Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited's weekend edition for Saturday 13 and Sunday 14 February 2010
By Arnie Coro
radio amateur CO2kk

Hi amigos radioaficionados around the world, now enjoying the revival of the higher frequency short wave bands ! Yes, the 15 meters amateur band has made a nice comeback...as my very good friend Raul CO8ZZ has told me in an e-mail he sent Thursday afternoon, after working a pile up of European stations on CW, using his two element Yagi beam antenna. Raul lives in Las Tunas province of eastern Cuba and is a very enthusiastic Dxer, having partipated in many contests also.

At CO2KK my own ham radio station, I have spent more time monitoring the 15, 12 and 10 meter bands for signs of DX signals, and so far the maximum useable frequency curve has made possible that the 21 megaHertz band stays open during local daylight hours.

More about the comeback of HF propagation later in today's program.

Item two... Thursday afternoon I received the visit of Josue , CO7RR , a young radio amateur operator that lives in Camaguey city the capital of that province of eastern Cuba, where he is the happy owner of the city's only full size 160 meters band half wave dipole... He has used this antenna very effectively to work DX on the so called Top Band during the solar cycle's extended minimum years, but now he will be switching his Dxing to the higher bands.

According to his tests, the full size 160 meters band half wave dipole antenna fed with 400 ohms impedance homebrew open wire transmission line works nicely on the higher bands, although he can not predict the radiation pattern, that on frequencies above 10 megaHertz has many lobes.

Josue and I discussed about his ongoing project that he is sharing with Douglas CO8DM with whom he attended engineering school at the Universidad de Camaguey... Josue graduated in Electrical Engineering and Douglas is a Chemical engineer, they are both now working on a Software Defined Receiver, that will soon be transformed into a transceiver.

SDR's or Software Defined Radios are at the forefront of today's radio technology... making possible really outstanding features at very low cost, because practically all the workload of the receiver is done by a computer....

Item three: Also related to Josue's visit...we went down to my new garage workshop where he became very interested in my portable 2 elements V beam antenna for the 2 meters band. The antenna is made using two TV telescopic whips "rabbit ears antennas", one for the driven element and the other acting as a reflector. My properly placing the reflector element at the correct distance from the driven element, the antenna shows an almost perfect match to 50 ohms coaxial cable, and also provides about 4 dB gain over a half wave dipole.

By placing both the driven element and the reflector in a letter V as in Victor, configuration, the antenna's gain is sligthly higher than what can be achieved with straight elements.

This portable 2 element V YAGI can be assembled in about two minutes... and taking it apart takes even less time !!!

The main purpose of this antenna design is to have it ready for deployment in case an emergency requires the use of amateur radio communications.
Item four: The higher you go up in frequency on the short wave spectrum... the lower ionospheric absorption of radio waves.

So, a low power transmitter will sound much stronger on 10 meters than when it is operated on 40 meters, just to give you a practical example... As HF propagation condition begin to improve, more and more radio amateurs will start operating on the 17, 15, 12 and 10 meter bands, making possible many nice DX contacts that will be made possible by the enhancement in solar activity.
Stay tuned for more radio hobby related information that will be following this short form station ID

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This is Radio Havana Cuba, the name of the show is Dxers Unlimited and amigos , science will soon have another powerful set of instruments to monitor the solar cycle... A new high tech satellite that went into orbit this week has, among its scientific instruments load one that goes by the name :


• Helioseismic and Magnetic Imager (HMI): that will be devoted to study the motions and magnetic fields at the Sun's surface, or photosphere, to determine what is happening inside our nearst star... the SUN.

This complex instrument will try to decipher the physics of the solar dynamo – that is the very source of Sun's activity. The dynamo regulates all forms of solar activity from the lightning-fast eruptions of solar flares to the slow decadal undulations of the sunspot cycle.

Another instrument that will send data to Earth is the

• Atmospheric Imaging Assembly (AIA): consisting of a suite of four telescopes that will image the corona, the outer layer of the Sun's atmosphere. The AIA filters cover 10 different wavelength bands, or colours, from the extreme ultraviolet to visible. It will see details on the Sun as small just as 725km across. These images will be acquired every 10 seconds. Previous observatories have taken pictures at best every few minutes.

The third instrument aboard the new satellite launched this week is known as the
Extreme Ultraviolet Variability Experiment (EVE): It will measure the Sun's energy output in extreme-ultraviolet (E-UV) wavelengths (this is called irradiance) with unprecedented precision. The Sun is at its most variable in the E-UV. E-UV rays can break apart atoms and molecules in the Earth upper atmosphere, creating a layer of ions that can severely disturb radio signals.

Scientists expect to obtain lots of information from this satellite, something that will help them to provide much more precise forecasts of solar activity than ever before.

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You are listening to Radio Havana Cuba, coming to you via short wave and also available as streaming audio from our website www.radiohc.cu, I am Arnie Coro , radio amateur CO2KK your host here in Havana where Saturday morning, when I was writing the script of the program we were enjoying a very nice cool temperature of around 22 degrees Centigrade or Celsius.

