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Re: [HCDX] Dxers Unlimited's mid week edition for 26-27 June
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited's midweek edition for 26-27 June 2007
By Arnie Coro
radio amateur CO2KK
Hi long time amigos radioaficionados and those who are listening for the
first time too... welcome to the midweek edition of Dxers Unlimited that
is certainly a very special one, as at the time you are listening to the
program, our nearest star the Sun has been inactive for a very long
period, with the daily sunspot count at ZERO for many consecutive
days... Now a new sunspot active region is slowly rotating into view,
and that will probably increase the solar flux above the extremely low
67 and 68 flux units that it has been hovering as of late. By the way,
any solar flux figure below 70 units , automatically sends the sunspot
count to ZERO .
Item two: Thank you amigos, to the many friends around the world that
have already sent birthday greetings..ahead of time, as I will be
celebrating my birthday Monday of next week. Some came in as early as
yesterday evening, as it seems that some of my good friends have very
well structured computerized data bases with their amigos birthdays
records !!!
Item three: Listening Friday evening on the AM medium wave broadcast
band to the recently upgraded Radio Reloj Pinar del Rio provincial
relay, operating on 790 kiloHertz and running 20 kiloWatts, its another
of the new solid state high technology transmitters that are replacing
the old power hungry vacuum tube broadcast equipment, in an effort by
Cuban broadcasting to make more efficient use of electricity by
replacing the obsolete transmitting plant as financial resources become
available. The new 20 kiloWatt 790 kiloHertz transmitter is located on
the outskirts of the city
of Pinar del Rio , about 100 miles west of Havana, and tests done by
RadioCuba engineers show that it has an overall conversion efficiency of
around 80 percent... that meaning that the new Radio Reloj relay will
save a lot of electricity while providing a much better service, because
it is also capable of modulating the carrier wave on positive peaks up
to 125 percent... A similar 10 kiloWatt transmitter was recently
installed by RadioCuba for the Radio Reloj City of Havana station on 950
kiloHertz, something that has improved the coverage of Radio Reloj in
three of the nation's western provinces.
More radio hobby related information coming to you in just a few seconds
as Dxers Unlimited's weekend edition continues...
...............
Si amigos, wish you could join my modest birthday party next Monday
afternoon... I will be meeting with family and friends for the
celebration, with little Claudia, my youngest daughter now almost two
and a half years old, Teresita, my elder daughter , Arnie Jr. and Roxana
my wife having prepared a cake and ice cream
party !!! Now here is the next item of today's program: Just added a
Light Emitting Diodes home brew lamp to act as the back light of my
favorite 2 meters band FM transceiver that was constantly burning the
very difficult to replace incandescent pilot lamp that illuminates the
liquid crystal display. A white light emitting diode and a resistor did
the job that , according to LED manufacturers specifications won't need
to be replaced in a very long , long time. I also did a similar
incandescent light bulb replacement on my small portable, a Grundig
FR200 " Recycle Power"radio. On this radio I replaced the high intensity
miniature incandescent lamp dash emergency light with a cluster of three
high intensity white diodes, that give a lot of light and use less than
half the electricity that the incandescent bulb requires to operate.
Some time ago a long time Dxers Unlimited listeners sent me the photos
of his modified Grundig FR200 receiver , to which he had changed the
light bulb for three high intensity white Light Emitting Diodes with
great success, and I just followed upon this nice idea .
The other modification that he made consists on an electronic
band spread, that is a voltage variable silicon diode that was added to
the local oscillator tuned circuit on the short wave bands, making
tuning a lot easier than with the radio's original mechanical analog
tuning. He told me that he could set the analog dial to a specific
position on the blank calibration scale, and then tune the radio with
the varicap
diode. Another thing he did to this very special "emergency
radio" was to add a beat frequency oscillator, so that single side band
and CW stations could be picked up..The BFO is switched on and off by a
miniature switch located on the back of the radio, right next to a
second variable resistor to control the voltage to a second voltage
variable or varicap diode.
One of the really nice features of the Grundig FR200 is that it uses up
very little electricity to operate... as a matter of fact three standard
double A cells will last for quite some time if you use the radio for
casual listening.
Again, it's an excellent set to have around in case there is a power
failure, and even if your batteries go dead, the Grundig FR 200 has a
crank type Direct Current Generator that will charge a small nickel
metal hydride battery pack, and even if the pack is in bad shape, the
radio will keep working all the time that you are cranking the generator !!!
.......
Si amigos, despite doomsday predictions that the radio hobby will just
vanish due to the now everywhere Internet, it's just not happening, and
what a paradox, the Internet is actually helping the radio hobby in the
specific case of amateur radio.
Never before in the more than one hundred years of the existence of our
wonderful hobby we have seen so much valuable information been made
available freely... There are thousands and thousands of amateur radio
websites, and the amount of technical information that can be downloaded
is absolutely amazing... There are websites that require many , many ,
hours to just take a look at, like the super antenna site courtesy of
W4RNL , Dr. L.B. Cebik, that can be found at http://www.cebik.com....
