Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s weekend edition for Dec 15-16 2007 By Arnie Coro Radio amateur CO2KK
Hi amigos radioaficionados around the world and in space…Seasons greetings and a Happy New Year 2008 to you all ! Welcome to the weekend edition of RHC’s twice weekly radio hobby program, featuring today a follow up on the update that we presented here during our most recent mid week edition about the recent significant increase in solar activity, that sent the daily sunspot number up to 44 , with the nice corresponding increase in the daytime maximum useable frequencies all around the world .
I am Arnie Coro, radio amateur CO2KK, and as always it is nice to have the opportunity of sharing with you about 17 minutes of on the air and on the world wide web time… Here is now item two: A very popular antenna for amateur radio operators that enjoy using the 2 meters band, the most popular ham band worldwide according to the most recent statistics, it’s a version of the J pole, a totally portable antenna, that can be assembled and taken down in just a few minutes and can be built using simple construction techniques with hand tools and a soldering iron.
As in the case of the magnetic loop that we presented here during the mid week edition of the program, there is no need for a machine shop for building this one, that can be transported very easily when built using either 300 ohms TV twinlead or the more expensive , but much better quality 450 ohms WINDOWS transmission line, and it also will fit easily into any travel bag…
More about the portable J pole antennas for the 2 meters band here at the weekend edition of Dxers Unlimited… Stand by for a few seconds, I’ll be back after a short break For station ID…
…………….
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and yes we do reply your QSL requests, via e-mail and also VIA AIR MAIL…and again amigos, we are now mailing our nice 2008 pocket calendar that you can request via e-mail or by sending a postcard… Now here is item two in detail., the J pole antenna made of TV twin lead or WINDOW 450 ohms transmission line, that is very inexpensive, easy to build and to adjust for minimum standing wave ratio using a standard standing wave VHF meter…You will only need to obtain the best possible quality TV 300 ohms twin lead, or for a much better antenna, use the harder to find and more expensive 450 ohms impedance transmission line with windows cut all along it to reduce the losses due to the presence of the polyethylene dielectric.
The antenna made using the 450 ohms WINDOWS line is not only much more rugged than the one made from standard TV 300 ohms twin lead, but also has a much wider bandwidth , something that may prove to be important if you need to operate all over the four megaHertz bandwidth of the
2 meters band.
The complete step by step building instructions with photos are about to be finished, and soon to be completed into a dot pdf file that can be sent via e-mail, so if you are interested in the possibility of homebrewing this nice, easy to build portable antenna for the two meters amateur band, just send me an e-mail to arnie@rhc.cu, or a postcard VIA AIR MAIL to Arnie Coro , Radio Havana Cuba, Havana Cuba.
……..
You are listening to the weekend edition of Dxers Unlimited and here is item three of today’s show… A visit to Arnie’s workshop, a section of the program that according to your e-mail messages, postcards and letters is also becoming very popular. The workbench of my workshop is , as usual, full of projects… that range from a battery charger under test after it was repaired, to the next generation regenerative receiver project, also under test. Alongside the receiver there is a 12 volts regulated power supply that was upgraded from a discrete component regulator to a much simpler and better integrated circuit regulator that is capable of providing up to one and a half amperes while also having much better protection against overloads than what was available from the original factory design… Si amigos, yes my friends, oui mes amis… you can upgrade and modify many nice pieces of equipment with just a few hours of work, this will require an analysis of the original circuits, and how you can upgrade the equipment with much more up to date technology. Among engineers, this is known as retrofitting, that meaning that you remove the old technology , add the new up to date components and circuits while retaining the parts that don’t need to be replaced… In the case of the power supply in question, I retained the original power transformer, bridge rectifier and electrolytic capacitors, while changing the voltage regulator circuit from a group of discrete components to the new high tech integrated circuit regulator. The tests of the upgraded power supply showed that short circuit protection is much better and voltage regulation has also improved significantly from zero to full load… By the way , this is a very good idea to apply to the so called Wal Wart power supplies used by many portable radios !
