By Arnie Coro CO2KK
Hola amigos radioaficionados all around the world welcome to this edition of Dxers Unlimited a program that is now celebrating our station’s 57th year on the air, always helping to promote the use of international radio broadcasting as a way to communicate, and of course that we also provide support for amateur radio hobby activities around the world.
This is Radio Havana Cuba , the name of the show is Dxers Unlimited, I am your host Arnaldo, Arnie, Coro , radio amateur CO2KK , and here is your information on a solar activity update…
Now hear this…. A sunspot from the next solar cycle was visible for just a few hours, but it was nevertheless a relevant event…. Now I will tell you why…. ….
Over the weekend, a magnetically reversed sunspot appeared in the sun’s northern hemisphere. Its high latitude locations is telling us that the slow transition between Solar Cycle 24 and Solar Cycle 25 appears to be underway because the reverse or backwards’ magnetic polarity mark it as a clear definite member of the next solar cycle.
Is Solar Minimum over? Not even close, but this development does suggest that Solar Cycle 25 is just starting ––
But solar activity continues to be very low, and there are no significant sunspots from cycle 24……
Si amigos You and I enjoy radio, we may have a wonderful time by traveling and spending a nice vacation at a remote island operating our low power amateur radio station using the Sun as the only power source or maybe, just after listening to this show, you are now getting ready to solder the last parts to the circuit board that will soon be connected to its power supply, antenna and loudspeaker ready to bring in that magical moment of the first station heard on a homebrew radio…
Sure amigos, even a three transistors home built regenerative receiver can become half of your minimalist amateur radio station. MY favorite one has one active regenerative detector stage followed by two common audio NPN transistors providing good volume to the headphones….
Yes amigos there are more than ninety one ways that you and I can make use of our spare time and enjoy the radio hobby… Here is now one of them that is winning more and more interest due to the challenges that it involves. Yes, I insist on talking about operating your own amateur station using a low power transmitter, never to exceed five WATTS when operating on CW Morse Code radiotelegraphy or using one of the really amazing digital communications modes….
Or you can go up to 10 WATTS when using single side band voice mode and still consider your station into the QRP very low power station …. QRP stands for low power operation, and as I just said it is attracting a lot of attention worldwide to the extent that QRP operators have achieved really amazing results even when using simple low cost antennas and home built radios…
Let me give you a recent example of a successful QRP minimalist station … Not too long ago I was testing a short wire antenna for the 20 meters band at the request of a ham radio friend that has very little space available to install his antennas. The antenna is just 6 meters that is about 20 feet long, and fed using a one to one broadband transformer plus a quarter wave radial ground system. His favorite band is 20 meters , so he challenged me to design , build and test a half size wire antenna. Half size meant in this particular case that the antenna’s overall length could not exceed 6 meters… the actual length of the active element, separated with insulators by 50 centimeters from the support masts… The antenna design called a highly efficient one to one impedance transformation RF transformer located at the center of the antenna …
This antenna is fed by the already mentioned one to one transformer , to prevent the outer part of the coaxial feed line from radiating and thus distorting the vertical radiation pattern… Once completed the prototype antenna was set up between two five meters high masts and carefully tested on the frequency of 14 point one megaHertz , using my PI network universal antenna tuner and standing wave ratio meter, because my friend wanted it to provide optimum performance at the low end of the 20 meters band where he operates on CW and Digital Modes.
Using advanced antenna modeling software, it was possible to estimate that this about half size antenna was down by about minus three to four decibels when compared with a full size dipole at the same height above average terrain…and to add to our joy ! We tested the compact antenna on the 17, 15, 12 and 10 meters amateur bands using my Universal PI network antenna tuner, finding out that it provided an excellent one to one standing wave ratio on the four bands between 18 and 29 megaHertz….
Well, it then took just a few minutes to connect my 5 Watt CW rig and start calling CQ on 14060 kiloHertz ,and was nice to hear not one but actually three stations coming back to my call. Later I reviewed the Reverse Beacon Network Internet site and found out that my CQ calls were picked up by several of the skimmers stations that monitor 20 meters. Taking a look at the power and standing wave ratio meter, I was happy to see four WATTS going to the antenna and a one point two to one standing wave ratio after tweaking the antenna tuners three knobs… So after exchanging signal reports with the three stations, I decided to go QRT, and call my friend to tell him that his antenna was ready to be taken down from its provisional installation at my home station and taken to his home to be installed.
Keep listening here to Dxers Unlimited middle of the week edition as it will continue after a short break for a station ID… I am your host Arnie Coro , radio amateur CO2KK …
This is Radio Havana Cuba, the name of the show is Dxers Unlimited and this special edition devoted to a compact HF antennas now continues….
Enrique is now the happy owner of the new compact antenna that make possible for him to operate not only on 20 meters but also on the 17, 15 , 12 and 10 meters bands.. He added that his other compact antenna, that is just an eleven meters long wire dipole with its two well built loading coils, also loads quite well on the 30 meters band by using his PI network antenna tuner….… He added that by using high Q factor loading coils, it is possible to achieve good efficiency, with the antennas behaving just at a minus 3 to 4 decibels below the radiation efficiency of full size half wave dipoles….
And he underscored the fact that 3 decibels is half of an S unit, something that is extremely difficult to measure in actual practice while communicating via the ionosphere, where fading of the signals can span one, two and even three or four S Units. Arnie, he said, a deep fade that sends the received signal down by three S units means an eighteen decibels signal loss…. so if I am using my minus three decibels gain antenna , no one can really tell the difference between it and the full size half wave dipole….
The present days very poor HF bands propagation conditions require the use of highly efficient digital modes like FT8, but Enrique adds that he is now calling CQ regularly on the OLIVIA digital keyboard to keyboard mode, with excellent results, and he adds, and here I quote : ARNIE, with the OLIVIA digital mode I know that there is a human being at the other end of the QSO, not just a dumb automatic robot left on the air to catch new prefixes !!!
Si amigos, yes my friends, the minimalist radio amateur digital station has proven to work very well, and of course that can also be used operating with the most traditional digital mode of them all — Morse Code RadioTelegraphy sent by hand and received by ear…. The one and only available for the pioneers of amateur radio !!!
NOW … coming to its end is your favorite radio hobby program, I will appreciate very much your signal reports and comments about this and other Radio Havana Cuba programs, that you can send by e mail to inforhc at enet dot cu, or Via Air Mail to Arnie Coro, Radio Havana Cuba, Havana , Cuba
I Hope to have you all listening to the weekend program on the air on Sundays and Mondays UTC days just after the top of the hour RHC News bulletin