Cuba: Dxers Unlimited's mid week edition for 26-27 October 2010

Radio Havana Cuba

Arnie Coro

radio amateur CO2KK

Send your comments about this program to;

inforhc at enet dot cu

Hi amigos radioaficionados around the world, and especially those of you getting ready to

enjoy the upcoming big ham radio single side band contest this coming weekend...

I am your host , Arnie Coro, radio amateur CO2KK, and here is our first headline...

Wolf number, as announced Monday by the Catania Astrophysical Observatory was up to 71.5 according to my records the highest daily figure so far for solar cycle 24 !

But, a very interesting observation regarding the five active sunspot regions on the solar

disc... none of them was showing a really complex magnetic configuration...

Item two...Cuban radio amateurs getting ready for the upcoming ham radio contest, where

discussing what would be the best strategy during a long lasting round table on the

40 meters band that took place on Sunday. 

The low power , single operator, single band

contest entry seems to be very popular among 

Cuban hams, because it provides the highest

chances of achieving a good place in the contest. 

Competing against high power stations

using sophisticated antenna systems is simply out of the question for the average radio

amateur... and the multi operator, multi transmitter stations just compete between themselves...

There is also a very nice contest slot that , when propagation conditions are good enough

is quite enjoyable... I am talking about single band QRP, or low power operation, that

is limited to 5 Watts , so it is quite a challenge …. My favorite way of entering those big worldwide contests is to operate on the 10 meters band , single operator , QRP...

If short wave propagation conditions are good enough so that the daytime maximum

useable frequency will reach up to 28 or 29 megaHertz , then 10 meters will be open

and you can enjoy making lots of contacts while running just 5 Watts into a simple antenna system, like a half wave sloping dipole...

Item three: Brazilian radio amateurs are among South America's most enthusiastic homebrewers of radios... 

Among their very elegant designs , an ultra simple single transistor transmitter that

can be built in less than an hour , has proven to be quite capable of making nice two way

contacts on the 20 meters ham band. 

The CURUMIN, named after a small colorful bird from the Amazonian forests, easily delivers 1 Watt output on CW, using a quartz crystal

for frequency control. 

My own version of the CURUMIN, uses a transistor recycled from the electron gun assembly of a computer monitor that delivers about 900 milliWatts of nice clean CW on 14.032 kiloHertz... the frequency of a quartz crystal that was also recycled from another circuit board that a friend gave to me some time ago.

The CURUMIN is a minimum parts count transmitter...and is powered from a gel cell

ex computer UPS battery !!!

Stay tuned for more radio hobby related information, coming to you from Havana...

I am Arnie Coro, radio amateur CO2KK, back here in a few seconds after a short break for station ID...

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Si amigos, this is Radio Havana Cuba, soon to be celebrating our 50^th anniversary

on the air.... 

Next year, on the first day of the month of May, we will be marking 50 years of short wave broadcasting !!!! Now here is item four of the mid week edition of the program...

It is still a rumor... but it is now so widespread that it looks like something is really happening regarding DRM , Digital Radio Mondiale , short wave broadcasts by the BBC and Deutsche Welle....

Both the British and the German broadcasting organizations are going through a complete

revision of their budgets, and it seemsquite obvious to me that they will drop the DRM transmissions, as the number of potential listeners , is very near zero.

DRM short wave broadcasts provide good audio quality, certainly better than the regular , traditional analog transmissions, but there are two things that make DRM short wave broadcasting at this moment a very poor investment of resources.

First of all, the lack or receivers continues to be the number one problem... DRM Digital Radio Mondiales receivers are very hard to find, to say the least, and when found, they cost a lot of money, as compared to a good quality analog radio.

In second place comes the fact that DRM via shortwave has a big shortcoming... once there is a fadeout, the program's audio comes to a total silence...

This is a very annoying problem, because in contrast to the slow fadeout and fade in of

analog signals, the digital DRM cuts in and out, leaving what is described by listeners as " a hole in the audio " in the middle of what you are listening , and from which it is impossible to recover any useful information..

According to several telecommunications experts with whom I have discussed DRM recently...the system seems to work quite well on the AM broadcast band during daylight hours but does not provide good reception at night via skywave, because the multi path propagation present during the evening hours behaves

exactly as they typical short wave signals.

