Tuesday, February 20, 2007

DXers Unlimited mid-week edition Feb 20-21

By Arnie Cororadio amateur CO2KK

Hi amigos radioaficionados around the world.. you are now listening to or reading the script of the mid week edition of Dxers Unlimited, the one and only radio hobby program that accepts the challenge of dealing with each and every aspect of this wonderful way of enjoying our spare time RADIO... from listening to the weakest daytime AM broadcast station that your radio is able to pick up, to watching the screen of your computer as extremely weak digital signals produce perfect copy thanks to the wonders of the unique PSK31 keyboard to keyboard digital communications mode... you can also be left without sleep trying to figure out why a new homebrew radio does not work as expected, or maybe you will simply fall asleep at the operating position of your amateur radio station during a contest..

YES AMIGOS, SI, sure, radio is a fascinating hobby and listening to Dxers Unlimited will certainly help you to enjoy it a lot more.. Here is now item one of this mid week edition of the program: Very low solar activity prevailed for several days, with a zero optical sunspot count happening for several days in a row, but that did not stopped enthusiastic participation in a worldwide CW Morse Code contest that took place during the weekend despite the fact that the higher frequency bands were not widely open.

I did worked several stations on the low edge of the 15 meteres or 21 megaHertz amateur band, and just a the end of the contest Sunday , at around 6 thirty PM my local time, my 1 Watt power output CW rig went on the air on 20 meters and several of the top contest stations completed a two way contact with my station , adding the new multiplier to their score.As always, ham radio contests boost activity a lot, and bands that were supposedly closed suddenly are full of signals from the contest participants that enjoy this type of amateur radio activity a lot.Item two: It is true, some specific types of electronic components are becoming more and more difficult to find, but radio hobby people are resourceful and find them in the most hard to believe places. For example, old desktop computers that are now replaced by faster machines are a treasure chest of parts for the radio experimenter.

Dinosaurs by today computer standards, ancient XT 286, 386, 486 and several of the earl Apple machines have lots of useful parts that can be recovered and used in your radio projects. Among the most popular parts to recycle from old computers are integrated circuit voltage regulators, quartz crystals and oscillator modules, high current diodes and high power transistors and field effect transistors from the power supplies, as well as nice metal cases that when properly modified will give your projects a professional touch. For example a local radio amateur here in Havana used an old 486 computer box to house his new five hundred watts linear amplifier. He only had to make a new front panel, and the top cover that can be opened very easily saved him a lot of metal work.

Another local ham has used a computer power supply box to house a switched mode power unit capable of delivering 20 amperes at 13.5 volts, and fully protected against overloads. This conversion from computer power supply to ham radio use is becoming very popular here in Cuba, as more of the older machines are phased out of service.Standby now for more radio hobby related topics coming up as Dxers Unlimited+s mid week edition continues... I am Arnie Coro in Havana, back with you in just a few seconds....

Si amigos, yes my friends, you are listening to Radio Havana Cuba or maybe reading the script of the program, or perhaps listening to your computer program that provides voice output from the screen text for those of you that can not see . Yes, I am posting the scripts of Dxers Unlimited not only at our website www.radiohc.cu ENGLISH page, but also at several Internet lists that have worldwide readership among radio hobby enthusiasts. And from the feedback I am receiving , this seems to be a really worthwhile effort.

Among the e'mail messages received from Dxers Unlimited-s script readers there is one from New Zealand, a country that is not withing our regular short wave broadcasts coverage, but that from time to time , especially during the equinoctial periods, receives our signals. According to listener Lou from New Zealand, he is able to pick up Radio Havana Cuba on the 9550 kiloHertz frequency starting in late February and continuing until around mid-April.

Lou sent a question to our ASK ARNIE section of the program... he wants to know more about the so called terminator line propagation that is how short wave radio signals travel with very little attenuation along the line that separates day and night.

