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Re: [HCDX] Dxers Unlimited´s mid week edition 22-23 July 2008 VERY GOOD E SKIP OPENINGS HAPPENING !!!
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited´s midweek edition 22-23 July 2008
By Arnie Coro
Radio amateur CO2KK
Hi amigos radioaficionados, around the world and orbiting planet Earth…
ONCE AGAIN, with a zero sunspot count, and a very low solar flux of 66
units at 10.7 centimeters wavelength, I give you my welcome to the mid
week edition of Dxers Unlimited .I am Arnaldo, Arnie, Coro, radio
amateur CO2KK, your host here at this Radio Havana Cuba twice weekly
program, devoted entirely to the promotion and development of our
wonderful hobby , yours and mine: RADIO… a hobby we can enjoy in so many
different ways that they defy imagination… from having the unique
opportunity of helping, via amateur radio, to send an urgently required
pharmaceutical product, a medicine, to a remote place where a doctor
needs it to save the live of a patient by coordinating a flight via
amateur radio, to saving the lives of people stranded in a totally
flooded area , where the rescue helicopter was guided to also via an
amateur radio station…you can also have the pleasure of enjoying the
beautiful sight of a valley below a TV tower where you and another radio
amateur have climbed to install a new 2 meters band repeater for your
radio club, or perhaps you may , as it happens to me very often, be
fascinated by the beautiful music heard on the 60 meter Tropical
Broadcast Band coming from several African stations… Si amigos, yes my
friends, oui mes amis, radio is a really challenging hobby, where you
can relax following a circuit diagram and placing small electronic
components to circuit boards in your quest towards a new receiver, or
simply, as I did last evening , just sit down a desolder parts from an
old circuit board, just removed from an XT computer power supply, a
piece of electronic equipment that otherwise will go to the junk yard
and pollute the environment. So far , my list of the many ways we can
enjoy our radio hobby has grown up to 84 and for sure, there are many
more to be explored.
Item two: Yes, it is absolutely true, the top quality microphones used
by cellphone manufacturers are ideal for amateur radio use. A broken
down, or an obsolete cellphone is a low cost source of two highly
valuable devices… a nice high quality electret microphone element, and
an also high quality optimized for voice communications earphone… So,
follow your friend ARNIE CORO´S advice and don´t let your friends throw
away the old analog cellphones before removing the microphone element
and the earphone capsule…
For your information, my amateur radio two meters band handie talkie, a
recycled unit itsefl, now has a much better microphone element than the
original one, thanks to that simple surgical electronic transplant
operation…The microphone from a Nokia analog cellphone has proven to
receive much better audio reports than those that I got with my factory
installed handy talkie built in microphone, an it took just about an
hour to extract the analog Nokia cellphone microphone element and then
install it on the old 1991 vintage YAESU FT 411 two meters band handie
talkie… Reports received on the local 145.190 Havana Metropolitan Area
repeater were very encouraging, with several of my friends telling me
that the Nokia microphone element from the cellphone was sounding much
better than the original element used by YAESU… And of course that as
soon as I am able to get a hold of another broken down cellphone I will
use it to replace the active element on an very old 6 meters band
transceiver that has received some not very nice audio quality reports
recently…
Item three: Radio hobby related questions keep coming in to inforhc at
enet dot cu on a daily basis, they add up, and now, again, I have a huge
backlog … but don´t worry that I hope to be able to catch up with during
the upcoming long weekend here in Cuba… In the meantime , here is the
answer to a question sent in several different forms by listeners from
places from Italy, South Africa, Canada and Australia, and as near to
Cuba as the Jamaica, that by the way, is the third closest to Cuba
nation… The Bahamas Cayo Lobos, or Lobos Key that forms part of the
Bahamas archipelago is just 22 kilometers away from the northern coast
of Cuba across the Old Bahamas Channel, so Bahamas is our closest
neighbor…and Haiti is just 77 kilometers across the strait that
separates the island of La Hispaniola from Cuba. Jamaica is 140
kilometers south of Cuba, separated by the Strait of Colon, named to
honor Christopher Columbus… Si amigos, radio and geography go together
quite well, and my kids learned a lot of geography by locating the
countries where the stations that I talked to via amateur radio were
located. Well back to the question, that has appeared here a number of
times… it is about wideband receiving antennas that can be built and
installed by the average short wave listener that obviously is not a
radio engineer… So now, here is ASK ARNIE, the most popular section of
Dxers Unlimited, answering today, again, the question, which broadband
antenna design is the easiest to homebrew by the average short wave
listener…
Well I must say that the reply to this question has to be divided in two
parts: the first part is about the FAN BROADBAND ANTENNA, that is the
easiest of them all to homebrew, and the second part is about the
somewhat more complicated TTFD or Tilted Terminated Folded Dipole
Broadband antenna, so well researched by my good friend and topmost
antenna ¨¨guru¨ Professor L.B. Cebik , radio amateur W4RNL, who sadly
passed a way a few weeks ago.
