[HCDX] RE; Dxers Unlimited´s mid week edition for 18-19 March 2008

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

Radio Havana Cuba

Dxers Unlimited

Dxers Unlimited´s midweek edition 18- 19 March 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 NO CORONAL HOLES, 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 to save the lives of people 
aboard a sinking boat via amateur radio, to enjoying the beautiful sight 
of a valley below a TV tower where you have climbed to install a new ham 
radio repeater for your radio club, or perhaps you may 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 placing small 
electronic components to circuit boards in your quest towards a new 
receiver, or simply desolder parts from old circuit boards removed from 
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 83 and for sure, there are many more to be 
explored.

Item two: A broken down, or an obsolete cellphone can be the source of 
two highly valuable devices… a nice high quality electret microphone 
element, and an also high quality optimized for voice communications 
earphone… So, don´t throw away the old analog cellphones before removing 
the microphone element and the earphone capsule… My amateur radio two 
meters band handie talkie now has a much better microphone element than 
the original one, thanks to that simple surgical electronic transplant 
operation… it took 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, telling me that 
the Nokia microphone element from the cellphone was a much better 
quality mike 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…

Item three: Radio hobby related questions keep coming in to arnie at rhc 
dot cu on a daily basis, they add up, and now I have a big backlog … 
that I hope to be able to catch up with during the weekend… In the 
meantime , here is the answer to a question sent in several different 
forms by nine listeners from places so far apart as South Africa and 
Australia, and as near to Cuba as the Bahamas, that by the way, is the 
closest to Cuba nation… because 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…The question 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 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.

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.

Let´s start with the medium sized FAN DIPOLE, that according to letters 
and e-mail messages received from Dxers Unlimited´s listeners around the 
world, is the one most feasible to homebrew and install… It is made of 
number 12 bare copper 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. 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 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…

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 !!! As the spring equinox 
approaches, 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 
getting ready for the upcoming Atlantic and Caribbean Tropical Hurricane 
Season, due to start on the first day of June. Among the many 
preparations in progress are reinforcing some of our two meters band 
repeaters antenna systems, so that they can be able to survive to more 
than 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… Be ready for the first nice equinoctial DX openings on the 17, 
15, 12 and 10 meters amateur bands…They will be starting during this 
week, so they 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… 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 anywhere to be seen, but again, the equinoctial 
DX will be here for us to enjoy despite the very low solar activity… 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 my 
friends !!!


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