Re: [HCDX] Dxers Unlimited's script weekend edition 28-29 April 2007

["Prof. Arnaldo Coro Antich" <inforhc@xxxxxxx>]

Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s weekend edition for 28-29 April 2007
By Arnie Coro
Radio amateur CO2KK

Hi amigos… welcome to the weekend edition of your favorite radio hobby 
program, coming to you from Havana, I am Arnaldo, Arnie, Coro, radio 
amateur CO2KK, your host here now ready to start today’s show with a 
news item…
It’s about the upcoming solar cycle 24 that  is expected to reach its 
maximum activity  late in  2011 or mid-2012
But scientists trying to forecast the next solar peak activity •  are 
split over whether there will be 90 sunspots or 140 sunspots…And as many 
of you Dxers Unlimited’s listeners know very well Solar storms can 
disrupt Earth communications
An Associated Press news dispatch on this topic says that the peak of 
the next sunspot cycle is expected in late 2011 or mid-2012 -- 
potentially affecting airline flights, communications satellites and 
electrical transmissions. But forecasters can't agree on how intense it 
will be.
A 12-member panel charged with forecasting the solar cycle said last 
Wednesday it is evenly split over whether the peak will be 90 sunspots 
or 140 sunspots.
The US Space Environment Center in Boulder, Colorado, tracks space 
weather and forecasts its changes, which can affect millions of dollars 
worth of activities such as oil drilling, car navigation systems and 
astronauts.
Half of the specialists predicted a moderately strong cycle of 140 
sunspots expected to peak in October of 2011, while the rest called for 
a moderately weak cycle of 90 sunspots peaking in August of 2012.
"We're hoping to achieve a consensus sometime in the next six to 12 
months," said Douglas Biesecker, a space environment center scientist 
who is chairman of the forecast panel.
An average solar cycle ranges from 75 to 155 sunspots.
During an active solar period, violent eruptions occur more often on the 
sun, the agency said. Solar flares and vast explosions, known as coronal 
mass ejections, shoot highly charged matter toward Earth.
Making these predictions is important for many businesses, which have 
been asking for a forecast for nearly a year, Biesecker said.
Just like coastal residents want a hurricane forecast as early as 
possible, so do those affected by solar activity, said Joseph Kunches, 
chief of forecast and analysis at the center, which is part of the 
National Oceanic and Atmospheric Administration.
Daniel Baker, director of the Laboratory for Atmospheric and Space 
Physics at the University of Colorado-Boulder, noted that more than $200 
billion satellites in space can be affected by changes in solar 
radiation as the cycle rises and falls.
In addition, Baker said, other problems include:
•  Airlines flying over the pole face loss of communications that could 
force them to use a different, longer route at an added cost of as much 
as $100,000 per flight.
•  The Global Positioning System is immensely important to commerce and 
can be disrupted by solar activity.
•  Operating floating oil rigs in the ocean requires keeping them 
positioned within a few inches to prevent damaging drilling gear. "They 
have to know when GPS is going to be accurate."
•  There is an increased radiation risk to humans in space.
•  Currents can be induced in long electrical transmission lines, 
causing blackouts.
In the past, such problems have been caused by solar super storms, he said.
"Storms don't have to be so super any more" to cause problems, Baker 
said, as more and more systems become susceptible to solar effects.
W. Dean Pesnell of NASA's Solar Dynamics Observatory said the solar 
storms also can heat the Earth's upper atmosphere, causing it to expand. 
This increases drag on satellites, slowing them down. It also affects 
the position of the space debris encircling the planet, and it is 
essential to keep track of that debris for the safety of space flight.
The forecasters said the current solar cycle will probably end next 
March 2008, when Solar Cycle 24 will begin. That will mean Cycle 23 
lasted 12 years, slightly longer than the usual 11-year cycle.
But now let me add that the forecast calling for Solar Cycle 24 about a 
year from now may prove to be wrong according to other solar astronomers 
that have been very carefully studying the past seven solar cycles.
For those of you wanting to know why the higher frequencies of the short 
wave spectrum are so quiet, the explanation is quite obvious; there is 
very little solar activity at this moment with many, many days without a 
single sunspot seen on the solar disk.
Stay here with me for more radio hobby related information as the 
weekend edition of Dxers Unlimited continues in a few seconds…
I am Arnie Coro in Havana, and my e-mail is arnie@xxxxxxxxx
…….
Si amigos, yes my friends, oui mes amis…when propagation conditions on 
the HF bands, from about 6 to 30 megaHertz are very poor, this is the 
time to enjoy VHF at its best... According to ionosphere research 
experts, very low solar activity seems to enhance the number and 
duration of sporadic E events, something that brings in DX on 
frequencies as high as even 250 megaHertz at times…And, as expected is 
ideal for amateur 10 and 6 meters band DX, TV DX on channels 2 to 6 in 
the Americas and FM broadcast band DX… Reports about sporadic E openings 
continue to come in from Dxers Unlimited’s listeners at many locations 
of the Northern Hemisphere…. Especially from North America, Southern and 
Central Europe and the Caribbean…
Now here is item three of today’s program, answering many requests 
received recently, here is more information about the SUPER ISLANDER 
single band amateur transceiver and how it is now evolving into a much 
more advanced, but still easy to build and adjust set. The SUPER 
ISLANDER MARK II is still in the process of final assembly at my 
workshop, but already I was able to test the VFO for stability and the 
receiver for both sensitivity and audio output. A local radio amateur 
that visited me last Tuesday came up with the idea of designing and 
building a solid state VFO, in order to replace the now classic vacuum 
tube design that goes back to more than 25 years ago , when the original 
Islander was born… On Friday, when I was starting to write the script of 
this program, he visited again with the prototype circuit board for the 
solid state VFO, and we connected it to the SUPER ISLANDER Mark II 
prototype by unsoldering the coaxial cable from the vacuum tube VFO and 
soldering in its place the new solid state VFO… All I can say is that we 
were both very pleased with the results, as frequency drift was really 
minimal, and the power drawn by the solid state VFO was really small, as 
expected. Because the SUPER ISLANDER’s power supply already provides a 
source of plus fully regulated plus 12 volts DC , this modification is 
one that is very easy to implement, and one that I am recommending to 
all Islander and Super Islander owners, as something really worthwhile 
to build and install.
The other module that we are now aiming to replace is the receiver’s 
audio section… that will also be converted to solid state… Currently we 
are testing different circuits, with two options in the works, one with 
discrete solid state devices that requires the use of several silicon 
NPN transistors, and the other that uses a low noise NPN silicon 
transistor pre-amp and an integrated circuit power output module.
As we always think in the actual possibilities of home brewers located 
at remote places, the two options will be published, so that builders 
can choose the one that is most convenient to them.
By using both a solid state VFO and also a solid state audio amplifier 
module, the SUPER ISLANDER MARK II will use up less electric power, and 
generate less heat.