Item five: Here is LA NUMERO UNO, the most popular section of Dxers Unlimited… YOU have questions and Arnie tries to answer them as fast as possible. Today’s first question came from listener Albert from Ireland…Amigo wants to know about the begining of the solar cycle, as he tells me in his e-mail that he was very happy about the possibility of the first sunspot of cycle 24 to be seen soon.
Well amigo Al, according to solar optical and magnetic observations taking place for the past several days, now scientists are almost sure that the new active solar region could very well be first sign of cycle 24, because of two very well known reasons: first the region is located at a high solar latitude, plus the fact that is has a reverse magnetic polarity.
The new cycle sunspots should start to appear at high solar latitudes, and a large number of them, but not all, should be showing a reversed magnetic polarity as compared to the majority of the sunspot active regions of the now ending cycle 23… The second question came from the Iceland, where the winter season is now in full swing, and as always making much more time available for homebrewing radios and listening to short wave, listener Ib, tells me in his e-mail that he is able to pick up several Radio Havana Cuba frequencies, among them 12000 kiloHertz as soon as it goes on the air at eleven hours UTC. Well amigo Ib , the reason you are picking up the 12000 kiloHertz Spanish language programs so clearly in Iceland, is that we are using a curtain array antenna that is beaming to 010 degrees azimuth, so your QTH is right into the main beam of the antenna, that has a beamwidth at the
– 3dB points of plus and minus 20 degrees or a little less…I also checked the maximum useable frequency and frequency of optimum traffic from Cuba to Iceland between 11 and 15 hours UTC, and 12000 kiloHertz is very well placed to provide such an excellent signal as you are reporting … Congratulations on your Spanish lessons, and yes, our announcers at the Despertar con Cuba morning show speak at a lower speed than the average Cubans do… !!The third answer to Dxers Unlimited’s listeners questions is now on the air, in order to catch up with a signficant backlog… Listener Ulrich
>from Dusseldorf , Germany sent a very nice e-mail message to
arnie@rhc.cu, in which he asks how he could install his short wave and amateur radio HF antennas with minimum losses, something that he asks because his apartment is located half way along a 10 stories high building… So the distance between the floor where his shack is located and the rooftop, where he is allowed to install the antennas is quite significant… Well amigo Ulrich, your best option is to use the highest possible quality , low loss coaxial cables…As you explain in your e-mail, the total length involved is more than 50 meters, between the antenna connector of your radios and the antennas located at the roof of the building. Although it is very expensive, the low loss aircell coaxial cable will last many years when properly installed, but, let me insist on those two words, properly installed, because you will need to properly seal and protect from the weather the cable and connectors.
You may want to think about the possibility of using one or two low loss cables and add a remotely controlled antenna switch so that the same cables will let you use several antennas, instead of running one cable for each antenna .
Amigo Ulrich, on the HF bands losses won’t be so significant, but on VHF and UHF , your long coaxial cable runs will have a negative impact on the performance of your amateur radio station, and there is nothing you can do about that !
And now amigos, as always at the end of the program , here is our exclusive and not copyrighted , in the public domain, Arnie Coro’s Dxers Unlimited’s HF plus low band VHF propagation update and forecast… Solar flux has now passed above the 90 units mark for the same time in many days…and solar activity is hovering between low and very low…
The effective sunspot number is now at 37, sending up the daytime maximum useable frequency up all around the world with some nice spots seeing up to 40 megaHertz frequencies propagating on North South paths .
Sporadic E openings should be becoming more and more frequent as we approach the winter solstice, and that’s good news for TV and FM broadcast band Dxers as well as 10 and 6 meter bands amateur radio operators. Hope to have you all listening to the midweek edition of Dxers Unlimited, Saturday and Sunday UTC days, and don’t forget to send me an e-mail with your signal reports and comments about the program, send mail to arnie@rhc.cu or VIA AIR MAIL to Arnie Coro , Radio Havana Cuba, Havana , Cuba
