Radio Havana Cuba Dxers Unlimited
Dxers Unlimited's mid week edition for January 2-3 2007 By Arnie Coro radio amateur CO2KK Hi amigos radioaficionados !!! Happy New Year 2007 !!! Welcome to the Year of the Quiet Sun, when solar cycle number 23 is expected to come to an end, although some scientists believe that it may last even until the middle of next year 2008... I am Arnaldo, Arnie, Coro, radio amateur CO2KK, your host here at this twice weekly radio hobby program that started some twenty years ago as a once a week ten minute show, that was only devoted to short wave listening, and has evolved into the most comprehensive radio hobby program now in existence, according to feedback from listeners like you , who keep Dxers Unlimited as your favourite show... ASK ARNIE, continues to be LA NUMERO UNO, the most popular section of the program , but closely followed by the HF plus low band VHF propagation forecast that goes at the end of the show,and if you thought that the number three most popular section of the program was the one devoted to technical topics , you were right, and this one came tied with the antennas topics section... Now some of your New Year's wishes that I have received with the many e-mail messages wishing us here at Radio Havana Cuba a happy 2007... Among the requests were to include more amateur radio hobby topics for beginners , now that in many countries, passing the amateur radio license test has been made easier by the removal of the CW Morse Code requirement. Another frequently mentioned request asks for more operating tips, including special propagation reports when amateur radio contests are approaching. Amigos, I want to thank you all very much for sending those valuable opinions, and be assured that Dxers Unlimited will continue to be your favourite radio hobby program , dealing with my now revised list of 80 different ways you and I enjoy this wonderful way of spending our spare time in a most fascinating and relaxing way... Stay tuned as the first Dxers Unlimited program of 2007 continues after a short break, I am Arnie Coro in Havana, back with you in a few seconds. ..... You are listening to Radio Havana Cuba, the name of this show is Dxers Unlimited, and when it started some twenty years ago , it was supposed to be devoted only to short wave listening, but now, you can learn here about such interesting aspects of the radio hobby as home brewing ultra simple radios and accepting the challenge of picking up long distance stations with them, or installing a magnetic loop antenna to make possible operating your amateur station from a high rise apartment building where no external antennas are allowed, you can also enjoy listening to the technical topics section contents, guiding you trough sometimes controversial technical stuff, like the so called Crossed Field Antenna , or CFA, one of the greatest scams ever in antenna technology... No amigo the CFA antenna doesn't work at all, and as a matter of fact, at least two of those antennas sold to broadcast stations have been the subject of great controversy that ended up in court. The most recent one is a lawsuit by a station located in the Isle of Man, that was erroneously led to believe that a CFA antenna would be better than any other “classic” design ... Si amigos, yes my friends, here at Dxers Unlimited, you can learn how to talk to ham radio operators via satellite using a hand-held dual band FM transceiver, or show your children how radio and computers working together can make possible extremely low power two way contacts around the world... Now, let's try to update the backlog of questions sent to ASK ARNIE during the past two weeks, when obviously many of you had a little more time to relax and listen to the radio, or surf the web and read the scripts of the program that are now available at several websites and mailing lists... Today's question, sent by three listeners, one in Canada, the other in Trinidad and Tobago and the third in Germany, they all three say in their e-mail messages sent to [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> , that they want to know more about digital radio broadcasting and how I see its future... So , here we go... First of all digital radio broadcasting as we know it today provides listening to a very small number of radio's worldwide audience... That's a fact that no one can deny... Second: The existence of several different digital broadcast technical standards is making a very negative impact in the expansion of this new technology, and in the third place is the fact that radio receivers for picking up digital broadcasts are still rather expensive, and in many instances hard to find. Digital broadcast technologies for local ground wave transmissions on both the AM long wave and medium wave bands, and also on the VHF FM bands, when received at a fixed site seem to work quite well now, and the audio quality that can be implemented is as good as one may want. But there are quite a few problems still to be solved when , for example, digital radio signals are received in areas where , in the case of AM medium wave broadcast band stations, the ground wave and the sky wave combine with each other randomly to produce a very annoying signal fading. Digital radio technology so far hasn't solved this problem, so when you are located inside that critical reception area, your radio's suddenly goes silent for certain short periods, a very annoying problem to say the least. Digital radio broadcasts on the FM band suffer from a similar problem due to the so called multipath propagation , so when you are travelling on a vehicle and listening to a digital station, you are likely to