wave ham bands... I have talked to pilots flying Jumbo jets across the Pacific Ocean, with members of an Antarctic expedition, with Cuban doctors providing medical care to patients in remote areas of Guatemala and for whom the amateur radio transceiver is a unique communications tool. There are many hams operating maritime mobile from sailboats cruising the Caribbean or from high speed container merchant vessels that keep going back and forth between ports across the Atlantic, taking only a few hours to unload their containers and load new ones to start a return journey. Yes amigos, there are radio amateur operators in remote villages of Africa, or in the middle of highly populated cities like New York, London , Paris or Tokyo, and they are able to operate on the HF bands by using unique antenna systems, like the remotely controlled magnetic loops... You can join them and enjoy amateur radio on the short wave bands that is going to take a turn for the better now that solar cycle 23 has come to an end...From July of this year on, my forecast calls for increasing solar activity , and that will bring in much better HF propagation conditions for at least five to seven years !!! Item two: coming up after a short break for station ID. I am Arnie Coro in Havana, and this is Dxers Unlimited's mid week edition... ....... Si amigos, you are listening to Radio Havana Cuba, coming to you via short wave, via Internet and also via satellite... Now here is item two: I am now back in Havana after a two week trip to the United Kingdom of Great Britain and Northern Ireland, where I attended the yearly meeting of the DRM Consortium, and also had the opportunity to exchange points of view about the future of broadcasting in general and of short wave broadcasting in particular with experts from many different countries that were attending the conference. Also, I was able to see the first run of a production model of the Morphy-Roberts DRM capable receiver, which is now selling in Europe. Still too expensive, but , it is available, and that is surely quite a difference from what was happening just a few months ago, when stations broadcasting using the Digital Radio Mondiale mode on short wave could only be heard using a radio receiver connected to a computer equipped with specially written software to decode the DRM signals. In contrast to the DAB or Eureka 147 digital broadcasting standard, that has proven to be quite successful in the United Kingdom and Denmark, with several millions of receivers sold, DRM is still facing the lack of easily available and relatively low cost receivers as its most relevant problem. During the meeting, that took place at the BBC Research Center, a lot of attention was given to further development of short wave transmitters capable of handling the very sophisticated DRM signals without suffering from lack of linearity and excessive bandwidth as it happens to be typically the case when short wave broadcasters use their existing equipment to transmit DRM , something that if not done properly can create many problems to stations located on adjacent channels. ........ ASK ARNIE, the most popular section of this program , continues to receive many e-mail messages, post cards and letters from listeners around the world that want to learn more about our wonderful hobby... Today I will answer Canadian listener Gary's question regarding the possibility of using DRM for amateur radio communications... And the answer is YES, there is now a software based on the DRM concept , that goes by the name of WIN DRM and that seems to work, although setting it up is not very easy according to what I have read recently....It does require a fast computer and a good quality transceiver to work properly... There are amigo Gary other digital voice modes now available too, but so far WIN DRM seems to be the one that is easiest to set up for the home experimenter... Second question at today's ASK ARNIE, also coming from Canada where several listeners are telling me that freezing rain has done damage to many wire antennas during the past several weeks... Antennas tied to tree branches can break them when ice forms along the wire ... Professional antenna systems used where icing is frequent are equipped with de-icing equipment, but these are really expensive and out of reach of amateur radio operators... So amigo Karl from Toronto, YES, you could design a wire antenna system so that it can be de-iced by passing a high intensity current , but as you have just heard this is quite expensive ...and requires that special precautions be taken by the owners of the antenna so that in case of a breakdown, the heating current will be immediately cut by an automatic device. .... Microphones.... microphones that are specially designed for voice communications are found at very low cost... you know where ??? You will find them inside discarded cellular telephones...And let me add that they make excellent mikes for ham radio equipment, often improving the rig's punch because engineers involved in cellular telephone equipment design have placed a lot of attention on the frequency response of the microphones, so that they will reproduce the human voice in the best possible way, and at the same time don't pick up either low frequency or high frequency noises that actually interfere with voice communications... So here is