Re: [HCDX] Dxers Unlimited's weekend edition 5-6 January 2008

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

Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s weekend edition 5-6 January 2008
By Arnie Coro
Radio amateur CO2KK
This is our first program of 2008 amigos !!!

Hi amigos radioaficionados around the world and in space… welcome to the 
weekend edition of Dxers Unlimited coming to you from Havana . I am 
Arnie Coro, radio amateur CO2KK , and it is my pleasure to begin another 
year during which Dxers Unlimited will be on the air, as always at the 
service of radio hobby enthusiasts , people like you and I who enjoy 
this wonderful way of spending our spare time.
Now here is our first item of today’s program, it’s certainly very 
important news, that I am sure is going to make everyone really happy… 
It’s news we were all waiting for ansiously… finally, it has happened, 
93 million miles away from Earth, the long awaited first reverse 
magnetic polarity high latitude sunspot group has appeared, signaling 
the start of solar cycle 24 !!!
Yes amigos, the Sun made headlines as
SOLAR CYCLE 24 BEGINS: Solar physicists have been waiting for the 
appearance of a reversed-polarity sunspot to signal the start of the 
next solar cycle. The wait is over. January the third a  magnetically 
reversed sunspot emerged at solar latitude 30 N,, and that amigos is 
what we were all waiting for …this is an almost one hundred percent 
assurance that the new cycle has now started, but let me add that the 
solar maximum for this new cycle is still several years away…
The magnetic configuration of bipolar sunspots with leading 
positive/negative polarity in the northern/southern hemisphere, is 
associated with solar cycle 23. According to what is known as the 
butterfly rule, the new high latitude sunspot region belongs to cycle 
24. It was named active region 10981 or just 981 for all practical 
purposes.
New solar cycles always begin with a high-latitude, reversed polarity 
sunspot, according to solar scientists."Reversed magnetic polarity " 
means a sunspot with opposite magnetic polarity compared to sunspots 
from the previous solar cycle. "High-latitude" refers to the sun's grid 
of latitude and longitude. Old cycle spots congregate near the sun's 
equator. New cycle spots appear higher, around 25 or 30 degrees latitude.
The region that appeared on Dec. 11th fitted both these criteria. It was 
high latitude (24 degrees N) and magnetically reversed. Just one 
problem: There wass no sunspot. That  region was just a bright knot of 
magnetic fields. If, however, these fields coalesced into a dark 
sunspot, scientists were ready to announce that Solar Cycle 24 had 
officially begun, something they could not do, as no sunspot appeared 
there, but things changed radically  early during 2008, when a real true 
active sunspot region was spotted by optical observations around the 
world. The new sunspot active region 981, at approximately 30 degrees 
latitude is a perfect match for all the criteria about the start up of a 
new solar cycle, so amigos, solar cycle 24 is now here with us. Now let 
me add that during the next several months sunspots from both cycles 
will be seen, those at high solar latitudes will be from cycle 24 and 
the ones near the solar equator will be the last ones from now coming to 
an end cycle 23…
As more sunspots from cycle 24 appear, we may see an upward swing in the 
daily solar flux, and that should improve shortwave propagation all 
along 2008.
Si amigos, yes my friends, oui mes amis… Cycle 24 is here and we are 
certainly happy that it finnally started !!! I’ll be back in just a few 
seconds after a short break for station ID. I am Arnie Coro in Havana…
…………….
You are listening to Radio Havana Cuba, the name of the show is Dxers 
Unlimited and here is item two of today’s program…Our antenna topics 
section will be devoted today to a special type of short wave antenna 
systems that are especially designed to provide short range ionospheric 
communications, using the so-called Near Vertical Incidence Skywave or 
NVIS propagation mode. NVIS antennas are very important for emergency 
communications systems, that use it when other systems suffer damages 
that reduce their traffic handling capacity or simply take them off the 
air. NVIS communications stations can be deployed anywhere and even one 
single individual is capable of setting up such a station in less than 
an hour, using low height wire antennas. Today, here at Dxers 
Unlimited’s antenna topics section we will be describing to you some of 
the most efficient NVIS antennas that have been used here in Cuba during 
tropical storms and hurricanes related emergencies, achieving a very 
high degree of reliability. The amateur bands used for NVIS systems here 
are 40 meters during the local daytime hours and 80 meters at night. The 
typical NVIS antenna is a half wave dipole installed at a very low 
height above the ground, so that the signal sent out by the antenna goes 
almost straight up at angles between 45 and 90 degrees. The signals come 
back to Earth with high intensity at distances from practically zero to 
around 700 kilometers around the transmitting station when the degree of 
ionization is at an adequate level. One interesting fact about NVIS 
communications is that they work quite well at rather low power levels, 
making possible for field stations to communicate using power outputs in 
the 10 to 100 Watt range. Base stations usually run higher power levels, 
but need to use the same type of low height antennas in order to assure 
