Radio Havana Cuba

Dxers Unlimited

Dxers Unlimited’s mid week edition for 18-19 December 2007 By Arnie Coro Radio amateur CO2KK

Hi amigos radioaficionados around the world and in space orbit… yes , you heard it right, there are amateur radio operators orbiting the Earth, as part of the crew of the International Space Station, and if you are lucky, you may one day have a two way radio contact with one of them… Space radio… one of the 82 ways you and I and the astronauts and cosmonauts enjoy our wonderful hobby amigos… I am Arnie Coro, radio amateur CO2KK, and here is item one of today’s program… with solar activity taking a turn for the better during several days, HF propagation conditions improved, as it was expected, and signals on the shortwave bands were stronger … but now, the Sun is back into very low activity, and we must wait for another group of sunspots to send the daily solar flux past the 85 to 90 mark, that makes the big difference… Item two: PSK31 and similar digital keyboard to keyboard amateur radio communications modes are able to provide nice two way QSO’s while using power outputs between 10 and 50 Watts. As a matter of fact very few if any of the energy conscious PSK31 ham operators ever exceeds the 50 Watts power output. At CO2KK , my ham radio station, I try to keep the

PSK31 mode power output between 10 and a maximum of 25 to 30 Watts, although the transceiver in use allows to run about 100 Watts… something that has proven to be not necessary to enjoy this wonderful communications mode that is able to provide reliable links even under very poor propagation conditions. Monday evening my local time, I spend about two hours enjoying both PSK31 and MFSK16 modes. The MFSK16 is a much more sophisticated digital mode, that uses more bandwidth, and that’s why it is perhaps not so popular, although its reliability under poor propagation is outstanding. During the two hours of operation of CO2KK on 40 meters, I was very pleased to enjoy two way contacts with several amateur radio operators that happen also to be Dxers Unlimited’s listeners, and that amigos, I can assure you is a most rewarding experience, when you are watching the text on the screen and the operator at the other end of the QSO writes that she or he have listened to Dxers Unlimited for a long time and still enjoys the show. Digital modes operation on 40 meters is now becoming more popular, second only the mainstay of PSK31 on 14.070 kiloHertz on the 20 meters band. 40 meters band operators are gathering around 7070 kiloHertz ,but European and African ham radio digital enthusiasts are also seen between 7030 and 7040 kiloHertz. My Monday evening PSK31 and MFSK16 two way contacts included one with Italy and a Russian station seen calling that I couldn’t complete. Stations from Michigan, New Hampshire, Atlanta , Georgia and Ohio provided nice two way contacts, with 100 percent copy, and as I said earlier, not one of them used more than 50 watts output power to , in this opportunity, wire antennas, as no station said anything about using Yagi type beam antennas for their 40 meters band operations. At CO2KK, my ham radio station, the 40 meters band antenna is a sloping dipole, that shows some directivity towards the North and North East. Si amigos, yes my friends, with a solar flux just barely above 80 units, PSK31 digital keyboard to keyboard contacts on 40 meters where very nice Monday evening, providing yours truly with about two hours of enjoyment and having the great opportunity of two way ham radio contacts with several Dxers Unlimited’s listeners in North America… Standby for more radio hobby information that will follow here in just a few seconds, when the mid week edition of Dxers Unlimited continues after a short break for station ID I am Arnie Coro radio amateur CO2KK, stay right on this frequency amigos !

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Si, esta es Radio Habana Cuba, yes this is Radio Havana Cuba, the name of the show is Dxers Unlimited and here is our next item… How to set up a PSK31 monitoring and communications station using recycled equipment.

Sure, you can enjoy the digital communications modes, by making that old laptop or desktop computer work together with an amateur radio transceiver. You don’t need the most fancy box full of sophisticated computing stuff… a very modest laptop running at 166 or 233 megaHertz CPU clock speed with 32 megs or RAM , will make possible for you to enjoy the digital modes. In order to make things easier for the computer I recommend using a lightweight LINUX operating system distribution, and a PSK31 program like the ones that are now available absolutely free of charge. Free and Open Source computing is here to stay amigos… and amateur radio operators are already taking note of those zero cost options. With a slightly faster machine, let’s say a CPU clock speed in the 800 megaHertz range, the performance of the free software is simply amazing. A nice LINUX distribution that I strongly recommend as a starter is PUPPY LINUX, that runs nicely , is bug free and can be upgraded very easily. My recycled Pentium II machine using a CELERON Mendocino CPU running at 333 megaHertz CPU clock speed and with 192 megs of RAM is the one I use for digital communications connected to the transceiver by means of an extremely simple to assemble homebrew radio to computer and computer to radio interface. The CPU clock speed is actually below the theoretical requirements of the FLDIGI multimodes digital communications software, so sometimes I still have a little trouble with the machine , but , this may be improved by using a simpler single mode PSK31 software that is also available for LINUX machines.