Among the items discussed was one focusing on the need to rewrite the computer code that makes DRM work, so that the audio can be recovered , even after a very deep fade has happened...

In the meantime, it seems quite logical that international broadcasters pressed with budget cuts , will drastically reduce, or even completely stop the DRM transmissions due to extremely low number of listeners capable of picking

up those broadcasts.

Item five: ASK Arnie, certainly the most popular section of Dxers Unlimited, brings in a lot of correspondence from listeners all around the world... I do reply directly via e-mail as soon as possible, and many of those replies do make it to the script of the program, because the questions asked are in my opinion of great interest to other listeners of the program... 

Here is a good example, last Friday, listener

Gary from Melbourne , Florida , USA, asked about how he could protect his radios

from nearby lightning … he said... 

Arnie, I know that there is no possibility of protection against a direct hit by a lightning bolt, except at extremely professional installations... and even then, many times those TV , radio and cellphones towers suffer damages when they take a direct hit.... 

But, Gary added, can you give me some guidelines about how to protect my radios , computers and TV sets from a nearby hit ….. Well amigo Gary... my first bit of advice , I am sure that you have heard it here many times before.... every time you finish playing with your radios, simply disconnect everything..

I mean everything, including the AC line power and your ground or earth connection. I

If you happen to be listening to your radios or using your ham radio station on the air, and you start to pick up loud static crashes... watch the local weather carefully, and if there are any signs of a thunderstorm... disconnect everything fast... at once... don't even wait to say goodbye if you are talking on the radio ….

Place the antenna cables far away from the operating table , because a nearby lightning strike may induce very high voltages that will make a spark jump to the nearest piece of electrical or electronic equipment that is at ground potential or near ground potential...

Make it a standard practice to keep all your radios disconnected from the antennas

power line and ground when they are not in use....

….........

And now here is our also very popular antenna topics section... that today will be reviewing an antenna that according to CO6CAC, Carlos, who is a very active Cuban radio amateur who you will be able to work during ham radio contests...

is an excellent antenna system for working DX... 

It is known as the DELTA LOOP, that when fed to generate a vertical radiation pattern, shows a very low wave take off angle that is ideal for Dxing.... Carlos told me recently that he was able to work many DX stations on the 30 meters band using the vertically polarized delta loop

fed with a 110 ohms twin wire transmission line... 

He used a four to one balun at the end of the 110 ohms twin line , and connected the 75 ohms coaxial feedline to his antenna tuner. 

As a matter of fact the 30 meters band DELTA LOOP, proved to work very well also on the 20 and 17 meters band... because it was very easy to match using the PI network antenna tuner.

One interesting fact about the DELTA LOOP or triangular antenna is that it requires just a single mast, and can be rotated manually very easily around the mast.

Also this antenna is a very good option for city dwellers, because it produces a vertically

polarized radiation pattern that reduces the possibility of causing interference to television reception that uses horizontally polarized antennas.

You can feed the DELTA LOOP directly with a quarter wave length of 75 ohms coaxial cable, and then connect the 50 ohms cable to it... But, then it will operate as a single band antenna system...

….............

And now, as always at the end of the show, when I am in Havana, here is Arnie Coro's exclusive and not copyrighted , in the public domain HF plus low band VHF propagation update and forecast... 

As we approach November, and the Sun continues to show signs of waking up, HF propagation conditions are taking a turn for the better... 

The Catania Solar Observatory WOLF number broke the record for solar cycle 24 on Tuesday October 26 when it reached 92 ... November is the month of the year when the ionosphere shows its highest concentration of free electrons at the different layers , that are also closer to the ground than at anytime of the year... 

So expect with the current solar numbers, that the HF bands will be opening up much more frequently...something that will be most welcome by the participants during this next weekend worldwide amateur radio contest, and dont forget to send your signal reports and comments via e mail to inforhc at enet dot cu , or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba,

Havana , Cuba

Source:Dxers Unlimited's mid week edition for 26-27 October 2010 http://bit.ly/cfpgQb

(Yimber Gaviria, Colombia)