that they are using the Near Vertical Incidence Skywave propagation 
mode. Another type of antenna recommended for these EMCOMMS or emergency 
communications stations is a full wave loop that is also installed at 
very low heights above the ground. One of the big mistakes that is often 
seen during communications emergencies is that field stations try to 
establish the NVIS mode links using vertical whip antennas, something 
that will prove to be a fruitless effort. Vertical antennas radiate at 
very low take off or departure angles, so very little radio frequency 
energy goes straight up as required for the NVIS mode to work. A few 
days ago a group of radio amateurs started to work on a new compact 
antenna system , that is smaller in size than a half wave dipole, while 
at the same time still been very efficient on the NVIS mode. The wire 
antenna , in its 40 meters band version requires just 11 meters of 
horizontal space between the masts or support structures, and is off 
center fed with coaxial cable and a coaxial cable choke to suppress the 
common mode radiation from the outside of the coax shield. The new 
antenna was designed using up to date sophisticated antenna modelling 
software and I am going to start testing the prototype next week. As 
soon as the preliminary test results are available, as always, I will be 
very happy to share them with Dxers Unlimited’s listeners and readers 
around the world.
……
And now here LA NUMERO UNO, the number one most popular section of Dxers 
Unlimited, here at the first 2008 edition of the program, YOU have 
questions and Arnie tries to answer them… Today’s question was sent by 
listener Mark in Ontario, Canada, and he wants to know more about low 
cost amateur radio equipment, because he tells me that he is on a 
shoestring budget, but nevertheless wants to start his own ham radio 
station. Well amigo Mark, not too long ago I made an attempt to create a 
low budget HF or short wave ham radio station, and after a few days , I 
was pretty happy with the results… Instead of trying to homebrew a 
sophisticated transceiver, my option uses a portable solid state short 
wave receiver that has a built in BFO or beat frequency oscillator. In 
my case the radio used for the project is a Sony ICF-7600-G portable, 
that is powered from four 1.5 volts penlight cells. The low cost ham 
station project includes a bandpass input filter and attenuator , with 
the transmit- receive switching incorporated into it, the 10 to 25 Watts 
power output solid state transmitter, and the AC power supply . No 
attempt was made to make anything miniature, in order to simplify the 
homebrewing. The Sony ICF7600-G is used with communications type 
earphones, and let me add that this is a CW , that is radiotelegraphy 
mode station, but a further development may turn it into a double side 
band voice station in the near future. The switching between receive and 
transmit is done while providing full protection to the front end of the 
portable receiver, and you can monitor the output of the transmitter by 
listening to the signal on the earphones. The whole station can be used 
for fully portable operation with a gell cell accumulator , that 
provides twelve volts DC to the transmitter, and 6 volts for the radio 
trough a simple one integrated circuit voltage regulator circuit. By 
using the SONY ICF-7600-G portable with its BFO, or any similar 
receiver, the low cost CW amateur station’s construction is simplified 
in a very significant way , because homebrewing a high quality digital 
readout receiver is quite a challenge, even for experienced radio 
amateurs. Assembling the bandpass input filter and RF attenuator and the 
transmit receive switching, the CW transmitter and the AC power supply 
while not a simple task is much more within the possibilities of 
homebrewers that are familiar with electronics and that can always 
obtain help from more experienced radio amateurs of your radio club. So 
amigo Mark, I have already e-mailed to you the block diagrams of this 
unique low cost amateur radio station project, as well as the circuit 
diagrams and some notes about the CW transmitter, the bandpass input 
filter and the transmit-receive switching system. This station is now on 
the air at CO2KK, operating on two bands, 40 and 20 meters with good 
results, despite the prevailing HF propagation conditions due to the 
extremely low solar activity. It like amigo Mark you are interested in 
learning more about this low cost approach ham radio station, just drop 
me an e-mail to arnie@xxxxxx, and I will send you the dot zip file with 
all the information required to duplicate this project.
……
And now amigos, as always at the end of the show, here is Arnie Coro’s 
Dxers Unlimited HF propagation update and forecast … Solar flux is at a 
rather low 80 units, and the K index, the three hourly geomagnetic 
disturbance indicator was at a rather high figure of 5 early morning 
Saturday my local time here in Havana, at 12 hours UTC. This is due to 
the effects of a high speed solar wind that will disrupt HF propagation 
at high latitudes during the next two days. The winter Sporadic E season 
is now coming to an end, and we will have to wait until late April for 
the spring summer E skip season to start. The effective sunspot number 
is 20, and the daily sunspot number is now 20… See you all at the 
midweek edition of the program amigos… Send your signal reports, QSL 
requests and radio hobby related questions to arnie@xxxxxx or VIA AIR 
MAIL to Arnie Coro Radio Havana Cuba, Havana, Cuba


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