Monday, June 08, 2009

DXers Unlimited weekend edition, June 6-7

Radio Havana Cuba
By Arnie Coro, CO2KK

Hi amigos radioaficionados ! You are listening to the weekend edition of your favorite listener oriented and technically minded radio hobby program.

Here is now our first item: Solar activity continues at very low level, although the only active sunspot region continues to keep the daily optical sunspot count above ZERO During this week we saw one day with a sunspot count of 23, the highest recorded in a long long time !!!

Another sunspot region seems to be developing right at the edge of the solar disc...Astronomers , both professional and amateurs alike, equipped with high tech solar telescopes should keep an eye focused at the edge of the solar disc's northern hemisphere... where the new action region may emerge at anytime now. The only may actually fade out before it moves out of sight from the Earth in the next few days....

Item two: Today ASK ARNIE, la numero uno, the most popular section of the program will be devoted to answering a question sent by listeners in Botswana, Africa, New Zealand, Saint Lucia in the Caribbean, Canada, the USA and a first time listener also from the Caribbean..who lives in Antigua, where he used to have a lot of very difficulty listening to short wave stations because of the presence of the now not operational BBC and Deutsch Welle super power relay facility.

Our amigo Derril from Antigua is also telling me that ha has been enjoying some nice FM DX from South America.

Those amigos who sent today's question are very interested about the so called Trans-equatorial ionospheric forward scatter propagation, that provides so interesting DX signals on frequencies as high as the two meters amateur band, TEP is much more frequent on the 10 meters and 6 meters bands. Although there are well verified reports of regular TEP propagation from the Caribbean to Brazil on the 2 meters amateur band.

All I can say amigos is that Trans-equatorial upper HF and VHF propagation was discovered by radio amateurs operating from Africa and the Mediterranean region, and so far scientists have not really reached an agreement about what causes this unique form of signal propagation that shows practically no relation to the solar cycle.

Examples of Trans-equatorial propagation include the reception of Brazilian FM stations operating from 88 to 108 megaHertz in Barbados, Trinidad and Tobago and Puerto Rico. Amateur two meters band signals from as far as northern Argentina reaching Puerto Rico, and the history making path between Zimbabwe and Cyprus, one of the first ones that was fully documented by radio amateurs during the early nineteen fifties.

There are some reports indicating that Trans-equatorial propagation has even sent the maximum useable frequency curve to well above 300 megaHertz, something that indicates an extremely high level of free electrons concentrations at F2 layer altitude.

I hope that this short explanation gives you an idea amigos of what Trans-equatorial forward scatter propagation is, and how it is still very much a mystery that science is trying to discover using sophisticated research tools like satellites equipped with ionospheric sounders that work in reverse, that is they send signals from space to the ionosphere at the same time that standard ionospheric sounders probe the ionosphere from below.

The fact that Trans-equatorial propagation happens at certain times of the year is the main clue that scientists are using to find a correlation that will fit and finally tell them why this extraordinary VHF and up to UHF bands propagation events happen.

More radio hobby related information follows in just a few seconds, asDxers Unlimited's weekend edition continues after a short station ID.

This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and it's on the air twice weekly for the enjoyment of our worldwide audience of radio hobby people.

Now here is item three: The Atlantic, Caribbean and Gulf of Mexico tropical hurricane season started the first day of June and already we have seen a very early instance of a low pressure area moving near Cape Hatteras, it had a a rather disorganized activity and never became the first storm of the season pouring.

Actually, this tropical event occurred before the season started. We have had lots of rain over Cuba's eastern provinces also related to the Atlantic , Caribbean and Gulf of Mexico tropical storms and hurricanes once again will be playing an important role to help to make better forecasts of the path of cyclones and hurricanes, by scientists now having access to use the data provided by a larger number of automatic ocean buoys of two types,. ones that are heavily anchored at some specific locations and others that will be launched from specially equipped aircraft and will be then keep track of the drift buoys as they move under the force of the storm's winds.