your friend's Arnie Coro's advice... start looking around for discarded cell-phones, and every time you find one, spend some time doing some surgery and removing the high quality communications microphone... Here at CO2KK , my amateur radio station, I replaced the microphone element on my 2 meter FM transceiver with one from a NOKIA cell-phone with outstanding results, according to my good friend Luis Rodriguez CO2LR, who is a very experienced radio engineer and devoted a lot of his valuable time to help me with the comparative tests... I was able to switch very fast from one microphone identical to the one that came with the FM transceiver to the NOKIA microphone element that was placed inside an identical mike case... According to Luis, the "talk power" of the cell-phone mike was really impacting, so I did two things after that test. One, I left the cell-phone mike element permanently connected to my rig, and two, I started a search for more discarded cell-phones to salvage their high quality communications type microphones !!! ....... Si amigos, yes my friends, oui mes amis... solar cycle 23 is now at its very end... we will still have to wait for about six months to have a clear confirmation , but according to observations made by solar scientists around the world, cycle 23 is going to end before the month of July, and from there on, what may happen is that solar activity will start to raise at a very fast pace... This is a typical solar cycle behavior, as the ascending phase is actually shorter than the decline. So expect a cycle 24 peak to happen between 2010 and 2011, and it seems like this upcoming cycle will be a very active one if you believe what some scientists are forecasting... Be it a very active or a moderately active cycle won't matter very much for most of us , as anything is going to be definitely better than the past year and half of extremely low solar activity that we have gone trough.... ...... Now , here is our technical topics section of Dxers Unlimited, and also very popular section of the program... Today technical topics will deal with an ever growing problem around the world... the presence of very high voltage spikes superimposed upon the alternating current power lines that supply electricity to our radio equipment. Not too long ago I was told my a friend who is an engineer of the national electrical utility, that they are really worried with the proliferation of switched mode power supplies, like the ones used by desktop computers,and that are now also becoming quite popular in other consumer electronic devices because they can be fixed easily , are lightweight and can be produced at much less cost than conventional transformer operated power supplies. One of the problems associated with this type of power supply is that it can put a lot of noise into the power lines from which it is taking energy to operate, something that is a big headache for short wave listeners ... My friend from the power company says that the operation of hundreds of thousands of desktop computers using the switched mode supplies as they all do, causes severe distortion to the sine wave of the power line, and that in turn has other undesirable effects... As a matter of fact, my friend added, for that very reason the Cuban national utility is enforcing among its industrial and commercial clients the use of automatic power factor correction capacitor banks. I then asked him if I could benefit at my home QTH by installing a pair of high quality oil filled capacitors right at the service entrance of the power line, and he said that doing so would certainly help to provide a low impedance path to high voltage high frequency spikes... A few days later , I made a provisional installation and it proved that my friend was absolutely right... after the two 10 microfarads at 330 volts AC capacitors where placed in parallel with the power line right next to the electricity meter, I immediately noticed a reduction in some of the noises that were usually heard on my HF radios, and also, a much lower noise level on the AM broadcast band !!! So, give this is a try, but don't forget to include fast acting fuses between the oil filled capacitors and the power line... And now amigos as always at the end of the program when I am here in Havana, this is Arnie Coro's HF plus low band VHF propagation update ... So far a very dissapointing tropospheric ducting DX season here in the Gulf of Mexico and the Caribbean. Although I was not here in Havana for the two weeks when the tropo season usually starts, radio amateurs to whom I have talked told me that no tropo DX was heard at all...This, of course is a weather related phenomena, and may be connected to the ongoing climate disturbances we are seen world wide. HF propagation conditions are poor because solar activity is extremely low...With several days of ZERO sun spots, and solar flux at rock bottom levels near 70 units... See you all at the weekend edition of the program amigos, and don't forget to take a little of your valuable time and send me your signal reports and comments about today's program as well as any radio hobby related questions you may have...send e-mail to [EMAIL PROTECTED] and 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 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. 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
