Dxers Unlimited
Dxers Unlimited's midweek edition for 9-10 March
2004
By Arnie Coro
radio amateur CO2KK
Hi amigos radioamateurs and shortwave listeners around the world. This is the
midweek edition of Dxers Unlimited coming to you from Havana. I am Arnie Coro,
radio amateur CO2KK, the host of this twice weekly program devoted to the
promotion and development of our wonderful hobby ... radio, the one and only you
and I can enjoy in more than 77 different ways... from homebrewing simple radios
like a two transistor plus one diode AM broadcast band receiver to designing and
building an Earth-Moon -Earth antenna array with no less than 12 long Yagis...Si
amigos, this is a most enjoyable hobby and now that the spring equinox here in
our northern hemisphere is just around the corner we are seeing some very
interesting propagation conditions that provide lots of DX even for radio
amateurs running low power and simple antennas... Now here is item one. Solar
flux moving slowly up and the A index, the planetary geomagnetic disturbance
indicator is at a rather nice and low level... Item two: results obtained with
the MICRO VERT simple antenna have surprised many of those who have built it ...
another simple antenna that also brings nice results despite its simplicity of
construction is the BOBTAIL curtain, an antenna especially useful for long haul
DX as it has a very low take off angle even at low heights. You will need quite
some space to install a three element BOBTAIL, but its smaller counterpart , the
HALF SQUARE will also provide rather outstanding results. A HALF SQUARE built
for the 10 meter amateur band using just wire and dacron fishing lines for
insulators is extremely easy to homebrew ... a similar antenna for the two meter
band is my favorite choice for accesing repeaters located in opposite
direction.Item three: Comments from listener Micheal Semon regarding variable
reception with deep fading and sometimes the signal just vannishing is quite
characteristic of short paths on frequencies above 6 megaHertz... That's the
reason why he can copy all day long the Radio
Rebelde station on 5025 kiloHertz, on the 60 meters Tropical Band , while our 6
and 9 megaHertz frequencies are sometimes difficult to copy at his QTH in
Florida when HF conditions are not too good. Item four of today's Dxers
Unlimited will be dealing with the HALF SQUARE antenna, Item five: Dxers
Unlimited's update on recent developments of the Cuban broadcast system: Item
five:
You already guessed it's going to be YOU HAVE QUESTIONS, and Arnie tries to
answer them section of the show, while Item 6 will bring Dxers Unlimited's
midweek edition to its end.
Standby for more radio hobby related information... on the air and on the web in
a few seconds..
.....
This is the midweek edition of Dxers Unlimited amigos, and here is our ANTENNA
TOPICS section of the program...today providing you with information about the
HALF SQUARE single band wire antenna. If you have space for just one horizontal
half wave dipole antena , my advice is not to install such antenna , and instead
try to use up the horizontal space to install a vertically polarized DX antenna,
the HALF SQUARE. My 20 meter band HALF SQUARE fed directly with RG213 coaxial
cable has proven to be anywhere between one and three S units above the half
wave wire dipole that it replaced.
The reason why the HALF SQUARE has proven to be so effective fo working DX , is
the fact that even at low height above the sorrounding terrain, the HALF SQUARE
sends out a low take off angle signal... in other words the HALF SQUARE will be
much more useful for Dxing than a half wave wire dipole, or even a two element
Yagi installed at low height.
Another important advantage of the HALF SQUARE is that it is vertically
polarized, something that produces much less interference than what is generated
by the use of any type of horizontally polarized antenna. The "wrong
polarization"has an outstanding effect in reducing TVI or television
interference... The TV signal reaching a TV set is horizontally polarized, and
that's why many newcomers to amateur radio are using the HALF SQUARE, a
vertically polarized antenna that will attenuate the horizontaly polarized
signal by as much between 100 and 1000 times, and that in turn will solve many
TVI problems .
There is something that you must know about both the HALF SQUARE and the BOBTAIL
vertical curtains, and that is the fact thay they are by design, single band
antennas.As my good friend Bob Chandler from the Ontario DX Association is one
of the most enthusiastic users of HALF SQUARE antennas for his CQ Zone 2 Contest
Stations way up north in Canada, I want to quote him here today...Bob told me
after a very succesful contest station operation using the HALF SQUARES that
they provided extremely good performance and could be transported very easily.
The Canadian contest team used PVC pipe masts that are both lightweight and
transparent to radio frequency energy, so that they don't distort the antenna's
radiation pattern.
Here in Havana, I am using a 2 meter band version of the HALF SQUARE to solve a
problem.
