Dxers Unlimited
Dxers Unlimited’s mid week edition for 22-23 May 2007
By Arnie Coro
Radio amateur CO2KK

Hi amigos radioaficionados , its 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 your’s 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 , just after 0500 hours UTC I did
a band scan, and was able to pick up very nice DX on the 20 meters
amateur band, clear signals on the CW segment, around 14060 kiloHertz,
the QRP spot frequency where low power enthusiasts gather to challenge
operator’s skills while running extremely low power transmitters… Then I
moved up a bit to the 19 meters international broadcast band, and sure
enough ! several nice DX stations 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 well under way, 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 an Sporadic E event in progress… 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@rhc.cu, again, slowly and phonetically,
arnie@rhc.cu, 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 Randolph wants to know
if he can adapt a discarded cellphone for amateur radio use. Well amigo
Randy, thanks for a very nice question, as first, second and third
generation cellphones are now becoming an environmental problem in many
countries, as technology evolves into much more sophisticated systems
that require different cellphones to operate with them. The only amateur
radio band that is near to the older and still in use cellphone 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
megaHert band, the one that is close enough to the first cellphone band
to make a conversion practical. According to what I have seen inside
discarded cellphone 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 cellphone set, and apparently
some radio amateurs have already achieved positive results with some
specific types of older technology cellphones… By the way amigo Randy, 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, that
can be easily adapted for ham radio use !!! Question number two: Came
>from Norway, where listener Olaf is picking up our 11760 kiloHertz
transmissions just after midnight his local time. Olaf wants to know why
is it possible to pick up Tropical Band stations from Latin America at
his QTH near Oslo 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 Olaf, 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,
the good news for you up North, is that lower solar activity will
improve your reception of Tropical Band stations for at least the next
year, according to the latest solar cycle forecasts. 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
asks ARNIE about static electricity charging his antenna all the time,
and the problems associated with sudden sparks coming from the antenna
even when its 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
kiloOHms two watt carbon resistors and connect them between the antenna
and ground… The 5 kiloOhm effective resistance will continuosly 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 THREE
single band 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 24 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 already 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 hobbyst friend to assemble for you a well protected
interface… I have seen too many radios, handie talkies, cellphones 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 overvoltage 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 overvoltage 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 overvoltage 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 down, and the Sun is exhibiting very few sunspots at this
moment, as a matter of fact , the number of sunspots has gone down
dramatically on Sunday and Monday… Solar flux is holding around 75 units
and solar activity will stay at very low levels according to latest
reports . The effective sunspot number is down to 13, and that’s the
number to use for making HF propagation forecasts if you happen to have
the software installed. Sporadic E events are highly 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 !!!Dont’t forget to send your signal reports and
comments about the program to arnie@rhc.cu, and YES I am able to receive
her also mp3 audio files with your recordings of Radio Havana Cuba as
heard at your QTH…
See you all at the weekend edition of Dxers Unlimited amigos !!!