[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [HCDX] [SWL] RE: Dxers Unlimited´s mid week edition for 19-20 February 2008
I would like to express my personal thanks, as well as gratitude for all
list subscribers, to our amigo Arnie Coro for his tireless efforts on behalf
of the Short-Wave listeners who benefit from DXERS Unlimited. As a QTH.NET
list admin for over ten years, a totally voluntary role, I know how seldom
anyone remembers to say 'thank you'. So thanks Arnie!
Duane W8DBF
Duane Fischer, W8DBF/WPE8CXO
dfischer@xxxxxxxx
HHI: Halligan's Hallicrafters International
http://www.w9wze.net
HHRP: Historic Halligan Radio Project
hhrp.w9wze.net
----- Original Message -----
From: "Prof. Arnaldo Coro Antich" <inforhc@xxxxxxx>
To: <odxa@xxxxxxxxxxxxxxx>; "HCDX" <hard-core-dx@xxxxxxxxxxxxxxxx>; "Gayle
Van Horn" <gaylemt@xxxxxxxxxx>; <swl@xxxxxxxxxxxxxxx>; <k1zz@xxxxxxxx>
Sent: Tuesday, February 19, 2008 10:54 AM
Subject: [SWL] RE: Dxers Unlimited´s mid week edition for 19-20 February
2008
RADIO HAVANA CUBA
DXERS UNLIMITED
DXERS UNLIMITED´S MIDWEEK EDITION FOR 19-20 Feb 2008
BY ARNIE CORO
RADIO AMATEUR CO2KK
Hi amigos radioaficionados… you are, as always, welcome to the mid week
edition of this, your favorite radio hobby program, Dxers Unlimited, the
one and only covering practically all aspects of our wonderful hobby, from
what can best be described as classic short wave listening, to backyard
radio astronomy, from homebrewing your own radios to participating in one
of the really big amateur radio contests with your own station… Si amigos,
I am Arnie Coro, radio amateur CO2KK and here is our first item of today´s
program. ARRL CW contest that took place during the weekend provided many
radio amateurs around the world with a very nice opportunity of working
some really rare DX spots, like Ducie Island, VP6DX, one of the best run
DX expeditions that I have heard in a long time…. I wanted to participate,
but had a backlog of ¨honey do this, and honey do that¨¨ so it wasn´t
possible to spend some time sitting at the operating position of CO2KK my
ham radio station… As a very good friend of mine, Jose Angel Amador CO2JA
likes to say, if you really want to take part in an amateur radio contest,
the best option is to do it away from home… By the way, Jose Angel was the
pioneer of amateur satellite communications here in Cuba… and he is now a
senior professor ot telecommunications engineering at our main technical
university here in Havana, where he has helped several students to obtain
their ham radio licenses…
Item two: Digital communications continue to make possible nice two way
ham radio contacts using low power and simple antennas even at the very
low ebb of the solar cycle…
Amateur digital communications have also opened up the hobby to hard of
hearing or deaf persons, thatare now able to enjoy ham radio by going on
the air using modes like PSK31 and MFSK16 that provide full on screen text
and graphics plus complete control of the station without the operator
having to listen to any sound… Item three: Had a bad computer crash at my
home QTH…so for the past several days I have had to work with a borrowed
machine, and so far the e-mail address book is still inside the broken
computer, that just refuses to produce a video output despite all my
efforts, including installing a plug in video card without any success…
SO my apologies to Dxers Unlimited´s listeners that had written e-mail
messages that I could not answer before the computer broke down… I am
planning to disassemble the broken computer and extract the hard drive to
so that the e-mail address book can be recovered…
More radio hobby related information coming up in a few seconds , when the
mid week edition of Dxers Unlimited will continue here in a few seconds… I
am Arnie Coro, radio amateur CO2KK in Havana… stay tuned…
…………………
Si amigos , you are listening to RADIO HAVANA CUBA, the name of the show
is Dxers Unlimited, and now here is item four of our program.. It is our
popular Technical Topics section that today will be dealing with yet
another version of a short dipole antenna for the 40 meters band… This was
one was created by a British radio amateur, GM4JMU and can be easily
homebrewed using readily available materials.
The overall length of this shortened 40 meter dipole is practically the
same as a 20 meters band half wave dipole,and it has proven to be pretty
effective in actual operation. A Cuban radio amateur friend built this
GM4JMU antenna and simply connected it in parallel with his existing half
wave 20 meter band dipole, so he very easily was able to achieve dual band
operation in a very limited space.
The GM4JMU dipole for 40 meters uses two very easy to build loading coils,
that consist of 40 turns of PVC insulated number 16 wire, of the type used
for household installations, that are wound on a plastic form of 40
millimeters diameter.
The actual length of the wire for makin each coil is ten meters and 25
centimeters… and the coils are located at 2.6 meters from the center
insulator. The length of wire after the coils is used to actually tune the
antenna to the part of 40 meters where you want to operate more often. You
start with about three meters of wire after each coil, install the antenna
at its operating height, and run a test for standing wave ratio between
7000 and 7200 kiloHertz. In my case, the antenna that I built was
resonated to obtain a minimum standing wave ratio on 7050 kiloHertz,
something that provided an excellent compromise to work both CW DX and the
Digital Modes , with the antenna showing a rather nice and low standing
wave ratio between 7000 and 7100 kiloHertz. As recommended by GM4JMU, I
used a one to one balun to feed the antenna with 50 ohms coaxial cable. 40
meters is an excellent amateur band for year round operation even during
the worst periods of the solar cycle, and for those of you without enough
space to install a full size 40 meters band dipole, the GM4JMU design is
an excellent compromise.
