RADIO HABANA CUBA
DXERS UNLIMITED
weekend edition unabridged for the BLOG, but shorter on the air due to air time available Sunday and Monday UTC days this past weekend !!! May 8 -9 2011

Hi amigos, welcome to the weekend edition of your favorite listener oriented, technically minded radio hobby program, coming today once again directly from right next to my ham radio station CO2KK, exactly as it happened many years ago, on the 27th of October of 1998, when I was sending an advance warning to radio amateurs in the Caribbean and Central America as the huge Hurricane Mitch was approaching the area. As many of you that heard that program remember well, a great number of radio amateurs in the Caribbean participated in a large scale communications effort related to one of the most powerful storms ever seen in the area ever.
Amateurs in Canada, the United States of America , South America and even from Europe helped by providing relays on the 40 meters band when long skip made it impossible to work on that band, and as expected practically all the 2 meters band repeaters in the affected areas were damaged or totallly destroyed by the hurricane force winds , landslides and the lack or commercial power. The availability of 80 and 40 meter band amateur equipment that can operate using small generators or even car batteries has proven to be a great assett when weather or earthquake emergencies destroy local telecomms facilities or makes using them almost impossible due to excessive traffic generated during the emergency. 40 meter bands long distance relays of weather data for stations located in the affected areas and the forecast centers is vitally important too
I am Arnie Coro, radio amateur CO2KK, your friend here in Havana and host of this twice weekly show devoted entirely to our wonderful hobby,yours and mine amigos RADIO !
Now here is item two , a detailed explanation of why emergency communications provided by amateur radio operators are essential during Hurricanes and Earthquakes, as well as large scale accidents . Hams using portable equipment that can be powered from standby power sources are able to keep vital links to the affected areas among the important information provided on those two way links are weather data taken at places were there are no official weather stations, advance warning from possible flooding and help during search and rescue operations.. later, after the storm is over, the amateur radio links are used to help medical aid workers, to select landing sites for helicopters and planes and in general to keep things moving during the post hurricane period.
Among the most interesting aspects of the way hams provide emergency communications is how simple antenna systems, low power radios and GOOD and very well trained OPERATORS combine to keep communications flowing
Most of present day amateur disaster area communications is done using SINGLE SIDE BAND VOICE, but the increasing availability of portable lower cost lap top and notebook computers are encouraging the use of digital radio links, which are much more reliable , use less power and are also less prone to interference. Computer to computer communication via a radio link is an ideal way of handling emergency traffic, but as a friend of mine likes to say it is a developed country approach, but lower priced computers that are now available are making possible implementing keyboard to keyboard emergency communications links by amateurs in less developed parts of the world.
More about emergency communications during natural disasters a little later in today's mid week edition of Dxers Unlimited, coming to you directly from my home QTH, right next to CO2KK my amateur radio station that is now part of not one or two, but actually three emergency communications networks on the 20, 40 and 2 meter bands
Now let's take a break I'll be back in a few seconds
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You are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited, and our URL, is www.radiohc.cu, again the fast and easy way to find us on the INTERNET is by cybersurfing to www.radiohc.cu, and while there please do take a look at my webpage Dxers Unlimited's contribution to the radio hobby via the NET... You may nowadays download a large number of very interesting files dealing with antennas, short wave propagation, solar activity etc that will help you to optimize your amateur radio station and make it much more useful for handling emergency communications whenever required. Yes amigos you can also request our QSL card, by just sending an e-mail directly to me send mail to inforhc at enet dot cu, again inforhc at enet dot cu
Now item three each edition of the big worldwide ham radio contests like the CQ World Wide SSB or the WPX prefix contest help quite a few newcomers to the amateur radio hobby to increase their total number of countries, or DX entities as they are now called... worked. Many Cuban radio amateurs both old and new participa in those challenging and interesting events and some of them have achieved very good results too.
Item four Trasatlantic medium wave AM band DX season is now over, something that happens about two to three weeks after the spring equinox and from now on due to the sustained increase in solar activity AM medium wave band DXing is going to become much more difficult, because of the expected increase in ionospheric absorption caused by the higher solar activity.Those AM band Dxes with good receivers, and the special antennas required are able to pull several of the most powerful stations from Europe and the Middle East quite easily during solar minimum years , by using narrow filters that let those stations come in between the 10 kiloHertz channel spacing used by AM broadcasters in the America's.
