Re: [HCDX] Dxers Unlimited's mid week edition for 10 April 2007

["Prof. Arnaldo Coro Antich" <inforhc@xxxxxxx>]

Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited's mid week edition for 10-11 April 2007

Hi amigos radio-aficionados around the world and also those of you 
orbiting the Earth, because, yes, there are amateur radio operators in 
space at this moment you are listening to Dxers Unlimited, and whenever 
they have some spare time, they do make some nice two meters band two 
way contacts with hams around the world. There are radio amateurs almost 
everywhere, as you can quickly find out by operating on one the short 
wave ham bands... I have talked to pilots flying Jumbo jets across the 
Pacific Ocean, with members of an Antarctic expedition, with Cuban 
doctors providing medical care to patients in remote areas of Guatemala 
and for whom the amateur radio transceiver is a unique communications 
tool. There are many hams operating maritime mobile from sailboats 
cruising the Caribbean or from high speed container merchant vessels 
that keep going back and forth between ports across the Atlantic, taking 
only a few hours to unload their containers and load new ones to start a 
return journey. Yes amigos, there are radio amateur operators in remote 
villages of Africa, or in the middle of highly populated cities like New 
York, London , Paris or Tokyo, and they are able to operate on the HF 
bands by using unique antenna systems, like the remotely controlled 
magnetic loops...
You can join them and enjoy amateur radio on the short wave bands that 
is going to take a turn for the better now that solar cycle 23 has come 
to an end...From July of this year on, my forecast calls for increasing 
solar activity , and that will bring in much better HF propagation 
conditions for at least five to seven years !!!
Item two: coming up after a short break for station ID. I am Arnie Coro 
in Havana, and this is Dxers Unlimited's mid week edition...
.......

Si amigos, you are listening to Radio Havana Cuba, coming to you via 
short wave, via Internet and also via satellite... Now here is item two: 
I am now back in Havana after a two week trip to the United Kingdom of 
Great Britain and Northern Ireland, where I attended the yearly meeting 
of the DRM Consortium, and also had the opportunity to exchange points 
of view about the future of broadcasting in general and of short wave 
broadcasting in particular with experts from many different countries 
that were attending the conference. Also, I was able to see the first 
run of a production model of the Morphy-Roberts DRM capable receiver, 
which is now selling in Europe. Still too expensive, but , it is 
available, and that is surely quite a difference from what was happening 
just a few months ago, when stations broadcasting using the Digital 
Radio Mondiale mode on short wave could only be heard using a radio 
receiver connected to a computer equipped with specially written 
software to decode the DRM signals.
In contrast to the DAB or Eureka 147 digital broadcasting standard, that 
has proven to be quite successful in the United Kingdom and Denmark, 
with several millions of receivers sold, DRM is still facing the lack of 
easily available and relatively low cost receivers as its most relevant 
problem.
During the meeting, that took place at the BBC Research Center, a lot of 
attention was given to further development of short wave transmitters 
capable of handling the very sophisticated DRM signals without suffering 
from lack of linearity and excessive bandwidth as it happens to be 
typically the case when short wave broadcasters use their existing 
equipment to transmit DRM , something that if not done properly can 
create many problems to stations located on adjacent channels.
........

ASK ARNIE, the most popular section of this program , continues to 
receive many e-mail messages, post cards and letters from listeners 
around the world that want to learn more about our wonderful hobby... 
Today I will answer  Canadian listener Gary's question regarding the 
possibility of using DRM for amateur radio communications... And the 
answer is YES, there is now a software based on the DRM concept , that 
goes by the name of WIN DRM and that seems to work, although setting it 
up is not very easy according to what I have read recently....It does 
require a fast computer and a good quality transceiver to work 
properly... There are amigo Gary other digital voice modes now available 
too, but so far WIN DRM seems to be the one that is easiest to set up 
for the home experimenter...
Second question at today's ASK ARNIE,  also coming from Canada where 
several listeners are telling me that freezing rain has done damage to 
many wire antennas during the past several weeks... Antennas tied to 
tree branches can break them when ice forms along the wire ... 
Professional antenna systems used where icing is frequent are equipped 
with de-icing equipment, but these are really expensive and out of reach 
of amateur radio operators... So amigo Karl from Toronto, YES, you could 
design a wire antenna system so that it can be de-iced by passing a high 
intensity current , but as you have just heard this is quite expensive 
...and requires that special precautions be taken by the owners of the 
antenna so that in case of a breakdown, the heating current will be 
immediately cut by an automatic device.
....