We have two long range mountaintop repeaters, one to the West and the other one
to the East of the Havana metropolitan area...With the HALF SQUARE I can reach
both of them with about 4 dB gain , providing excellent communication while
running only one Watt on my 2 meter band handie talkie... If you need more
information about both the BOBTAIL three element and the HALF SQUARE two element
vertical arrays , go to http://www.cebik.com
the wonderful website created by Dr. L.B. Cebik Ph D , amateur radio operator
W4RNL, who has made available to the world's amateur radio enthusiasts an
incredible collection of antenna information... again the URL is
http://www.cebik.com
.....
Si amigos, we are working hard here to improve the quality and reliability of
Cuba's broadcasting service on short wave, AM , FM and Television. RadioCuba,
the totally state owned company that is in charge of the transmitters is now
well advanced into the installation of new AM, FM and TV transmitters all along
the Cuban archipelago. At the Isle of Youth, Radio Caribe is now with a new 5
kiloWatt AM transmitter operating on 1220 kiloHertz and RadioCuba engineers also
installed an FM transmitter there operating on 101.7 megHertz with 3 kiloWatts
effective radiated power, more than enough to cover the Isle of Youth and the
adjacent Cayo Largo tourist resort. At the same time, the Cuban Broadcast
Institute implemented a modernization plan at the Radio Caribe studios using
digital technology. The Radio Caribe studios are linked to the FM transmitter
using a digital UHF link, and soon the analog UHF link to the AM site will be
replaced by a new digital one too. Similar projects are in progress all along
the Cuban archipelago, like for example in Matanzas province, east of Havana,
where the old Radio Rebelde 30 kiloWatt Tesla transmitter that I helped to
install in 1963 was replaced by a new solid state 25 kiloWatt transmitter
capable of up to 140 percent positive peak modulation. Radio Rebelde's Matanzas
relay is operating on 620 kiloHertz , while at the same site, a new Radio Reloj
network also solid state transmitter is running 5 kiloWatts on 860 kiloHertz,
improving the coverage of that news and information broadcast service.
Cuba's fourth national TV network transmitters are now also being installed and
it is expected that the fourth national TV program service will soon be on the
air.
Now,here is item five: The popular you have questions and Arnie tries to answer
them... You can send your questions to
arnie@rhc.cu , and the answer will go right back to your mailbox pretty
fast... Here is today's question: It was sent by listener Kate in Vancouver...
She says that now she is having some difficulty copying the 9820 kiloHertz
English language broadcast from Radio Havana Cuba... Well amiga Kate, I ran
several computer software programs used here to calculate the frequencies that
should be used for a given part of the world, solar activity etc. and sure, you
are right, each time a geomagnetic disturbance caused by the now so frequent
coronal holes is in progress, reception of our 9820 kiloHertz in Vancouver
should be rather difficult, especially when the antenna is not beaming in your
direction. Let me remind you and other Radio Havana Cuba listeners located along
the Pacific Coast of North America, that we beam into that area from 05 to 07
UTC ... If you are able to listen to us from 01 to 04 hours UTC , then you are
actually picking up the beam that is centered on the Great Lakes Region of North
America, so the signal intensity at that time in Vancouver should not be very
strong...
Maybe soon we will be able to broadcast on one more frequency , so that at the
same time we may be beaming both the Great Lakes Region on one frequency
and the Pacific Coast using another frequency
Today's second question, came from South Africa, where several listeners are
reporting our 11760 kiloHertz English language broadcast... Amigo Alex
from Cape Town wants to know if I have heard about a new version of the BAYLISS
crank up generator that is capable of providing power to a radio for periods
lasting up to two hours.
Well amigo Alex, I have seen and actually tested several models of AM, FM and
SHORT WAVE radios that use the crank-up Bayliss generator for powering up
the receiver by cranking up for about 30 seconds to make the radio play for
about half and hour. By the way , for those of you that have not heard about the
BAYLISS crank-up generator, let me explain that it was invented by a South
African and is now becoming extremely popular not only for powering radios, but
also for many other applications where expensive batteries may be replaced by
this unique system. The BAYLISS Direct Current crank up generator is a very
reliable source of electricity for powering up radios during emergencies !!!
And now amigos, as always at the end of the program , here is Arnie Coro's Dxers
Unlimited's HF propagation update and forecast .Solar flux is now hovering
around 110 units, and it is expected that starting tomorrow March the tenth, the
Earth will be entering into a stream of high speed solar wind coming from a
coronal hole located at a geoeffective position, and this in other words means
that propagation conditions will take a downward turn for the next two to three
days,especially a latitudes above 40 degrees North. Very slight chances of
sporadic E openings at this moment, while chances for tropospheric ducting are
increasing especially all along th Gulf of Mexico region. I hope to see you all
at the weekend edition of the program amigos , and don't forget to send me an
e-mail with your comments about the program, as they do help make a better Dxers
Unlimited for you all !!!
