Radio Havana Cuba

Dxers Unlimited's weekend edition for 11-12 Nov 2006

By Arnie Coro

radio amateur CO2KK

Hi amigos radioaficioandos... with our now traditional salute... Hi
amigos radioaficionados, I am very happy to start today's weekend
edition of your favorite radio hobby Dxers Unlimited with yours truly
Arnie Coro writing and reading the script of this twice weekly program
devoted to the promotion and development of our wonderful , fascinating
and also low cost hobby: RADIO... Yes, low cost because even with your
little clock radio that wakes you up in the morning with that buzzing
alarm, you can hunt for DX stations on the AM broadcast band during this
time of the year, when atmospheric noise levels go trough a minimum in
the Northern Hemisphere... Now here is item one: Tropical Band stations
located about 20 degrees North and South of the Equator deliver the best
signals to receivers located at higher latitudes two times every year...
during the spring and autumn equinoctial periods... but don't forget
that long winter nights , with very low atmospheric noise are also good
to hunt for Tropical Band DX stations, of which the easier ones include
Radio Rebelde's 5025 kiloHertz frequency that is on the air 24 hours ,
although it can be heard at long distances only during the period from
local sunset to local sunset here in Cuba... when ionospheric absorption
is of course much lower than during local daytime hours.

Tropical Band stations provide a daytime service area covering several
hundred kilometers around the location of the transmitter, but after
sunset, their signals can be heard much farther away... Item two: Also
related to propagation on frequencies below 8 megaHertz or so...

Winter season propagation is now here, and with it, radio amateurs will
be enjoying much better DX possibilities on the 160, 80 and 40 meter
bands during local evening hours... Low solar activity associated with
low ionospheric absorption of frequencies below 10 megaHertz and the
lower height of the F layer during November and December combine to
bring in much better signals on the 1.8, 3.5 and 7.0 megaHertz amateur
bands...

Stay tuned now for more radio hobby related information coming to you
>from Havana... I am Arnie Coro,and my ham radio call sign is CO2KK, just
in case you hear me calling CQ DX during the weekend amigos !!!

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

This is the weekend edition of Dxers Unlimited, and here is item three:
Devote more time to going on the air with your amateur radio station...
especially on the HF bands... Lack of activity is now a big problem on
the nine HF bands from 160 to 10 meters, and as a well known expert in
international radio rules and regulations said recently, the amateur
bands that are seeing very little use are likely to become targets of
the spectrum hungry users at upcoming international radio conferences
that deal with the use of the radio frequency spectrum... It's use it or
loose it, the expert underscored, when he was particularly critical of
the little use that some of the amateur bands are getting, as verified
by spectrum analyzer sweeps done by several national telecommunications
administrations... So, let's do it amigos, let's put those transceivers
and transmitters on the air on the HF bands... so that future
generations won't have to talk about the ex- ten meters or the e- twelve
meters amateur bands or something like that...!!!

Item four: ASK ARNIE, la numero uno, the most popular section of Dxers
Unlimited is now on the air... QUESTION about the Super J two meters
band low cost antenna made from copper wire, PVC pipe, plastic PVC tape
and plastic cable ties... It was sent by amigo Randall in Idaho, USA...
He wants to know if this low cost, simple, and easy to build antenna can
be designed for use on the 70 centimeters band... Randall tells me in
his e-mail that there are at least three 70 centimeters band repeaters
that he could use, if he had a better antenna... But his budget is on a
shoestring, so he can't buy a commercial high gain omnidirectional
antenna for the 440 to 450 megaHertz segment of the 70 centimeters
band...ANSWER: Sure amigo Randall, it is very easy to build a low cost
SUPER J for the 70 centimeters band... and I have already sent you an
e-mail with all the exact dimensions of the antenna, so that you can
homebrew one during the weekend... As a matter of fact, while
calculating your 70 centimeter band antenna, I realized that I only had
a YAGI and a quarter wave vertical monopole antenna for that band... So
after finishing with the numbers crunching session, I went to my
workshop and made a SUPER J, then proceeded to test it in my terrace...
and it worked extremely well. It was built using number 10 bare copper
wire, a section of two inch PVC water pipe and six cable ties, a female
coaxial connector and an antenna to mast clamp... Placed just at 2
meters or six feet above the floor of the open terrace, the Super J was
heard well by several amateurs located up to thirty miles away from my
home !!! So amigo Randall, thanks twice, one for sending the question
and second for making me realize that I had no omnidirectional gain
antenna for the 70 centimeter band. By the way, here in Havana we don't
have yet a 70 centimeter band repeater, but one is in the works... What
we do is monitor 439.100 and everyone that goes on the air just makes a
call on that local calling frequency, something that is working quite
well... We are just a few stations on that band at this moment, but I
expect more Cuban radio amateurs to operate on 70 centimeters FM in the
near future... but weak signal SSB and CW is another story !!!