There are sites devoted to specific
modes like the Dr. Oliver Phelp's digital communications mode website,
and there are also lots of sites devoted to radio wave propagation,
home brewing of radios, contests, antique radios... you name it, so
again, we are seeing a very interesting thing happening in front of our
eyes... the Internet, that was supposed to be the end of amateur radio
and the radio hobby in general, is actually now helping more and more
people enjoy the hobby in a much more plentiful and I must add also
inexpensive way !!! But be aware that some radio amateurs think
different as regards to making their websites freely available to anyone
, by demanding copyright privileges as if their websites were run as
commercial operation... but fortunately those are just a few exceptions
and the true amateur radio spirit of cooperation with anyone interested
in the promotion and development of the radio hobby seems to prevail in
at least a one hundred to one ratio in favor of freely available
technical information.
.....
Si amigos, yes my friends, thanks for joining me today on this mid weekk
edition of Dxers Unlimited... And now here is the very popular antenna
topics section of the show...
devoted today to a peculiar antenna system that is known
as " The DIPOLES NEST ", a very easy to home brew High end of the HF,
low band VHF and high Band VHF antenna.
A few weeks ago I quickly assembled a NEST OF DIPOLES, to solve a
friend's antenna problem... The system has
a dipole cut for 28.4 megaHertz on the 10 meters band, his favorite HF
band, another one cut for 50.3 megaHertz on 6 meters and yet another one
cut from 145.000 megaHertz on 2 meters.
They are all fed using the single RG 58U 50 ohms coaxial cable that
my friend had at hand, and as expected, I used a first balun choke coil
for the two meters dipole, made by looping 6 turns of the cable on a 1.5
inch diameter PVC pipe coil form, followed by another air wound choke
coil of 6 inches diameter aiming at decoupling the radio frequency of
the 10 and 6 meters band from from flowing on the outside of the braid
of the coaxial cable.
The dipoles were made with number 8 PVC insulated copper wire, something
that required careful tuning of each dipole, because the dimensions of
antennas using insulated wires are different from the ones using bare
copper or aluminum wire.
Anyway, the three dipoles are kept separated from each other by small
lengths of polyethylene pipe, and in a second antenna, the separation
between the dipoles was achieved with lengths of the center insulator of
heavy duty RG17 coaxial cable, also an excellent HF, VHF and UHF
insulating material.
The procedure to set up the antenna involved using a good quality HF
standing wave ratio meter for tuning up the 10 meters band antenna first
, and a similar VHF instrument for setting up the 6 and 2 meters bands
dipoles in sequence. In this second version, as always, something new
came to my mind, and we decided to include yet another dipole, a fourth
one, tuned to the center of the aircraft VHF band...that for voice
communications spans from 118 to 136 megaHertz, so we cut the dipole for
127 megaHertz. This antenna was not adjusted for transmission, because
it will always be a receive only antenna as you may realize.
The four dipoles " Nest of Dipoles" HF, plus 3 VHF bands antenna works
very well on 10 meters, 6 meters, the aircraft band and the ham two
meters band.
Installing the two antennas was a rather easy job, as they are quite
compact... because the longest dipole, the one for 10 meters is just
about 5 meters or 16 feet long. Both antennas were installed as 45
degrees tilted dipoles, a compromise to achieve good pick up and
transmission of both vertical and horizontally polarized waves.
If you need to install these dipole nests at a distance longer than
about 20 meters or 60 feet from your radio equipment, then please
consider the need to change to more expensive and less loss coaxial
cable types, like the RG-213 or RG-8, in order to reduce the signal loss
typical of the RG58 type cables.
By the way , a similar dipoles 'nest' can be built for other frequency
ranges too... VHF-UHF radio amateurs can make
a nice nest for 6 meters, 2 meters and 70 centimeters, and ideal system
to carry on the backpack with one of the new ultracompact multi band
amateur radio transceivers like
the YAESU FT817 or the ICOM 706...These antennas are
lightweight, easy to repair on the field, and will cost you next to
nothing as compared with similar commercially built
versions...But again, I insist that you will need to invest quite
some time adjusting them for minimum standing wave ratio...
And now amigos, as always at the end of the show here is our exclusive
and not copyrighted HF plus low band VHF propagation update and
forecast... The latest forecast for the solar minimum is telling us that
it may be actually happening right now , but other scientists believe
that the tail end of solar cycle 23 will extend until the first half of
2008. The latest solar data are simply typical of minimum solar activity
with zero sunspot count, solar flux below 70 units and a very quiet
geomagnetic field...the expected average sunspot number for June is
expected to reach the rock bottom figure of 5... Expect also some really
amazing sporadic E skip openings during the next several days ,with
multiple hop E skip giving radio amateurs the unique opportunity of
working transcontinental DX between Africa, Europe and the Americas.
Don't forget to set aside a little of your valuable time to send me a
signal report and your comments about the program, send them to
arnie@xxxxxx, again arnie@xxxxxx and VIA AIR MAIL, send mail to Arnie
Coro Radio Havana Cuba, Havana, Cuba . Hope to have you all listening
to our weekend edition next Saturday and Sunday UTC days amigos !!!
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