RADIO HABANA CUBA
DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, MAY 22, 2001
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hello, amigos! You are now listening to the mid-week edition of Dxers Unlimited, the radio hobby show that comes to you on the air and on our Dxers Unlimited website, and the one and only program to which you can actually subscribe and receive the script of each and every show right on your computer screen! I am Arnie Coro, radio amateur CO2KK, your friend here in Havana, and here are some of the headlines....
SOLAR ACTIVITY is now back on the way up; in other words, the minimum for the last solar rotation is now a thing of the past... NOW, we all must wait and see how two very interesting solar active sunspot regions behave as they rotate into view... Northern hemisphere Short Wave listeners and radio amateurs are now seeing the typical summer ionosphere... and the average noise level on the HF bands from 3 to 30 megaHertz has increased significantly, as the thunderstorm season continues to develop...
More about HF propagation, as always at the end of the show, so stay with me here right on this same frequency. My sound engineer and producer is Margarita Delgado, you are tuned to Radio Havana Cuba, and Ill be back in just a few seconds...
This is Radio Havana Cuba, where you, the listener always comes first!!! The name of the show is Dxers Unlimited, and YES we do provide a free e-mail subscription so that you can read the scripts of this show via e-mail, too... Have paper and pencil or pen at hand so that you can copy how to subscribe to our Dxers mailing list...
Now here is item two: Interesting thread at one of the Short Wave Listening e-mail lists... it had to do with antennas and how they can actually damage certain types of modern radios that are not protected against the high voltages that develop when long antennas pick up a lot of static electricity, and one of the postings dealt with another really important related topic -- the danger that a ground connection can pose to one of the new high-tech solid-state, microprocessor-controlled receivers. In fact, the best approach to follow with those nice radios is to simply disconnect them from the AC power line, the external antenna and the ground connection, once you finish listening to them.... AND, never, never use those high-tech radios when a thunderstorm is near, as even very far away lightning can induce enough voltage on your antenna that will cause a severe breakdown of your input amplifier device, be it a bipolar or field effect transistor...
Not too long ago, a listener from the United Kingdom asked me if old vacuum tube radios really were better protected against static electricity and high induced voltages on the antennas, and my e-mail answer was simply YES, ABSOLUTELY -- the nature of vacuum tube technology affords an extra protection to those old radios, and the fact is that all attempts to install equivalent protections for solid state modern high-tech radios have not accomplished what was intended... in other words, for those new receivers, the best approach is to simply disconnect them when a thunderstorm approaches, and keep them completely isolated from the AC power line, the external antenna and ground connection when not in use!!!
This is Dxers Unlimited's mid-week edition, and YES, you can subscribe to Arnie Coros Dxers Unlimiteds mailing list, just send an e-mail message to MAJORDOMO AT RHC DOT CU, leave the subject line blank and in the body of the message just write subscribe dxers_l. That is the word subscribe, a space, then dxers, that is delta, x-ray, echo, romeo, sierra, then type UNDERSCORE, that's the little line below the line of text, which in most keyboards is typed by pressing SHIFT and the key which is between the number zero and the PLUS sign, well, for those of you who asked, that's the UNDERSCORE!!!! Again, send your e-mail message to MAJORDOMO AT RHC DOT CU, then leave the subject line in blank, and in the body of the message type subscribe dxers_l, then the MAJORDOMO software will send you an automatic reply and information on what to do in case you want to unsubscribe... We normally send the scripts to the e-mail distribution list the same day that the program is on the air, amigos, and YES, the scripts are in HTML format, so that you can also see some nice graphics that can't be seen on the AMPLITUDE MODULATED Short Wave radio!
Page three, item three: My treasure chest of electronic components, actually of recycled electronic components, is growing bigger almost every day... and it is simply amazing to see how very high-quality high-tech parts would have been sent to a dump, if they had not been saved from destruction by a friendly hand. As my good Canadian friend Bruce Atchinson said recently, recycling electronic components provides experimenters with lots of parts for their circuits, so that one does not need to buy everything brand new when building something. A good example: this past week I was given two damaged computer power supplies, really old ones, and my students Carlos Alberto and Pedro at the Youth Computer and Electronics Club of my neighborhood, where I am a voluntary instructor, spent about two hours carefully dismantling one of them... From that single power supply, we desoldered and then tested high current diodes, a diode bridge rectifier, two high power transistors, and a carload of electrolytic capacitors, PLUS two three terminal voltage regulators, a 7812 and a 7805... Other goodies desoldered included three non-linear special resistors used as transient supressors and several toroid ferrite cores.
Just dis-assembling that old 286 power supply gave us enough parts to complete three projects that we have started at the Club -- a workbench variable voltage power supply, a fixed output 12 volts at 1 amp power supply and a regenerodyne receiver...
