Radio Habana Cuba: Dxers Unlimited mid-week edition for June 13, 2000
By Arnie Coro, radio amateur CO2KK
Hello amigos!!! Welcome to the mid week edition of your favorite radio hobby program on short wave. I am Arnie Coro here in Havana, and here is our menu for today: Short wave radio once again disrupted due to yet another geomagnetic storm. This time, it was caused by a coronal mass ejection that followed one of the four solar flares that ocurred last week.
Item two: Users of digital communications systems via radio are growing, and one good solid reason for this growth is reliability... Amateurs are obtaining fantastic results with the keyboard to keyboard teletype style PSK31,and commercial users are moving to other similarly looking communications protocols that provide much higher reliability than SSB voice... So, in a few years' time, we may not be able to hear many voices talking on the HF radio spectrum anymore.
Item three: Sporadic E was interesting during the weekend to say the least... seems like the stormy geomagnetic conditions interacted in one way or the other with the typical summer sporadic E layers producing some very interesting results for participants in the VHF contest.
Item four: several broacasters testing digital audio transmissions via shortwave, but there are too few receivers available at the moment to be able to monitor those broadcasts... seems like the old vacuum tube final amplifier short wave transmitters can handle the digital signals pretty well, and that is good news to those short wave broadcasters that thought they will need new transmitters to benefit from digital radio.
Item five: one of the most recent additions to the high end short wave receiver market seems to be loaded with lots of problems, like birdies, overloading etc. So follow Arnie Coro's advice and don't jump and buy a new receiver design until it is fully debugged ... you will save a lot of money and a lot of headaches too. If you do need a new receiver at this very moment, shop around for some of the standard digital models that we have seen around for at least two or three years, and let me tell you that there are at least two or three of them in the table top models range that are show both outstanding perfomance and reliability.
Now, let's take a short break for station ID... Margarita Delgado is my sound engineer and producer... I am Arnie Coro, radio amateur CO2KK, back with you in a few seconds...
You are listening to the English Language Broadcast of Radio Havana Cuba, the name of the show is Dxers Unlimited, and now here is our ever-popular "you have questions ... and Arnie has the answers" section of Dxers Unlimited: Question today comes from a very recently licensed amateur radio operator, he has just received his amateur radio license and wants to know which are his two best bets for enjoying the radio hobby on both HF and VHF. Well, amigo from the UK, this is a really difficult question, as it will depend on too many factors that must be analyzed, but for the typical newcomer to the hobby, my advice is that you start on the VHF 2 meter band using FM both via local and semi-local repeaters and using simplex. A handie talkie or a 10 to 25 watt station plus a simple, easy to build yourself antenna, will give you many QSO's or amateur radio contacts, and by operating on two meters, the world's most popular amateur band, you will very probably meet several local amateurs that will be willing to help you learn more about radio. Now for the HF bands, my choice is one: 40 meters, the 7 megaHertz amateur band, which will provide daytime contacts with very good communications quality to a distance of around 500 to up to 1000 miles, and which during the local evening hours will let you work around the world with a simple wire antenna and a 10 to 50 watt power output. So again, for VHF, two meters, with maybe 70 centimeters as a distant second option, and on HF, no doubt 7 megaHertz is the ideal beginners' band of them all.
Now item six: A second question to be answered here today, as I have lots of them in cue here. This question is related to the no ground radials antenna that I talked about here during our last weekend edition. Yes my friend, it is definetely a VERTICAL radiator, producing vertically polarized waves, and NO, it DOES NOT NEED A SINGLE ground wire radial, not a single one. The HALF SQUARE is a two element vertical which, again, is described by antenna experts as a Self Contained Vertical Array, which does not require ground radials at all. As I also said during our weekend edition, this antenna can be scaled up and down from 80 meters all the way up to two meters, something I can guarantee, as I have done it myself several times, though I have never had enough space available to test an SCV Half Square on the 160 meter band, the only amateur band that is described as a MEDIUM FREQUENCY assignment. So, you can be sure that if you build your HALF SQUARE with vertical elements that are very close to 0.28 wavelength and the horizontal single wire transmission line of about 0.45 wavelength, the antenna will perform very nicely indeed.
