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Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited's mid week edition for 22-23 December 2009
By Arnie Coro
radio amateur CO2KK
Hi amigos radioaficionados around the world and in space ! I am Arnie Coro your host here in Havana and here is today's big headline " Sunspots are back " , let me repeat it again, in case there was a little fading on the short wave signal.... " Sunspots are back ", and for the past several days, the ionosphere has received the impact of a much higher solar radiation, that is certainly helping to improve HF propagation conditions.
After a very lengthy period of extremely low solar activity, this week has become the showcase to the highest population of sunspots seen in several years.
The big question that scientists are now asking themselves begins with a big IF... Heliophysicists, the solar experts, are asking IF this sudden upsurge of solar activity is the signal of the real start up of solar cycle 24...
We short wave listeners and radio amateurs are not worrying a lot about what's going to happen during the next solar rotations , the Carrington rotations as they are known to honor the scientist that discovered the phenomenon ...we are just enjoying the much better propagation conditions right now, as well as what the much better DX that is going to be picked up by our receivers during the next five to seven days as a consequence of the increase in the daily sunspot count and ten dot seven centimeters wavelength solar flux.
Item two: Closely associated with our number one headline... as solar activity increases, Dxers all around the world will begin to explore the higher frequency short wave bands, and as always , it is a very good idea, in the case of amateur radio operators, to call CQ DX many times on the 17, 15, 12 and 10 meter bands, even if you don't hear anything during your first bandscan.
Due to the much higher expected daytime maximum useable frequencies, your chances of enjoying a nice band opening are increased by instead of just listening , start calling CQ DX, especially around the well established DX spot frequencies, like for example 28.400 and 28.495 on the ten meters band, and 21.295 on fifteen meters when you are looking for single side band DX contacts...
For those of you that enjoy the very popular PSK31 digital keyboard to keyboard communications mode... the spot frequencies are well known too, and you should start calling CQ DX on PSK31 as soon as your favorite propagation forecasting program shows the possibility of openings ... just fill in the solar activity blank spaces on your propagation forecasting software with the following data...
Sunspot number 25, A index 5 and try with a K index of between 0 and 2... those are ballpark figures for the present stage of solar activity...
Never mind that today the sunspot number may be 43... use 25 , because the software will more properly give you the REAL propagation conditions prevailing today with that average ...
In a few seconds I will give you an example of how this works from my QTH amigos... standby now for a short break ... I am Arnie Coro, radio amateur CO2KK in Havana.
................
Si amigos, sure, you are listening to the mid week edition of your favorite radio hobby program, the one and only that always tries to bring you the most up to date HF bands propagation updates, as well as topics related to the more than 85 ways you and I enjoy this wonderful hobby...
Now, as promised, here is an example of how the sustained increase in solar activity that has lasted now for more than a week, has helped to improve short wave propagation...
Early morning local time here in Havana, I am now able to hear amateur radio stations located in Europe and West Africa on the 20 and 17 meter bands...something that had not happened for a long time...
Because of the position of the Sun at seven o'clock in the morning my local time , that is 12 noon Universal Time Coordinated , the ionosphere layers that provide the two hop propagation between Cuba and both Western Europe and Western Africa, have already received a significant amount of solar radiation, so the number of free electrons per cubic centimeter is high enough to send back to Earth signals on frequencies between 14 and 18 megaHertz, and maybe even up to 21 megaHertz at the peak time. The 15 meters amateur band openings will be short lasting, but they may be increasing both in frequency of events and duration during the next few days, especially if solar activity continues to increase.
Item three: Breadboard radios.... yes , you heard it right... breadboard radios were typical of the early days of our hobby, at times when experimenters enjoyed the unique feelings of achievement brought by a two way radio contact made possible using a radio receiver and transmitter that they had just finished building.
As one old timer here in Havana likes to say, you enjoy a two way QSO with a factory made transceiver full of features... but your enjoyment increases exponentially if your QSO, your two way ham radio contact is made using a homebrew receiver and transmitter...
Antique breadboard building techniques have been resurrected by radio hobby enthusiasts with excellent results, and although not all newly built breadboard radios are exact replicas of the nineteen twenties equipment, they all have one thing in common that makes them a joy to operate: the homebrew breadboard rigs do require a lot of operating skills....
Now let me give you an example: my recently finished breadboard transmitter was assembled using a large three quarters inch marine plywood "chassis"... No attempt was made to miniaturize the 20 Watts power Master Oscillator Power Amplifier or MOPA transmitter. It has a built in power supply , with a big 6.3 volts at 5 amperes current rating filament transformer and a one to one 120 volts to 120 volts isolation transformer for the plate voltage supply.
