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Re: [HCDX] Dxers Unlimited's script for 14 -15 August 2007
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s mid week edition for 14-15 August 2007
By Arnie Coro
Radio amateur CO2KK
Hi amigos radioaficionados, it’s nice to have you all listening to the
mid week edition of this radio program that is entirely, absolutely
devoted not to one specific aspect of the hobby, but to all the more
than 81 ways that you and I enjoy it! I am Arnie Coro, radio amateur
CO2KK , your host here in sunny Havana and here is today’s menu: If you
followed yours truly advice during our last several programs, I am sure
that you have enjoyed listening under excellent propagation conditions
late in the evening local time… Monday, after 0500 hours UTC I did a
band scan here, and was able to pick up very nice DX on the 40 meters
amateur band, clear signals on the CW segment, between 7000 and 7050
kilohertz, and even on the QRP spot frequencies where low power
enthusiasts gather to challenge operator’s skills while running
extremely low power transmitters, 7030 and 7040 kilohertz I was able to
pick up several stations … Then I moved up a bit to the 25 meters
international broadcast band, and sure enough ! several nice DX stations
from the Pacific Basin provided armchair copy too. So, again, whenever
your having a hard time falling asleep during the next several weeks,
remember that summer propagation conditions on the HF bands are much
better after local sunset, because during the daytime, ionospheric
thermal expansion sends the maximum useable frequency way down !!! And
by the way, very late in the evening listening or operating HF ham radio
equipment is also much better due to a general reduction in man made
noise !!
Item two: Sporadic E season is now coming to an end, and I am writing
this script at just after nine thirty in the morning local time, while
keeping my TV set tuned to channel 2, and my 6 meter band transceiver
tuned to 50.125 kilohertz , the calling frequency for the North America
and Caribbean regions… Monitoring the low band TV channels provides very
early warning of a Sporadic E event in progress… Item three: one of the
main topics among radio amateurs that live in areas that may be affected
by tropical storms is “Amateur radio operations during emergency
situations”, and Cuban amateurs that have had first hand experience
keeping communications operating even during the middle of a category
four hurricane that have proven to be very valuable for ham operators of
other nearby nations. Item four: Yes, I won’t forget of including ASK
ARNIE in every Dxers Unlimited that goes on the air, because, according
to your e-mail messages and letters, it is certainly the most popular
section of the program closely followed by Arnie Coro’s Dxers
Unlimited’s HF plus low band VHF propagation updates and forecast... If
time permits, I will also include today our tips and techniques section,
as it is becoming quite popular too...
Standby for more radio hobby related information, coming to you from Havana…
I’ll be back in just a few seconds after a brief musical intercut..
….
You are listening to Radio Havana Cuba, the name of the show is Dxers
Unlimited, and yes, we do encourage listener’s feedback, as a very
effective way of improving this program, send your comments, opinions,
and ideas on how to make Dxers Unlimited better directly to my computer
… send mail to arnie@xxxxxx <mailto:arnie@xxxxxx>, again, slowly and
phonetically, arnie@xxxxxx <mailto:arnie@xxxxxx>, and if you are not yet
in cyberspace, just drop me a postcard to Arnie Coro, Radio Havana Cuba,
Havana, Cuba.
Now here is ASK ARNIE… THE most popular section of this show. Today‘s
first question came from New York, USA.. listener Jonathan from Syracuse
wants to know if he can adapt a discarded cell phone for amateur radio
use. Well amigo Jonathan, thanks for a very nice question, as first,
second and third generation cell phones are now becoming an
environmental problem in many countries, as technology evolves into much
more sophisticated systems that require different cell phones to operate
with them. The only amateur radio band that is near to the older and
still in use cell phone band around 900 megaHertz is not authorized by
telecommunications administrations at a worldwide scale, as a matter of
fact, only a few countries authorize their amateur radio operators to
use the 900 megaHertz band, the one that is close enough to the first
cell phone band to make a conversion practical. According to what I have
seen inside discarded cell phone sets, the only possible approach for
converting them into ham radio transceivers for the 900 megaHertz band
is by means of software access to the programming of the cell phone set,
using the proper interphase that is often kept as a trade secret by the
cell phone manufacturers, but apparently some radio amateurs have
already achieved positive results with some specific types of older
technology cell phones…an indication that they had access to both the
interface and the software to reprogram the cell phones. By the way
amigo Randolph, a much easier conversion from new information and
communications technologies professional equipment to amateur radio
applications can be achieved with the so called WI-FI wireless
networking equipment, which can be easily adapted for ham radio use !!!
Question number two: Came from Sweden, where listener Bjorn is picking
up our 11760 kilohertz transmissions just after midnight his local time.
