Dear amigos of Dxers Unlimited: I want to thank you all for the many nice e-mail congratulation messages received here at [EMAIL PROTECTED] Wish you all a very properous and peaceful YEAR 2008 ! Dxers Unlimited is a labor of love, as you all know, and I will try to make it more interesting and appealing during 2008 for your enjoyment. HAPPY NEW YEAR 2008 TO ALL DXERS UNLIMITED LISTENERS !!!
AND NOW HERE IS THE SCRIPT OF THE LAST SHOW OF 2007... Radio Havana Cuba Dxers Unlimited last weekend edition for 2007 December 29-30 2007 By Arnie Coro Radio amateur CO2KK Hi amigos radioaficionados around the world and in space… this is the year’s 2007 last Dxers Unlimited program, and I wish you HAPPY NEW YEAR 2008 TO ALL !!!! Welcome to the weekend edition of your favorite radio hobby program, coming to you from sunny Havana, where our very specially mild winter weather is providing us with beautiful days for going to the beach , swimming , sailing or just relaxing in the shade watching the blue sea !!! I am Arnie Coro, radio amateur CO2KK, your friend here in Cuba, now ready to read today’s menu: ITEM ONE No sunspots in sight at this moment, putting an end of what may now be surely described as the year of the solar minimum or as scientists like to call it, the Year of the Quiet Sun… Amigos as 2007 comes to an end, the very quiet Sun tells us that the chances of solar flares happening during the next several days are practically zero,so the solar flux levels are going to stay at extremely low levels down during the first few days of 2008. … ITEM TWO:TV DX winter season well in progress at this moment, with sporadic E skip events happening all around North America, the Caribbean Europe and Northern Africa. At least TWO recent sporadic E opening sent the maximum useable frequency up past the two meters amateur band , making reception of FM stations from more than one thousand miles away possible even with portable radios and their telescopic whip antennas… ITEM Three: Listeners questions continue to come in via e-mail, postcards, letters and fax messages, a recent one from India, really surprised me, as normally the show is not heard so far during the solar minimum years… But the use of high gain curtain antennas and 100 and 250 kiloWatt transmitters explains why English speaking listeners from India, Pakistan and Bangladesh are picking up Dxers Unlimited.. NEXT: More about low cost , easy to build ham radio equipment, in this particular case as part of the ASK ARNIE section of the program ,and at the end of the show, our exclusive and not copyrighted HF YEAR 2008 HF PROPAGATION FORECAST , a special feature of this year end edition of Dxers Unlimited.Stay tuned for more radio hobby related information, coming to you from Havana. , I am Arnie Coro radio amateur CO2KK ,ready to be back with you in just a few seconds… …. Si amigos , this is Radio Havana Cuba, and you can send your signal reports and comments about our program sto [EMAIL PROTECTED], or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, and we will send you our nice QSL card for your collection of station’s verified . And NOW , here is ASK ARNIE, THE most popular section of Dxers Unlimited., QUESTION number sent by listener Marlon in Ireland: Marlon collects old radio magazine, that he says, and I fully agree with him , have a wealth of radio hobby related know-how. Marlon wants to know more about a regenerative receiver circuit he saw published by Radio Communications magazine Technical Topics Section. Marlon tells me that the actual detector circuit is a cascode formed with two triodes, and he wants to know If I have tested this regenerative detector configuration. Well amigo Marlon those old radio magazines often provide unique opportunities for assembling circuits that show amazing performance, exactly what will happen to you if you carefully duplicate the circuit of the regenerative cascode detector receiver published by the British Radio Communications magazine many years ago. I found out that the control of regeneration with this circuit is amazingly smooth, and that using a ECC88 dual triode, I was able to make if work nicely even on the 6 meters or 50 megaHertz amateur band. Instead of using the so called converters ahead of short wave receivers to pick up the higher frequency bands, you may want to try this cascode regenerative with the ECC88 VHF type dual triode . Well amigo Marlon, as you may realize a converter is nothing but a complete front end of a radio receiver, it usually includes a radio frequency amplifier stage, a mixer and a local oscillator, while the cascode regenerative receiver operates right on the frequency you are going to try to receive.You you can get away without the radio frequency amplifier stage by using a well designed front end filter, but adding a radio frequency amplifier to the cascode detector will certainly improve its performance. Converters designed for the VHF and UHF bands do need the RF stage, but VHF regenerative detectors were usually built without the benefit of the RF amplifier stage,and one could tell people in the neighborhood were listening, because regenerative detectors radiate a signal on the same frequency they are picking up, so you could always hear a swish swich sounding signal when a nearby regenerative detector was tuning across the frequency you were listening two. Also in the old days used the then best available vacuum tubes that provided good gain and low noise were used for the radio frequency amplifier stages, but common triodes prevailed for the regenerative detector stages.. The really good converters used a crystal controlled local injection oscillator. Even today, adding a homebrew converter ahead of a regenerative detector receiver cost receiver can provide outstanding results, s an antenna. VHF Converters are no longer required for all practical purposes, as like I explained here recently, modern HF receivers are including an extended tuning range up around 54 megaHertz and in some cases up to the two meters amateur band. Amigo Marlon, the cascode regenerative detector circuit receiver is not too difficult to homebrew, and the ECC88 followed by a dual triode audio