Amateur radio has developed a lot after computers began to be used, not only for actual keyboard to keyboard modes, but also for digital voice, and for making better HF propagation forecasts that provide the ham radio operator with optimized information about the state of the different bands, so as to make the available operating time much more enjoyable… Some people said that the Internet was going to cause the death of amateur radio, but fortunately this hasn’t happened although one must admit that there now many amateurs spend much more time cybersurfing than trying to make two way contacts with other hams around the world or across town… ……..

QSL, QSL , QSL on the air to the several amateur radio operators that made contact with CO2KK using PSK31 and MFSK15 digital modes early Tuesday UTC day… Si amigos, QSL on the air, and also my personal CO2KK QSL will go to all of you, together with my Holiday Seasons Greetings and a Wish for a Nice and Prosperous New Year …By the way according to the solar scientists 2008 is going to be , now without almost any doubt the first year of solar cycle 24… But they can’t reach consensus, they can’t agree if cycle 24 is going to be a high activity or an average activity cycle, so our only choice is to just relax, wait and watch the sunspots start to populate the higher latitudes of the solar disk …Now our next item of this mid week edition of Dxers Unlimited, LA NUMERO UNO, the most popular section of the show.. YOU have questions and Arnie, your friend in Havana tries to answer them. The first question was sent by listener Gabriel, from Oklahoma , USA… he wants to know more about the fan dipole antenna elements, and if there are specific design equations for them. Well amigo Gabe, the term fan dipole is a very broad concept, so the answer to your question depends on the actual type of antenna we are talking about. The conical fan dipole is in my opinion an excellent choice if you are going to install a single short wave antenna. You will need more wire, and the supporting structures will have to deal with more weight , but the performance of the conical fan dipole will make all your efforts worthwhile. For example amigo Gabe, a conical fan dipole using six wires on each side , with a total overall length of 15 meters or around 50 feet, will provide excellent broadband coverage from 6 megaHertz all the way up to 50 megaHertz, but of course that the radiation pattern, both horizontal , and vertical will change a lot from the low to the high end of the operating range. The conical fan dipole uses wires that are 7.5 meters long each , that’s about 25 feet , and they are spread out into a circle that has a diameter of 2.5 meters… This antenna is essentially a FAT DIPOLE, so it shows a low Q factor, and is very easy to match with an antenna tuner when fed with 400 ohms balanced transmission line. In actual practice, this antenna when installed at an average height above ground of about 10 to 12 meters is an excellent all around performer for short wave listening and amateur radio operation. Yes amigo Gabriel, it weights more than a dipole made with a single wire radiator, but the increase in bandwidth that you achieve is well worth the effort, and also, these conical fan dipoles are pretty looking antennas too!!! You can also homebrew the balanced 400 ohms transmission line, and connect the antenna to a set of two balanced to unbalanced transformers or baluns, one with a one to one ratio and the other one with a four to one ratio. The baluns are connected to a coaxial cable that to which the antenna tuner is attached. My PI network antenna tuner, with its wide range of matching possibilities works nicely with this conical fan dipole HF antenna providing high performance on the amateur bands between 40 and 10 meters, and about minus 2 db to minus 4 dB loss on the 80 meters band, as compared to a standard half wave full size wire dipole cut for each specific band. As a matter of fact the 15 meters long conical fan dipole shows some actual gain on the bands above 20 meters, and the performance on the 6 meters band has proven to be simply amazing amigo ¡ If you need more information on how to homebrew the conical fan dipole HF broadband antenna, just send an e-mail to arnie@rhc.cu, and I will send you a computer file in dot zip compressed format with the complete step by step instructions on how to build both the antenna and the balanced transmission line… And now amigos as always at the end of the show, here is Arnie Coro’s Dxers Unlimited HF plus low band VHF propagation update and forecast.

Winter Sporadic E season now in full swing… TV DX signals from Central America and the South of the USA coming in here yesterday, as well as strong signals from 10 meters and 6 meters amateur band beacons. Solar flux now moving down after several day of enhanced activity and the effects of the high speed solar wind from a geoeffective positioned solar coronal hole will disrupt HF propagation at higher latitudes for the next two days… The effective sunspot number SSN is around 20 and the A index up to 22 , due to the high speed solar wind… See you all at the weekend edition of the program and also on 40 meters around 7070 kiloHertz during my local evening hours using the wonderful PSK31 digital mode… Dont forget to send your signal reports and comments to arnie@rhc.cu or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba