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Re: [HCDX] Dxers Unlimited's mid week edition for 27-28 November 2007
Dxers Unlimited
Dxers Unlimited's midweek edition for 27-28 November 2007
By Arnie Coro
radio amateur CO2KK
Hi amigos radioaficionados 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 81
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 16 long 17 elements
Yagis...Si amigos, this is a most enjoyable hobby and now that the
winter DX season is in full swing here in our northern hemisphere r we
are seeing some very interesting propagation conditions that provide
lots of DX even for radio amateurs running low power and simple
antennas...And this is happening despite the very low solar activity
that has prevailed from many weeks now. Here is item one. Solar flux at
rock bottom lvels while 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 above ground. 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 or 15 meters
amateur bands 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 Miguel 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 for 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 a similar 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 asn 100 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 125 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 on the air too.
Now,here is item five: The popular you have questions and Arnie tries to
answer them...
You can send your questions to arnie@xxxxxx , 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 6000 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 6000
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 05 hours UTC , then you are actually
picking up the beam that is centered on Eastern 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 to Eastern North America, the Great
Lakes Region on two frequencies 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 72 units, and it is expected to continue at very
low levels, optical sunspot count near ZERO and now the effects from a
coronal hole that was located at a geoeffective position have ended,
and this in other words means that propagation conditions will be a
little better 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 !!!
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