As stated earlier, present day breadboard rigs may or may not be exact replicas of the circuits published in the very early days Radio Amateurs Handbooks... in my case, the breadboard MOPA was assembled as a teaching aid for the amateur radio training program , so it is not a replica. That's why it uses a modern high tech solid state power supply made from recycled silicon rectifiers that came from broken compact fluorescent light bulbs, and large electrolytic capacitors recycled from broken down computer power supplies...
For those of you familiar with power supply safety, that's why I included the one to one isolation transformer. I can operate the solid state power supply in two modes... as a voltage doubler, or as a voltage tripler.... to provide plate and screen grid voltage to the two vacuum tubes used by the breadboard transmitter...
The rig is crystal controlled, operates on the 40 meter band and is capable of delivering up to 20 watts of nice and clean CW signals , that so far have allowed me to work four continents despite the very poor propagation conditions that have prevailed for the past three months, and that now , fortunately are changing for the better....
Ah... before I forget, in the interest of safety, I did spent a lot of time making a chicken mesh protective cover for the breadboard rig.... My ham radio license study group can see the rig's parts clearly , but there is no danger of electrical shock... By the way , in the early days of ham radio, people were not so aware of the dangers of electrical shock, and there were quite a number of fatal accidents due to people coming in contact with the high voltage power supplies...
If you ever plan on building a breadboard receiver or transmitter, be sure to include into your project's list of materials, everything required to build a protective cover to prevent accidental contact with the rig's high voltage !!!
For those of you that already have obtained your amateur radio license, let me add one additional warning, regarding the use of vintage replicas...
Present day radio frequency spectrum regulations require that additional filtering be provided to those vintage replica rigs in case the transmitters are going to be used on the air ... This will require building of buying a radio frequency filter designed so that the rig will then comply with the rules and regulations regarding the out of band energy radiated .
In my case, the 20 Watts breadboard MOPA transmitter uses a PI network for the plate load, and it is connected to a low pass filter that has a very sharp cut-off above 20 megaHertz. The low pass filter was built so that similar home brew rigs could be operated up to the 20 meters band without worrying about non compliance with what the International Telecommunications Union's regulations describe as " non essential radiations", a fancy description for harmonics , out of band and spurious emissions !!!
More about the 20 Watts breadboard MOPA, built mostly from recycled components in an upcoming edition of Dxers Unlimited.... And if you want to know more about this two old vacuum tubes plus several not so old silicon rectifiers transmitter , just send me an e-mail to inforhc at enet dot cu, again inforhc at enet dot cu, and I will send you a file with a full description of this nice rig that may soon be duplicated by another local Havana radio amateur operator.... who came to visit me just to see the MOPA , after we made a two way contact on 40 meters and he could not believe that is was a homebrew transmitter !!!
............
Seasons greetings amigos, yes, Seasons greetings and best wishes for a nice 2010 to all Dxers Unlimited listeners around the world, and to those of you that read the scripts published on my blog, let me say that 2010 will see the blog updated much more often, as I have now decided to upload the scripts to the Blog as soon as I finish writing them.... the blog is at http://dxersunlimited.blogspot.com
again, http://dxersunlimited.blogspot.com.
Also , I am going to look back and see if the old scripts that were not uploaded to the blog can be made available too amigos...
And now a short final item before the HF plus low band VHF propagation update ...
Help preserve Planet Earth from the highly polluting electronic junk... before throwing away to the garbage dump a piece of electronic equipment...think about the possibility of recycling at least some parts from it...
The wonderful Master Oscillator Power Amplifier 40 meters CW transmitter described here today , was built using mostly , about ninety percent of it, from recycled electronic components that came from compact fluorescent light bulbs, a 286 vintage computer, a nineteen fifties TV set that was not a collectors item and several other sources , including a FAX machine and dot matrix printer... they all provided not only the electronic components, but also much of the hardware required to build the rig amigos !!!
........
Ready now to copy our twice weekly HF plus low band VHF propagation update and forecast.
Solar activity still rated as LOW, despite the existence of five active solar sunspot regions at the time I was writing this script, around 13:00 UTC Tuesday , that was 8 o'clock in the morning local time.
Solar flux will be soon reaching 85 units, and maybe moving up to 90 ... The daytime maximum useable frequency curve is already showing a very nice upward displacement, so be on the lookout for DX on frequencies above 15 mega Hertz just after your local sunset. Don't forget to set aside a little time to send me your comments about today's program , signal reports and any radio hobby related question you may want to ASK ARNIE.... send 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 .
