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 now 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 dot 3 hundred megaHertz to 145 dot 8 megaHertz for simplex FM mode operation, and they will also make use of several FM two meters band repeaters operating from 145 dot one hundred and ten to 145 dot four hundred and niney megaHertz. The long range FM repeater at the Loma de Salon mountain is on 145 dot 110 megaHertz and covers the eastern part of Pinar del Rio province, 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 sorrounding 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 3 amperes rated reverse polarity protecion diode, but this approach is impossible with the latest generation of low cost dual band 2 meters and 70 centimeters hand helds 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…

Si 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 autuom  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…

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