So, let´s start with the FAN DIPOLE , after a short break for station
ID… stay right on this frequency or world wide web connection , as Dxers
Unlimited´s mid week edition continues in a few seconds… I am Arnie Coro
in Havana…
…..
Si amigos, you are listening to Radio Havana Cuba´s radio hobby program…
Now , as promised here is information on how to assemble and install
your own fan dipole antenna, one of the easiest to build broadband
systems for short wave reception.
In actual practice, I have tested and experimented with three different
sizes of FAN ANTENNAS… one, designed to work from 3 to 10 megaHertz, but
also capable of good performance up to around 20 or 22 megaHertz,
another one of a much more practical size that works nicely from 6 to 18
megaHertz and a compact, much smaller version that was designed during
the peak of solar cycle 23 for optimum performance between 15 and 45
megaHertz. As you may realize , these antennas cover a typical three to
one frequency ratio, but they will still provide rather good reception
on higher frequencies. Antenna engineers will tell you that ideally, the
professional fan dipoles are designed to cover a two to one frequency
ratio, but in actual practice, and using a well designed antenna tuner,
the frequency range covered can be extended to a three to one ratio, as
explained earlier during the program…
Now let me begin by describing the medium sized FAN DIPOLE, that
according to letters and e-mail messages received from Dxers Unlimited´s
listeners around the world, is the best compromise, the one most
feasible to homebrew and install… It is made of number 12 bare copper
antenna wire. You start by cutting six identical lengths of wire that
are 9 and a half meters long each… Each wire is attached at one end to a
high quality insulator, that you can even make yourself to save money
using high quality polyethilene plastic tubing. The FAN antenna is a
dipole, that has three wires on each side of the center insulator, that
is made from a heavy piece of polyethylene used as a kitchen cutting
board in its original application.
You will have to drill several holes to the polyethylene cutting board
in order to hold the six wires to it, and also to hold the antenna
feeder wires.
The wires forming each leg of the antenna spread out from the center
insulator so that at the end they are separated by one and a half meters
from each other ….
The antenna feedline is connected to each of the wires forming the
dipole, and my advice is to use a very easy to homebrew air dielectric
one to one balun or balanced to unbalanced transformer that will
interconnect the antenna to a coaxial cable feedline.
The overall length of the actual antenna is about 20 meters, including
the required insulated cords that hold the antenna wires to the two
support structures.
The actual antenna length is 18 meters, so it will operate as a dipole
with broadband characteristics between 6 and 18 megaHertz, allowing very
nice reception of the international short wave broadcast bands starting
at 49 meters, and going up to 41, 31,25, 22, 19 and 16 meters… So you
end up with an antenna that works very well for receiving the seven most
used international short wave broadcast band… But that´s not all amigos
!!! There are more good things about this FAN DIPOLE… it will allow
amateur radio operators to use if on 40, 30, 20, 17 ,15, 12 and 10
meters too…again on the seven most active short wave ham bands…
And because the antenna works so nicely from 6 to 18 megaHertz it will
make a very worthwhile addition to your communications utilities
monitoring station too.