Dxers Unlimited
Dxers Unlimited's mid week edition for 22-23 December 2009
By Arnie Coro
radio amateur CO2KK
Hi amigos radioaficionados around the world and in space ! I am Arnie Coro your host here in Havana and here is today's big headline " Sunspots are back " , let me repeat it again, in case there was a little fading on the short wave signal.... " Sunspots are back ", and for the past several days, the ionosphere has received the impact of a much higher solar radiation, that is certainly helping to improve HF propagation conditions.
After a very lengthy period of extremely low solar activity, this week has become the showcase to the highest population of sunspots seen in several years.
The big question that scientists are now asking themselves begins with a big IF... Heliophysicists, the solar experts, are asking IF this sudden upsurge of solar activity is the signal of the real start up of solar cycle 24...
We short wave listeners and radio amateurs are not worrying a lot about what's going to happen during the next solar rotations , the Carrington rotations as they are known to honor the scientist that discovered the phenomenon ...we are just enjoying the much better propagation conditions right now, as well as what the much better DX that is going to be picked up by our receivers during the next five to seven days as a consequence of the increase in the daily sunspot count and ten dot seven centimeters wavelength solar flux.
Item two: Closely associated with our number one headline... as solar activity increases, Dxers all around the world will begin to explore the higher frequency short wave bands, and as always , it is a very good idea, in the case of amateur radio operators, to call CQ DX many times on the 17, 15, 12 and 10 meter bands, even if you don't hear anything during your first bandscan.
Due to the much higher expected daytime maximum useable frequencies, your chances of enjoying a nice band opening are increased by instead of just listening , start calling CQ DX, especially around the well established DX spot frequencies, like for example 28.400 and 28.495 on the ten meters band, and 21.295 on fifteen meters when you are looking for single side band DX contacts...
For those of you that enjoy the very popular PSK31 digital keyboard to keyboard communications mode... the spot frequencies are well known too, and you should start calling CQ DX on PSK31 as soon as your favorite propagation forecasting program shows the possibility of openings ... just fill in the solar activity blank spaces on your propagation forecasting software with the following data...
Sunspot number 25, A index 5 and try with a K index of between 0 and 2... those are ballpark figures for the present stage of solar activity...
Never mind that today the sunspot number may be 43... use 25 , because the software will more properly give you the REAL propagation conditions prevailing today with that average ...
In a few seconds I will give you an example of how this works from my QTH amigos... standby now for a short break ... I am Arnie Coro, radio amateur CO2KK in Havana.
................
Si amigos, sure, you are listening to the mid week edition of your favorite radio hobby program, the one and only that always tries to bring you the most up to date HF bands propagation updates, as well as topics related to the more than 85 ways you and I enjoy this wonderful hobby...
Now, as promised, here is an example of how the sustained increase in solar activity that has lasted now for more than a week, has helped to improve short wave propagation...
Early morning local time here in Havana, I am now able to hear amateur radio stations located in Europe and West Africa on the 20 and 17 meter bands...something that had not happened for a long time...
Because of the position of the Sun at seven o'clock in the morning my local time , that is 12 noon Universal Time Coordinated , the ionosphere layers that provide the two hop propagation between Cuba and both Western Europe and Western Africa, have already received a significant amount of solar radiation, so the number of free electrons per cubic centimeter is high enough to send back to Earth signals on frequencies between 14 and 18 megaHertz, and maybe even up to 21 megaHertz at the peak time. The 15 meters amateur band openings will be short lasting, but they may be increasing both in frequency of events and duration during the next few days, especially if solar activity continues to increase.
Item three: Breadboard radios.... yes , you heard it right... breadboard radios were typical of the early days of our hobby, at times when experimenters enjoyed the unique feelings of achievement brought by a two way radio contact made possible using a radio receiver and transmitter that they had just finished building.
As one old timer here in Havana likes to say, you enjoy a two way QSO with a factory made transceiver full of features... but your enjoyment increases exponentially if your QSO, your two way ham radio contact is made using a homebrew receiver and transmitter...
Antique breadboard building techniques have been resurrected by radio hobby enthusiasts with excellent results, and although not all newly built breadboard radios are exact replicas of the nineteen twenties equipment, they all have one thing in common that makes them a joy to operate: the homebrew breadboard rigs do require a lot of operating skills....
Now let me give you an example: my recently finished breadboard transmitter was assembled using a large three quarters inch marine plywood "chassis"... No attempt was made to miniaturize the 20 Watts power Master Oscillator Power Amplifier or MOPA transmitter. It has a built in power supply , with a big 6.3 volts at 5 amperes current rating filament transformer and a one to one 120 volts to 120 volts isolation transformer for the plate voltage supply.
