Dxers Unlimited
Dxers Unlimited's weekend edition for 30 - 31 August 2003




Hi amigos radioaficionados ... welcome to the weekend edition of your favorite listener oriented
radio hobby program... I am Arnie Coro, radio amateur CO2KK your host here in Havana, and as always
its my pleasure to share with you about seventeen minutes of on the air and on the web showtime ...
YES, you can listen to our live audio stream from www.radiohc.cu ! again, our URL is www.radiohc.cu,
and now here is item one for today: September just around the corner, and according to solar
scientists we are going to see a significant increase in propagation disturbances due to the
particular position of the Earth at this time of the year combining with the still active solar
cycle... Aurora Borealis events will be happening much more frequently, so be ready for them if you
live at latitudes above 40 degrees North ...Item two: 11760 khz making it nicely to the Toronto ,
Canada area according to a very nice report sent by our good friend Bob Chandler a member of the
Ontario DX Association and the QRZ Column editor for Listening Inn magazine... Bob tells me in his
e-mail that the new transmitter has nice audio and that the signal level is quite good there at
around 0200 UTC... that's 10 pm in the evening their local time in Toronto. By the way , we are
testing 11760 kiloHertz from 0500 to 0700 UTC with our regular English language broadcast, in
parallel with 9820 and 9550 kiloHertz... Item three: Especially shielded computers , designed so
that they will produce minimum radio frequency interference , cost a lot of money, but they are
required by many professional users. For example, sophisticated command, control and communications
centers that are so dependent nowadays on the use of computers, have found out that standard run of
the mill personal computers, the popular PCs are not suited for the job, as they may interfere,
sometimes at the most critical moments, with the radios used to handle emergency traffic... More
about shielded computers, and how you can learn from what it's done to reduce the radio frequency
energy leaking from the machines , later in today's edition of Dxers Unlmited : Item four, our
popular ASK ARNIE section of Dxers Unlimited will be answering today a question sent in by a
listener in Florida, USA... Gary wants to know what's the best frequency or frequencies to pick up
planet JUPITER radio signals, as he wants to show to his high school students how JUPITER can be
heard on the radio... I will also answer another question from a listener in northern Mexico,
Gabriel , wants to know about the possibilities of producing an artificial ionosphere...And at
always at the end of the program, have your notepad and or taperecorder at hand for picking up Arnie
Coro's Dxers Unlimited's HF plus low band VHF propagation update and forecast... Jose Izquierdo is
my sound engineer today, stay tuned as the program continues in just a few seconds...

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arnie@rhc.cu, again, let me repeat it slowly, that's my direct e-mail address, arnie@rhc.cu, the one
I check many times each day in order to keep in touch with Dxers Unlimited's worldwide audience...
YES, its certainly nice to receive so many e-mail messages from all around the world telling me both
what you like and what you don't like about the show amigos ¡.... And now here is item three:
Totally shielded computers and monitors... yes, they do exist and they do cost a lot of money...
totally shielded machines , with special interfacing interconnecting cables, power supplies that
have a lot of radio frequency suppresion devices inside and monitors that are built into steel cases
instead of plastic, are mandatory at many specialized applications. Command, control and
communications centers are the number one clients for those especially built machines... as I said
they do cost a lot of money, because among other things they are not mass produced... BUT, we can
learn from those especially shielded computers... for example, I found out that now practically all
of those special machines come with solid state displays, flat panel screens that operate using low
voltages and don't require the dreadful sawtooth high voltage waveforms that generate such terrible
radio noise. I also inspected several of those specially built machines and found out that the
keyboards, yes the keyboards are also especially built, and instead of a plastic case, they are
embedded into a steel casing... And last but not least, the cables connecting the machine to the
power line go first trough special radio frequency filters, that are also used to prevent radio
frequency leaking from the keyboard connecting cable... Infra-red light is used for the mouse, and
the motherboards are selected so that they don't have oscillators that operate on certain specific
frequencies.

Si amigos, you want a computer right next to your radios... among other things to keep a nice log
with a logbook software program of your choice, and also to enjoy the myriad of digital
communications modes, without forgetting about the wonderful propagation predictions that can be
made in just a couple of minutes with a computer... BUT at the same time , you don't want that
machine to generate S9 PLUS noise all over the spectrum, and that's why we can all benefit from the
noise reduction technology for computers developed for those specialized applications... At CO2KK my
amateur radio station, I achieved a rather significant reduction in noise level, by just installing
four ferrite split core chokes... two for the keyboard to desktop computer cable, one for the mouse
and another one for the monitor's video cable... By the way , the monitor video cable already had on
ferrite toroid choke built in,but adding the second one reduced the noise level , so I just kept it
right at the connector that sends the video from the desktop machine to the monitor...

