Wednesday, July 18, 2018

Dxers Unlimited, midweek edition July 17

Radio Havana Cuba - Dxers Unlimied - 17 July 2018
Arnie Coro, CO2KK

Hi amigos radioaficionados...listening via short wave and also by means of our streaming audio from am your host Arnie Coro,radio amateur CO2KK now ready to start the middle of the week edition of your favorite radio hobby program.

Item One...As anyone monitoring the HF bands will easily find out,the low solar activity continues to limit the chances of short wave propagation on frequencies above15megaHertz,even during the best times of the day at any given location.The exception comes when sporadic E layer openings move the maximum usable frequency up past the25megaHertz range. Observations confirm that solar cycle 24 continues to show very weak activity as compared with any of the previous 5 solar cycles. As a matter of fact today Tuesday July 17 we have seen so far twenty consecutive days without sunspots…

Item Two:You have questions and I do my best to answer them...Yes amigos,every day the e'mail brings in most interesting questions from listeners all around the world...Like for example the one sent by Manuel from Mexico City, who listens regularly to our 15140 kiloHertz frequency. Manuel is asking why it is not possible for him in Mexico city to pick up shortwave stations from other countries in the Americas besides Cuba, Brazil and  his local Radio EducaciĆ³n that he receives via the ground wave signal.

Well amigo Manuel, first of all,let me tell you that at this moment they are fewer stations from the shortwave bands with high enough power to be heard on a regular basis. Venezuela was in the process of installing its first international broadcasting transmitting station,but that project is now  at a standstill.

This is Radio Havana Cuba,the name of the show is Dxers Unlimited,and yes amigos,we do send QSL cards to listeners that report our programs, and this is done absolutely free of charge.

Now part two of the answer to amigo Manuel, who lives just outside Mexico City. Besides Radio Havana Cuba,that can be picked up,using a rather simple short wave receiving antenna,you may be able also to pick up several stations from Brazil, as well as maybe Peru and Bolivia,are also on the air, especially on the 60,49 and 31meters bands,but most of them are using low power and simple low cost antenna systems because they are intended to provide local or regional coverage.

When HF bands propagation conditions are good,you may pick up several of those low power stations from Peru, Bolivia, Ecuador, Colombia and Mexico. Reception of those low power shortwave broadcasts, mainly on the 60 and 49meters band, and also at times on 31 meters. This will usually take place very late in the evening during your local time or just before local sunrise.

For both shortwave listeners and amateur radio operators that live in urban areas the installation of an adequate antenna for obtaining best results within the frequency range from 3.5to 29.7 megaHertz is quite a challenge to say the least.City dwelllers, and especially those who live in apartment building face a great challenge when trying to listen or to operate on the 80 to 10 meters ham bands, because of the severe restrictions imposed nowadays regarding the installation of external antennas on any type of building and the extremely high local noise levels.

The rooftops of high rise apartment buildings are an ideal location for VHF,UHF and microwave operation. If you happen to be living at one of the top floors, but are quite useless for that purpose if your apartment is located close to the ground requiring the installation of a very long length of transmission line needed to reach a rooftop antenna and this,if you are fortunate to obtain permission to install it by the building managers. But, despite all those difficulties,I very often come across a ham radio operator that with a lot of ingenuity that manages to operate, for example,on the 20,17 15 and 10 meters bands,using different types of compact antennas.

Fortunately the 12 and 10 meters  HF bands require a much smaller size of antennas small enough to make them fit across a balcony rail. However, 20,17 and 15 meters are certainly the most popular DX bands when propagation conditions are let's say,normal or slightly above normal, and that is why people living in housing facilities with severe restrictions as regards to the installation of external antennas,try, in the first place to put up an antenna system that can be tuned to 20,17and15meters.

One of the regular Dxers Unlimited's listeners,who is also an avid ham radio operator asked about what could be done to install an antenna for the 20,17 and 15 meters band that could fit into his apartment's balcony that measured from one end to the other roughly 5meters or about sixteen and a half feet. That is just enough to install a dual band 12 and 10 meters fan dipole. His already in use 12 and 10 meters fan dipole dipole has brought some local contacts,and also some DX when the band is open,but as everyone now is fully aware,the 10 meter band openings via the F2 layer are going to become very rare indeed due to the lack of solar activity. Remember what I said at the opening of today's program, 20 consecutive days without sunspots

Besides buying an expensive professional magnetic loop antenna with remote tuning, there is another option for our listeners who want to operate on the 20, 17 and 15 meters band. Build a compact short dipole antenna using two easy to make loading coils and two end loading capacitive hats,that will make possible to operate on the 20,17 and 15meters bands with rather good efficiency, and also on the 30meters band with somewhat reduced performance.You must use a balun or balanced to unbalanced one to one broadband transformer at the feedpoint of the antenna. The antenna I suggested fits perfectly into a slightly less than 15 feet or five meters of horizontal space,and when fed via factory made or a homebrew one to one balun and using a wide range antenna tuner has proven to provide excellent performance. One good advantage of this antenna is that it can be installed in a couple of minutes when you want to operate or listen to the radio,and likewise it can be taken down and placed in storage at a corner of the balcony ! The good efficiency of this antenna design despite its short length, is due to the use of two carefully built high Q loading coils and the nice looking well designed end loading spiders,that act as an effective capacitive load.

The two loading spiders are built using four wires that are carefully soldered to a circle made of 6millimeters or about a quarter of an inch copper tubing.Each leg of the antenna is just two and a quarter meters long and they end up connecting to the end loading spiders. The center insulator supports a one to one balun transformer,and the antenna is fed with a short length of RG213 or RG8X coaxial cable that connects it to the antenna tuner. So far,all our experiments with this antenna have proven that it will work quite well with a simple antenna tuner,making possible to operate on the 20, 17and 15 meters bands, as well as on the12,10 and even 6meters band too using an antenna tuner.The fact that the antenna is located inside a balcony,places some limitations as regards to both the overall coverage and also limits its use to power levels not to exceed 25watts for safety reasons regarding the exposure to radio frequency energy.

If you want to learn more about this compact antenna system,especially designed for apartment dwellers, just drop me an email to inforhc at enet dot cu,again 

And now as always at the end of the show, here is Arnie Coro's Dxers Unlimited's HF propagation update and forecast. Expect sporadic E openingsto become less and less frequent after the end of July and solar activity continues to be low but the night time maximum useable frequency curve continues to exhibit its usual upward swing that starts after sunset,something typical of the northern hemisphere summer season.Solar flux around 70 to72 units.And please don't forget to send your signal reports and comments about this and other RHC programs to or via air mail to Arnie Coro, Radio Havana Cuba, Havana Cuba
(Arnie Coro/R Habana Cuba)