Olaf wants to know why it is possible to pick up Tropical Band stations
from Latin America at his QTH near Malmo, Sweden, with such good
signals, and he mentions picking up Radio Rebelde on 5025 kilohertz very
clearly after the station installed its new transmitter and antenna.
Well amigo Bjorn, Tropical Band signals will continue to propagate
better and better as solar activity continues to move down towards the
end of solar cycle 23. When solar flux figures between 70 and 80 units
prevail for many days, ionospheric absorption is at a minimum and that
will certainly help signals below 5 or 6 megaHertz propagate much
better. Another important factor regarding low frequency propagation is
the connection between geomagnetic latitude and signal attenuation,
something that has puzzled scientists for many years. So, now the bad
news for you up North, is that the expected increase in solar activity
will certainly spoil your reception of Tropical Band stations as soon as
the solar flux figure moves to a monthly average of more than 100 units
amigo !!! When old man Sol comes back into high activity, ionospheric
absorption will increase and Tropical Band signals will not propagate so
well during solar maximum years.
Question number three: This one came from Kansas, USA, listener Barry
ASK’s ARNIE about static electricity charging his antenna all the time,
and the problems associated with sudden sparks coming from the antenna
even when it’s disconnected… Well amigo Barry, here is my advice…
install a good ground system at your location, even a single ground rod
, well driven into the soil of the garden will work, and then buy a pair
of 10 kilo Ohms two watt carbon resistors and connect them between thee
antenna and ground… The 5 kilo Ohm effective resistance will
continuously drain the static electricity picked up by your antenna to
ground, saving your radio receiver’s front end solid state devices from
a quick death, caused by the static discharging trough the radio, as it
has unfortunately happened to you already… My advice is that you connect
the antenna to the radio only when you are using it, and at any signs of
even a far away thunderstorm or the presence of CUMULUS NIMBUS type of
storm clouds, disconnect the radio and start reading or assembling your
new homebrew radio project !!!
Static electricity discharging to ground trough your radio’s very
delicate solid state devices will burn them up, as many solid state
receiver users have learned the hard way. My latest HURRICANE TWO ham
radio transceiver, intended to operate during emergencies has a unique
front end protection, provided by the use of a vacuum tube radio
frequency amplifier stage, that is much more immune to static damages
than solid state transistors of any type.
Although the vacuum tube stage requires an additional 150 volts DC power
supply, the protection provided is well worth the additional components
required !!!
By the way amigos, don’t forget that we are now well into the summer
thunderstorm season, so it is always a very good practice to keep all
your radio and electronic equipment disconnected from the antennas,
ground systems and power line when they are not in use, and as I said a
while earlier, it is also extremely good practice to disconnect all
radio equipment whenever a thunderstorm is approaching !!!
….
TIPS and TECHNNIQUES is fast becoming popular among Dxers Unlimited’s
worldwide audience and cyber surfers that read my scripts via the
INTERNET… so, I am trying to include this section in almost every
program. Today’s tip : When you are going to use any radio equipment
connecting it to an automobile or truck electrical system as a power
source, STOP, STOP, STOP, before doing it, and build yourself or ask an
electronic hobbyist friend to assemble for you a well protected
interface… I have seen too many radios, handie talkies, cell phones and
CD portable players killed by connecting them directly to automotive
electric systems that may generate , under the worst case scenario
conditions, voltages as high as 17 or even 20 volts from alternators
that are not properly regulated… The typical automotive electric system
goes normally up to 15 or 16 volts to be able to charge the battery, so
any electronic device that is not properly protected against such high
voltage will simply be killed sooner or later by the over voltage
damage. Before connecting any radio or electronic equipment to a car,
truck, airplane or boat electric system run a very exhaustive check of
the system while it is operating and be sure that your equipment is
capable of handling the highest voltages that are generated by the
particular system. My practical solution to this problem for the typical
12 to 14 volts required by amateur radio equipment, is to assemble an
interface that provides both reverse polarity and over voltage
protection, and install such interface in the car, truck, mobile home,
boat or aircraft, so that the radios are always safe from both reverse
polarity connection and over voltage accidents !!!
And now amigos, as always at the end of the program, here is Arnie
Coro’s HF plus low band VHF propagation update and forecast… Solar flux
is moving at extremely low levels, the sunspot count on Tuesday was
ZERO, and the solar flux barely reaching 68 units, the Sun is spotless
at this moment. I expect that this very low solar activity will continue
right trough the present solar rotation. Sporadic E events are still
probable during the next 10 days, so be on the lookout for this unique
propagation mode that sends the maximum useable frequency curve shooting
up even as high as 150 megahertz at times !!!
See you all at the weekend edition of Dxers Unlimited amigos !!!And
don’t forget to send your signal reports and comments about the program
to arnie@xxxxxx <mailto:arnie@xxxxxx> or VIA AIR MAIL to Arnie Coro,
Radio Havana Cuba, Havana, Cuba.
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