Older machines, the ones that are now going into retirement , are ideal for radio hobby
applications... even rather slow by today standards computers will provide valuable service at your
amateur radio station or short wave listening post !!! By adding just a few easy to install radio
frequency noise suppresion devices, you can certainly improve the compatibility between your
computer and your radios amigos !!!

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This is Dxers Unlimited's weekend edition coming to you on the air and on the web... you can also
read our scripts at www.radiohc.cu, go to English and then to Dxers to read the latest script posted
there... Now amigos here is our popular ASK ARNIE,the section of Dxers Unlimited that answers your
radio hobby related question NO MATTER WHAT DIFFICULT THEY MAY BE... Yes , this is Arnie's no matter
what difficult question you make gets answered part of the program, and remember that there are more
than 70 ways you and I can enjoy this wonderful hobby: RADIO... Question one for today, came from
nearby Florida, listener Gary wants to know the best frequency to pick up Planet Jupiter's radio
signals.... Well amigo JOVIAN RADIO ASTRONOMY, is made possible by the super high energy radio
transmissions originating from Planet Jupiter... they are natural radio signals, and they can best
be picked up with simple equipment from about 18 to 40 megaHertz, with a very nice area in the 20 to
22 megaHertz region of the short wave spectrum. JOVIAN RADIO ASTRONOMY is practiced by a small group
of enthusiasts, that even build their own receivers and antennas for picking up those signals, that
when heard trough earphones of loudspeakers sound to me like waves washing ashore at the beach..
Jupiter signals will show a peak next October according to astronomers, so if you really want to
start planetary radio astronomy work as amigo Gary in Florida, there is not much time to get
ready.... An array of two phased dipoles, or a two to four element Yagi antenna is enough to pick up
Jupiter, and if you use sophisticated digital signal processing software and a computer sound card,
your observations can make significant contributions to radio astronomy ...Do remember that the
world's first full time radio astronomer was a radio amateur, an American by the name of Grote
Reber, who designed and built the first parabolic radio telescope !!! So amigo Gary, do a nice
INTERNET Search Engines sweep and learn more about JOVIAN RADIO ASTRONOMY , one of the more than 70
ways to enjoy playing with your radios !!! Now today's number two question.. Miguel from Baja
California, where he listens every day to RHC on 9820 Kilohertz, send this question to ASK ARNIE...
Miguel wants to know if an artificial ionosphere can be produced by man... Well amigo Miguel, there
are two ways to do it,and both seem to me quite aggressive to mother Nature... One is the horrendous
ionospheric heaters using high power radio transmitters coupled to high gain vertical incidence
antennas in order to heat up the ionosphere and generate more free electrons... Experiments have
shown that it is technically possible to heat the ionosphere to such an extent so as to produce a
localized area where free electron concentration will reach very high levels... Concerned scientists
have warned against such experiments, as no one really knows the possible consequences of the
artificial heating of the ionosphere to enhance its radio refractive properties... The other , also
very aggressive to the environment technology, is launching into the ionosphere certain chemicals or
even copper needles in order to increase the maximum useable frequency reached at a certain
location... Chemicals interact with the rarified gases above the Earth, and again, no one really
knows what possible consequences this may have... So amigo Miguel, the answer is YES, it has been
done, the ionospheric heating experiments and the launching of chemical into the ionosphere using
rockets are the two ways that I know by means an artificial ionosphere of sorts can be produced, and
as I said, both ways are terrible to the environment to say the least !!!

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And now amigos, as always at the end of the show, here is Arnie Coro's HF plus low band VHF
propagation forecast..... Solar flux hovering around 120 units, and as a matter of fact rather
stable ... On Monday UTC day we may see the K index go up , and later the sum of the days eight K
index figures show a significant increase due to a high speed solar wind expected to impact the
Earth's magnetosphere. Propagation conditions continue to improve as compared to those we had during
the middle of this summer, and the trend should continue as we approach the autoumn equinox in about
three weeks from now... Late night local time reception in the region of the spectrum between 12 and
18 megaHertz should bring in some interesting DX...See you all next Tuesday and Wednesday UTC days
at the mid week edition of your favorite radio hobby program, Dxers Unlimited with Arnie Coro