Dxers Unlimited midweek edition for Tuesday 9 October
2018 Hola amigos radioaficionados all around the world ... I am Arnie Coro, radio
amateur CO2KK, your host here at this the middle of the week edition of
Dxers Unlimited, your favorite radio hobby program....coming to you on the air
and on the world wide web streaming audio , PLUS also on four FM broadcast band
frequencies here in Cuba.
Here is Item One...hurricane Michael impacted the western
part of Cuba with sustained winds exceeding 114 kilometers per hour and torrential
rains.
According to Cuban weather expert Miguel Angel Hernandez,
the north right quadrant of the storm will be slowly moving across the Yucatan
Straight that separates Cuba from Mexico. As soon as the Cuban Civil Defense
issued its first tropical storm alert, radio amateurs of the Pinar del Rio
branch of the Cuban Federation of Radio Amateurs started to set up the
emergency communications systems planned for the bad weather conditions.
They will be operating on the two meters band on
frequencies from 144.300 MHz to 145.8
MHz for simplex FM mode operation, and they will also make use of several FM
two meters band repeaters operating from 145.110 and 10 to 145.490 MHz.
The long range FM repeater at the Loma de Salon mountain
is on 145,110 MHz and covers the eastern part of Pinar del Rio province, it has
full coverage of Artemisa province and also provides service to fixed stations
with external antennas located in Mayabeque and La Habana provinces of western
Cuba.
Si amigos, this is the middle of the week edition of
Dxers Unlimited. I was writing this script Monday afternoon when the first
rain bands of tropical hurricane Michael were already producing constant rain
fall over La Habana.
Further to the west and south west, it was already
raining heavily, as the storm was approaching western Cuba. For this particular
hurricane related emergency, I will keep a close watch on the use of our 40
meters National Emergency Nets due to the very poor HF propagation conditions
via the Near Vertical Incidence Skywave propagation mode.
Again, most emergency related traffic is expected to be
on two meters FM, making the best possible use of the already existing
repeaters located at TV stations towers and mountain top sites.
This is Dxers Unlimited, and here is now the very popular
ASK ARNIE section of the show.... Today I am answering a request by several
newcomers to amateur radio that want to know what equipment is needed to
provide emergency communications.... first of all, you must understand that
providing to your community back up emergency communications is a very complex
matter It must be understood that the real strength of amateur radio comes from
the commitment to provide volunteer services by operators that usually will form
part of a radio club. EMCOMMS as they are known require to own and have ready
to operate transceivers, antennas, batteries, generators and supplies to keep
those stations operational.
Even the most simple low cost two meters, and seventy
centimeters dual band FM handie talkie is capable of providing vital links
between disaster areas and government authorities, that have lost contact when
the cellphone systems and the fiber optic cables networks collapse, like in the
case of an earthquake or a hurricane.
Yes, a less than fifty US dollars 2 meters and 70
centimers handheld FM radio can become a most useful link, especially if you
add to it the following three items.
# Number One: at least one, or better yet two more
additional batteries.
# Number Two: a flexible battery charger that can be
connected to a generator or to a car or truck, yacht or aircraft electric
system.
# Number Three: at least one omnidirectional antenna that
can replace the handie talkie's small stub helically wound low efficiency unit
provided with the radio. Better yet add a second portable YAGI antenna of at
least three elements that can be easily transported, assembled in a few minutes
and that will come with a portable telescopic mast capable of placing the
vertically polarized YAGI at no less than three meters above any surrounding
objects.
Si amigos, yes my friends, as you hear this program there
are more than
50 Cuban radio amateurs that have activated the National
Emergency Net to provide alternative communications in the areas of western
Cuba that received the impact of category 1 Hurricane Michael expected to reach
the southern USA starting on Tuesday.
Many of them use their handheld FM two meters band
transceivers as part of the equipment used for local communications, and standard
SSB transceivers for operating on the 40 and 80 meters bands.
This is Radio Havana Cuba, the name of the show is Dxers
Unlimited and here is our popular technical topics section, devoted today to
providing protection against wrong battery polarity connections that can
produce very serious damages to radio equipment.
This is especially important during emergencies, when you
may need to connect your radios to an external high ampere hours capacity
battery. You would not mind to loose around three quarters of a volt on the
feed voltage that will happen when a high current silicon diode is inserted
into the positive wire of your radio and the battery.
If by mistake the battery is connected with the wrong
polarity, the big silicon diode will provide protection, as no current will
flow. This is my ultra-simple solution against wrong battery polarity mistakes,
that I have incorporated as part of the emergency communications kit.
In the case of some two meters band FM hand held
transceivers of the older generation, some of them have enough space inside to
include the required three-amperes rated reverse polarity protection diode, but
this approach is impossible with the latest generation of low cost dual band
two-meters and 70 centimeters hand held, that are extremely compact. For those
radios I use a connection to the external battery that incorporates the high
current protection diode.
Using a recycled three to five amperes rating silicon
diode will provide all the required protection, but if you are a perfectionist
and want to spend the extra money, then using a very low voltage drop MOSFET
device or a SCHOTTKY diode, will reduce the voltage drop from about seven
hundred millivolts to just two hundred millivolts.
See amigos, yes my friends, if you ever use external
batteries to provide power to your radios, follow my advice and add reverse
polarity protection to all of them...the cost is minimal and preventing wrong
polarity connections is vital for the survival of your radios.
The reports keep coming in as the autumn Trans
Equatorial Propagation season peak is now in progress.Every day I keep
receiving advisories about TEP openings from radio amateurs in the Caribbean and
South America.
Most frequent reports make reference to 10 meters band
QSO's, while less number of them report 6 meters band openings across the
equator. So, my advice for you is, to keep a close watch at the way the maximum
usable frequency curve moves up especially during the afternoon and early
evening hours, local time when chances of TEP openings are more likely to
happen..
And now amigos at the end of the show a short form space
weather and solar activity report PREDICTIONS FOR 10 Oct 2018, 10CM FLUX: 071 /
AP: 011 PREDICTIONS FOR 11 Oct 2018, 10CM FLUX: 071 / AP: 007
COMMENT: There were no sunspots nor flares on the visible
solar disc of the Sun in the past 24 hours.
Amigos see you at the weekend edition of Dxers Unlimited
next Sunday and Monday UTC days just after the top of the hour news bulletin.
(Arnie Coro)