section feeding a beam tetrode audio output will provide room filling audio . The cascode regenerative with the ECC88 dual VHF triode tube will make a nice low band VHF receiver , useful for monitoring 6 meters during the summer sporadic E season. Remember to tune set the receiver to the calling frequency of your part of the world… In the Americas it is 50.125, while in other regions world it is 50.110. megaHertz where most of the activity on 6 meters is concentrated around the world. You are listening to Radio Havana Cuba, and this is our most popular section of the program ASK ARNIE, now with QUESTION NUMBER TWO,it Came from Trinidad and Tobago, another beautiful Caribbean nation that I have had the nice opportunity of visiting and sharing time with many of the local enthusiastic radio amateur operators. Llistener Mark , who tells me that he picks up our 9550 kiloHertz Caribbean edition, tells me in his e-mail that he wants to know more about the Near Vertical Incidence Skywave antennas, that are now so often mentioned in amateur radio publications. Well amigo Mark, NVIS or Near Vertical Incidence Skywave antennas are becoming very popular among radio amateur emergency networks, because they will provide reliable communications at short distances on the 80, 60 and 40 meters bands, while using average power outputs of between 20 and 100 Watts. As you well know, when a tropical hurricane impacts upon one of our island nations, electricity distribution networks are disconnected by the power company for safety reasons, and you must operate using batteries or a diesel or gasoline engine coupled to a generator. When using battery power, you want to keep the power output as low as possible, and this is why the NVIS mode is so effective. Here in Cuba we have found that by installing a highly effective NVIS antenna, we can keep communications going while the stations are running between 20 and 50 Watts, and when conditions are good, we can switch down to 10 Watts and keep the emergency net operating. An effective NVIS antenna for the 80, 60 or 40 meters bands is not too difficult to design and install, and one nice feature is that you won’t need tall masts to make it work nicely. NVIS are also very useful at noisy locations, because they don’t pick up signals at the lower take off angles. . Well amigo Mark, NVIS systems are first of all low profile antennas, they are easy to install, and above all, NVIS systems can be built very easily and at low cost by anyone . My NVIS 40 meters band antenna is a nice example of what I am talking about. Many Cuban amateur radio stations have built it and keep it ready all the year round, but especially from June to the end of November during the Atlantic and Caribbean Tropical Hurricane Season… And for those of you who listen regularly to Dxers Unlimited let me add that the number one most popular project,the one that received more requests from listeners for its complete building instructions and circuit diagrams was the AUSTRALIAN FUN MOORABIN regenerative solid state receiver. My prototype HULA HOOP magnetic antenna that is built using a toy HULA HOOP , a length of TV type coaxial cable, and a receiving type variable capacitor and takes less than a couple of hours to complete, was the second most popular project requested to [EMAIL PROTECTED] via e-mail or to Arnie Coro, Radio Havana Cuba, Havana Cuba, via AIR MAIL postcard or letter. About the second most popular project , the HULA HOOP antenna, you will be spending most of your construction assembling the base where the HULA HOOP is fixed, so that it may be rotated. My HULA HOOP MAGNETIC LOOP provides excellent reception from 10 to 30 megaHertz, but it also works quite well with powerful station from 5 to 10 megaHertz. . The HULA HOOP MAGNETIC LOOP is possibly one of the lowest cost high performnce indoor antennas that exists,maybe second only to my very popular BROOMSTICK antenna. Let me add that the HULA HOOP MAGNETIC LOOP tunes quite sharply and it does require constant retuning of the air spaced variable capacitor with even a very slight change in frequency. BUT, peaking the antenna tuning for maximum signal is quite easy to do, and at the same time it provides ultra-sharp selectivity right at the antenna, that helps a lot to reduce unwanted noise and cross modulation problems caused by high powered stations that affect low priced receivers so badly. As a matter of fact, using my HULA HOOP MAGNETIC LOOP with a low cost digital receiver has proved to be a very interesting experience, as the radio’s performance is enhanced signficantly due to the extra selectivity at the front end provided by the magnetic loop antenna system. And now amigos, at the end of the program, here is Arnie Coro’s Dxers Unlimited’s 2008 HF propagation forecas, yes you heard it right, this is an advance of what should be happening next year on the HF bands.…Expect low solar activity to continue during the first half of 2008, solar cycle 23 keeps fading away, but at the same time we should start to see more high latitude and reverse magnetic polarity sunspots that belong to the new cycle 24, overlaping with an eventual low latitude sunspot belonging to cycle 23. During the second half of 2008, HF propagation conditions will take a turn for the better and we will all be able to once again enjoy nice DX that will be heard better and better during 2009, 2010 and of course during the peak year of cycle 24, expected to happen sometime between 2010 and 2012, something that is difficult to predict right at this moment. Amigos HAPPY NEW YEAR 2008 TO YOU ALL, and don’t forget to send your much appreciated comments, signal reports and of course radio hobby related questions that help to keep Dxers Unlimited alive for your enjoyment… Send mail to [EMAIL PROTECTED] or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba. See you all at the NEW YEARS EDITION OF DXERS UNLIMITED AMIGOS ! I AM YOUR FRIEND ARNIE CORO IN HAVANA WISHING YOU ALL NOTHING BUT THE BEST,AMIGOS. ---[Start Commercial]--------------------- Order your WRTH 2008: http://www.hard-core-dx.com/redirect2.php?id=wrth2008 ---[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