Then, as an education tool, I made my students, the six of them in this class, make a list of those components that we had recycled and tested to be good, and proceed to try to find the actual value of them in two of the most popular electronic component sales catalogs... You should had seen their faces when, using the solar-powered calculator, they added up what the whole bunch of parts was worth! Then I emphasized to them that resistors, diodes, transistors and most capacitors exhibit a life cycle that most of the time exceeds the actual useful life of the equipment.
This is not the case with electrolytic capacitors, which have to be tested very, very carefully and reformed properly after long-term storage. They also learned that electrolytic capacitors are one of the components that fail most often, and I showed them why several of the capacitors removed from the 286 power supply that we had just taken apart should be discarded and not recycled, due to the fact that they were leaking trough the wire lead's seals... Although modern, present day, electrolytic capacitors are much better than the ones made half a century ago, they still are a weak link in electronic equipment.
Yes, you can send your radio hobby related questions to arnie@radiohc.org or via AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba. You will receive a faster answer via e-mail of course!
And here is today's question, sent in by a listener in Montana, USA: Arnie, what type of antenna would be best for monitoring the 10 meter band for openings... The reason I ask is that I already have a nice 4 element 10 meter Yagi, which has a rather narrow horizontal beamwidth.
ANSWER... well amigo, congratulations for your nice Yagi, and you can install a pair of horizontal dipoles, properly phased with a coaxial line to generate an omnidirectional horizontal antenna pattern... This approach is, in my humble opinion, much better than installing a vertical antenna, and safer to, as verticals do tend to behave as lightning rods, something that can prove to be really very dangerous during the thunderstorm season. You can find how to properly phase the two horizontal dipoles to configure the almost omnidirectional pattern in any of the popular Radio or Antenna Handbooks.
And by the way, according to my findings here, the 10 meter band is open for DX much more than theoretical considerations will admit... Monitoring the 10 meter beacons band, from 28.100 to 28.300, will very often bring to your attention that the band is certainly open to one part of the world or another, but at that moment no amateur radio signals are heard because there is simply no amateur station on the air... SO, lets keep 10 meters for ham radio, and do call CQ DX every time you hear those beacons coming in, amigo!!!
Now items four, five and six in a row: Item four -- short answers to short questions: YES, by all means use half-inch diameter coaxial cable whenever possible instead of RG58U or RG59U; half-inch RG8 and RG213, for 50 ohms and RG11 and similar cables for 75 ohms are a much better option for any permanent installation... Item five, also a short answer to a friend in Barbados... Yes, amigo, we do broadcast to the Caribbean on 9550 kiloHertz, and we soon hope to have a much better signal down your way when our phased dipoles array beaming to the Caribbean is back on service after a major overhaul now in progress. And finally item six, answering a question sent by a listener in New York: Yes, amigo, for short wave receiving and low-power transmitting applications you can use many low cost plastics as antenna insulators... one the best, of course, is high-density polyethylene which works well up to the UHF frequencies, but again almost any recycled plastic will work well. For example, my portable SKYWAVE antennas used during the hurricane season here are made using homebrew center and end insulators that came from plastic brooms! And I can tell you that they work very well indeed.
And now amigos, as always at the end of the show, here is Arnie Coros Dxers Unlimiteds HF plus 6 meters propagation update and forecast: Solar activity now moving UP, and we may see some interesting fireworks coming from a solar sunspots active region that is now rotating into view... Solar flux Tuesday was getting near 150 units, but it is going to take at least two or three more days before the daytime maximum useable frequencies recover from the period of minimum activity that has just ended.
For short wave listeners here is special advice: During this time of the year in the Northern Hemisphere, the 19 and 16 meter bands provide excellent DX reception starting at about one hour before your local sunset, and sometimes extending for up to four hours past local sunset in the case of 19 meters and about two hours in the case of 16 meters.
Radio amateurs wanting to enjoy nice two-way chats with their friends will find the always somewhat-crowded 20 meter band open well past after sunset for single hop skip, something that reduces interference significantly, making possible nice chats with your friends without far away stations making QRM.
Finally, TV Dxers, FM broadcast band DXers and 6 meter band ham operators should continue to enjoy the summer sporadic E season now in progress, one which yours truly, due to a very tight work schedule, has not enjoyed at all. Si, yes, oui -- CO2KK has not made a single Sporadic E season contact this year yet, something that can best be described as unsual to say the least...
So amigos, we will have somewhat better HF propagation during the next three to five days... See you on 10 meters, right at my favorite spot 28.500, and don't forget to send your comments about the show, QSL requests, and questions to arnie@radiohc.org. It's always my pleasure to be ready to help you learn more about this wonderful hobby...RADIO!
Arnie Coro CO2KK
Havana, Cuba
May 22, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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