.......

You are listening to the weekend edition of Dxers Unlimited coming to
you from Havana... and YES, we do QSL, with a beautiful 45th Anniversary
of Radio Havana Cuba QSL card...send your signal reports, comments about
this and other RHC programs to arnie@rhc.cu, or VIA AIR MAIL to Arnie
Coro, Radio Havana Cuba, Havana, Cuba... Now here is our next item of
today's program... our also very popular antenna topics section of the
show... Today I want to add a few comments about the Super J antenna for
both two meters and seventy centimeters... It can certainly be built
using 5/8 of a wavelength vertical elements, that are , of course longer
than the half wave elements... But, the longer elements will add very
little gain to the antenna, and make matching the antenna to the feed
line more difficult... The phasing between the two or three vertical 5/8
wavelength elements is achieved by means of 3/8 of a wavelength phasing
sections.. while in the case of the half wavelength elements the phasing
sections are quarter wavelength transformers... I have built both
antennas and found so little difference in performance between the two
under actual, practical, real life conditions that I am recommending
everyone to homebrew the simpler SUPER J antennas with two or three half
wave lengths vertical elements in phase... As results achieved with the
much simpler and shorter version are practically identical to the
results with the longer antenna, there is not much incentive to
complicate things when they can can be kept simple and yet highly
effective !!!

......

Lithium -ion batteries used by laptop and notebook computers are
dangerous to say the least... as many of you may have heard,there is a
massive recall of lithium ion batteries now going on, because they have
already caused many fires... So , here is your friend Arnie Coro's
advice, stick to the old nickel cadmium or nickel metal-hydride
rechargeable batteries for your radios... and don't forget to use the
special chargers required by the nickel metal hydride batteries...Again,
don't use lithium ion rechargeable batteries, even if they are given
away , because, I repeat they are really dangerous, especially when they
are charged , but as many users of laptop and notebook computers have
recently learned the hard way, the lithium ion batteries may go up in
flames at any moment...

And in an also battery related item, let me tell you that the big, deep
cycle golf cart type of batteries are the way to go if you want to have
a really useful emergency power backup system... The deep cycle high
capacity golf cart standard lead acid cells will provide many years of
service when proper care is given to them, and they will be alive and
well, ready for action, when an emergency situation makes it necessary
to have instant power available... You can even charge those batteries
with a solar panel and voltage regulator combination, so that there is
no need to keep a constant watch on their state of charge, as this is
accomplished automatically...

Last but not least... now that we are talking about emergencies, think
about the convenience of buying several of the new high tech light
emitting diodes cluster lamps... They are expensive, that's true, but
they are much more rugged and reliable than any other emergency
lightning system, and another important fact is that they are real power
savers... producing much more light output per ampere of current drawn
>from the batteries than any other type of lamps. Emergency lights are an
essential part of your radio emergency kit, and they should be checked
periodically and kept ready for action , because you never know at what
time of the day an emergency situation will require using your amateur
radio station, or for how long the emergency is going to last...

And now as always at the end of Dxers Unlimited, here is Arnie Coro's HF
plus low band VHF propagation update and forecast... A minor geomagnetic
storm reaching the G1 level happened during Friday UTC day, but for all
practical purposes its over by the time you are hearing this
program... Predictions for November 12 are 95 solar flux units and the A
index at 12, and one day after on November 13th the solar flux is
expected to continue near 95 units, but the A index should go down to
around 8 units.. The solar activity was very low and is
expected to remain so, as the big isolated sunspot continues its
slow decay. Nevertheless, an occasional C flare could still occur in
that lonely active region.Optical sunspot count on Friday was 12, and as
I said before there is just one lonely but rather large sunspot on the
solar disk... Expect much better HF propagation during the next two or
three days, and then things will take a downward turn as there will be
very little ionization of the upper atmosphere due to the very low solar
activity.

Don't forget to send your signal reports and comments about the program
to arnie@rhc.cu, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba,
Havana, Cuba.