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Re: [HCDX] Dxers Unlimited's weekend edition for 15-16 December 2007
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s weekend edition for Dec 15-16 2007
By Arnie Coro
Radio amateur CO2KK
Hi amigos radioaficionados around the world and in space…Seasons
greetings and a Happy New Year 2008 to you all ! Welcome to the weekend
edition of RHC’s twice weekly radio hobby program, featuring today a
follow up on the update that we presented here during our most recent
mid week edition about the recent significant increase in solar
activity, that sent the daily sunspot number up to 44 , with the nice
corresponding increase in the daytime maximum useable frequencies all
around the world .
I am Arnie Coro, radio amateur CO2KK, and as always it is nice to have
the opportunity of sharing with you about 17 minutes of on the air and
on the world wide web time… Here is now item two: A very popular
antenna for amateur radio operators that enjoy using the 2 meters band,
the most popular ham band worldwide according to the most recent
statistics, it’s a version of the J pole, a totally portable antenna,
that can be assembled and taken down in just a few minutes and can be
built using simple construction techniques with hand tools and a
soldering iron.
As in the case of the magnetic loop that we presented here during the
mid week edition of the program, there is no need for a machine shop for
building this one, that can be transported very easily when built using
either 300 ohms TV twinlead or the more expensive , but much better
quality 450 ohms WINDOWS transmission line, and it also will fit easily
into any travel bag…
More about the portable J pole antennas for the 2 meters band here at
the weekend edition of Dxers Unlimited…
Stand by for a few seconds, I’ll be back after a short break
For station ID…
…………….
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and
yes we do reply your QSL requests, via e-mail and also VIA AIR MAIL…and
again amigos, we are now mailing our nice 2008 pocket calendar that you
can request via e-mail or by sending a postcard… Now here is item two
in detail., the J pole antenna made of TV twin lead or WINDOW 450 ohms
transmission line, that is very inexpensive, easy to build and to adjust
for minimum standing wave ratio using a standard standing wave VHF
meter…You will only need to obtain the best possible quality TV 300 ohms
twin lead, or for a much better antenna, use the harder to find and more
expensive 450 ohms impedance transmission line with windows cut all
along it to reduce the losses due to the presence of the polyethylene
dielectric.
The antenna made using the 450 ohms WINDOWS line is not only much more
rugged than the one made from standard TV 300 ohms twin lead, but also
has a much wider bandwidth , something that may prove to be important if
you need to operate all over the four megaHertz bandwidth of the
2 meters band.
The complete step by step building instructions with photos are about to
be finished, and soon to be completed into a dot pdf file that can be
sent via e-mail, so if you are interested in the possibility of
homebrewing this nice, easy to build portable antenna for the two meters
amateur band, just send me an e-mail to arnie@xxxxxx, or a postcard VIA
AIR MAIL to Arnie Coro , Radio Havana Cuba, Havana Cuba.
……..
You are listening to the weekend edition of Dxers Unlimited and here is
item three of today’s show… A visit to Arnie’s workshop, a section of
the program that according to your e-mail messages, postcards and
letters is also becoming very popular. The workbench of my workshop is ,
as usual, full of projects… that range from a battery charger under test
after it was repaired, to the next generation regenerative receiver
project, also under test. Alongside the receiver there is a 12 volts
regulated power supply that was upgraded from a discrete component
regulator to a much simpler and better integrated circuit regulator that
is capable of providing up to one and a half amperes while also having
much better protection against overloads than what was available from
the original factory design… Si amigos, yes my friends, oui mes amis…
you can upgrade and modify many nice pieces of equipment with just a few
hours of work, this will require an analysis of the original circuits,
and how you can upgrade the equipment with much more up to date
technology. Among engineers, this is known as retrofitting, that meaning
that you remove the old technology , add the new up to date components
and circuits while retaining the parts that don’t need to be replaced…
In the case of the power supply in question, I retained the original
power transformer, bridge rectifier and electrolytic capacitors, while
changing the voltage regulator circuit from a group of discrete
components to the new high tech integrated circuit regulator. The tests
of the upgraded power supply showed that short circuit protection is
much better and voltage regulation has also improved significantly from
zero to full load… By the way , this is a very good idea to apply to the
so called Wal Wart power supplies used by many portable radios !