As stated earlier, present day breadboard rigs may or may not be exact replicas of the circuits published in the very early days Radio Amateurs Handbooks... in my case, the breadboard MOPA was assembled as a teaching aid for the amateur radio training program , so it is not a replica. That's why it uses a modern high tech solid state power supply made from recycled silicon rectifiers that came from broken compact fluorescent light bulbs, and large electrolytic capacitors recycled from broken down computer power supplies...
For those of you familiar with power supply safety, that's why I included the one to one isolation transformer. I can operate the solid state power supply in two modes... as a voltage doubler, or as a voltage tripler.... to provide plate and screen grid voltage to the two vacuum tubes used by the breadboard transmitter...
The rig is crystal controlled, operates on the 40 meter band and is capable of delivering up to 20 watts of nice and clean CW signals , that so far have allowed me to work four continents despite the very poor propagation conditions that have prevailed for the past three months, and that now , fortunately are changing for the better....
Ah... before I forget, in the interest of safety, I did spent a lot of time making a chicken mesh protective cover for the breadboard rig.... My ham radio license study group can see the rig's parts clearly , but there is no danger of electrical shock... By the way , in the early days of ham radio, people were not so aware of the dangers of electrical shock, and there were quite a number of fatal accidents due to people coming in contact with the high voltage power supplies...
If you ever plan on building a breadboard receiver or transmitter, be sure to include into your project's list of materials, everything required to build a protective cover to prevent accidental contact with the rig's high voltage !!!
For those of you that already have obtained your amateur radio license, let me add one additional warning, regarding the use of vintage replicas...
Present day radio frequency spectrum regulations require that additional filtering be provided to those vintage replica rigs in case the transmitters are going to be used on the air ... This will require building of buying a radio frequency filter designed so that the rig will then comply with the rules and regulations regarding the out of band energy radiated .
In my case, the 20 Watts breadboard MOPA transmitter uses a PI network for the plate load, and it is connected to a low pass filter that has a very sharp cut-off above 20 megaHertz. The low pass filter was built so that similar home brew rigs could be operated up to the 20 meters band without worrying about non compliance with what the International Telecommunications Union's regulations describe as " non essential radiations", a fancy description for harmonics , out of band and spurious emissions !!!
More about the 20 Watts breadboard MOPA, built mostly from recycled components in an upcoming edition of Dxers Unlimited.... And if you want to know more about this two old vacuum tubes plus several not so old silicon rectifiers transmitter , just send me an e-mail to inforhc at enet dot cu, again inforhc at enet dot cu, and I will send you a file with a full description of this nice rig that may soon be duplicated by another local Havana radio amateur operator.... who came to visit me just to see the MOPA , after we made a two way contact on 40 meters and he could not believe that is was a homebrew transmitter !!!
............
Seasons greetings amigos, yes, Seasons greetings and best wishes for a nice 2010 to all Dxers Unlimited listeners around the world, and to those of you that read the scripts published on my blog, let me say that 2010 will see the blog updated much more often, as I have now decided to upload the scripts to the Blog as soon as I finish writing them.... the blog is at http://dxersunlimited.blogspot.com
again, http://dxersunlimited.blogspot.com.
Also , I am going to look back and see if the old scripts that were not uploaded to the blog can be made available too amigos...
And now a short final item before the HF plus low band VHF propagation update ...
Help preserve Planet Earth from the highly polluting electronic junk... before throwing away to the garbage dump a piece of electronic equipment...think about the possibility of recycling at least some parts from it...
The wonderful Master Oscillator Power Amplifier 40 meters CW transmitter described here today , was built using mostly , about ninety percent of it, from recycled electronic components that came from compact fluorescent light bulbs, a 286 vintage computer, a nineteen fifties TV set that was not a collectors item and several other sources , including a FAX machine and dot matrix printer... they all provided not only the electronic components, but also much of the hardware required to build the rig amigos !!!
........
Ready now to copy our twice weekly HF plus low band VHF propagation update and forecast.
Solar activity still rated as LOW, despite the existence of five active solar sunspot regions at the time I was writing this script, around 13:00 UTC Tuesday , that was 8 o'clock in the morning local time.
Solar flux will be soon reaching 85 units, and maybe moving up to 90 ... The daytime maximum useable frequency curve is already showing a very nice upward displacement, so be on the lookout for DX on frequencies above 15 mega Hertz just after your local sunset. Don't forget to set aside a little time to send me your comments about today's program , signal reports and any radio hobby related question you may want to ASK ARNIE.... send 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 .
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