The weather buoys will be using HF, VHF and UHF frequencies for passing along the data that they are picking up with their sensors. The HF signals can reach long distances but are not very reliable, the VHF data stream is pointing upwards to the airplane that will pick up the data, and the UHF transmitter will send its signals to a special antenna that will be beaming up to a satellite with a very broad beam so that the rough seas will not stop the signal from reaching the satellite, and that requires the use of a special broad beam antenna and a rather high power. The use of forward error correction digital transmission modes is essential in order to assure that the data picked up by the buoys will reach its destination at the weather forecasters offices.

A new form of Dxing... maybe !!! May monitoring the ocean anchored and drift weather buoys becoming number 90 of our list of ways of enjoying this wonderful hobby ?... Who knows ?

As many of you know, there are radio hobby people that devoted all their time to picking up low power beacons or low power transmitters used at airports to provide information to the arriving public, so it's not difficult to imagine that as soon as these buoys start to operate, some Dxers will try at once to pick up their weather data streams.

By the way, I have picked up a great number of drift nets beacons and similar transmitters used by sea going fishing trawlers that operate them near or inside the 160 meters amateur band.

Homebrew your radios, si amigos, GO AHEAD !!! Don't think it over twice,you can start by assembling a simple easy to build crystal set using high impedance headphones to provide excellent listening volume without the need of battery power. I have in my workshop a demonstration crystal radio that picks up seven of the City of Havana's most powerful local stations.

I show my visitors how this radio that uses a large size tuning coil wound on a length of two inch or 50 millimeters diameter PVC pipe, when connected to my 40 meters band half wave dipole antenna provides excellent easy listening audio volume on the two thousand ohms impedance headphones.

The crystal set has also a simple interface so that if can feed a two transistor audio amplifier fed from a nine volts battery that produces room filling volume using a bass reflex cabinet with an eight inch speaker.

Radio Progreso's 640 kiloHertz 50 kiloWatts AM transmitter here in Havana,sounds great on this amplified crystal set , of which I always keep several computer printouts to give away to visitors to my workshop, because this is a nice way to bring them into our wonderful hobby !

Phase two of this project will be to prepare some parts kits from recycled and fully tested electronic components and , and to include a length of PVC pipe and the enamele insulated wire to wind the coil...

The crystal set is assembled using a piece of plywood, and I am keeping several ready cut ones , also to give away to visitors who wish to attempt to build their first radio. The nice thing is that for those that can't find the high impedance headphones required for the amplifier-less radio, assembling the simple two stage transistor audio amplifier is very easy , following my written and graphic instructions, and then they can use any low impedance headphones of the type used by MP3 , cassette or other audio players !

By the way , this simple radio is an excellent receiver for emergency situations , as the 9 volts battery will last for a very long time , because the two transistors draw very little current when in operation.

The parts count is minimal, and it is very difficult to do something wrong if you follow the written text and the pictorials provided in my instructions booklet !

With the millions of electronic gadgets, from old TVs , computers, fax machines, waiting to be recycled the amount of parts available after just a couple of hours of disassembling broken down or retired equipment for recycling its parts will provide more than enough components to make many of these simple receivers...

And now amigos just before going QRT, here is our exclusive and not copyrighted HF plus low band VHF propagation update and forecast: solar flux around 70 to 71 units, down from the 75 units it reached earlier in the week.

The daily sunspot count has moved from 15 to 23 then down to 19 and later two times to 17 , following the path of solar active region 1019 that is now desintegrating and fading away...

The already high probability of Sporadic E openings will be increasing from day to day, especially during this first three weeks of June. Keep checking the FM broadcast band for signs of DX stations, that usually show up on locally unused channels, or atop of weak semi-locals.

Hope to have you all listening to our mid week edition of Dxers Unlimited , next Tuesday and Wednesday UTC days… send your signal reports, comments about the program and radio hobby questions to, again and VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Cortesia de Manolo de la Rosa
(Arnie Coro)