Wednesday, June 03, 2009

Radio Havana, DXers Unlimited June 2-3 edition

By Arnie Coro, CO2KK

Hi amigos radioaficionados worldwide ! Welcome to the mid week edition of your favorite listener oriented radio hobby program, always trying to bring to you the latest HF plus low band VHF propagation information, plus as many technical aspects of our hobby as possible.

I am Arnaldo, Arnie, Coro, radio amateur CO2KK, your host at this twice weekly radio hobby program, and here is now item one:

solar activity picking up, an active sunspot region ,number 1019 is clearly visible, and this one is definetely a cycle 24 spot.

Also, photos of the solar limb show what may well be another active sunspot region about to rotate into view... Now, let me tell you about the direct consequences of even a single sunspot active region on the Earth's ionosphere.

When the free electrons concentration is at such a low level as it happens when solar flux is below 70 units for many days at a time, even a small increase in the flux, as we are seen right now, makes a marked improvement on the propagation conditions , especially on frequencies between 10 and 20 megaHertz.

For example, here in Havana, a Tuesday morning local time bands scan showed that the fifteen megaHertz signal from WWV in Boulder , Colorado, was at the highest signal to noise ratio in many days.

Another finding was that the signals from a short wave broadcast station located in Chile could be heard with a good signal to noise ratio on the 16 meters or 17.5 to 18.0 megaHertz band.

I could also pick up several amateur radio stations on the CW segment of the 20 meters band, during another observation period that spanned from 12 to 13 hours UTC...

So be on the lookout for making good use of this slight, but as explained earlier, significant increase in solar activity ...

Item two: From Radio Havana Cuba's engineering department comes the news that our 11770 kiloHertz 25 meters band frequency is been heard well in southern Europe , as well as all along the East Coast of North America.

Item three: A quick reply to a question sent by listener Stefan from Canada about the ongoing search operation launched to try to find where the Air France A330 aircraft went down. Monitoring the aircraft HF bands brought some very interesting exchanges between ground stations and the Brazilian aircraft that finally found floating debris that almost for sure belong to the aircraft.

Yes amigo Stefan, whenever a search and rescue operation is in progress you will be able to pick up a lot of traffic on certain frequencies used routinely for aircraft HF single sideband communications, and on some other frequencies you may pick up also SSB voice exchanges between ships arriving at the scene of the accident.

In this particular case, knowing Portuguese did help to understand what the search planes were describing when they finally spoted the location where seats and other debris from Air France flight AF 447 were found.

Item four: An add on to item three: Long Distance Operations Centers use Single Sideband Voice communications on the HF aircraft bands, in order to keep contact with planes flying out of range of the VHF band frequencies.

The distance that a plane can be still heard at the VHF frequencies depends on two main elements: first the altitude of the aircraft, and second on the particular VHF propagation conditions at a given moment.

HF aircraft communications are much less reliable than the VHF signals,and often require that the crew change frequencies several times until they can find one that provides an effective link to remote Long Distance Operations Center or LDOC, that have to keep track of the flights as they proceed along the flight plan, checking their position at certain locations that are given a name that is tied to specific geographical coordinates.

By the way , listening to HF SSB voice mode aircraft communications is one of the more than 85 ways that you can enjoy our wonderful hobby, yours and mine: RADIO !!!

Stay tuned for more radio hobby related information coming up in a few seconds after a short break for station ID, I am Arnie Coro, CO2KK in Havana...


You are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited and this is our mid week edition on the air on Tuesdays and Wednesdays UTC days... Hire is now item five:

The Atlantic, Caribbean and Gulf of Mexico Tropical Hurricane Season Season began on Monday , the first day of June and will last until the 30^th of November...

Radio amateurs all along the areas that may be hit by storms have by now completed the preparations in order to be able to provide emergency communications whenever required.

Equipment capable of operating using batteries , portable antennas that can be quickly set up , and the organization of emergency nets are very important elements of any effort aiming at providing alternate links when the normal communications systems fail or are used to the top of their possibilities.

Here in the Caribbean, tropical storms and hurricanes are carefully followed by the weather services,and as soon as they start to develop, radio amateurs are ready to deploy their stations well ahead of the path of the storm.

Among the important services provided by the amateurs are passing along precise weather data to the main meteorological services, so that they can keep accurate track of the storms. Other ham stations are installed at shelters, hospitals and clinics, as well as near dams and water reservoirs.

Here in Cuba, during the very active 2008 hurricane season,more than one thousand radio amateurs participated in providing alternate emergency communications to the Civil Defense Disasters Command Posts , something that was recognized by the Government and also brought some very nice reports from the mass media that have generated a lot of interest in the people in our hobby.


Si amigos, sure, radio is a technical hobby, and many of us enjoy homebrewing our radios, antennas, and accessories.

Improving your listening post of amateur radio station is always rewarding.

Take for example a local friend that could not operate on the 40 meters band, because he didn't had enough space to install a full size 40 meters band half wave dipole.

When I heard him on 2 meters complaining about not having enough space to install a 40 meters band antenna, I told him that a very effective short antenna could be easily made, and that the difference in signal strength between this half size antenna and the full size one was in the order of between one third and one half of an S unit, something very difficult to detect .

So I proceeded to provide him with the step by step building and assembling instructions for the half size 40 meters band antenna.

About a week later, he came back to me, again on the local 2 meters band repeater, telling me that he had built the half size dipole with excellent results.

Amigo Eduardo also added that he was able to trim the antenna to resonance on 7050 kiloHertz achieving a low standing wave ratio from the low end of the band to about 7125 kiloHertz, something that according to him was very rewarding as he could operate on CW, the digital modes and single side band voice .

The antenna uses two easily made loading coils ,located at about 2.5 meters from each side of the center insulator, and the overall length is about 10 meters, or roughly one half of the length of the standard half wave dipole for the 40 meters band.

Eduardo told me that he started by adding about 3 meters of wire to the end of each loading coil, and the proceeded to trim the length until he achived the lowest possible standing wave ratio on 7050 kiloHertz.

His antenna was strung between a mast that he installed at the flat roof of his home, and a nearby pine tree, and so far has proven to be very effective not only for short distance near vertical incidence skywave communications while the Sun is out, but also as a rather good antenna for working DX during the local evening hours,especially when using the PSK31 digital communications mode.


And now amigos, as always at the end of the program here is Arnie Coro's Dxers Unlimited's HF plus low band VHF propagation update and forecast.

Participants on the CW WPX Contest during the past weekend that heard our forecast were able to work many 10 meter band stations via the Sporadic E propagation mode that provided mainly single hop skip signals, but that also eventually brought some double hop propagation too. As explained during our weekend edition, at peak times the 21 megaHertz or 15 meters band also was open, but in this case for both
sporadic E and F2 layer propagation.

Now as you hear this, active sunspot region 1019 is developing, and there are even chances for a class C solar flare to erupt from that area of the Sun. Solar flux should increase to around 75 units, so HF propagation should take a turn for the better during the next three days.

Sporadic E events should be happening at a very high rate during the next three weeks...So check the low band TV channel frequencies and the FM broadcast band !!!

Join me Saturday and Sunday for the weekend edition of Dxers Unlimited and don't forget to send your signal reports, comments and radio hobby related questions to inforhc and enet dot cu or via air mail to Arnie Coro , Radio Havana Cuba, Havana, Cuba