As the project evolves, it seems that soon we may end up with a totally 
solid state receiver section of the transceiver, using the locally 
available active devices. This will make possible running the SUPER 
ISLANDER MARK ll  on receive only mode directly from a storage battery, 
a very useful feature when the station is used as part of an emergency 
communications network.
In an upcoming edition of Dxers Unlimited, I will continue to provide 
more information on how this homebrew amateur double sideband and CW 
transceiver continues to evolve into a much more up to date piece of 
equipment…
……
QSL on the air, QSL on the air… yes amigos QSL on the air to listener 
Craig near Ottawa , Canada that reports difficulties in picking up our 6 
megahertz band frequencies during the past several days of extremely low 
solar activity…These reports are a clear demonstration that during the 
period of really minimum solar activity the nighttime maximum useable 
frequency for the typical 2000 kilometers F layer single hop propagation 
path can dip below 6.5 megaHertz and even lower, making reception rather 
difficult to say the least…But as already mentioned at the beginning of 
the program, solar cycle 24 seems to be just around the corner, and as 
soon as we see the first reverse magnetic polarity sunspots that signal 
the start up of the new cycle, propagation is going to take a turn for 
the better …
…..
This is Dxers Unlimited’s weekend edition and here is ASK ARNIE, the 
most popular section of the program … Listeners Harry and Claude from 
Iowa and South Carolina in the USA want to know if backscatter 
propagation can happen during solar minimum, and the answer is that 
unless extremely high transmitter powers are involved, backscatter 
ionospheric propagation is not going to happen during extended periods 
of very low solar activity… So again, HF backscatter propagation is a 
phenomena strongly associated with periods of high and very high solar 
activity, which are a few years away from now …
And now just before going QRT here is Arnie Coro’s HF plus low band VHF 
propagation update and forecast… One rather large sunspot came into 
existence this week, it is  solar active region 953 and it has sent up 
the daily solar flux from baseline levels to well past the 80 flux units 
mark… Due to its present position on the solar disk, there are good 
chances for this sunspot active region to grow in size and further boost 
the solar activity that as I said earlier, has seen many days with a 
totally blank solar disk, with zero sunspot count. Be on the lookout for 
Sporadic E openings that will be happening mainly from 7 am to 11 am 
local time and from 3 pm to 9 pm local time. Send your signal reports 
and comments about the show to arnie@xxxxxx, or VIA AIR MAIL to Arnie 
Coro, Radio Havana Cuba, and Havana, Cuba



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