The SIX WIRE FAN DIPOLE, is also a nice looking antenna system, that can
be installed easily by just two persons… Please don´t attempt to install
this antenna all by yourself, because it will be rather difficult due to
the many wires involved…
Keep in mind that antenna work can be dangerous, so you must be
extremely careful when doing it, and never work alone on your antenna
installation projects, use all safety precautions and keep well away
from nearby power lines. Also, stop immediately at any signs of a nearby
thunderstorm…
I remember many years ago, when I heard a thunder clap several seconds
after receiving a big electrical shock from the antenna wire I was
holding in my hands while another person was pulling up the antenna .
By the way , the air core balanced to unbalanced wide band transformer
is made on a length of white PVC pipe of twelve millimeters diameter to
which three interlaced wires are wound for a total of twelve turns… This
makes a very nice high performance low loss BALUN, that will cost next
to nothing…
For cable runs no longer than 15 to 20 meters you can use RG58 or RG59
coaxial cable, but if the antenna is located more than 20 meters away
from the shack,, it is a much better option to use LOWER LOSS RG213 50
ohms coaxial cable…
One final comment about this general purpose broadband short wave
antenna system… I have even used it, with the help of an antenna tuner,
to operate on the 6 meters or 50 megaHertz amateur band, and made
contacts with stations several thousand miles away from Havana !!!
There is no magic involved in the overall length of this antenna or in
the separation of the wires at the ends… just plain good sound radio
engineering , confirmed by actual highly reliable practical results… Of
the three FAN DIPOLE designs , the one just described is certainly the
most popular one, although the smaller more compact version has also
received good comments from Dxers Unlimited´s listeners that have built
it because they had no other choice due to lack of enough space to
install the 18 meters long version of the FAN ANTENNA…
If you need any help , or want to clarify something about this antenna
design, just send an e mail to arnie at rhc dot cu and I will be very
happy to reply as soon as possible… The better antennas you have, the
more you will always enjoy our hobby amigos !!! Installing a new short
wave antenna will be a very rewarding project amigos !!!
……
You are listening to the mid week edition of Dxers Unlimited, and here
is now our next item…it´s about amateur radio operators here in Cuba now
ready to provide ,whenever needed, emergency communications for the
ongoing Atlantic and Caribbean Tropical Hurricane Season. The season
began on the first day of June. Among the many preparations made this
year were reinforcing some of our two meters band repeaters antenna
systems, so that they can be able to survive to more than 120 or even
150 miles per hour winds. Antennas installed atop high towers that are
located high up in mountains or high raise buildings are always
subjected to extreme forces that can destroy them precisely at the time
that they are most needed, and that´s why our radio clubs are involved
in the building and installation of very rugged antennas for the two
meters band repeaters that play such an important role handling
emergency communications…
And now amigos at the end of the show, here is Arnie Coro´s exclusive
and not copyrighted HF plus low band VHF propagation update and
forecast…Solar flux at base level of 66 units, zero sunspots, and a high
speed solar wind is expected to disrupt HF propagation at higher
latitudes for several days. Be ready for more really good sporadic E
openings on the 17, 15, 12 , 10 and 6 meters amateur bands…The nice
strong E skip signals are a very good solid reason to keep your ham
radio transceivers on and tuning around the many beacons that provide
information about band openings, especially on 10 and 6 meters … If you
hear even just one single beacon, then it´s time to start calling CQ DX
and raise some activity on the band where the beacon is heard… Solar
flux still at very low levels and no signs of cycle 24 sunspots, … See
you all at the weekend edition of Dxers Unlimited next Saturday and
Sunday amigos !!! And don´t forget to send me an e-mail with your signal
reports and comments about the program, plus any radio hobby related
questions that you may want to ask, as always I am at your service here
my friends !!!
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