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Re: [HCDX] Dxers Unlimited's mid week edition for 2-3 January 2007
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited's mid week edition
for January 2-3 2007
By Arnie Coro
radio amateur CO2KK
Hi amigos radioaficionados !!! Happy New Year 2007 !!! Welcome to the
Year of the Quiet Sun, when solar cycle number 23 is expected to come to
an end, although some scientists believe that it may last even until the
middle of next year 2008...
I am Arnaldo, Arnie, Coro, radio amateur CO2KK, your host here at this
twice weekly radio hobby program that started some twenty years ago as a
once a week ten minute show, that was only devoted to short wave
listening, and has evolved into the most comprehensive radio hobby
program now in existence, according to feedback from listeners like you
, who keep Dxers Unlimited as your favourite show... ASK ARNIE,
continues to be LA NUMERO UNO, the most popular section of the program ,
but closely followed by the HF plus low band VHF propagation forecast
that goes at the end of the show,and if you thought that the number
three most popular section of the program was the one devoted to
technical topics , you were right, and this one came tied with the
antennas topics section... Now some of your New Year's wishes that I
have received with the many e-mail messages wishing us here at Radio
Havana Cuba a happy 2007... Among the requests were
to include more amateur radio hobby topics for beginners , now that in
many countries, passing the amateur radio license test has been made
easier by the removal of the CW Morse Code requirement. Another
frequently mentioned request asks for more operating tips, including
special propagation reports when amateur radio contests are approaching.
Amigos, I want to thank you all very much for sending those valuable
opinions, and be assured that Dxers Unlimited will continue to be your
favourite radio hobby program , dealing with my now revised list of 80
different ways you and I enjoy this wonderful way of spending our spare
time in a most fascinating and relaxing way...
Stay tuned as the first Dxers Unlimited program of 2007 continues after
a short break, I am Arnie Coro in Havana, back with you in a few seconds.
.....
You are listening to Radio Havana Cuba, the name of this show is Dxers
Unlimited, and when it started some twenty years ago , it was supposed
to be devoted only to short wave listening, but now, you can learn here
about such interesting aspects of the radio hobby as home brewing ultra
simple radios and accepting the challenge of picking up long distance
stations with them, or installing a magnetic loop antenna to make
possible operating your amateur station from a high rise apartment
building where no external antennas are allowed, you can also enjoy
listening to the technical topics section contents, guiding you trough
sometimes controversial technical stuff, like the so called Crossed
Field Antenna , or CFA, one of the greatest scams ever in antenna
technology... No amigo the CFA antenna doesn't work at all, and as a
matter of fact, at least two of those antennas sold to broadcast
stations have been the subject of great controversy that ended up in
court. The most recent one is a lawsuit by a station located in the Isle
of Man, that was erroneously led to believe that a CFA antenna would be
better than any other “classic” design ...
Si amigos, yes my friends, here at Dxers Unlimited, you can learn how to
talk to ham radio operators via satellite using a hand-held dual band
FM transceiver, or show your children how radio and computers working
together can make possible extremely low power two way contacts around
the world...
Now, let's try to update the backlog of questions sent to ASK ARNIE
during the past two weeks, when obviously many of you had a little more
time to relax and listen to the radio, or surf the web and read the
scripts of the program that are now available at several websites and
mailing lists... Today's question, sent by three listeners, one in
Canada, the other in Trinidad and Tobago and the third in Germany, they
all three say in their e-mail messages sent to arnie@xxxxxx
<mailto:arnie@xxxxxx> , that they want to know more about digital radio
broadcasting and how I see its future... So , here we go... First of all
digital radio broadcasting as we know it today provides listening to a
very small number of radio's worldwide audience... That's a fact that no
one can deny... Second: The existence of several different digital
broadcast technical standards is making a very negative impact in the
expansion of this new technology, and in the third place is the fact
that radio receivers for picking up digital broadcasts are still rather
expensive, and in many instances hard to find.
Digital broadcast technologies for local ground wave transmissions on
both the AM long wave and medium wave bands, and also on the VHF FM
bands, when received at a fixed site seem to work quite well now, and
the audio quality that can be implemented is as good as one may want.
But there are quite a few problems still to be solved when , for
example, digital radio signals are received in areas where , in the case
of AM medium wave broadcast band stations, the ground wave and the sky
wave combine with each other randomly to produce a very annoying signal
fading. Digital radio technology so far hasn't solved this problem, so
when you are located inside that critical reception area, your radio's
suddenly goes silent for certain short periods, a very annoying problem
to say the least.
Digital radio broadcasts on the FM band suffer from a similar problem
due to the so called multipath propagation , so when you are travelling
on a vehicle and listening to a digital station, you are likely to
experience the same annoying total drop outs in service.
