Dxers Unlimited
Dxers Unlimited's weekend edition for 5-6 April 2003

By Arnie Coro

CO2KK

Hi amigos radioaficionados ! Yes !!! Your radio is tuned to Radio Havana Cuba's twice weekly radio
hobby program, the one and only with the most up to date short wave propagation updates and
forecasts... and By the Way ... propagation is rather disturbed right now, so if you notice poor
reception , it is certainly a consequence of the effects of high speed solar wind impacting upon the
Earth's magnetosphere... Item two: Radio is a lot of fun, and you can become part of more of it by
exploring the different ways that you and I can enjoy the hobby.. for example, normally few
international broadcasts short wave listeners are aware of the fact that radios capable of receiving
single side band signals will open up a completely new world for them. That's why I insist on the
fact that when you are ready to upgrade to a better radio receiver, ALWAYS, and I mean it amigos,
ALWAYS go for a radio that has a beat frequency oscillator and a product detector, so that you can
listen not only to CW Morse Code amateur radio communications, but also to Single Side Band voice,
and pick up , with the help of your computer some of the very interesting digital communications
modes. Are you ready to UPGRADE to a better radio ? OK, sure, go ahead, but don't dispose of your
present receiver amigos... because owning two radios will allow you to enjoy the hobby a lot
more.... For example, you can be taping a program on one radio, for listening to it later, and then
continue to explore a specific band for DX at the same time. Some hobbyists have more than 2 or 3
radios, usually devoting one of them for portable work when traveling.

Item three: One of the problems that homebrewers of radios have to deal with is how to find the
parts , the electronic components to make them, YES, its becoming more difficult , but keep listen
to Dxers Unlimited's weekend edition and I will be telling you how to find lots of parts to be able
to complete your electronic projects . Item four: Our very popular YOU have Questions and Arnie
tries to answer them, a fast tract way of solving your radio hobby related

problems... send your questions to arnie@rhc.cu, and also via e-mail Arnie Coro, Radio Havana Cuba,
Havana, Cuba. Then as always at the end of the program, you will be able to hear our exclusive and
not copyrighted , in the public domain, HF plus 50 megaHertz propagation update and forecast.
Margarita Delgado is my sound engineer and producer, I am Arnie Coro in Havana, stay tuned, Dxers
Unlimited will continue in just a few seconds.

.........

You are listening to the weekend edition of your favorite radio hobby program, coming to you from
Radio Havana Cuba, and here is now you have questions and Arnie tries to answer them... Today's
question comes from several listeners, from as far apart locations as Argentina and Norway !!! The
seven of them happen to be amateur radio operators, and they all want to hear yours truly opinion
about the HALF SQUARE antenna . The seven of them are Dxers, and they are looking forward to the
upcoming extended period of low and very low solar activity expected to last until at least the year
2008 !!!. Well amigos, once again I must declare myself as n advocate of the HALF SQUARE antenna
array, even though, I must emphasize that it is a SINGLE BAND ANTENNA ... Among the many advantages
I see for the HALF SQUARE, is the fact that it is a low cost antenna that will provide the all
important LOW TAKE OFF ANGLE essential for working DX. My experiments with HALF SQUARE antennas have
gone from the 2 meter band all the way up to 20 meters, and I have not tested

on the lower frequencies, because the HALF SQUARE antennas for the 40 and 80 meter bands need rather
tall masts that I don't have available at my home QTH. Anyway, the answer to your question amigos
!!! SURE, go ahead, try the HALF SQUARE, but be careful with the way you feed the antenna, as you
should avoid feedline radiation, and the only way to achieve this is to install a coaxial choke
balun right at the feedpoint. For those of you not familiar with the coaxial choke balun, it is a
very simple way of canceling the radiation from the outside of the shield of the cable by coiling no
less than six turns of the coaxial cable with a diameter that will depend on the operating
frequency. For the typical 20 to 10 meter bands HALF SQUARE, the coaxial cable coil diameter should
be about 20 centimeters or 10 inches, and it is not really critical. The HALF SQUARE antenna
radiates on two main lobes,and this you must take into consideration, because you will want to
install the antenna favoring the most wanted directions. Or you can do what I did with my 6 meter
band HALF SQUARES, just install two of them with a switch , so that I may cover DX signals from all
compass headings !!! The HALF SQUARE is easy to build, and also very easy to adjust, but again, I
must remind you that it is a single band antenna. Dxers at this stage of the solar cycle will like
to build HALF SQUARES for 20, 17 or15 meters,as the 12 and 10 meter bands are now much less active
due to the lower solar activity !!!

......