Item five: Here is LA NUMERO UNO, the most popular section of Dxers
Unlimited… YOU have questions and Arnie tries to answer them as fast as
possible. Today’s first question came from listener Albert from
Ireland…Amigo wants to know about the begining of the solar cycle, as
he tells me in his e-mail that he was very happy about the possibility
of the first sunspot of cycle 24 to be seen soon.
Well amigo Al, according to solar optical and magnetic observations
taking place for the past several days, now scientists are almost sure
that the new active solar region could very well be first sign of cycle
24, because of two very well known reasons: first the region is located
at a high solar latitude, plus the fact that is has a reverse magnetic
polarity.
The new cycle sunspots should start to appear at high solar latitudes,
and a large number of them, but not all, should be showing a reversed
magnetic polarity as compared to the majority of the sunspot active
regions of the now ending cycle 23…
The second question came from the Iceland, where the winter season is
now in full swing, and as always making much more time available for
homebrewing radios and listening to short wave, listener Ib, tells me in
his e-mail that he is able to pick up several Radio Havana Cuba
frequencies, among them 12000 kiloHertz as soon as it goes on the air at
eleven hours UTC. Well amigo Ib , the reason you are picking up the
12000 kiloHertz Spanish language programs so clearly in Iceland, is that
we are using a curtain array antenna that is beaming to 010 degrees
azimuth, so your QTH is right into the main beam of the antenna, that
has a beamwidth at the – 3dB points of plus and minus 20 degrees or a
little less…I also checked the maximum useable frequency and frequency
of optimum traffic from Cuba to Iceland between 11 and 15 hours UTC, and
12000 kiloHertz is very well placed to provide such an excellent signal
as you are reporting … Congratulations on your Spanish lessons, and yes,
our announcers at the Despertar con Cuba morning show speak at a lower
speed than the average Cubans do… !!
The third answer to Dxers Unlimited’s listeners questions is now on the
air, in order to catch up with a signficant backlog… Listener Ulrich
from Dusseldorf , Germany sent a very nice e-mail message to
arnie@xxxxxx, in which he asks how he could install his short wave and
amateur radio HF antennas with minimum losses, something that he asks
because his apartment is located half way along a 10 stories high
building… So the distance between the floor where his shack is located
and the rooftop, where he is allowed to install the antennas is quite
significant… Well amigo Ulrich, your best option is to use the highest
possible quality , low loss coaxial cables…As you explain in your
e-mail, the total length involved is more than 50 meters, between the
antenna connector of your radios and the antennas located at the roof of
the building. Although it is very expensive, the low loss aircell
coaxial cable will last many years when properly installed, but, let me
insist on those two words, properly installed, because you will need to
properly seal and protect from the weather the cable and connectors.
You may want to think about the possibility of using one or two low loss
cables and add a remotely controlled antenna switch so that the same
cables will let you use several antennas, instead of running one cable
for each antenna .
Amigo Ulrich, on the HF bands losses won’t be so significant, but on VHF
and UHF , your long coaxial cable runs will have a negative impact on
the performance of your amateur radio station, and there is nothing you
can do about that !
And now amigos, as always at the end of the program , here is our
exclusive and not copyrighted , in the public domain, Arnie Coro’s Dxers
Unlimited’s HF plus low band VHF propagation update and forecast… Solar
flux has now passed above the 90 units mark for the same time in many
days…and solar activity is hovering between low and very low…
The effective sunspot number is now at 37, sending up the daytime
maximum useable frequency up all around the world with some nice spots
seeing up to 40 megaHertz frequencies propagating on North South paths .
Sporadic E openings should be becoming more and more frequent as we
approach the winter solstice, and that’s good news for TV and FM
broadcast band Dxers as well as 10 and 6 meter bands amateur radio
operators. Hope to have you all listening to the midweek edition of
Dxers Unlimited, Saturday and Sunday UTC days, and don’t forget to send
me an e-mail with your signal reports and comments about the program,
send mail to arnie@xxxxxx or VIA AIR MAIL to Arnie Coro , Radio Havana
Cuba, Havana , Cuba
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