When on a field trip some time ago, I was able to take with me both a
short GM4JMU dipole and a fullsize antenna for the 40 meters band. I ran
comparative tests and not surprisingly, the difference between the two
antennas was barely noticeable. According to antenna modeling software the
GM4JMU and similar half size shortened half wave dipoles should be between
minus 3 and minus 6 dB below a full size antenna, depending on how high
the short antenna is installed above average terrain. So, even in the
worst possible scenario this short antennas are one S unit below their
full size counterpart, with the advantage that they may , in many cases,
make the difference between been able to operate on 40 meters or not…Now,
don´t think that this antenna is as easy to install and get running as a
full size half wave dipole… you will need to be patient and tune the
antenna to resonate to the part of the 40 meters band you want to operate,
but once this is done, you won´t need to do any further adjustments if you
don´t move the antenna from the place where you installed and adjusted it…
……………….
If you have a particularly difficult place to install a short wave
receiving or transmitting antenna, just send me the description of the
location, and maybe a photo or diagram, so that I can recommend options
that may allow you to enjoy the use of a better antenna system… send mail
to arnie at rhc dot cu or VIA AIR MAIL send a letter to Arnie Coro, Radio
Havana Cuba, Havana, Cuba…
Si amigos, yes my friends, space restrictions, condominium and owners
associations antenna banning can be circumvented with the usual radio
hobby people ingenuity… Do keep in mind that even a very small outdoor
antenna will usually be a much better performer than one that is located
indoors amigos !!!
……..
QSL, QSL on the air, QSL on the air to the many Dxers Unlimited listeners
around the world that have sent me their thank you notes for publishing
the scripts of the show by means of several Internet radio hobby mailing
lists.. Among the latest ones that are publishing the scripts of the
program for the benefit of their readers are the ANTENNEX Webzine antenna
discussion list, and the also popular swl list that is distributed via the
qsl.net site…If you know of any other e-mail radio hobby distribution list
that is also reproducing Dxers Unlimited script please let me know about
it… send mail to arnie at rhc dot cu… again arnie at rhc dot cu.
And now here is our next item…it´s about the testing of recycled
electronic components salvaged from broken down or discarded equipment. My
storage bins are presently full of recycled electronic components.. and
finally I was able to start a long time project aiming at testing each
recycled part in storage and from now on testing newly salvaged parts
before putting them in storage…The latest piece of equipment that became
available for dis-assembly and total recycling of its components is a SONY
Betamax VCR machine, that will probably take a few more days to take if
apart completely. It is a treasure chest of both electronic components and
mechanical parts, including a lot of very useable hardware…
A nice power transformer, large electrolytic capacitors and several
optocouplers that are very useful when building digital radio interface
boxes required to operate between a computer running a digital modes
communications program and a transceiver. The optocouplers are very
effective in isolating the computer from the radio, providing protection
to the machine´s serial or USB ports…
VCR machines will become in the not too distant future yet another nice
source for recycling electronic components , as DVD´s and hard drives
recorders become more and more popular among TV viewers… So keep a close
watch around for those VCR machines that are going to be phased out by the
new recording and video reproduction technologies amigos !!!
Other sources of recycling are computer monitors, especially the older
ones, that will provide your parts bins with a lot of high quality
components including a large number of discrete transistors and first
generation integrated circuits that can be easily desoldered from the
circuit boards…
…………………
And now amigos, as always when I am here in Havana, get ready to copy
Arnie Coro´s exclusive and not copyrighted propagation update and
forecast… Solar activity is expected to continue at very low levels for
the next month or so… Scientists are anxiously awaiting for yet another
sunspot that can be attributed to the new solar cycle, something that will
really confirm that the new cycle has really started… Solar flux should
remain between 70 and 75 units for the next three to five days, and this
will mean that the maximum daytime useable frequency for the best
propagation paths would briefly exceed the 21 to 23 megaHertz range, with
the frequency of optimum traffic curve hovering around eighteen megahertz
during your local daytime hours, something that will explain the good
reception achieved on the 16 meters international shortwave broadcast
band…
For amateur radio operators that come in from work after five or six PM
local time the 20 meters band will be closing very shortly after you
arrive at your home QTH, leaving those of you that are good CW operators
with the nice option of operating on the 30 meters or ten point one
megahertz amateur band… The rest of the evening your two choices will be
40 meters and 80 meters, with 40 meters much more attractive for Dxing
with low powers and not too efficient antennas… DO keep in mind that
digital modes, especially the popular PSK31 are much more effective to
communicate when poor propagation conditions due to very low solar
activity prevail, something that is exactly what is happening now… See you
all the the weekend edition of the program next Saturday and Sunday UTC
days amigos…
_______________________________________________
List Administrator: Duane Fischer, W8DBF (WPE8CXO) **For Assistance:
dfischer@xxxxxxxx ** HHI Halligan's Hallicrafters International and
www.w9wze.net
http://mailman.qth.net/mailman/listinfo/swl
Help: http://mailman.qth.net/faq.htm
--
No virus found in this incoming message.
Checked by AVG Free Edition. Version: 7.5.516 / Virus Database:
269.20.7/1283 - Release Date: 2/16/2008 2:16 PM
---[Start Commercial]---------------------
Order your WRTH 2008:
http://www.hard-core-dx.com/redirect2.php?id=wrth2008
---[End Commercial]-----------------------
________________________________________
Hard-Core-DX mailing list
Hard-Core-DX@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/hard-core-dx
http://www.hard-core-dx.com/
_______________________________________________
THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
and/or modified under the conditions set down in the Design Science License
published by Michael Stutz at
http://www.gnu.org/licenses/dsl.html