Microphones.... microphones that are specially designed for voice 
communications are found at very low cost... you know where ???
You will find them inside discarded cellular telephones...And let me add 
that they make excellent mikes for ham radio equipment, often improving 
the rig's punch because engineers involved in cellular telephone 
equipment design have placed a lot of attention on the frequency 
response of the microphones, so that they will reproduce the human voice 
in the best possible way, and at the same time don't pick up either low 
frequency or high frequency noises that actually interfere with voice 
communications...
So here is your friend's Arnie Coro's advice... start looking around for 
discarded cell-phones, and every time you find one, spend some time 
doing some surgery and removing the high quality communications 
microphone... Here at CO2KK , my amateur radio station, I replaced the 
microphone element on my 2 meter FM transceiver with one from a NOKIA 
cell-phone with outstanding results, according to my good friend Luis 
Rodriguez CO2LR, who is a very experienced radio engineer and devoted a 
lot of his valuable time to help me with the comparative tests... I was 
able to switch very fast from one  microphone identical to the one that 
came with
the FM transceiver to the NOKIA microphone element that was placed 
inside an identical mike case... According to Luis, the "talk power" of 
the cell-phone mike was really impacting, so I did two things after that 
test. One, I left the cell-phone mike element permanently connected to 
my rig, and two, I started a search for more discarded cell-phones to 
salvage their high quality communications type microphones !!!
.......
Si amigos,  yes my friends, oui mes amis... solar cycle 23 is now at its 
very end... we will still have to wait for about six months to have a 
clear confirmation , but according to observations made by solar 
scientists around the world, cycle 23 is going to end before the month 
of July, and from there on, what may happen is that solar activity will 
start to raise at a very fast pace... This is a typical solar cycle 
behavior, as the ascending phase is actually shorter than the decline. 
So expect a  cycle 24 peak to happen between 2010 and 2011, and it seems 
like this upcoming cycle will be a very active one if you believe what 
some scientists are forecasting...
Be it a very active or a moderately active cycle won't matter very much 
for most of us , as anything is going to be definitely better than the 
past year and half of extremely low solar activity that we have gone 
trough....
......

Now , here is our technical topics section of Dxers Unlimited, and also 
very popular section of the program... Today technical topics will deal 
with an ever growing problem around the world... the presence of very 
high voltage spikes superimposed upon the alternating current power 
lines that supply electricity to our radio equipment. Not too long ago I 
was told my  a friend who is an engineer of the national electrical 
utility, that they are really worried with the proliferation of switched 
mode power supplies, like the ones used by desktop computers,and that 
are now also becoming quite popular in other consumer electronic devices 
because they can be fixed easily , are lightweight and can be produced 
at much less cost than conventional transformer operated power supplies.
One of the problems associated with this type of power supply is that it 
can put a lot of noise into the power lines from which it is
taking energy to operate, something that is a big headache for short 
wave listeners ... My friend from the power company says that the 
operation of hundreds of thousands of desktop computers using the 
switched mode supplies as they all do, causes severe distortion to the 
sine wave of the power line, and that in turn has other undesirable 
effects... As a matter of fact, my friend added, for that very reason 
the Cuban national utility is enforcing among its industrial and 
commercial clients the use of automatic power factor correction 
capacitor banks. I then asked him if I could benefit at my home QTH by 
installing a pair of high quality oil filled capacitors right at the 
service entrance of the power line, and he said that doing so would 
certainly help to provide a low impedance path to high voltage high 
frequency spikes... A few days later , I made a provisional installation 
and it proved that my friend was absolutely right... after the two 10 
microfarads at 330 volts AC capacitors where placed in parallel with the 
power line right next to the electricity meter, I immediately noticed a 
reduction in some of the noises that were usually heard on my HF radios, 
and also, a much lower noise level on the AM broadcast band !!! So, give 
this is a try, but don't forget to include fast acting fuses between the 
oil filled capacitors and
the power line...
And now amigos as always at the end of the program when I am here in 
Havana, this is Arnie Coro's HF plus low band VHF propagation update ... 
So far a very dissapointing tropospheric ducting DX season here in the 
Gulf of Mexico and the Caribbean. Although I was not here in Havana for 
the two weeks when the tropo season usually starts,  radio amateurs to 
whom I have talked told me that no tropo DX was heard at all...This, of 
course is a weather related phenomena, and may be connected to the 
ongoing climate disturbances we are seen world wide. HF propagation 
conditions are poor because solar activity is extremely low...With 
several days of ZERO sun spots, and solar flux at rock bottom levels 
near 70 units... See you all at the weekend edition of the program 
amigos, and don't forget to take a little of your valuable time and send 
me your signal reports and comments about today's program as well as any 
radio hobby related questions you may have...send e-mail to arnie@xxxxxx 
and VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana , Cuba.
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