Yes, of course, there are ways to go around this problem, but they will
require a totally different technology that will include a high degree
of redundancy into the digital streams, and a sophisticated receiver
that will actually do a lot o signal processing before sending the audio
to the loudspeakers or headphones !!!
Later in today's program, I'll tell you more about DRM, Digital Radio
Mondiale's efforts to broadcast using short waves, that so far have
proven to be a total failure.....
.....
Si amigos, 2007 is here now, and during the next 363 days we are going
to watch how solar activity continues to go down, taking us into solar
minimum... So be prepared for very poor HF propagation conditions that
will keep the bands above fifteen megahertz totally dead ...
Now here is , as requested by many listeners, more information about a
radio noise related topic... Those sending the request wanted to know if
it is true that the new high intensity light emitting diodes lamps are a
good replacement for the energy saving fluorescent electronic lamps that
generate so much radio frequency noise.
Well amigos, so far the high intensity light emitting diode lamps that I
have learned about seem to require the use of a certain number of those
devices in order to achieve enough light output, as technology has not
yet provided a large size light emitting diode , large enough to produce
a light output similar to even a small 5 Watt incandescent bulb... But,
let me say that I am still in doubt with the new high intensity light
emitting diode replacement lamps, because I haven't had the opportunity
of seeing how do they provide the low voltage required to operate the
LEDs... If the low voltage is obtained by means of a simple dropping
resistor and rectifier diodes combination, then the lamps will not
generate radio frequency noise, but if some type of radio frequency
oscillator is used, then they will cause interference to radio
reception, as is the case with the present day energy savers fluorescent
lamps that make radio reception so difficult wherever they are in use.
Been an experimentally minded person, as I am, during the long new
year's eve weekend I decided to do some experiments with light emitting
diodes that I were at hand. These are not the high intensity white light
diodes, but served well for my purpose of testing the way that they can
be supplied with the low direct current voltage required for their
operation. I ended up with two really nice cluster lamps, one made with
five red el e dees, and the other one made with five green ones...First
thing I learned during the experiment was that the green diodes require
a higher voltage to operate, and in second place was the fact that for
some reason it was better to feed the diodes with individual voltage
dropping resistors than placing them in series connection to use a
single voltage dropping resistor... Anyway, the experiments were a
success, but both lamps, the red and the green , had to be powered from
a four and a half to six volts direct current source, that could be
either three or four series connected batteries, or an AC power supply...
Now, I must wait for feedback from Dxers Unlimited listeners around the
world, to provide your own personal experiences with the high intensity
light emitting diodes lamps, in order to see if your results match with
my experiments here, and the reason for having to ask you for this
practical results is that so far I haven't been able to obtain some high
intensity white light emitting diodes ...
So , if you have already tested the new white light high intensity LED
lamps, please send the results of your noise tests to arnie@xxxxxx
<mailto:arnie@xxxxxx>, again its arnie@xxxxxx <mailto:arnie@xxxxxx> , so
that they can be shared with Dxers Unlimited's worldwide audience
amigos... And don't forget that if you can obtain enough of those
diodes, assembling your own lamp to replace the energy saving
fluorescent noise maker nearest to your radio is certainly going to be a
nice weekend project too...
.....
As promised, here are some comments about DRM , Digital Radio Mondiale
broadcasts of short wave and the problems they are causing to other
stations using the classic AM technology... According to the opinion of
a senior Cuban broadcast engineer that has observed several DRM
transmissions using sophisticated spectrum analysis hardware and
software,he is of the opinion that most of the time the excessive
bandwidth used by the DRM signals has to do with poorly adjusted
transmitters, mentioning that DRM's is a very demanding transmission
mode that requires an extremely linear transmitter, something that in
his opinion is not possible from older equipment forced to broadcasting
DRM signals....
And now amigos as always at the end of the program... here is Arnie
Coro's Dxers Unlimited's HF , plus low band VHF propagation update and
forecast...
Solar activity is now oscillating from very low to low,solar flux around
90 units, and a high speed six hundred kilometres per second solar wind
is causing some geomagnetic disturbances. The solar active sunspot
region that produced the big X flares during the previous rotation is
back now, but it has decayed, so only class C or an occasional class M
flares are expected. The winter sporadic E season is about to come to an
end now, as we move away from the winter solstice... Enjoy the radio
hobby amigo,and share
your experience with others by sending me your comments and questions to
arnie@xxxxxx <mailto:arnie@xxxxxx> or VIA AIR MAIL to Arnie Coro, Radio
Havana Cuba, Havana, Cub
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