Well amigo Lou, I must say that the also known as GRAY LINE PROPAGATION continues to fascinate me more than fourty years after I worked an Australian station on 40 meteres while running a very low power homebrew transmitter during a Dx expedition to the Isle of Youth to activate the then very rare CO4 prefix. The time window for working Australian, New Zeland and Japanese stations from the Isle of Youth, south of Cuba was not very long, but it was really worth to set the alarm clock for a very early wake up and enjoy nice two way contacts while running just 5 Watts into a sloping dipole antenna.

Several years later, after that very succesful Dx expedition to the Isle of Youth a group of Cuban radio amateurs went to Avalos Key, a small island near the Isle of Youth where a worldwide skin diving tournament took place. We made very good use of that opportunity to once again enjoy the fantastic GRAY LINE or TERMINATOR LINE PROPAGATION mode from the Caribbean to Australia, New Zealand , Japan and many of the Pacific Islands... that seems to take place even during solar minimum years.

Many US and Canadian amateurs vacationing in the Caribbean have also enjoyed this unique propagation path that works with very low power transmiters and simple antenna systems. Just a half wave dipole sloping from a high mast near the ocean is all you will need to work many DX stations , even while running low power...

Now here is item three: It also part of ASK ARNIE today... I am now answering a question sent by listener Eva Maria, from Spain, who was able to pick up our 11760 kiloHertz signal late at night her local time. Eva Maria says that she is studying English and uses her short wave radio to pick up English language broadcasts to train her ear, and that is how she found out about Dxers Unlimited.

I already sent her via e-mail our URL , so that she can listen to the program via the Internet streaming audio feed, that is on from 05 to 07 hours UTC, rather early in the morning for Eva Maria, but she said she has to wake up early to catch a train that takes her to Barcelona where she works...

It is an almost one hour ride and she has to be at the train station very early in the morning, so she is able to listen to Dxers Unlimited as she gets ready to go to work.Si amigos, Dxers Unlimited is now available to you all via short wave , on the world wide web audio stream and also you can read the scripts by visiting our website at www.radiohc.cu/ This is the mid week edition of Dxers Unlimited amigos, and here is item four of today.s program... Another visit to my radio , electronics and computers workshop. Join me and learn about how an old Pentium II computer is now back on line using the KNOPPIX LINUX free software operating system that has made possible that this old machine is providing very nice copy of radio amateur signals using the PSK31 keyboard to keyboard communications mode.

The old Pentium II running at 333 megaHertz CPU clock frequency and with just 128 megabytes of RAM is using a small 4 gigabytes IDE hard drive, and a black and white VGA monitor... This very simple computer system configuration provides perfect copy of PSK31 and other digital communications modes, using an old sound card for signal processing. An also freeware program, DIGIPAN is used for working PSK31 stations mostly on 20 meters during the local daytime hours and on 40 meters at night.

I have also loaded into the old revived Pentium II several LINUX free software programs that allow me to make instant propagation predictions, keep a nice log of all the two way contacts and even connect to the local ISP for reading the e'mail. Old Pentium II and Pentium III computers are ideal for your radio shack amigos, and if you are able to spend some money buying a solid state flat screen monitor, the noise coming from the cathode ray tube monitor will just vannish...

Using the LINUX free and open source operating system reduces the cost of software to ZERO, and you will be amazed about the excellent performance that the most recent LINUX distributions are able to achieve even with programs that do require above average computer processing power. My just completed REVIVED Pentium II at 333 megaHertz machine is a very good example of how older machines can be used for many radio hobby applications, and also as a nice standby in case your main home computer fails...

By the way old laptops and notebooks no longer able to run the very sophisticated WINDOWS programs run very nicely using KNOPPIX LINUX, that loads from a single compact disk and is very easily installed by anyone knowing how to type and follow instructions...And as I said a while ago, ham radio operators around the world are writing more and more software that runs nicely using the LINUX operating system, and they will cost you absolutely nothing amigos !!!..

(Arnie Coro)