At around nine o'clock I started a short wave bands scan that brought a lot of signals on the fifteen meters or 21 megaHertz amateur band. Fifteen meters was well open as solar activity continues to enhance the free electrons concentration of the ionosphere.

Now here is our next item: QSL on the air, QSL on the air to listeners that have sent signal reports and comments about our station's programs, and also have asked radio hobby related questions. Listener Carol from Atlanta , Georgia wrote that she was able to pick up our 6000 kiloHertz frequency with a 55555 SINPO report during the past several evenings.

Carol also commented that her small portable radio when connected to a magnetic loop antenna was able to pick up many more stations.

Her magnetic loop can be tuned from 5 to 15 megaHertz , and it also provides to her a way to cancel out computer hash that comes from a noisy machine owned by her next door neighbor.

Magnetic loop antennas can be installed indoors and they do not require any special fittings. As a matter of fact you can store them away easily after use.

A receive only magnetic loop can be made using half inch coaxial cable, and an air spaced variable capacitor.

The loop is connected to the receiver by means of a smaller wire loop that is about one fifth of the diameter of the tuned loop.

The coaxial cable that makes the loop can be supported by a wooden or PVC pipe frame, that you can make yourself . I am really surprised that there are no commercial versions of the receive only tuneable magnetic loop antenna available.

You can buy in North America, Europe and Asia transmitting type magnetic loops but they are very expensive, because when designed to operate as a transmitting antenna they must use large diameter copper pipe and sophisticated tuning capacitors.

Professional magnetic loop antennas use vacuum variable capacitors for tuning by means of a remote control system... but our short wave listener's version are manually tuned because the antenna is usually placed right next to the receiver.

Just to give you an example of how well a receive only magnetic loop works, a 60 centimeters or 2 feet diameter loop made of RG213 coaxial cable and using an ex- broadcast band receiver 365 picofarads air spaced variable capacitor , I ran a comparative test between the loop and the radio's telescopic whip, as part of a demonstration done to a group of ham radio operators that were visiting here last week.

They all were amazed about the dramatic improvement that was achieved when connecting the magnetic loop to the portable Sony ICF7600G digital receiver and peaking the loop's tuning capacitor for maximum signal.

Si amigos, yes my friends, oui mes amis...a receive only magnetic loop is an excellent weekend project that doesn't require the use of special tools... so it can be accomplished by any one knowing how to work with a hacksaw, PVC pipe or wood, and a soldering iron !!!

If you want to know more about my receive only low cost magnetic loop, just send an e-mail to inforhc at enet dot cu, again inforhc at enet dot cu or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.

And now amigos , as always at the end of the show, here is our exclusive, not copyrighted , in the public domain HF plus low band VHF propagation forecast...

Solar activity has stayed at low levels but it may shift upwards to moderate, as cycle 24 continues to surprise scientists with more and more sunpost groups showing up one after the other. We are even expecting a class X solar flare at anytime.

So far the most powerful flare reached the M8.3 level , causing the typical short wave blackout that happened in the parts of the Earth where the Sun was above the horizon at the time of the event.

Radio amateur operators are enjoying the best propagation conditions on the bands above 10 megaHertz of the past four years.

If the Sun continues to produce more sunspots, we may soon be able to enjoy excellent F2 layer propagation on the 10 meters band day in and day out.

According to my observations, the increase in solar activity has certainly reduced the range of both the 160 and 80 meters band due to the marked increase in ionospheric absorption, and the same is happening to signals on the 120 , 90 and 60 meters Tropical Bands.

Be on the lookout for possible sudden openings on 6 meters that may happen at anytime now... Yes amigos, the sunspots are back, and with them much better short wave radio propagation conditions that you wil be able to enjoy for at least four or five more years !!!

Just to give you an idea of what is happening 93 million miles away from us...The high sunspot number for the week was 71 on February 8,and the average for the week was 43.3 a, weekly average that high had not happened since the week of March 27 through April 4 in 2008, when it was 43.6. The daily sunspot number hasn't been as high as 71 since May 28, 2006 when it was 78. The earlier reading that reached that level or more was 105 on April 6, 2006.
Don't forget to send me an e-mail to inforhc at enet dot cu telling about your impressions about this digital text edition of my Dxers Unlimited radio show amigos... I will surely appreciate very much your comments and ideas on how to make it better in the future !
Also... don't forget to spend more time operating on the amateur bands, if you already have a valid ham radio license... we all need you on the air amigos... please remember that if the amateur bands are not used... they may become the target of commercial and other professional users that may show spectrum analyzers displays of our empty bands !!!
Posted by Arnaldo Coro at 8:32 PM 0 comments Links to this post
Sunday, February 7, 2010
Dxers Unlimited's weekend edition 6-7 February 2010
Dear amigos :
I am once again trying to update this BLOG ... something that is not always possible due to the combined workload at RHC and my teaching duties...
I will appreciate very much comments from those of you that see it... regarding its the usefulness of publishing every script of the program here.
Send mail to inforhc at enet dot cu with your comments and suggestions
Thanks in advance for taking the time to do it

73 and DX
Arnie