According to my practical results on the 15, 10 and 6 meter bands, the HALF SQUARE shows much more apparent, and I repeat this word apparent, gain than the roughly 4 decibels of gain over a dipole in free space that it shows during computer modelling with up-to-date antenna modelling software. There is, in my opinion, a very good reason for this outstanding performance shown by the HALF SQUARE, and that is none other than the extra gain that comes from a much lower take off angle than what can be achieved with a dipole or a Yagi at the same height above ground. In other words, amigo from Canada who asked the question, although the theoretical gain of the two element Half Square array is about 4 decibels above a dipole or 4 dbD, in actual practice, at least on the bands I have tested it longer, 15, 10 and 6 meters, the antennas show a gain that appears to be as if you had installed a three or even a four element Yagi at the height of the single wire transmission line that feeds the verticals. AND, by the way, I have always installed my HALF SQUARE ARRAYS with the single wire transmission line as high as possible, so that the vertical elements hang down from the elevated feeder, something that brings the high current portion of the radiating elements higher above the ground than if you do it all the way around. The HALF SQUARE is certainly a single band antenna system when you use it for transmitting, although it does offer reasonable performance as a receiving antenna over a much wider frequency range. As a good friend of mine said recently, you can't ask more of those 3 pieces of wire hanging from dacron rope between two not-too-tall masts, Arnie...
QSL cards, hard copy verification of reception of our broadcasts, are sent to all of you that request them, and we do it as it should be done, free of charge to the listener. Ao, send your signal reports and comments about our programming to Arnie Coro, Radio Havana Cuba, Havana, Cuba and you will receive your RHC QSL sent via AIR MAIL to your QTH. You can also send your QSL request via e-mail to arnie@radiohc.org, and expect a much faster turnaround time for the QSL to reach you, of course.
Now item eight: Two important safety tips for the summer thunderstorm season now in progress: BY ALL MEANS, disconnect all your radio and computing equipment from the wall plugs after you finish using them. Don't just turn them off, take a little extra time and unplug everything from the AC power lines and the phone lines, and of course unplug and remove all the antenna cables away from your radios no less than three feet or one meter from the equipment. Last, but not least, disconnect the GROUND wire too, as many of the recent mishaps I have heard about came via the ground connections. At least three amateurs who had their stations damaged by lightnning told me that they had everything disconnected, but their equipment was damaged anyway. At my question, "Did you have your ground disconnected from the equipment?" all three of them said no. So follow Arnie Coro's advice do not operate your radios whenever there is a thunderstorm nearby, and once you finish operating, disconnect everything -- ac power, antennas and ground wires.
And now, amigos, just before going QRT, here is Arnie Coro's HF PLus 6 meters propagation update and forecast: Solar activity will continue to move between low and moderate, with a chance of an occasional highly energetic solar flare that will make activity for that specific day be described as HIGH. Solar flux is now around 180 units, somewhat lower than what was expected for this particular phase of the solar rotation. Expect high probability of Sporadic E events, and as I have said during the past three weeks, HF propagation conditions are going to be much better after your local sunset, on frequencies even as high as 21 megaHertz amigos!!!
Don't forget to send your signal reports and comments about Dxers Unlimited; they are really important to keep this show as close to its worldwide audience as it can be. See you on six meters around 50.125 and on 15 meters around 21.295 kiloHertz for a nice QSO when those bands are open!!!
Arnie Coro CO2KK
Havana, Cuba
13 June, 2000Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba
PO Box 6240, Havana, CUBA 10600
phone: 53-7-814243
phone res: 53-7-301794
e-mail: arnie@radiohc.org
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