Among the easy ones from the other side of the Atlantic, are several super power stations operating at the high end of the band, from about 1400 to 1620 kilohertz. Don't be surprised if at around your local midnight, when the sun is just rising in Europe, at least two or three of those MEGAWATT stations make themselves heard via powerful heterodynes or whistles between the AM stations on this side of the Atlantic.It is worth looking for those tell tale heterodynes, which are the result of the Region I stations in Europe and the Middle East using a different channel spacing those stations are spaced at 9 kilohertz from each other, so only in very few channels they land at zero beat with the stations in the Americas. But again, the next AM broadcast band DX season due to happen around September is going to be worse than any of the previous ones ... because it is going to happen when solar flux figures are expected to be averaging above 120 units or higher !!! So, we must wait until at least 2015 for the ideal Long Wave and Medium Wave Bands DX seasons to be as good as they were between 2005 and 2010 amigos !!!
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You are listening to Dxers Unlimited's mid week edition, the audio quality of today's show is limited to a 3 kilohertz bandwidth due to the use of a standard phone line which is not broadcast quality to tape the show if you ever wanted to know about audio response,here is a good example of what happens when the bandwidth is restricted between the 300 and 3000 Hertz or cycles per second of a phone line Yes amigos, restricted audio bandwidth can actually improve reception, as more of the transmitter's power is used to modulated the frequencies to which your ear responds best !

Now item fiveArnie Coro's workshop today , I'll tell you about a super simple 2 element 2 meter band Yagi beam antenna which is ideal for emergency work it is built using either standard TV antenna elements, or heavy gauge copper wire The support for the antenna is made from. One of my favorite antenna building materials you guessed right amigos a BROOMSTICKThis is a very compact antenna that will provide about 4 or maybe a little more dB gain over a standard half wave dipole, but of course, many more db's above the typical rubber duck antenna used by hand held radios or handie talkies The dimensions for this antenna are very easy to remember, if you choose to do your homework in METRIC The reflector element is 101 centimeters long and the dipole driven element is 98 centimeters long The two are separated by 50 centimeters of BROOMSTICK BOOM and the antenna's driven element is fed using standard 50 ohm coaxial cable I leave about 30 of 40 more centimeters of broomstick behing the REFLECTOR ELEMENT, so that I can tie the antenna to any available supporting structure This is a portable emergency antenna system.. so it is made with low cost materials.. the elements can be taken from an old TV antenna, or you may buy aluminium tubing of about 10 millimeters or 1 centimeter diameter.. better yet, you can make the antenna elements from heavy copper wire , a number 10 or number 8 will be ideal The dipole element is fed at the center, so the two sides should be mounted on a piece of insulating material like acrilic plastic, polyethilene or PVCIn one emergency situation I made one of this antennas by just placing the two sides of the dipole driven element directly to the broomstick boom, separating them by about 2 centimeters It worked quite well because the weather was nice and dry ! But you should use good insulation if you want the antenna to work well even when it is raining or snowing This is about the lowest cost "amplifier" that you can think offSee by the numbers a rubber duck antenna used on a typical two meter handie talkie has a loss of about 6 db relative to a half wave dipole
Now Arnie Coro's UL:TRA LOW COST 2 METER BROOMSTICK YAGI has a 4 dB gain over a dipole in other words, if you replace the rubber duckie with my 2 element makeshift antenna , your signal will be a WHOOPING 10 db more powerful, or 10 times LOUDER than when you used the little rubber duck antenna One of the advantages of this ultra simple YAGI , is that it does not require any instruments to put it into operation if you follow my data, 101 centimeters for the reflector, 98 centimeters for the driven element and 50 centimeters separation between the two elements, the antenna will have a fairly low standing wave ratio if fed with 50 ohm cable, and it will work quite OK with a somewhat higher SWR if the only cable at hand is of the 75 ohm type One of the many applications of this field emergency antenna is to use it to access a distant repeater that can not be reached using the handie talkie's factory antenna Ah ! before I forget , the other thing you will need to complete this antenna besides the BROOMSTICK, the two elements, the insulator for the center of the driven element and the coaxial cable, is , OF COURSE, a coaxial male connector that will fit with your transceiver, usually a BNC male type connector YES AMIGOS, antennas for 2 meter emergency work need not cost a fortune and can be improvised from whatever is at hand even that old BROOMSTICK gathering dust somewhere in the attic or the garage !