Amigos, you are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited, and this is
not the only show I do here... May I invite you to join me Sundays and Mondays UTC days or Thursdays
and Fridays UTC days at Breakthrough, our Science, Technology and the Environment update... a
program where you will learn about how Cuba is working to apply the most recent advances of science
and the technology to develop the nation, and also to protect the environment for the future
generations... You can visit our website at www.radiohc.cu and then go to the English page to pick
up our program schedule. There you will also find the Dxers Unlimited's WebPages, with the scripts
of the most recent shows for you to read... Now here is another of today's topics... how to find
parts for your radio hobby projects.. First of all, I recommend that you join a local radio club,
and learn about the many activities that radio clubs organize, including, of course, the fleamarkets
and hamfests... There at the hamfests you can have a good time, learn a lot about the radio hobby,
and explore the many items for sale that radio amateurs usually bring to the hamfest's fleamarkets.
For example, a Canadian friend told me recently in an e-mail that he had bought a plastic bag full
of transistors, no less than 500 of them for just two Canadian dollars... the transistors were a
very popular small signal type that could best be described as a sort of universal device, and that
bagfull will soon be landing here in Havana, as my friend has donated it to the Plaza Radio Club's
beginners project... Similarly you can find resistors, capacitors, printed circuit boards full of
highly valuable parts that can be desoldered and recycled very successfully... Another excellent
source of electronic components is recycling old computers of the first generations, as the newer
ones have such a high degree of integration that they are not worth the effort. Computer power
supplies have proven to be a treasure chest of parts for the parts required to assemble vacuum tube
radio's power supplies, as they are always high capacity high voltage electrolytics and silicon
rectifiers. My 150 volts DC standard power supply that provides all the needs of the popular
REGENERODYNE uses a lot of parts recycled from an old AT machine switched mode power supply... You
can also look around for old TV sets, fax machines, old radios, computer monitors... you name it !
But be especially careful when handling TV sets and computer monitors, as the cathode ray tubes are
really dangerous to work with when you are trying to remove the parts... In that case, don't attempt
to work with them if you are not fully aware of how to deal with the high vacuum picture tubes !!!
Si amigos, yes my friends, oui mes amis, you do need electronic components, nuts and bolts, fittings
, PC boards etc. to make your own radios , but they can be found at very low cost or even for free
it you know where to look !!!

............

Radio Havana Cuba will soon be celebrating its 42nd anniversary... And I am studying the possibility
of organizing a contest for Dxers Unlimited's listeners... The contest will be a lot of fun, and as
soon as I have the rules ready, you will be learning about it... The idea is to run the contest
during the whole month of May, so that everyone participating may have a good chance to win one of
the prizes !!! Now item four: A note about the HENTENNA that was pending from a recent show... The
HENTENNA , when used for horizontal polarization must be installed with the long sides of it in a
vertical position !!! Surprising as it may seem , that's the way to do it, and when using the
HENTENNA on 2 meters FM, do remember to install it so that the long sides of the rectangle are
parallel to the ground... It is something that is not so obvious, and that has caused that some
builders of the HENTENNA wondered what was happening , as the antenna did not seemed to work
properly ... and they thought that the antenna was not a good design... BUT, after twisting the
position of the antenna all around, the found out that it works really very well !!! So , again, be
aware that contrary to what you

may think , the HENTENNA is used horizontally for vertical polarization, that is , you place the
long sides of the HENTENNA parallel to the ground when working two meters FM that is vertically
polarized !!!

OK ! Now let me see if there is something else that is missing from today's menu...OK, I found it, I
wanted to mention the fact that SOLAR CORONAL HOLES receive designator codes too, like sunspot
active regions, and today in our HF propagation update and forecast you will hear ,for the first
time hear the designators of the CORONAL HOLES that are causing the recent geomagnetic disturbances
due to the ejection of charged particles from them that reach the Earth's magnetosphere... So now,
here it Arnie Coro's exclusive and not copyrighted HF plus 6 meters propagation update and forecast.

The geomagnetic field was expected to be quiet to minor storm on April 5 due to a high speed stream
from coronal hole CH29 and quiet to unsettled on April 6-7. Quiet to active is likely on April 8 as
a high speed stream from CH30 reaches Earth, with unsettled to minor storm conditions possible on
April 9-12 when the high speed stream from CH31 dominates the solar wind. Long distance medium wave
(AM) band propagation along east-west paths over high and upper middle latitudes is very poor,
propagation along north-south paths is poor to fair.

Solar activity is expected to be moderate for the next two days, dropping off to low when Region 324
(S11W40) makes its way off the visible disk.We may see some very interesting F2 layer anomalies
during the next five to seven days, all caused by the high speed solar wind. See you at the mid week
edition of Dxers Unlimited next Tuesday and Wednesday UTC days and don't forget to send me your
signal reports and comments about the show, as well as any radio hobby related questions you may
want to know about. send mail to arnie@rhc.cu, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba,
Havana, Cuba