experience the same annoying total drop outs in service. Yes, of course, there are ways to go around this problem, but they will require a totally different technology that will include a high degree of redundancy into the digital streams, and a sophisticated receiver that will actually do a lot o signal processing before sending the audio to the loudspeakers or headphones !!! Later in today's program, I'll tell you more about DRM, Digital Radio Mondiale's efforts to broadcast using short waves, that so far have proven to be a total failure..... ..... Si amigos, 2007 is here now, and during the next 363 days we are going to watch how solar activity continues to go down, taking us into solar minimum... So be prepared for very poor HF propagation conditions that will keep the bands above fifteen megahertz totally dead ... Now here is , as requested by many listeners, more information about a radio noise related topic... Those sending the request wanted to know if it is true that the new high intensity light emitting diodes lamps are a good replacement for the energy saving fluorescent electronic lamps that generate so much radio frequency noise. Well amigos, so far the high intensity light emitting diode lamps that I have learned about seem to require the use of a certain number of those devices in order to achieve enough light output, as technology has not yet provided a large size light emitting diode , large enough to produce a light output similar to even a small 5 Watt incandescent bulb... But, let me say that I am still in doubt with the new high intensity light emitting diode replacement lamps, because I haven't had the opportunity of seeing how do they provide the low voltage required to operate the LEDs... If the low voltage is obtained by means of a simple dropping resistor and rectifier diodes combination, then the lamps will not generate radio frequency noise, but if some type of radio frequency oscillator is used, then they will cause interference to radio reception, as is the case with the present day energy savers fluorescent lamps that make radio reception so difficult wherever they are in use. Been an experimentally minded person, as I am, during the long new year's eve weekend I decided to do some experiments with light emitting diodes that I were at hand. These are not the high intensity white light diodes, but served well for my purpose of testing the way that they can be supplied with the low direct current voltage required for their operation. I ended up with two really nice cluster lamps, one made with five red el e dees, and the other one made with five green ones...First thing I learned during the experiment was that the green diodes require a higher voltage to operate, and in second place was the fact that for some reason it was better to feed the diodes with individual voltage dropping resistors than placing them in series connection to use a single voltage dropping resistor... Anyway, the experiments were a success, but both lamps, the red and the green , had to be powered from a four and a half to six volts direct current source, that could be either three or four series connected batteries, or an AC power supply... Now, I must wait for feedback from Dxers Unlimited listeners around the world, to provide your own personal experiences with the high intensity light emitting diodes lamps, in order to see if your results match with my experiments here, and the reason for having to ask you for this practical results is that so far I haven't been able to obtain some high intensity white light emitting diodes ... So , if you have already tested the new white light high intensity LED lamps, please send the results of your noise tests to [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>, again its [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> , so that they can be shared with Dxers Unlimited's worldwide audience amigos... And don't forget that if you can obtain enough of those diodes, assembling your own lamp to replace the energy saving fluorescent noise maker nearest to your radio is certainly going to be a nice weekend project too... ..... As promised, here are some comments about DRM , Digital Radio Mondiale broadcasts of short wave and the problems they are causing to other stations using the classic AM technology... According to the opinion of a senior Cuban broadcast engineer that has observed several DRM transmissions using sophisticated spectrum analysis hardware and software,he is of the opinion that most of the time the excessive bandwidth used by the DRM signals has to do with poorly adjusted transmitters, mentioning that DRM's is a very demanding transmission mode that requires an extremely linear transmitter, something that in his opinion is not possible from older equipment forced to broadcasting DRM signals.... And now amigos as always at the end of the program... here is Arnie Coro's Dxers Unlimited's HF , plus low band VHF propagation update and forecast... Solar activity is now oscillating from very low to low,solar flux around 90 units, and a high speed six hundred kilometres per second solar wind is causing some geomagnetic disturbances. The solar active sunspot region that produced the big X flares during the previous rotation is back now, but it has decayed, so only class C or an occasional class M flares are expected. The winter sporadic E season is about to come to an end now, as we move away from the winter solstice... Enjoy the radio hobby amigo,and share your experience with others by sending me your comments and questions to [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cub ---[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